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[Git][ghc/ghc][wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL] 42 commits: base: don't expose GHC.Num.{BigNat, Integer, Natural}
by Sven Tennie (＠supersven) 24 Jan '26

24 Jan '26

Sven Tennie pushed to branch wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL at Glasgow Haskell Compiler / GHC Commits: 30f442a9 by Teo Camarasu at 2026-01-20T13:57:26-05:00 base: don't expose GHC.Num.{BigNat, Integer, Natural} We no longer expose GHC.Num.{BigNat, Integer, Natural} from base instead users should get these modules from ghc-bignum. We make this change to insulate end users from changes to GHC's implementation of big numbers. Implements CLC proposal 359: https://github.com/haskell/core-libraries-committee/issues/359 - - - - - 75a9053d by Teo Camarasu at 2026-01-20T13:58:07-05:00 base: deprecate GHC internals in GHC.Num Implements CLC proposal: https://github.com/haskell/core-libraries-committee/issues/360 - - - - - 9534b032 by Andreas Klebinger at 2026-01-20T13:58:50-05:00 ghc-experimental: Update Changelog I tried to reconstruct a high level overview of the changes and when they were made since we introduced it. Fixes #26506 Co-authored-by: Teo Camarasu <teofilcamarasu(a)gmail.com> - - - - - 346f2f5a by Cheng Shao at 2026-01-20T13:59:30-05:00 hadrian: remove RTS options in ghc-in-ghci flavour This patch removes the RTS options passed to ghc in ghc-in-ghci flavour, to workaround command line argument handling issue in hls/hie-boot that results in `-O64M` instead of `+RTS -O64M -RTS` being passed to ghc. It's not a hadrian bug per se, since ghc's own ghc-in-ghci multi repl works fine, but we should still make sure HLS works. Closes #26801. - - - - - 759fd15a by Andreas Klebinger at 2026-01-21T16:05:28-05:00 Don't build GHC with -Wcompat Without bumping the boot compiler the warnings it produces are often not actionable leading to pointless noise. Fixes #26800 - - - - - 3172db94 by Torsten Schmits at 2026-01-21T16:06:11-05:00 Use the correct field of ModOrigin when formatting error message listing hidden reexports - - - - - 485c12b2 by Cheng Shao at 2026-01-21T16:06:54-05:00 Revert "hadrian: handle findExecutable "" gracefully" This reverts commit 1e5752f64a522c4025365856d92f78073a7b3bba. The underlying issue has been fixed in https://github.com/haskell/directory/commit/75828696e7145adc09179111a0d631b… and present since 1.3.9.0, and hadrian directory lower bound is 1.3.9.0, so we can revert our own in house hack now. - - - - - 5efb58dc by Cheng Shao at 2026-01-21T16:07:36-05:00 rts: fix typo in TICK_ALLOC_RTS This patch fixes a typo in the `TICK_ALLOC_RTS` macro, the original `bytes` argument was silently dropped. The Cmm code has its own version of `TICK_ALLOC_RTS` not affected by this typo, it affected the C RTS, and went unnoticed because the variable `n` happened to also be available at its call site. But the number was incorrect. Also fixes its call site since `WDS()` is not available in C. - - - - - c406ea69 by Cheng Shao at 2026-01-21T16:07:36-05:00 rts: remove broken & unused ALLOC_P_TICKY This patch removes the `ALLOC_P_TICKY` macro from the rts, it's unused, and its expanded code is already broken. - - - - - 34a27e20 by Simon Peyton Jones at 2026-01-21T16:08:17-05:00 Make the implicit-parameter class have representational role This MR addresses #26737, by making the built-in class IP have a representational role for its second parameter. See Note [IP: implicit parameter class] in ghc-internal:GHC.Internal.Classes.IP In fact, IP is (unfortunately, currently) exposed by base:GHC.Base, so we ran a quick CLC proposal to agree the change: https://github.com/haskell/core-libraries-committee/issues/385 Some (small) compilations get faster because they only need to load (small) interface file GHC.Internal.Classes.IP.hi, rather than (large) GHC.Internal.Classes.hi. Metric Decrease: T10421 T12150 T12425 T24582 T5837 T5030 - - - - - ca79475f by Cheng Shao at 2026-01-21T16:09:00-05:00 testsuite: avoid re.sub in favor of simple string replacements This patch refactors the testsuite driver and avoids the usage of re.sub in favor of simple string replacements when possible. The changes are not comprehensive, and there are still a lot of re.sub usages lingering around the tree, but this already addresses a major performance bottleneck in the testsuite driver that might has to do with quadratic or worse slowdown in cpython's regular expression engine when handling certain regex patterns with large strings. Especially on i386, and i386 jobs are the bottlenecks of all full-ci validate pipelines! Here are the elapsed times of testing x86_64/i386 with -j48 before this patch: x86_64: `Build completed in 6m06s` i386: `Build completed in 1h36m` And with this patch: x86_64: `Build completed in 4m55s` i386: `Build completed in 4m23s` Fixes #26786. Co-authored-by: Codex <codex(a)openai.com> - - - - - 88c93796 by Zubin Duggal at 2026-01-21T16:09:42-05:00 ghc-toolchain: Also configure windres on non-windows platforms. It may be needed for cross compilation. Fixes #24588 - - - - - 9788c0ec by Cheng Shao at 2026-01-21T16:10:24-05:00 ghci: print external interpreter trace messages to stderr instead of stdout This patch makes ghci print external interpreter trace messages to stderr instead of stdout, which is a much saner choice for diagnostic information. Closes #26807. - - - - - 0491f08a by Sylvain Henry at 2026-01-22T03:44:26-05:00 GC: don't use CAS without PARALLEL_GC on If we're not using the parallel GC, there is no reason to do a costly CAS. This was flagged as taking time in a perf profile. - - - - - 211a8f56 by Sylvain Henry at 2026-01-22T03:44:26-05:00 GC: suffix parallel GC with "par" instead of "thr" Avoid some potential confusion (see discussion in !15351). - - - - - 77a23cbd by fendor at 2026-01-22T03:45:08-05:00 Remove blanket ignore that covers libraries/ - - - - - 18bf7f5c by Léana Jiang at 2026-01-22T08:58:45-05:00 doc: update Flavour type in hadrian user-settings - - - - - 3d5a1365 by Cheng Shao at 2026-01-22T08:59:28-05:00 hadrian: add missing notCross predicate for stage0 -O0 There are a few hard-coded hadrian args that pass -O0 when compiling some heavy modules in stage0, which only makes sense when not cross-compiling and when cross-compiling we need properly optimized stage0 packages. So this patch adds the missing `notCross` predicate in those places. - - - - - ee937134 by Matthew Pickering at 2026-01-22T09:00:10-05:00 Fix ghc-experimental GHC.Exception.Backtrace.Experimental module This module wasn't added to the cabal file so it was never compiled or included in the library. - - - - - 1b490f5a by Zubin Duggal at 2026-01-22T09:00:53-05:00 hadrian: Add ghc-{experimental,internal}.cabal to the list of dependencies of the doc target We need these files to detect the version of these libraries Fixes #26738 - - - - - cdb74049 by Cheng Shao at 2026-01-22T14:52:36-05:00 rts: avoid Cmm loop to initialize Array#/SmallArray# Previously, `newArray#`/`newSmallArray#` called an RTS C function to allocate the `Array#`/`SmallArray#`, then used a Cmm loop to initialize the elements. Cmm doesn't have native for-loop so the code is a bit awkward, and it's less efficient than a C loop, since the C compiler can effectively vectorize the loop with optimizations. So this patch moves the loop that initializes the elements to the C side. `allocateMutArrPtrs`/`allocateSmallMutArrPtrs` now takes a new `init` argument and initializes the elements if `init` is non-NULL. - - - - - 4c784f00 by Cheng Shao at 2026-01-22T14:53:19-05:00 Fix testsuite run for +ipe flavour transformer This patch makes the +ipe flavour transformer pass the entire testsuite: - An RTS debug option `-DI` is added, the IPE trace information is now only printed with `-DI`. The test cases that do require IPE trace are now run with `-DI`. - The testsuite config option `ghc_with_ipe` is added, enabled when running the testsuite with `+ipe`, which skips a few tests that are sensitive to eventlog output, allocation patterns etc that can fail under `+ipe`. This is the first step towards #26799. Co-authored-by: Codex <codex(a)openai.com> - - - - - be8e5236 by Ben Gamari at 2026-01-23T03:28:45-05:00 hadrian: Bump QuickCheck upper bound This patch bumps QuickCheck upper bound to 2.18. selftest rule manually tested to work with current latest QuickCheck-2.17.1.0. - - - - - 5aa328fb by Zubin Duggal at 2026-01-23T03:29:30-05:00 Add genindex to index.rst. This adds a link to the index in the navigation bar. Fixes #26437 - - - - - 917ab8ff by Oleg Grenrus at 2026-01-23T10:52:55-05:00 Export labelThread from Control.Concurrent - - - - - 3f5e8d80 by Cheng Shao at 2026-01-23T10:53:37-05:00 ci: only push perf notes on master/release branches This patch fixes push_perf_notes logic in ci.sh to only push perf notes on master/release branches. We used to unconditionally push perf notes even in MRs, but the perf numbers in the wip branches wouldn't be used as baseline anyway, plus this is causing a space leak in the ghc-performance-notes repo. See #25317 for the perf notes repo size problem. Co-authored-by: Codex <codex(a)openai.com> - - - - - ad6a866f by Matthew Pickering at 2026-01-24T13:04:41+01:00 Add missing req_interp modifier to T18441fail3 and T18441fail19 These tests require the interpreter but they were failing in a different way with the javascript backend because the interpreter was disabled and stderr is ignored by the test. - - - - - cff3b64a by Matthew Pickering at 2026-01-24T13:04:41+01:00 Use explicit syntax rather than pure - - - - - 89b99ec9 by Matthew Pickering at 2026-01-24T13:04:41+01:00 packaging: correctly propagate build/host/target to bindist configure script At the moment the host and target which we will produce a compiler for is fixed at the initial configure time. Therefore we need to persist the choice made at this time into the installation bindist as well so we look for the right tools, with the right prefixes at install time. In the future, we want to provide a bit more control about what kind of bindist we produce so the logic about what the host/target will have to be written by hadrian rather than persisted by the configure script. In particular with cross compilers we want to either build a normal stage 2 cross bindist or a stage 3 bindist, which creates a bindist which has a native compiler for the target platform. Fixes #21970 - - - - - 74884e43 by Matthew Pickering at 2026-01-24T13:04:41+01:00 hadrian: Fill in more of the default.host toolchain file When you are building a cross compiler this file will be used to build stage1 and it's libraries, so we need enough information here to work accurately. There is still more work to be done (see for example, word size is still fixed). - - - - - 51d74191 by Matthew Pickering at 2026-01-24T13:04:41+01:00 hadrian: Disable docs when cross compiling Before there were a variety of ad-hoc places where doc building was disabled when cross compiling. * Some CI jobs sets --docs=none in gen_ci.hs * Some CI jobs set --docs=none in .gitlab/ci.sh * There was some logic in hadrian to not need the ["docs"] target when making a bindist. Now the situation is simple: * If you are cross compiling then defaultDocsTargets is empty by default. In theory, there is no reason why we can't build documentation for cross compiler bindists, but this is left to future work to generalise the documentation building rules to allow this (#24289) - - - - - 683805fa by Matthew Pickering at 2026-01-24T13:12:23+01:00 hadrian: Build stage 2 cross compilers * Most of hadrian is abstracted over the stage in order to remove the assumption that the target of all stages is the same platform. This allows the RTS to be built for two different targets for example. * Abstracts the bindist creation logic to allow building either normal or cross bindists. Normal bindists use stage 1 libraries and a stage 2 compiler. Cross bindists use stage 2 libararies and a stage 2 compiler. * hadrian: Make binary-dist-dir the default build target. This allows us to have the logic in one place about which libraries/stages to build with cross compilers. Fixes #24192 New hadrian target: * `binary-dist-dir-cross`: Build a cross compiler bindist (compiler = stage 1, libraries = stage 2) This commit also contains various changes to make stage2 compilers feasible. ------------------------- Metric Decrease: ManyAlternatives MultiComponentModulesRecomp MultiLayerModulesRecomp T10421 T12425 T12707 T13035 T13379 T15703 T16577 T18698a T18698b T18923 T1969 T21839c T3294 T4801 T5030 T5321Fun T5642 T783 T9198 T9872d T9961 parsing001 T5321FD T6048 T12227 T18140 T18282 T9233 ------------------------- Co-authored-by: Sven Tennie <sven.tennie(a)gmail.com> Fix rebase: settings-use-distro-mingw is now staged - - - - - e94ce6d8 by Matthew Pickering at 2026-01-24T13:12:23+01:00 ci: Test cross bindists We remove the special logic for testing in-tree cross compilers and instead test cross compiler bindists, like we do for all other platforms. - - - - - 938984ed by Matthew Pickering at 2026-01-24T13:12:23+01:00 ci: Introduce CROSS_STAGE variable In preparation for building and testing stage3 bindists we introduce the CROSS_STAGE variable which is used by a CI job to determine what kind of bindist the CI job should produce. At the moment we are only using CROSS_STAGE=2 but in the future we will have some jobs which set CROSS_STAGE=3 to produce native bindists for a target, but produced by a cross compiler, which can be tested on by another CI job on the native platform. CROSS_STAGE=2: Build a normal cross compiler bindist CROSS_STAGE=3: Build a stage 3 bindist, one which is a native compiler and library for the target - - - - - cbb70ab9 by Matthew Pickering at 2026-01-24T13:12:23+01:00 hadrian: Refactor system-cxx-std-lib rules0 I noticed a few things wrong with the hadrian rules for `system-cxx-std-lib` rules. * For `text` there is an ad-hoc check to depend on `system-cxx-std-lib` outside of `configurePackage`. * The `system-cxx-std-lib` dependency is not read from cabal files. * Recache is not called on the packge database after the `.conf` file is generated, a more natural place for this rule is `registerRules`. Treating this uniformly like other packages is complicated by it not having any source code or a cabal file. However we can do a bit better by reporting the dependency firstly in `PackageData` and then needing the `.conf` file in the same place as every other package in `configurePackage`. Fixes #25303 - - - - - 3f2c109c by Sven Tennie at 2026-01-24T13:12:23+01:00 ci: Increase timeout for emulators Test runs with emulators naturally take longer than on native machines. Generate jobs.yml - - - - - 6d150122 by Sven Tennie at 2026-01-24T13:12:23+01:00 ghc: Distinguish between having an interpreter and having an internal one Otherwise, we fail with warnings when compiling tools. Actually, these are related but different things: - ghc can run an interpreter (either internal or external) - ghc is compiled with an internal interpreter - - - - - de085b96 by Matthew Pickering at 2026-01-24T13:12:23+01:00 ci: Javascript don't set CROSS_EMULATOR There is no CROSS_EMULATOR needed to run javascript binaries, so we don't set the CROSS_EMULATOR to some dummy value. - - - - - a5ef0073 by Sven Tennie at 2026-01-24T13:12:23+01:00 Javascript skip T23697 See #22355 about how HSC2HS and the Javascript target don't play well together. - - - - - 9b1ddd73 by Sven Tennie at 2026-01-24T13:12:23+01:00 Mark T24602 as fragile It was skipped before (due to CROSS_EMULATOR being set, which changed for JS), so we don't make things worse by marking it as fragile. - - - - - e5280690 by Sven Tennie at 2026-01-24T13:12:23+01:00 Windows needs NM_STAGE0 as well The stage0 always needs nm. - - - - - 7a499f6a by Sven Tennie at 2026-01-24T13:12:23+01:00 T17912 sometimes works for windows-validate This seems to be timing related. However, just simply increasing the timeout (sleep) statement of this test didn't help. Maybe, it has been flaky on CI before. - - - - - 142 changed files: - .gitignore - .gitlab/ci.sh - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - compiler/GHC/Builtin/Names.hs - compiler/GHC/Unit/State.hs - compiler/ghc.cabal.in - configure.ac - distrib/configure.ac.in - docs/users_guide/9.16.1-notes.rst - docs/users_guide/index.rst - docs/users_guide/runtime_control.rst - ghc/GHC/Driver/Session/Mode.hs - ghc/GHCi/UI.hs - ghc/Main.hs - ghc/ghc-bin.cabal.in - hadrian/README.md - hadrian/bindist/config.mk.in - hadrian/cfg/default.host.target.in - + hadrian/cfg/system.config.host.in - hadrian/cfg/system.config.in - + hadrian/cfg/system.config.target.in - hadrian/doc/user-settings.md - hadrian/hadrian.cabal - hadrian/src/Base.hs - + hadrian/src/BindistConfig.hs - hadrian/src/Builder.hs - hadrian/src/Context.hs - hadrian/src/Expression.hs - hadrian/src/Flavour.hs - hadrian/src/Flavour/Type.hs - hadrian/src/Hadrian/Builder.hs - hadrian/src/Hadrian/Haskell/Cabal/Parse.hs - hadrian/src/Hadrian/Haskell/Cabal/Type.hs - hadrian/src/Hadrian/Haskell/Hash.hs - hadrian/src/Hadrian/Oracles/TextFile.hs - hadrian/src/Hadrian/Utilities.hs - hadrian/src/Oracles/Flag.hs - hadrian/src/Oracles/Flavour.hs - hadrian/src/Oracles/Setting.hs - hadrian/src/Oracles/TestSettings.hs - hadrian/src/Packages.hs - hadrian/src/Rules.hs - hadrian/src/Rules/BinaryDist.hs - hadrian/src/Rules/CabalReinstall.hs - hadrian/src/Rules/Compile.hs - hadrian/src/Rules/Docspec.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Generate.hs - hadrian/src/Rules/Gmp.hs - + hadrian/src/Rules/Libffi.hs - hadrian/src/Rules/Library.hs - hadrian/src/Rules/Lint.hs - hadrian/src/Rules/Program.hs - hadrian/src/Rules/Register.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings.hs - hadrian/src/Settings/Builders/Cabal.hs - hadrian/src/Settings/Builders/Common.hs - hadrian/src/Settings/Builders/Configure.hs - hadrian/src/Settings/Builders/DeriveConstants.hs - hadrian/src/Settings/Builders/Ghc.hs - hadrian/src/Settings/Builders/Hsc2Hs.hs - hadrian/src/Settings/Builders/RunTest.hs - hadrian/src/Settings/Builders/SplitSections.hs - hadrian/src/Settings/Default.hs - hadrian/src/Settings/Flavours/Benchmark.hs - hadrian/src/Settings/Flavours/Development.hs - hadrian/src/Settings/Flavours/GhcInGhci.hs - hadrian/src/Settings/Flavours/Performance.hs - hadrian/src/Settings/Flavours/Quick.hs - hadrian/src/Settings/Flavours/QuickCross.hs - hadrian/src/Settings/Flavours/Quickest.hs - hadrian/src/Settings/Flavours/Validate.hs - hadrian/src/Settings/Packages.hs - hadrian/src/Settings/Program.hs - hadrian/src/Settings/Warnings.hs - libraries/base/base.cabal.in - libraries/base/changelog.md - libraries/base/src/Control/Concurrent.hs - libraries/base/src/Data/Array/Byte.hs - libraries/base/src/GHC/Num.hs - − libraries/base/src/GHC/Num/BigNat.hs - − libraries/base/src/GHC/Num/Integer.hs - − libraries/base/src/GHC/Num/Natural.hs - libraries/base/src/System/CPUTime/Utils.hs - libraries/base/src/System/Timeout.hs - libraries/base/tests/IO/all.T - libraries/base/tests/all.T - libraries/ghc-bignum/ghc-bignum.cabal - libraries/ghc-compact/tests/all.T - libraries/ghc-experimental/CHANGELOG.md - libraries/ghc-experimental/ghc-experimental.cabal.in - libraries/ghc-experimental/src/GHC/Exception/Backtrace/Experimental.hs - libraries/ghc-experimental/src/GHC/TypeNats/Experimental.hs - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/src/GHC/Internal/Classes.hs - + libraries/ghc-internal/src/GHC/Internal/Classes/IP.hs - libraries/ghc-internal/tests/backtraces/all.T - libraries/ghci/GHCi/Server.hs - m4/fp_find_nm.m4 - m4/fptools_set_platform_vars.m4 - m4/prep_target_file.m4 - rts/AllocArray.c - rts/AllocArray.h - rts/ClosureTable.c - rts/Heap.c - rts/PrimOps.cmm - rts/RtsFlags.c - rts/Threads.c - rts/Trace.c - rts/Weak.c - rts/include/Cmm.h - rts/include/rts/Flags.h - rts/include/stg/Ticky.h - rts/rts.cabal - rts/sm/Evac.c - rts/sm/Evac_thr.c → rts/sm/Evac_par.c - rts/sm/Scav_thr.c → rts/sm/Scav_par.c - rts/sm/Storage.c - testsuite/driver/runtests.py - testsuite/driver/testglobals.py - testsuite/driver/testlib.py - testsuite/driver/testutil.py - testsuite/ghc-config/ghc-config.hs - testsuite/tests/ghc-e/should_fail/all.T - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - testsuite/tests/interface-stability/ghc-experimental-exports.stdout - testsuite/tests/interface-stability/ghc-experimental-exports.stdout-mingw32 - testsuite/tests/interface-stability/ghc-prim-exports.stdout - testsuite/tests/interface-stability/ghc-prim-exports.stdout-mingw32 - testsuite/tests/javascript/closure/all.T - testsuite/tests/rts/Makefile - testsuite/tests/rts/all.T - testsuite/tests/rts/ipe/all.T - testsuite/tests/th/TH_implicitParams.stdout - + testsuite/tests/typecheck/should_compile/T26737.hs - testsuite/tests/typecheck/should_compile/all.T - utils/ghc-toolchain/exe/Main.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/e0424e2d8596d2d2ebf2856372714b… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/e0424e2d8596d2d2ebf2856372714b… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][master] ci: remove duplicate keys in .gitlab-ci.yml
by Marge Bot (＠marge-bot) 24 Jan '26

24 Jan '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 414b9593 by Cheng Shao at 2026-01-24T07:11:51-05:00 ci: remove duplicate keys in .gitlab-ci.yml This patch removes accidentally duplicate keys in `.gitlab-ci.yml`. The YAML spec doesn't allow duplicate keys in the first place, and according to GitLab docs (https://docs.gitlab.com/ci/yaml/yaml_optimization/#anchors) the latest key overrides the earlier entries. - - - - - 1 changed file: - .gitlab-ci.yml Changes: ===================================== .gitlab-ci.yml ===================================== @@ -1050,10 +1050,6 @@ abi-test: optional: true dependencies: null image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-fedora43:$DOCKER_REV" - rules: - - if: $CI_MERGE_REQUEST_ID - - if: '$CI_COMMIT_BRANCH == "master"' - - if: '$CI_COMMIT_BRANCH =~ /ghc-[0.9]+\.[0-9]+/' tags: - x86_64-linux script: View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/414b9593406e2b37cb7f403245ed3d8… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/414b9593406e2b37cb7f403245ed3d8… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/jeltsch/obtaining-os-handles] 3 commits: Export labelThread from Control.Concurrent
by Wolfgang Jeltsch (＠jeltsch) 24 Jan '26

24 Jan '26

Wolfgang Jeltsch pushed to branch wip/jeltsch/obtaining-os-handles at Glasgow Haskell Compiler / GHC Commits: 917ab8ff by Oleg Grenrus at 2026-01-23T10:52:55-05:00 Export labelThread from Control.Concurrent - - - - - 3f5e8d80 by Cheng Shao at 2026-01-23T10:53:37-05:00 ci: only push perf notes on master/release branches This patch fixes push_perf_notes logic in ci.sh to only push perf notes on master/release branches. We used to unconditionally push perf notes even in MRs, but the perf numbers in the wip branches wouldn't be used as baseline anyway, plus this is causing a space leak in the ghc-performance-notes repo. See #25317 for the perf notes repo size problem. Co-authored-by: Codex <codex(a)openai.com> - - - - - 30e249fe by Wolfgang Jeltsch at 2026-01-24T10:27:27+02:00 Add operations for obtaining operating-system handles This contribution implements CLC proposal #369. It adds operations for obtaining POSIX file descriptors and Windows handles that underlie Haskell handles. Those operating system handles can also be obtained without such additional operations, but this is more involved and, more importantly, requires using internals. - - - - - 25 changed files: - .gitlab/ci.sh - libraries/base/base.cabal.in - libraries/base/changelog.md - libraries/base/src/Control/Concurrent.hs - + libraries/base/src/System/IO/OS.hs - libraries/base/src/System/Timeout.hs - libraries/base/tests/IO/all.T - + libraries/base/tests/IO/osHandles001FileDescriptors.hs - + libraries/base/tests/IO/osHandles001FileDescriptors.stdout - + libraries/base/tests/IO/osHandles001WindowsHandles.hs - + libraries/base/tests/IO/osHandles001WindowsHandles.stdout - + libraries/base/tests/IO/osHandles002FileDescriptors.hs - + libraries/base/tests/IO/osHandles002FileDescriptors.stderr - + libraries/base/tests/IO/osHandles002FileDescriptors.stdin - + libraries/base/tests/IO/osHandles002FileDescriptors.stdout - + libraries/base/tests/IO/osHandles002WindowsHandles.hs - + libraries/base/tests/IO/osHandles002WindowsHandles.stderr - + libraries/base/tests/IO/osHandles002WindowsHandles.stdin - + libraries/base/tests/IO/osHandles002WindowsHandles.stdout - libraries/ghc-internal/ghc-internal.cabal.in - + libraries/ghc-internal/src/GHC/Internal/System/IO/OS.hs - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 Changes: ===================================== .gitlab/ci.sh ===================================== @@ -493,6 +493,11 @@ function fetch_perf_notes() { } function push_perf_notes() { + if [[ "${CI_COMMIT_BRANCH:-}" != "master" ]] && [[ ! "${CI_COMMIT_BRANCH:-}" =~ ghc-[0-9]+\.[0-9]+ ]]; then + info "Perf notes are only pushed on master/release branches" + return + fi + if [[ -z "${TEST_ENV:-}" ]]; then return fi ===================================== libraries/base/base.cabal.in ===================================== @@ -255,6 +255,7 @@ Library , System.Exit , System.IO , System.IO.Error + , System.IO.OS , System.Mem , System.Mem.StableName , System.Posix.Internals ===================================== libraries/base/changelog.md ===================================== @@ -22,6 +22,8 @@ * `GHC.Conc.throwSTM` and `GHC.Conc.Sync.throwSTM` now carry a `HasCallStack` constraint and attach a `Backtrace` annotation to the thrown exception. ([GHC #25365](https://gitlab.haskell.org/ghc/ghc/-/issues/25365)) * `GHC.Conc.catchSTM` and `GHC.Conc.Sync.catchSTM` now attach `WhileHandling` annotation to exceptions thrown from the handler. ([GHC #25365](https://gitlab.haskell.org/ghc/ghc/-/issues/25365)) * Remove `GHC.JS.Prim.Internal.Build`, as per [CLC #329](https://github.com/haskell/core-libraries-committee/issues/329) + * Export `labelThread` from `Control.Concurrent`.([CLC proposal #376](https://github.com/haskell/core-libraries-committee/issues/376)) + * Add a new module `System.IO.OS` with operations for obtaining operating-system handles (file descriptors, Windows handles). ([CLC proposal #369](https://github.com/haskell/core-libraries-committee/issues/369)) ## 4.22.0.0 *TBA* * Shipped with GHC 9.14.1 ===================================== libraries/base/src/Control/Concurrent.hs ===================================== @@ -82,6 +82,9 @@ module Control.Concurrent ( -- * Weak references to ThreadIds mkWeakThreadId, + -- * Thread debugging + labelThread, + -- * GHC's implementation of concurrency -- |This section describes features specific to GHC's ===================================== libraries/base/src/System/IO/OS.hs ===================================== @@ -0,0 +1,62 @@ +{-# LANGUAGE Safe #-} + +{-| + This module bridges between Haskell handles and underlying operating-system + features. +-} +module System.IO.OS +( + -- * Obtaining file descriptors and Windows handles + withFileDescriptorReadingBiased, + withFileDescriptorWritingBiased, + withWindowsHandleReadingBiased, + withWindowsHandleWritingBiased, + withFileDescriptorReadingBiasedRaw, + withFileDescriptorWritingBiasedRaw, + withWindowsHandleReadingBiasedRaw, + withWindowsHandleWritingBiasedRaw + + -- ** Caveats + -- $with-ref-caveats +) +where + +import GHC.Internal.System.IO.OS + ( + withFileDescriptorReadingBiased, + withFileDescriptorWritingBiased, + withWindowsHandleReadingBiased, + withWindowsHandleWritingBiased, + withFileDescriptorReadingBiasedRaw, + withFileDescriptorWritingBiasedRaw, + withWindowsHandleReadingBiasedRaw, + withWindowsHandleWritingBiasedRaw + ) + +-- ** Caveats + +{-$with-ref-caveats + #with-ref-caveats#There are the following caveats regarding the above + operations: + + * Flushing of buffers can fail if the given handle is readable but not + seekable. + + * If one of these operations is performed as part of an action executed by + 'System.IO.Unsafe.unsafePerformIO', + 'System.IO.Unsafe.unsafeInterleaveIO', or one of their “dupable” + variants and the user-provided action receives an asychnchronous + exception and does not catch it, then the following happens: + + - Before the overall computation is suspended, the blocking of handle + operations is removed. + + - When the computation is later resumed due to another evaluation + attempt, the blocking of handle operations is reinstantiated, the + Haskell-managed buffers are flushed again, and the user-provided + action is run from the beginning. + + Repeating the previously executed part of the user-provided action + cannot be avoided apparently. See the @[async]@ note in the source code + of "GHC.Internal.IO.Handle.Internals" for further explanation. +-} ===================================== libraries/base/src/System/Timeout.hs ===================================== @@ -29,7 +29,6 @@ import GHC.Internal.Control.Exception (Exception(..), handleJust, bracket, asyncExceptionToException, asyncExceptionFromException) import GHC.Internal.Data.Unique (Unique, newUnique) -import GHC.Conc (labelThread) import Prelude -- $setup ===================================== libraries/base/tests/IO/all.T ===================================== @@ -186,3 +186,15 @@ test('T17912', [only_ways(['threaded1']), when(opsys('mingw32'),expect_broken(1) test('T18832', only_ways(['threaded1']), compile_and_run, ['']) test('mkdirExists', [exit_code(1), when(opsys('mingw32'), ignore_stderr)], compile_and_run, ['']) + +test('osHandles001FileDescriptors', omit_ways(['winio', 'winio_threaded']), compile_and_run, ['']) +test('osHandles001WindowsHandles', only_ways(['winio', 'winio_threaded']), compile_and_run, ['']) +test('osHandles002FileDescriptors', when(opsys('mingw32'), skip), compile_and_run, ['']) +test('osHandles002WindowsHandles', only_ways(['winio', 'winio_threaded']), compile_and_run, ['']) +# It would be good to let `osHandles002FileDescriptors` run also on +# Windows with the file-descriptor-based I/O manager. However, this +# test, as it is currently implemented, requires the `unix` package. +# That said, `UCRT.DLL`, which is used by GHC-generated Windows +# executables, emulates part of POSIX, enough for this test. As a +# result, this test could be generalized to also supporting Windows, but +# this would likely involve creating bindings to C code. ===================================== libraries/base/tests/IO/osHandles001FileDescriptors.hs ===================================== @@ -0,0 +1,23 @@ +{-# LANGUAGE TypeApplications #-} + +import Control.Monad (mapM_) +import Control.Exception (SomeException, try) +import System.IO (stdin, stdout, stderr) +import System.IO.OS + ( + withFileDescriptorReadingBiasedRaw, + withFileDescriptorWritingBiasedRaw, + withWindowsHandleReadingBiasedRaw, + withWindowsHandleWritingBiasedRaw + ) + +main :: IO () +main = mapM_ ((>>= print) . try @SomeException) $ + [ + withFileDescriptorReadingBiasedRaw stdin (return . show), + withFileDescriptorWritingBiasedRaw stdout (return . show), + withFileDescriptorWritingBiasedRaw stderr (return . show), + withWindowsHandleReadingBiasedRaw stdin (return . const "_"), + withWindowsHandleWritingBiasedRaw stdout (return . const "_"), + withWindowsHandleWritingBiasedRaw stderr (return . const "_") + ] ===================================== libraries/base/tests/IO/osHandles001FileDescriptors.stdout ===================================== @@ -0,0 +1,6 @@ +Right "0" +Right "1" +Right "2" +Left <stdin>: withWindowsHandleReadingBiasedRaw: inappropriate type (handle does not use Windows handles) +Left <stdout>: withWindowsHandleWritingBiasedRaw: inappropriate type (handle does not use Windows handles) +Left <stderr>: withWindowsHandleWritingBiasedRaw: inappropriate type (handle does not use Windows handles) ===================================== libraries/base/tests/IO/osHandles001WindowsHandles.hs ===================================== @@ -0,0 +1,23 @@ +{-# LANGUAGE TypeApplications #-} + +import Control.Monad (mapM_) +import Control.Exception (SomeException, try) +import System.IO (stdin, stdout, stderr) +import System.IO.OS + ( + withFileDescriptorReadingBiasedRaw, + withFileDescriptorWritingBiasedRaw, + withWindowsHandleReadingBiasedRaw, + withWindowsHandleWritingBiasedRaw + ) + +main :: IO () +main = mapM_ ((>>= print) . try @SomeException) $ + [ + withFileDescriptorReadingBiasedRaw stdin (return . show), + withFileDescriptorWritingBiasedRaw stdout (return . show), + withFileDescriptorWritingBiasedRaw stderr (return . show), + withWindowsHandleReadingBiasedRaw stdin (return . const "_"), + withWindowsHandleWritingBiasedRaw stdout (return . const "_"), + withWindowsHandleWritingBiasedRaw stderr (return . const "_") + ] ===================================== libraries/base/tests/IO/osHandles001WindowsHandles.stdout ===================================== @@ -0,0 +1,6 @@ +Left <stdin>: withFileDescriptorReadingBiasedRaw: inappropriate type (handle does not use file descriptors) +Left <stdout>: withFileDescriptorWritingBiasedRaw: inappropriate type (handle does not use file descriptors) +Left <stderr>: withFileDescriptorWritingBiasedRaw: inappropriate type (handle does not use file descriptors) +Right "_" +Right "_" +Right "_" ===================================== libraries/base/tests/IO/osHandles002FileDescriptors.hs ===================================== @@ -0,0 +1,28 @@ +import Data.Functor (void) +import Data.ByteString.Char8 (pack) +import System.Posix.Types (Fd (Fd), ByteCount) +import System.Posix.IO.ByteString (fdRead, fdWrite) +import System.IO (stdin, stdout, stderr) +import System.IO.OS + ( + withFileDescriptorReadingBiased, + withFileDescriptorWritingBiased + ) + +main :: IO () +main = withFileDescriptorReadingBiased stdin $ \ stdinFD -> + withFileDescriptorWritingBiased stdout $ \ stdoutFD -> + withFileDescriptorWritingBiased stderr $ \ stderrFD -> + do + regularMsg <- fdRead (Fd stdinFD) inputSizeApproximation + void $ fdWrite (Fd stdoutFD) regularMsg + void $ fdWrite (Fd stderrFD) (pack errorMsg) + where + + inputSizeApproximation :: ByteCount + inputSizeApproximation = 100 + + errorMsg :: String + errorMsg = "And every single door\n\ + \That I've walked through\n\ + \Brings me back, back here again\n" ===================================== libraries/base/tests/IO/osHandles002FileDescriptors.stderr ===================================== @@ -0,0 +1,3 @@ +And every single door +That I've walked through +Brings me back, back here again ===================================== libraries/base/tests/IO/osHandles002FileDescriptors.stdin ===================================== @@ -0,0 +1 @@ +We've got to get in to get out ===================================== libraries/base/tests/IO/osHandles002FileDescriptors.stdout ===================================== @@ -0,0 +1 @@ +We've got to get in to get out ===================================== libraries/base/tests/IO/osHandles002WindowsHandles.hs ===================================== @@ -0,0 +1,49 @@ +import Control.Monad (zipWithM_) +import Data.Functor (void) +import Data.Char (ord) +import Foreign.Marshal.Alloc (allocaBytes) +import Foreign.Storable (pokeElemOff) +import System.IO (stdin, stdout, stderr) +import System.IO.OS + ( + withWindowsHandleReadingBiased, + withWindowsHandleWritingBiased + ) + +main :: IO () +main = withWindowsHandleReadingBiased stdin $ \ windowsStdin -> + withWindowsHandleWritingBiased stdout $ \ windowsStdout -> + withWindowsHandleWritingBiased stderr $ \ windowsStderr -> + do + withBuffer inputSizeApproximation $ \ bufferPtr -> do + inputSize <- win32_ReadFile windowsStdin + bufferPtr + inputSizeApproximation + Nothing + void $ win32_WriteFile windowsStdout + bufferPtr + inputSize + Nothing + withBuffer errorMsgSize $ \ bufferPtr -> do + zipWithM_ (pokeElemOff bufferPtr) + [0 ..] + (map (fromIntegral . ord) errorMsg) + void $ win32_WriteFile windowsStderr + bufferPtr + errorMsgSize + Nothing + where + + withBuffer :: DWORD -> (Ptr Word8 -> IO a) -> IO a + withBuffer = allocaBytes . fromIntegral + + inputSizeApproximation :: DWORD + inputSizeApproximation = 100 + + errorMsg :: String + errorMsg = "And every single door\n\ + \That I've walked through\n\ + \Brings me back, back here again\n" + + errorMsgSize :: DWORD + errorMsgSize = fromIntegral (length errorMsg) ===================================== libraries/base/tests/IO/osHandles002WindowsHandles.stderr ===================================== @@ -0,0 +1,3 @@ +And every single door +That I've walked through +Brings me back, back here again ===================================== libraries/base/tests/IO/osHandles002WindowsHandles.stdin ===================================== @@ -0,0 +1 @@ +We've got to get in to get out ===================================== libraries/base/tests/IO/osHandles002WindowsHandles.stdout ===================================== @@ -0,0 +1 @@ +We've got to get in to get out ===================================== libraries/ghc-internal/ghc-internal.cabal.in ===================================== @@ -328,6 +328,7 @@ Library GHC.Internal.System.Exit GHC.Internal.System.IO GHC.Internal.System.IO.Error + GHC.Internal.System.IO.OS GHC.Internal.System.Mem GHC.Internal.System.Mem.StableName GHC.Internal.System.Posix.Internals ===================================== libraries/ghc-internal/src/GHC/Internal/System/IO/OS.hs ===================================== @@ -0,0 +1,323 @@ +{-# LANGUAGE Safe #-} +{-# LANGUAGE CPP #-} +{-# LANGUAGE RankNTypes #-} + +{-| + This module bridges between Haskell handles and underlying operating-system + features. +-} +module GHC.Internal.System.IO.OS +( + -- * Obtaining file descriptors and Windows handles + withFileDescriptorReadingBiased, + withFileDescriptorWritingBiased, + withWindowsHandleReadingBiased, + withWindowsHandleWritingBiased, + withFileDescriptorReadingBiasedRaw, + withFileDescriptorWritingBiasedRaw, + withWindowsHandleReadingBiasedRaw, + withWindowsHandleWritingBiasedRaw + + -- ** Caveats + -- $with-ref-caveats +) +where + +import GHC.Internal.Control.Monad (return) +import GHC.Internal.Control.Concurrent.MVar (MVar) +import GHC.Internal.Control.Exception (mask) +import GHC.Internal.Data.Function (const, (.), ($)) +import GHC.Internal.Data.Functor (fmap) +#if defined(mingw32_HOST_OS) +import GHC.Internal.Data.Bool (otherwise) +#endif +import GHC.Internal.Data.Maybe (Maybe (Nothing), maybe) +#if defined(mingw32_HOST_OS) +import GHC.Internal.Data.Maybe (Maybe (Just)) +#endif +import GHC.Internal.Data.List ((++)) +import GHC.Internal.Data.String (String) +import GHC.Internal.Data.Typeable (Typeable, cast) +import GHC.Internal.System.IO (IO) +import GHC.Internal.IO.FD (fdFD) +#if defined(mingw32_HOST_OS) +import GHC.Internal.IO.Windows.Handle + ( + NativeHandle, + ConsoleHandle, + IoHandle, + toHANDLE + ) +#endif +import GHC.Internal.IO.Handle.Types + ( + Handle (FileHandle, DuplexHandle), + Handle__ (Handle__, haDevice) + ) +import GHC.Internal.IO.Handle.Internals (withHandle_', flushBuffer) +import GHC.Internal.IO.Exception + ( + IOErrorType (InappropriateType), + IOException (IOError), + ioException + ) +import GHC.Internal.Foreign.Ptr (Ptr) +import GHC.Internal.Foreign.C.Types (CInt) + +-- * Obtaining POSIX file descriptors and Windows handles + +{-| + Executes a user-provided action on an operating-system handle that underlies + a Haskell handle. Before the user-provided action is run, user-defined + preparation based on the handle state that contains the operating-system + handle is performed. While the user-provided action is executed, further + operations on the Haskell handle are blocked to a degree that interference + with this action is prevented. + + See [below](#with-ref-caveats) for caveats regarding this operation. +-} +withOSHandle :: String + -- ^ The name of the overall operation + -> (Handle -> MVar Handle__) + {-^ + Obtaining of the handle state variable that holds the + operating-system handle + -} + -> (forall d. Typeable d => d -> IO a) + -- ^ Conversion of a device into an operating-system handle + -> (Handle__ -> IO ()) + -- ^ The preparation + -> Handle + -- ^ The Haskell handle to use + -> (a -> IO r) + -- ^ The action to execute on the operating-system handle + -> IO r +withOSHandle opName handleStateVar getOSHandle prepare handle act + = mask $ \ withOriginalMaskingState -> + withHandleState $ \ handleState@Handle__ {haDevice = dev} -> do + osHandle <- getOSHandle dev + prepare handleState + withOriginalMaskingState $ act osHandle + where + + withHandleState = withHandle_' opName handle (handleStateVar handle) +{- + The 'withHandle_'' operation, which we use here, already performs masking. + Still, we have to employ 'mask', in order do obtain the operation that + restores the original masking state. The user-provided action should be + executed with this original masking state, as there is no inherent reason to + generally perform it with masking in place. The masking that 'withHandle_'' + performs is only for safely accessing handle state and thus constitutes an + implementation detail; it has nothing to do with the user-provided action. +-} +{- + The order of actions in 'withOSHandle' is such that any exception from + 'getOSHandle' is thrown before the user-defined preparation is performed. +-} + +{-| + Obtains the handle state variable that underlies a handle or specifically + the handle state variable for reading if the handle uses different state + variables for reading and writing. +-} +handleStateVarReadingBiased :: Handle -> MVar Handle__ +handleStateVarReadingBiased (FileHandle _ var) = var +handleStateVarReadingBiased (DuplexHandle _ readingVar _) = readingVar + +{-| + Obtains the handle state variable that underlies a handle or specifically + the handle state variable for writing if the handle uses different state + variables for reading and writing. +-} +handleStateVarWritingBiased :: Handle -> MVar Handle__ +handleStateVarWritingBiased (FileHandle _ var) = var +handleStateVarWritingBiased (DuplexHandle _ _ writingVar) = writingVar + +{-| + Yields the result of another operation if that operation succeeded, and + otherwise throws an exception that signals that the other operation failed + because some Haskell handle does not use an operating-system handle of a + required type. +-} +requiringOSHandleOfType :: String + -- ^ The name of the operating-system handle type + -> Maybe a + {-^ + The result of the other operation if it succeeded + -} + -> IO a +requiringOSHandleOfType osHandleTypeName + = maybe (ioException osHandleOfTypeRequired) return + where + + osHandleOfTypeRequired :: IOException + osHandleOfTypeRequired + = IOError Nothing + InappropriateType + "" + ("handle does not use " ++ osHandleTypeName ++ "s") + Nothing + Nothing + +{-| + Obtains the POSIX file descriptor of a device if the device contains one, + and throws an exception otherwise. +-} +getFileDescriptor :: Typeable d => d -> IO CInt +getFileDescriptor = requiringOSHandleOfType "POSIX file descriptor" . + fmap fdFD . cast + +{-| + Obtains the Windows handle of a device if the device contains one, and + throws an exception otherwise. +-} +getWindowsHandle :: Typeable d => d -> IO (Ptr ()) +getWindowsHandle = requiringOSHandleOfType "Windows handle" . + toMaybeWindowsHandle + where + + toMaybeWindowsHandle :: Typeable d => d -> Maybe (Ptr ()) +#if defined(mingw32_HOST_OS) + toMaybeWindowsHandle dev + | Just nativeHandle <- cast dev :: Maybe (IoHandle NativeHandle) + = Just (toHANDLE nativeHandle) + | Just consoleHandle <- cast dev :: Maybe (IoHandle ConsoleHandle) + = Just (toHANDLE consoleHandle) + | otherwise + = Nothing + {- + This is inspired by the implementation of + 'System.Win32.Types.withHandleToHANDLENative'. + -} +#else + toMaybeWindowsHandle _ = Nothing +#endif + +{-| + Executes a user-provided action on the POSIX file descriptor that underlies + a handle or specifically on the POSIX file descriptor for reading if the + handle uses different file descriptors for reading and writing. The + Haskell-managed buffers related to the file descriptor are flushed before + the user-provided action is run. While this action is executed, further + operations on the handle are blocked to a degree that interference with this + action is prevented. + + If the handle does not use POSIX file descriptors, an exception is thrown. + + See [below](#with-ref-caveats) for caveats regarding this operation. +-} +withFileDescriptorReadingBiased :: Handle -> (CInt -> IO r) -> IO r +withFileDescriptorReadingBiased = withOSHandle "withFileDescriptorReadingBiased" + handleStateVarReadingBiased + getFileDescriptor + flushBuffer + +{-| + Executes a user-provided action on the POSIX file descriptor that underlies + a handle or specifically on the POSIX file descriptor for writing if the + handle uses different file descriptors for reading and writing. The + Haskell-managed buffers related to the file descriptor are flushed before + the user-provided action is run. While this action is executed, further + operations on the handle are blocked to a degree that interference with this + action is prevented. + + If the handle does not use POSIX file descriptors, an exception is thrown. + + See [below](#with-ref-caveats) for caveats regarding this operation. +-} +withFileDescriptorWritingBiased :: Handle -> (CInt -> IO r) -> IO r +withFileDescriptorWritingBiased = withOSHandle "withFileDescriptorWritingBiased" + handleStateVarWritingBiased + getFileDescriptor + flushBuffer + +{-| + Executes a user-provided action on the Windows handle that underlies a + Haskell handle or specifically on the Windows handle for reading if the + Haskell handle uses different Windows handles for reading and writing. The + Haskell-managed buffers related to the Windows handle are flushed before the + user-provided action is run. While this action is executed, further + operations on the Haskell handle are blocked to a degree that interference + with this action is prevented. + + If the Haskell handle does not use Windows handles, an exception is thrown. + + See [below](#with-ref-caveats) for caveats regarding this operation. +-} +withWindowsHandleReadingBiased :: Handle -> (Ptr () -> IO r) -> IO r +withWindowsHandleReadingBiased = withOSHandle "withWindowsHandleReadingBiased" + handleStateVarReadingBiased + getWindowsHandle + flushBuffer + +{-| + Executes a user-provided action on the Windows handle that underlies a + Haskell handle or specifically on the Windows handle for writing if the + Haskell handle uses different Windows handles for reading and writing. The + Haskell-managed buffers related to the Windows handle are flushed before the + user-provided action is run. While this action is executed, further + operations on the Haskell handle are blocked to a degree that interference + with this action is prevented. + + If the Haskell handle does not use Windows handles, an exception is thrown. + + See [below](#with-ref-caveats) for caveats regarding this operation. +-} +withWindowsHandleWritingBiased :: Handle -> (Ptr () -> IO r) -> IO r +withWindowsHandleWritingBiased = withOSHandle "withWindowsHandleWritingBiased" + handleStateVarWritingBiased + getWindowsHandle + flushBuffer + +{-| + Like 'withFileDescriptorReadingBiased' except that Haskell-managed buffers + are not flushed. +-} +withFileDescriptorReadingBiasedRaw :: Handle -> (CInt -> IO r) -> IO r +withFileDescriptorReadingBiasedRaw + = withOSHandle "withFileDescriptorReadingBiasedRaw" + handleStateVarReadingBiased + getFileDescriptor + (const $ return ()) + +{-| + Like 'withFileDescriptorWritingBiased' except that Haskell-managed buffers + are not flushed. +-} +withFileDescriptorWritingBiasedRaw :: Handle -> (CInt -> IO r) -> IO r +withFileDescriptorWritingBiasedRaw + = withOSHandle "withFileDescriptorWritingBiasedRaw" + handleStateVarWritingBiased + getFileDescriptor + (const $ return ()) + +{-| + Like 'withWindowsHandleReadingBiased' except that Haskell-managed buffers + are not flushed. +-} +withWindowsHandleReadingBiasedRaw :: Handle -> (Ptr () -> IO r) -> IO r +withWindowsHandleReadingBiasedRaw + = withOSHandle "withWindowsHandleReadingBiasedRaw" + handleStateVarReadingBiased + getWindowsHandle + (const $ return ()) + +{-| + Like 'withWindowsHandleWritingBiased' except that Haskell-managed buffers + are not flushed. +-} +withWindowsHandleWritingBiasedRaw :: Handle -> (Ptr () -> IO r) -> IO r +withWindowsHandleWritingBiasedRaw + = withOSHandle "withWindowsHandleWritingBiasedRaw" + handleStateVarWritingBiased + getWindowsHandle + (const $ return ()) + +-- ** Caveats + +{-$with-ref-caveats + #with-ref-caveats#This subsection is just a dummy, whose purpose is to serve + as the target of the hyperlinks above. The real documentation of the caveats + is in the /Caveats/ subsection in the @base@ module @System.IO.OS@, which + re-exports the above operations. +-} ===================================== testsuite/tests/interface-stability/base-exports.stdout ===================================== @@ -120,6 +120,7 @@ module Control.Concurrent where isCurrentThreadBound :: GHC.Internal.Types.IO GHC.Internal.Types.Bool isEmptyMVar :: forall a. MVar a -> GHC.Internal.Types.IO GHC.Internal.Types.Bool killThread :: ThreadId -> GHC.Internal.Types.IO () + labelThread :: ThreadId -> GHC.Internal.Base.String -> GHC.Internal.Types.IO () mkWeakMVar :: forall a. MVar a -> GHC.Internal.Types.IO () -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak (MVar a)) mkWeakThreadId :: ThreadId -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak ThreadId) modifyMVar :: forall a b. MVar a -> (a -> GHC.Internal.Types.IO (a, b)) -> GHC.Internal.Types.IO b @@ -10047,6 +10048,17 @@ module System.IO.Error where userError :: GHC.Internal.Base.String -> IOError userErrorType :: IOErrorType +module System.IO.OS where + -- Safety: Safe + withFileDescriptorReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + module System.IO.Unsafe where -- Safety: Unsafe unsafeDupablePerformIO :: forall a. GHC.Internal.Types.IO a -> a ===================================== testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs ===================================== @@ -120,6 +120,7 @@ module Control.Concurrent where isCurrentThreadBound :: GHC.Internal.Types.IO GHC.Internal.Types.Bool isEmptyMVar :: forall a. MVar a -> GHC.Internal.Types.IO GHC.Internal.Types.Bool killThread :: ThreadId -> GHC.Internal.Types.IO () + labelThread :: ThreadId -> GHC.Internal.Base.String -> GHC.Internal.Types.IO () mkWeakMVar :: forall a. MVar a -> GHC.Internal.Types.IO () -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak (MVar a)) mkWeakThreadId :: ThreadId -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak ThreadId) modifyMVar :: forall a b. MVar a -> (a -> GHC.Internal.Types.IO (a, b)) -> GHC.Internal.Types.IO b @@ -10085,6 +10086,17 @@ module System.IO.Error where userError :: GHC.Internal.Base.String -> IOError userErrorType :: IOErrorType +module System.IO.OS where + -- Safety: Safe + withFileDescriptorReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + module System.IO.Unsafe where -- Safety: Unsafe unsafeDupablePerformIO :: forall a. GHC.Internal.Types.IO a -> a ===================================== testsuite/tests/interface-stability/base-exports.stdout-mingw32 ===================================== @@ -120,6 +120,7 @@ module Control.Concurrent where isCurrentThreadBound :: GHC.Internal.Types.IO GHC.Internal.Types.Bool isEmptyMVar :: forall a. MVar a -> GHC.Internal.Types.IO GHC.Internal.Types.Bool killThread :: ThreadId -> GHC.Internal.Types.IO () + labelThread :: ThreadId -> GHC.Internal.Base.String -> GHC.Internal.Types.IO () mkWeakMVar :: forall a. MVar a -> GHC.Internal.Types.IO () -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak (MVar a)) mkWeakThreadId :: ThreadId -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak ThreadId) modifyMVar :: forall a b. MVar a -> (a -> GHC.Internal.Types.IO (a, b)) -> GHC.Internal.Types.IO b @@ -10327,6 +10328,17 @@ module System.IO.Error where userError :: GHC.Internal.Base.String -> IOError userErrorType :: IOErrorType +module System.IO.OS where + -- Safety: Safe + withFileDescriptorReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + module System.IO.Unsafe where -- Safety: Unsafe unsafeDupablePerformIO :: forall a. GHC.Internal.Types.IO a -> a ===================================== testsuite/tests/interface-stability/base-exports.stdout-ws-32 ===================================== @@ -120,6 +120,7 @@ module Control.Concurrent where isCurrentThreadBound :: GHC.Internal.Types.IO GHC.Internal.Types.Bool isEmptyMVar :: forall a. MVar a -> GHC.Internal.Types.IO GHC.Internal.Types.Bool killThread :: ThreadId -> GHC.Internal.Types.IO () + labelThread :: ThreadId -> GHC.Internal.Base.String -> GHC.Internal.Types.IO () mkWeakMVar :: forall a. MVar a -> GHC.Internal.Types.IO () -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak (MVar a)) mkWeakThreadId :: ThreadId -> GHC.Internal.Types.IO (GHC.Internal.Weak.Weak ThreadId) modifyMVar :: forall a b. MVar a -> (a -> GHC.Internal.Types.IO (a, b)) -> GHC.Internal.Types.IO b @@ -10047,6 +10048,17 @@ module System.IO.Error where userError :: GHC.Internal.Base.String -> IOError userErrorType :: IOErrorType +module System.IO.OS where + -- Safety: Safe + withFileDescriptorReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withFileDescriptorWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Foreign.C.Types.CInt -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleReadingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiased :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + withWindowsHandleWritingBiasedRaw :: forall r. GHC.Internal.IO.Handle.Types.Handle -> (GHC.Internal.Ptr.Ptr () -> GHC.Internal.Types.IO r) -> GHC.Internal.Types.IO r + module System.IO.Unsafe where -- Safety: Unsafe unsafeDupablePerformIO :: forall a. GHC.Internal.Types.IO a -> a View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/61cc761584802db8012864d37e98d0… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/61cc761584802db8012864d37e98d0… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/jeltsch/stability-risk-3-module-deprecation] 2 commits: Enable `CPP` in the modules to be deprecated
by Wolfgang Jeltsch (＠jeltsch) 24 Jan '26

24 Jan '26

Wolfgang Jeltsch pushed to branch wip/jeltsch/stability-risk-3-module-deprecation at Glasgow Haskell Compiler / GHC Commits: 8218bab7 by Wolfgang Jeltsch at 2026-01-23T20:12:43+02:00 Enable `CPP` in the modules to be deprecated - - - - - 10375ab2 by Wolfgang Jeltsch at 2026-01-23T20:26:19+02:00 Remove `WARNING` pragma for `GHC.GHCi` - - - - - 8 changed files: - libraries/base/src/GHC/Event/TimeOut.hs - libraries/base/src/GHC/Float/RealFracMethods.hs - libraries/base/src/GHC/GHCi.hs - libraries/base/src/GHC/GHCi/Helpers.hs - libraries/base/src/GHC/IO/Handle/Internals.hs - libraries/base/src/GHC/IO/Handle/Types.hs - libraries/base/src/GHC/IO/SubSystem.hs - libraries/base/src/System/Posix/Internals.hs Changes: ===================================== libraries/base/src/GHC/Event/TimeOut.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + -- | -- Module : GHC.Event.TimeOut -- Copyright : (c) Tamar Christina 2018 ===================================== libraries/base/src/GHC/Float/RealFracMethods.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# LANGUAGE Safe #-} {-# OPTIONS_HADDOCK not-home #-} ===================================== libraries/base/src/GHC/GHCi.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# OPTIONS_HADDOCK not-home #-} -- | @@ -26,7 +28,6 @@ module GHC.GHCi {-# DEPRECATED ["GHC.GHCi is deprecated and will be removed in GHC 10.02. See https://github.com/well-typed/reinstallable-base/tree/main/hackage-uses-of-… for context."] #-} - {-# WARNING "This is an unstable interface." #-} (GHCiSandboxIO(..), NoIO() ) where ===================================== libraries/base/src/GHC/GHCi/Helpers.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# LANGUAGE Safe #-} -- | ===================================== libraries/base/src/GHC/IO/Handle/Internals.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# LANGUAGE Safe #-} {-# OPTIONS_HADDOCK not-home #-} ===================================== libraries/base/src/GHC/IO/Handle/Types.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# LANGUAGE Safe #-} {-# OPTIONS_HADDOCK not-home #-} ===================================== libraries/base/src/GHC/IO/SubSystem.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# LANGUAGE Safe #-} -- | ===================================== libraries/base/src/System/Posix/Internals.hs ===================================== @@ -1,3 +1,5 @@ +{-# LANGUAGE CPP #-} + {-# LANGUAGE Safe #-} {-# OPTIONS_HADDOCK not-home #-} View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f8d79956211a8cb14976c27b2b89a2… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f8d79956211a8cb14976c27b2b89a2… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 3 commits: ci: remove duplicate keys in .gitlab-ci.yml
by Marge Bot (＠marge-bot) 24 Jan '26

24 Jan '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 1097d050 by Cheng Shao at 2026-01-24T00:11:01-05:00 ci: remove duplicate keys in .gitlab-ci.yml This patch removes accidentally duplicate keys in `.gitlab-ci.yml`. The YAML spec doesn't allow duplicate keys in the first place, and according to GitLab docs (https://docs.gitlab.com/ci/yaml/yaml_optimization/#anchors) the latest key overrides the earlier entries. - - - - - 79fd9a8c by Cheng Shao at 2026-01-24T00:11:04-05:00 hadrian: drop obsolete configure/make builder logic for libffi This patch drops obsolete hadrian logic around `Configure libffiPath`/`Make libffiPath` builders, they are no longer needed after libffi-clib has landed. Closes #26815. - - - - - 709cdf16 by Simon Hengel at 2026-01-24T00:11:05-05:00 Fix typo in roles.rst - - - - - 5 changed files: - .gitlab-ci.yml - docs/users_guide/exts/roles.rst - hadrian/src/Context.hs - hadrian/src/Settings/Builders/Configure.hs - hadrian/src/Settings/Builders/Make.hs Changes: ===================================== .gitlab-ci.yml ===================================== @@ -1050,10 +1050,6 @@ abi-test: optional: true dependencies: null image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-fedora43:$DOCKER_REV" - rules: - - if: $CI_MERGE_REQUEST_ID - - if: '$CI_COMMIT_BRANCH == "master"' - - if: '$CI_COMMIT_BRANCH =~ /ghc-[0.9]+\.[0-9]+/' tags: - x86_64-linux script: ===================================== docs/users_guide/exts/roles.rst ===================================== @@ -38,7 +38,7 @@ trouble. The way to identify such situations is to have *roles* assigned to type variables of datatypes, classes, and type synonyms. -Roles as implemented in GHC are a from a simplified version of the work +Roles as implemented in GHC are based on a simplified version of the work described in `Generative type abstraction and type-level computation <https://www.seas.upenn.edu/~sweirich/papers/popl163af-weirich.pdf>`__, published at POPL 2011. ===================================== hadrian/src/Context.hs ===================================== @@ -11,7 +11,7 @@ module Context ( pkgLibraryFile, pkgConfFile, pkgStampFile, resourcePath, objectPath, contextPath, getContextPath, libPath, distDir, distDynDir, - haddockStatsFilesDir, ensureConfigured, autogenPath, rtsContext, rtsBuildPath, libffiBuildPath + haddockStatsFilesDir, ensureConfigured, autogenPath, rtsContext, rtsBuildPath ) where import Base @@ -93,14 +93,6 @@ rtsContext stage = vanillaContext stage rts rtsBuildPath :: Stage -> Action FilePath rtsBuildPath stage = buildPath (rtsContext stage) --- | Build directory for in-tree 'libffi' library. -libffiBuildPath :: Stage -> Action FilePath -libffiBuildPath stage = buildPath $ Context - stage - libffi - (error "libffiBuildPath: way not set.") - (error "libffiBuildPath: inplace not set.") - pkgFileName :: Context -> Package -> String -> String -> Action FilePath pkgFileName context package prefix suffix = do pid <- pkgUnitId (stage context) package ===================================== hadrian/src/Settings/Builders/Configure.hs ===================================== @@ -8,8 +8,7 @@ configureBuilderArgs :: Args configureBuilderArgs = do stage <- getStage gmpPath <- expr (gmpBuildPath stage) - libffiPath <- expr (libffiBuildPath stage) - mconcat [ builder (Configure gmpPath) ? do + builder (Configure gmpPath) ? do targetArch <- queryTarget queryArch targetPlatform <- queryTarget targetPlatformTriple buildPlatform <- queryBuild targetPlatformTriple @@ -28,16 +27,3 @@ configureBuilderArgs = do -- option. <> [ "--enable-alloca=malloc-notreentrant" | targetArch == "wasm32" ] <> [ "--with-pic=yes" ] - - , builder (Configure libffiPath) ? do - top <- expr topDirectory - targetPlatform <- queryTarget targetPlatformTriple - way <- getWay - pure [ "--prefix=" ++ top -/- libffiPath -/- "inst" - , "--libdir=" ++ top -/- libffiPath -/- "inst/lib" - , "--enable-static=yes" - , "--enable-shared=" - ++ (if wayUnit Dynamic way - then "yes" - else "no") - , "--host=" ++ targetPlatform ] ] ===================================== hadrian/src/Settings/Builders/Make.hs ===================================== @@ -12,12 +12,8 @@ makeBuilderArgs = do threads <- shakeThreads <$> expr getShakeOptions stage <- getStage gmpPath <- expr (gmpBuildPath stage) - libffiPaths <- forM [Stage1, Stage2, Stage3 ] $ \s -> expr (libffiBuildPath s) let t = show $ max 4 (threads - 2) -- Don't use all Shake's threads - mconcat $ - (builder (Make gmpPath ) ? pure ["MAKEFLAGS=-j" ++ t]) : - [ builder (Make libffiPath) ? pure ["MAKEFLAGS=-j" ++ t, "install"] - | libffiPath <- libffiPaths ] + builder (Make gmpPath) ? pure ["MAKEFLAGS=-j" ++ t] validateBuilderArgs :: Args validateBuilderArgs = builder (Make "testsuite/tests") ? do View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/988ad0e40e4d89bed0c1997cef399f… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/988ad0e40e4d89bed0c1997cef399f… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T26503] Implement QualifiedStrings (#26503)
by Brandon Chinn (＠brandonchinn178) 24 Jan '26

24 Jan '26

Brandon Chinn pushed to branch wip/T26503 at Glasgow Haskell Compiler / GHC Commits: c811b1db by Brandon Chinn at 2026-01-23T18:29:09-08:00 Implement QualifiedStrings (#26503) See Note [Implementation of QualifiedStrings] - - - - - 56 changed files: - compiler/GHC/Builtin/Names/TH.hs - compiler/GHC/Builtin/Types.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Hs/Lit.hs - compiler/GHC/HsToCore/Pmc/Desugar.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Errors/Ppr.hs - compiler/GHC/Parser/Errors/Types.hs - compiler/GHC/Parser/Lexer.x - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Error/Codes.hs - compiler/GHC/Types/StringMeta.hs - docs/users_guide/9.16.1-notes.rst - + docs/users_guide/exts/qualified_strings.rst - libraries/ghc-boot-th/GHC/Boot/TH/Ppr.hs - libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs - libraries/ghc-internal/src/GHC/Internal/TH/Lib.hs - libraries/ghc-internal/src/GHC/Internal/TH/Syntax.hs - libraries/template-haskell/Language/Haskell/TH/Lib.hs - testsuite/tests/driver/T4437.hs - testsuite/tests/ghc-api/annotations-literals/literals.stdout - testsuite/tests/ghc-api/annotations-literals/parsed.stdout - testsuite/tests/interface-stability/template-haskell-exports.stdout - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpParsedAstComments.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_compile/DumpTypecheckedAst.stderr - + testsuite/tests/qualified-strings/Makefile - + testsuite/tests/qualified-strings/should_compile/Example/Length.hs - + testsuite/tests/qualified-strings/should_compile/all.T - + testsuite/tests/qualified-strings/should_compile/qstrings_redundant_pattern.hs - + testsuite/tests/qualified-strings/should_compile/qstrings_redundant_pattern.stderr - + testsuite/tests/qualified-strings/should_fail/Example/Length.hs - + testsuite/tests/qualified-strings/should_fail/Makefile - + testsuite/tests/qualified-strings/should_fail/all.T - + testsuite/tests/qualified-strings/should_fail/qstrings_bad_expr.hs - + testsuite/tests/qualified-strings/should_fail/qstrings_bad_expr.stderr - + testsuite/tests/qualified-strings/should_fail/qstrings_bad_pat.hs - + testsuite/tests/qualified-strings/should_fail/qstrings_bad_pat.stderr - + testsuite/tests/qualified-strings/should_fail/qstrings_multiline_no_ext.hs - + testsuite/tests/qualified-strings/should_fail/qstrings_multiline_no_ext.stderr - + testsuite/tests/qualified-strings/should_run/Example/ByteStringAscii.hs - + testsuite/tests/qualified-strings/should_run/Example/ByteStringUtf8.hs - + testsuite/tests/qualified-strings/should_run/Example/Text.hs - + testsuite/tests/qualified-strings/should_run/Makefile - + testsuite/tests/qualified-strings/should_run/all.T - + testsuite/tests/qualified-strings/should_run/qstrings_expr.hs - + testsuite/tests/qualified-strings/should_run/qstrings_expr.stdout - + testsuite/tests/qualified-strings/should_run/qstrings_pat.hs - + testsuite/tests/qualified-strings/should_run/qstrings_pat.stdout - + testsuite/tests/qualified-strings/should_run/qstrings_th.hs - + testsuite/tests/qualified-strings/should_run/qstrings_th.stdout - utils/check-exact/ExactPrint.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c811b1db19a5c693266c24afcd1cea1… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c811b1db19a5c693266c24afcd1cea1… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/26699] 4 commits: Export labelThread from Control.Concurrent
by recursion-ninja (＠recursion-ninja) 24 Jan '26

24 Jan '26

recursion-ninja pushed to branch wip/26699 at Glasgow Haskell Compiler / GHC Commits: 917ab8ff by Oleg Grenrus at 2026-01-23T10:52:55-05:00 Export labelThread from Control.Concurrent - - - - - 3f5e8d80 by Cheng Shao at 2026-01-23T10:53:37-05:00 ci: only push perf notes on master/release branches This patch fixes push_perf_notes logic in ci.sh to only push perf notes on master/release branches. We used to unconditionally push perf notes even in MRs, but the perf numbers in the wip branches wouldn't be used as baseline anyway, plus this is causing a space leak in the ghc-performance-notes repo. See #25317 for the perf notes repo size problem. Co-authored-by: Codex <codex(a)openai.com> - - - - - e53501c6 by Recursion Ninja at 2026-01-23T20:38:40-05:00 Migrating the simplest types required for Trees That Grow progress from GHC.Types.Basic to Language.Haskell.Syntax.Basic. Related function definitions were also moved. Outputable type-class instances are defined in GHC.Utils.Outputable. Binary instance of Boxity was moved to GHC.Utils.Binary. Migrated types: * TopLevelFlag * RuleName * TyConFlavour * TypeOrData * NewOrData - - - - - f2fb67fd by Recursion Ninja at 2026-01-23T20:38:40-05:00 Exposing 'OverlapFlag' and 'OverlapMode' through thier own modules. Breaking module import cycles and placing 'Binary' instances in the proper module - - - - - 58 changed files: - .gitlab/ci.sh - compiler/GHC/Core/InstEnv.hs - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Hs/Decls.hs - compiler/GHC/Hs/Extension.hs - + compiler/GHC/Hs/Extension.hs-boot - compiler/GHC/Hs/Instances.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Errors/Types.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Header.hs - compiler/GHC/Rename/Env.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Names.hs - compiler/GHC/Rename/Splice.hs - compiler/GHC/Tc/Deriv.hs - compiler/GHC/Tc/Deriv/Utils.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Gen/Head.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Utils/Env.hs - compiler/GHC/Tc/Utils/Instantiate.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Types/Basic.hs - + compiler/GHC/Types/ImportLevel.hs - compiler/GHC/Types/Name.hs - + compiler/GHC/Types/Name/RdrName.hs - compiler/GHC/Types/Name/Reader.hs - + compiler/GHC/Types/OverlapFlag.hs - + compiler/GHC/Types/OverlapMode.hs - compiler/GHC/Types/SourceText.hs - compiler/GHC/Types/ThLevelIndex.hs - compiler/GHC/Unit/Module/Deps.hs - compiler/GHC/Unit/Module/Graph.hs - compiler/GHC/Unit/Module/ModSummary.hs - compiler/GHC/Unit/Types.hs - compiler/GHC/Utils/Binary.hs - compiler/GHC/Utils/Outputable.hs - compiler/Language/Haskell/Syntax/Basic.hs - compiler/Language/Haskell/Syntax/Decls.hs - compiler/Language/Haskell/Syntax/Extension.hs - compiler/ghc.cabal.in - libraries/base/changelog.md - libraries/base/src/Control/Concurrent.hs - libraries/base/src/System/Timeout.hs - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - utils/haddock/haddock-api/src/Haddock/Backends/Hoogle.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Types.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/5456a01f0ee8a155a1ce53bd78bcae… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/5456a01f0ee8a155a1ce53bd78bcae… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/deepseq-primop] 14 commits: GC: don't use CAS without PARALLEL_GC on
by Cheng Shao (＠TerrorJack) 24 Jan '26

24 Jan '26

Cheng Shao pushed to branch wip/deepseq-primop at Glasgow Haskell Compiler / GHC Commits: 0491f08a by Sylvain Henry at 2026-01-22T03:44:26-05:00 GC: don't use CAS without PARALLEL_GC on If we're not using the parallel GC, there is no reason to do a costly CAS. This was flagged as taking time in a perf profile. - - - - - 211a8f56 by Sylvain Henry at 2026-01-22T03:44:26-05:00 GC: suffix parallel GC with "par" instead of "thr" Avoid some potential confusion (see discussion in !15351). - - - - - 77a23cbd by fendor at 2026-01-22T03:45:08-05:00 Remove blanket ignore that covers libraries/ - - - - - 18bf7f5c by Léana Jiang at 2026-01-22T08:58:45-05:00 doc: update Flavour type in hadrian user-settings - - - - - 3d5a1365 by Cheng Shao at 2026-01-22T08:59:28-05:00 hadrian: add missing notCross predicate for stage0 -O0 There are a few hard-coded hadrian args that pass -O0 when compiling some heavy modules in stage0, which only makes sense when not cross-compiling and when cross-compiling we need properly optimized stage0 packages. So this patch adds the missing `notCross` predicate in those places. - - - - - ee937134 by Matthew Pickering at 2026-01-22T09:00:10-05:00 Fix ghc-experimental GHC.Exception.Backtrace.Experimental module This module wasn't added to the cabal file so it was never compiled or included in the library. - - - - - 1b490f5a by Zubin Duggal at 2026-01-22T09:00:53-05:00 hadrian: Add ghc-{experimental,internal}.cabal to the list of dependencies of the doc target We need these files to detect the version of these libraries Fixes #26738 - - - - - cdb74049 by Cheng Shao at 2026-01-22T14:52:36-05:00 rts: avoid Cmm loop to initialize Array#/SmallArray# Previously, `newArray#`/`newSmallArray#` called an RTS C function to allocate the `Array#`/`SmallArray#`, then used a Cmm loop to initialize the elements. Cmm doesn't have native for-loop so the code is a bit awkward, and it's less efficient than a C loop, since the C compiler can effectively vectorize the loop with optimizations. So this patch moves the loop that initializes the elements to the C side. `allocateMutArrPtrs`/`allocateSmallMutArrPtrs` now takes a new `init` argument and initializes the elements if `init` is non-NULL. - - - - - 4c784f00 by Cheng Shao at 2026-01-22T14:53:19-05:00 Fix testsuite run for +ipe flavour transformer This patch makes the +ipe flavour transformer pass the entire testsuite: - An RTS debug option `-DI` is added, the IPE trace information is now only printed with `-DI`. The test cases that do require IPE trace are now run with `-DI`. - The testsuite config option `ghc_with_ipe` is added, enabled when running the testsuite with `+ipe`, which skips a few tests that are sensitive to eventlog output, allocation patterns etc that can fail under `+ipe`. This is the first step towards #26799. Co-authored-by: Codex <codex(a)openai.com> - - - - - be8e5236 by Ben Gamari at 2026-01-23T03:28:45-05:00 hadrian: Bump QuickCheck upper bound This patch bumps QuickCheck upper bound to 2.18. selftest rule manually tested to work with current latest QuickCheck-2.17.1.0. - - - - - 5aa328fb by Zubin Duggal at 2026-01-23T03:29:30-05:00 Add genindex to index.rst. This adds a link to the index in the navigation bar. Fixes #26437 - - - - - 917ab8ff by Oleg Grenrus at 2026-01-23T10:52:55-05:00 Export labelThread from Control.Concurrent - - - - - 3f5e8d80 by Cheng Shao at 2026-01-23T10:53:37-05:00 ci: only push perf notes on master/release branches This patch fixes push_perf_notes logic in ci.sh to only push perf notes on master/release branches. We used to unconditionally push perf notes even in MRs, but the perf numbers in the wip branches wouldn't be used as baseline anyway, plus this is causing a space leak in the ghc-performance-notes repo. See #25317 for the perf notes repo size problem. Co-authored-by: Codex <codex(a)openai.com> - - - - - 50f8212e by Cheng Shao at 2026-01-24T02:31:10+01:00 WIP - - - - - 46 changed files: - .gitignore - .gitlab/ci.sh - docs/users_guide/index.rst - docs/users_guide/runtime_control.rst - hadrian/doc/user-settings.md - hadrian/hadrian.cabal - hadrian/src/Flavour.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Settings/Packages.hs - libraries/base/changelog.md - libraries/base/src/Control/Concurrent.hs - libraries/base/src/System/Timeout.hs - libraries/ghc-compact/tests/all.T - + libraries/ghc-experimental/cbits/DeepSeq.cmm - libraries/ghc-experimental/ghc-experimental.cabal.in - + libraries/ghc-experimental/src/GHC/DeepSeq.hs - libraries/ghc-experimental/src/GHC/Exception/Backtrace/Experimental.hs - libraries/ghc-internal/tests/backtraces/all.T - rts/AllocArray.c - rts/AllocArray.h - rts/ClosureTable.c - rts/Heap.c - rts/PrimOps.cmm - rts/RtsFlags.c - rts/Threads.c - rts/Trace.c - rts/Weak.c - rts/include/rts/Flags.h - rts/rts.cabal - rts/sm/Evac.c - rts/sm/Evac_thr.c → rts/sm/Evac_par.c - rts/sm/Scav_thr.c → rts/sm/Scav_par.c - testsuite/driver/testglobals.py - testsuite/driver/testlib.py - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - testsuite/tests/interface-stability/ghc-experimental-exports.stdout - testsuite/tests/interface-stability/ghc-experimental-exports.stdout-mingw32 - + testsuite/tests/primops/should_run/DeepSeqPrimOp.hs - + testsuite/tests/primops/should_run/DeepSeqPrimOp.stdout - testsuite/tests/primops/should_run/all.T - testsuite/tests/rts/Makefile - testsuite/tests/rts/all.T - testsuite/tests/rts/ipe/all.T The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/cc7f670ca68926d31e3a6a0273219e… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/cc7f670ca68926d31e3a6a0273219e… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 3 commits: ci: remove duplicate keys in .gitlab-ci.yml
by Marge Bot (＠marge-bot) 23 Jan '26

23 Jan '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 4db54426 by Cheng Shao at 2026-01-23T16:40:26-05:00 ci: remove duplicate keys in .gitlab-ci.yml This patch removes accidentally duplicate keys in `.gitlab-ci.yml`. The YAML spec doesn't allow duplicate keys in the first place, and according to GitLab docs (https://docs.gitlab.com/ci/yaml/yaml_optimization/#anchors) the latest key overrides the earlier entries. - - - - - 4500d552 by Cheng Shao at 2026-01-23T16:40:29-05:00 hadrian: drop obsolete configure/make builder logic for libffi This patch drops obsolete hadrian logic around `Configure libffiPath`/`Make libffiPath` builders, they are no longer needed after libffi-clib has landed. Closes #26815. - - - - - 988ad0e4 by Simon Hengel at 2026-01-23T16:40:30-05:00 Fix typo in roles.rst - - - - - 5 changed files: - .gitlab-ci.yml - docs/users_guide/exts/roles.rst - hadrian/src/Context.hs - hadrian/src/Settings/Builders/Configure.hs - hadrian/src/Settings/Builders/Make.hs Changes: ===================================== .gitlab-ci.yml ===================================== @@ -1050,10 +1050,6 @@ abi-test: optional: true dependencies: null image: "registry.gitlab.haskell.org/ghc/ci-images/x86_64-linux-fedora43:$DOCKER_REV" - rules: - - if: $CI_MERGE_REQUEST_ID - - if: '$CI_COMMIT_BRANCH == "master"' - - if: '$CI_COMMIT_BRANCH =~ /ghc-[0.9]+\.[0-9]+/' tags: - x86_64-linux script: ===================================== docs/users_guide/exts/roles.rst ===================================== @@ -38,7 +38,7 @@ trouble. The way to identify such situations is to have *roles* assigned to type variables of datatypes, classes, and type synonyms. -Roles as implemented in GHC are a from a simplified version of the work +Roles as implemented in GHC are based on a simplified version of the work described in `Generative type abstraction and type-level computation <https://www.seas.upenn.edu/~sweirich/papers/popl163af-weirich.pdf>`__, published at POPL 2011. ===================================== hadrian/src/Context.hs ===================================== @@ -11,7 +11,7 @@ module Context ( pkgLibraryFile, pkgConfFile, pkgStampFile, resourcePath, objectPath, contextPath, getContextPath, libPath, distDir, distDynDir, - haddockStatsFilesDir, ensureConfigured, autogenPath, rtsContext, rtsBuildPath, libffiBuildPath + haddockStatsFilesDir, ensureConfigured, autogenPath, rtsContext, rtsBuildPath ) where import Base @@ -93,14 +93,6 @@ rtsContext stage = vanillaContext stage rts rtsBuildPath :: Stage -> Action FilePath rtsBuildPath stage = buildPath (rtsContext stage) --- | Build directory for in-tree 'libffi' library. -libffiBuildPath :: Stage -> Action FilePath -libffiBuildPath stage = buildPath $ Context - stage - libffi - (error "libffiBuildPath: way not set.") - (error "libffiBuildPath: inplace not set.") - pkgFileName :: Context -> Package -> String -> String -> Action FilePath pkgFileName context package prefix suffix = do pid <- pkgUnitId (stage context) package ===================================== hadrian/src/Settings/Builders/Configure.hs ===================================== @@ -8,8 +8,7 @@ configureBuilderArgs :: Args configureBuilderArgs = do stage <- getStage gmpPath <- expr (gmpBuildPath stage) - libffiPath <- expr (libffiBuildPath stage) - mconcat [ builder (Configure gmpPath) ? do + builder (Configure gmpPath) ? do targetArch <- queryTarget queryArch targetPlatform <- queryTarget targetPlatformTriple buildPlatform <- queryBuild targetPlatformTriple @@ -28,16 +27,3 @@ configureBuilderArgs = do -- option. <> [ "--enable-alloca=malloc-notreentrant" | targetArch == "wasm32" ] <> [ "--with-pic=yes" ] - - , builder (Configure libffiPath) ? do - top <- expr topDirectory - targetPlatform <- queryTarget targetPlatformTriple - way <- getWay - pure [ "--prefix=" ++ top -/- libffiPath -/- "inst" - , "--libdir=" ++ top -/- libffiPath -/- "inst/lib" - , "--enable-static=yes" - , "--enable-shared=" - ++ (if wayUnit Dynamic way - then "yes" - else "no") - , "--host=" ++ targetPlatform ] ] ===================================== hadrian/src/Settings/Builders/Make.hs ===================================== @@ -12,12 +12,8 @@ makeBuilderArgs = do threads <- shakeThreads <$> expr getShakeOptions stage <- getStage gmpPath <- expr (gmpBuildPath stage) - libffiPaths <- forM [Stage1, Stage2, Stage3 ] $ \s -> expr (libffiBuildPath s) let t = show $ max 4 (threads - 2) -- Don't use all Shake's threads - mconcat $ - (builder (Make gmpPath ) ? pure ["MAKEFLAGS=-j" ++ t]) : - [ builder (Make libffiPath) ? pure ["MAKEFLAGS=-j" ++ t, "install"] - | libffiPath <- libffiPaths ] + builder (Make gmpPath) ? pure ["MAKEFLAGS=-j" ++ t] validateBuilderArgs :: Args validateBuilderArgs = builder (Make "testsuite/tests") ? do View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/12aebc0c3fe4093ae4e33a8bdff571… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/12aebc0c3fe4093ae4e33a8bdff571… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/26805] Fix two bugs in short-cut constraint solving
by Simon Peyton Jones (＠simonpj) 23 Jan '26

23 Jan '26

Simon Peyton Jones pushed to branch wip/26805 at Glasgow Haskell Compiler / GHC Commits: 3ff419a9 by Simon Peyton Jones at 2026-01-23T17:45:02+00:00 Fix two bugs in short-cut constraint solving There are two main changes here: * Use `isSolvedWC` rather than `isEmptyWC` in `tryShortCutSolver` The residual constraint may have some fully-solved, but still-there implications, and we don't want them to abort short cut solving! That bug caused #26805. * In the short-cut solver, we abandon the fully-solved residual constraint; but we may thereby lose track of Givens that are needed, and either report them as redundant or prune evidence bindings that are in fact needed. This bug stopped the `constraints` package from compiling; see the trail in !15389. The second bug led me to (another) significant refactoring of the mechanism for tracking needed EvIds. See the new Note [Tracking needed EvIds] in GHC.Tc.Solver.Solve It's simpler and much less head-scratchy now. Some particulars: * An EvBindsVar now tracks NeededEvIds * We deal with NeededEvIds for an implication only when it is fully solved. Much simpler! * `tryShortCutTcS` now takes a `TcM WantedConstraints` rather than `TcM Bool`, so that is can plumb the needed EvIds correctly. * Remove `ic_need` and `ic_need_implic` from Implication (hooray), and add `ics_dm` and `ics_non_dm` to `IC_Solved`. Pure refactor * Shorten data constructor `CoercionHole` to `CH`, following general practice in GHC. * Rename `EvBindMap` to `EvBindsMap` for consistency - - - - - 28 changed files: - compiler/GHC/Core/TyCo/Rep.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/Core/TyCo/Tidy.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Gen/Default.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Solver/Default.hs - compiler/GHC/Tc/Solver/Dict.hs - compiler/GHC/Tc/Solver/Equality.hs - compiler/GHC/Tc/Solver/InertSet.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Solver/Solve.hs - compiler/GHC/Tc/TyCl/Instance.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Types/Evidence.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Tc/Zonk/TcType.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/Types/Var.hs - compiler/GHC/Utils/Trace.hs - + testsuite/tests/simplCore/should_compile/T26805.hs - + testsuite/tests/simplCore/should_compile/T26805.stderr - testsuite/tests/simplCore/should_compile/all.T - + testsuite/tests/typecheck/should_compile/T26805a.hs - testsuite/tests/typecheck/should_compile/all.T Changes: ===================================== compiler/GHC/Core/TyCo/Rep.hs ===================================== @@ -1688,11 +1688,9 @@ holes `HoleCo`, which get filled in later. -- | A coercion to be filled in by the type-checker. See Note [Coercion holes] data CoercionHole - = CoercionHole { ch_co_var :: CoVar - -- See Note [Coercion holes] wrinkle (COH2) - - , ch_ref :: IORef (Maybe CoercionPlusHoles) - } + = CH { ch_co_var :: CoVar -- See Note [Coercion holes] wrinkle (COH2) + , ch_ref :: IORef (Maybe CoercionPlusHoles) + } data CoercionPlusHoles = CPH { cph_co :: Coercion @@ -1714,7 +1712,7 @@ instance Data.Data CoercionHole where dataTypeOf _ = mkNoRepType "CoercionHole" instance Outputable CoercionHole where - ppr (CoercionHole { ch_co_var = cv }) = braces (ppr cv) + ppr (CH { ch_co_var = cv }) = braces (ppr cv) instance Outputable CoercionPlusHoles where ppr (CPH { cph_co = co, cph_holes = holes }) @@ -1723,7 +1721,7 @@ instance Outputable CoercionPlusHoles where , text "cph_holes =" <+> ppr holes ]) instance Uniquable CoercionHole where - getUnique (CoercionHole { ch_co_var = cv }) = getUnique cv + getUnique (CH { ch_co_var = cv }) = getUnique cv -- | A CoHoleSet stores a set of CoercionHoles that have been used to rewrite ===================================== compiler/GHC/Core/TyCo/Subst.hs ===================================== @@ -892,8 +892,7 @@ subst_co subst co in cos' `seqList` cos' -- See Note [Substituting in a coercion hole] - go_hole h@(CoercionHole { ch_co_var = cv }) - = h { ch_co_var = updateVarType go_ty cv } + go_hole h@(CH { ch_co_var = cv }) = h { ch_co_var = updateVarType go_ty cv } -- | Perform a substitution within a 'DVarSet' of free variables, -- returning the shallow free coercion variables. ===================================== compiler/GHC/Core/TyCo/Tidy.hs ===================================== @@ -357,7 +357,7 @@ tidyCo env co go_cv cv = tidyTyCoVarOcc env cv - go_hole (CoercionHole cv r) = (CoercionHole $! go_cv cv) r + go_hole (CH cv r) = (CH $! go_cv cv) r -- Tidy even the holes; tidied types should have tidied kinds tidyCos :: TidyEnv -> [Coercion] -> [Coercion] ===================================== compiler/GHC/Tc/Errors.hs ===================================== @@ -399,7 +399,7 @@ reportImplic ctxt implic@(Implic { ic_skols = tvs _ -> False warnRedundantConstraints :: SolverReportErrCtxt -> CtLocEnv -> SkolemInfoAnon -> [EvVar] -> TcM () --- See Note [Tracking redundant constraints] in GHC.Tc.Solver +-- See Note [Tracking needed EvIds] in GHC.Tc.Solver warnRedundantConstraints ctxt env info redundant_evs | not (cec_warn_redundant ctxt) = return () ===================================== compiler/GHC/Tc/Gen/Default.hs ===================================== @@ -22,7 +22,7 @@ import GHC.Tc.Errors.Types import GHC.Tc.Gen.HsType import GHC.Tc.Solver.Monad ( runTcS ) import GHC.Tc.Solver.Solve ( solveWanteds ) -import GHC.Tc.Types.Constraint ( isEmptyWC, andWC, mkSimpleWC ) +import GHC.Tc.Types.Constraint ( isSolvedWC, andWC, mkSimpleWC ) import GHC.Tc.Types.Origin ( CtOrigin(DefaultOrigin) ) import GHC.Tc.Utils.Env import GHC.Tc.Utils.Monad @@ -296,7 +296,7 @@ simplifyDefault cls dflt_ty@(L l _) , text "inst_pred:" <+> ppr inst_pred , text "all_wanteds " <+> ppr all_wanteds , text "unsolved:" <+> ppr unsolved ] - ; let is_instance = isEmptyWC unsolved + ; let is_instance = isSolvedWC unsolved ; return $ if | is_instance , ClassPred _ tys <- classifyPredType inst_pred ===================================== compiler/GHC/Tc/Gen/Expr.hs ===================================== @@ -199,6 +199,9 @@ tcPolyExprCheck expr res_ty -> TcM (HsExpr GhcTc) outer_skolemise (Left ty) thing_inside = do { (wrap, expr') <- tcSkolemiseExpectedType ty thing_inside + ; traceTc "outer_skol" (vcat [ text "wrap" <+> ppr wrap + , text "expr'" <+> ppr expr' + , text "wrapped" <+> ppr (mkHsWrap wrap expr') ]) ; return (mkHsWrap wrap expr') } outer_skolemise (Right sig) thing_inside = do { (wrap, expr') <- tcSkolemiseCompleteSig sig thing_inside ===================================== compiler/GHC/Tc/Solver/Default.hs ===================================== @@ -272,10 +272,9 @@ unsatisfiableEv_maybe v = (v,) <$> isUnsatisfiableCt_maybe (idType v) -- solve all the other Wanted constraints, including those nested within -- deeper implications. solveImplicationUsingUnsatGiven :: (EvVar, Type) -> Implication -> TcS Implication -solveImplicationUsingUnsatGiven - unsat_given@(given_ev,_) +solveImplicationUsingUnsatGiven unsat_given impl@(Implic { ic_wanted = wtd, ic_tclvl = tclvl, ic_binds = ev_binds_var - , ic_need_implic = inner, ic_info = skol_info }) + , ic_info = skol_info }) | isCoEvBindsVar ev_binds_var -- We can't use Unsatisfiable evidence in kinds. -- See Note [Coercion evidence only] in GHC.Tc.Types.Evidence. @@ -283,9 +282,7 @@ solveImplicationUsingUnsatGiven | otherwise = do { wcs <- nestImplicTcS skol_info ev_binds_var tclvl $ go_wc wtd ; setImplicationStatus $ - impl { ic_wanted = wcs - , ic_need_implic = inner `extendEvNeedSet` given_ev } } - -- Record that the Given is needed; I'm not certain why + impl { ic_wanted = wcs } } where go_wc :: WantedConstraints -> TcS WantedConstraints go_wc wc@(WC { wc_simple = wtds, wc_impl = impls }) ===================================== compiler/GHC/Tc/Solver/Dict.hs ===================================== @@ -663,6 +663,12 @@ Some wrinkles: of the caller (#15164). You might worry about having a solved-dict that uses a Given -- but that too will have been subject to short-cut solving so it's fine. +(SCS4) In `tryShortCutSolver`, when deciding if we have "completely solved" the + constraint, we must use `isSolvedWC` not `isEmptyWC`. The latter says "False" + if the residual constraint has any implications, even solved ones; and we + don't want to reject short-cut solving just because we have some leftover + /solved/ implications. #26805 was a case in point. + Note [Shortcut solving: incoherence] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This optimization relies on coherence of dictionaries to be correct. When we @@ -742,7 +748,8 @@ try_inert_dicts inerts dict_w@(DictCt { di_ev = ev_w, di_cls = cls, di_tys = tys = -- There is a matching dictionary in the inert set do { -- For a Wanted, first to try to solve it /completely/ from top level instances -- See Note [Shortcut solving] - ; short_cut_worked <- tryShortCutSolver (isGiven ev_i) dict_w + ; dflags <- getDynFlags + ; short_cut_worked <- tryShortCutSolver dflags (isGiven ev_i) dict_w ; if | short_cut_worked -> stopWith ev_w "shortCutSolver worked(1)" @@ -770,7 +777,8 @@ try_inert_dicts inerts dict_w@(DictCt { di_ev = ev_w, di_cls = cls, di_tys = tys ; continueWith () } -- See Note [Shortcut solving] -tryShortCutSolver :: Bool -- True <=> try the short-cut solver; False <=> don't +tryShortCutSolver :: DynFlags + -> Bool -- True <=> try the short-cut solver; False <=> don't -> DictCt -- Work item -> TcS Bool -- True <=> success -- We are about to solve a [W] constraint from a [G] constraint. We take @@ -778,30 +786,25 @@ tryShortCutSolver :: Bool -- True <=> try the short-cut solver; False <=> -- Note that we only do this for the sake of performance. Exactly the same -- programs should typecheck regardless of whether we take this step or -- not. See Note [Shortcut solving] -tryShortCutSolver try_short_cut dict_w@(DictCt { di_ev = ev_w }) - | not try_short_cut - = return False - | otherwise - = do { dflags <- getDynFlags - ; if | CtWanted (WantedCt { ctev_pred = pred_w }) <- ev_w - - , not (couldBeIPLike pred_w) -- Not for implicit parameters (#18627) +tryShortCutSolver dflags try_short_cut dict_w + | try_short_cut + , DictCt { di_ev = ev_w } <- dict_w + , CtWanted (WantedCt { ctev_pred = pred_w }) <- ev_w + , not (couldBeIPLike pred_w) -- Not for implicit parameters (#18627) - , not (xopt LangExt.IncoherentInstances dflags) + , not (xopt LangExt.IncoherentInstances dflags) -- If IncoherentInstances is on then we cannot rely on coherence of proofs -- in order to justify this optimization: The proof provided by the -- [G] constraint's superclass may be different from the top-level proof. -- See Note [Shortcut solving: incoherence] - - , gopt Opt_SolveConstantDicts dflags + , gopt Opt_SolveConstantDicts dflags -- Enabled by the -fsolve-constant-dicts flag - -> tryShortCutTcS $ -- tryTcS tries to completely solve some contraints - do { residual <- solveSimpleWanteds (unitBag (CDictCan dict_w)) - ; return (isEmptyWC residual) } + = tryShortCutTcS $ -- tryTcS tries to completely solve some contraints + solveSimpleWanteds (unitBag (CDictCan dict_w)) - | otherwise - -> return False } + | otherwise + = return False {- ******************************************************************* @@ -836,7 +839,7 @@ try_instances inerts work_item@(DictCt { di_ev = ev@(CtWanted wev), di_cls = cls ; case lkup_res of OneInst { cir_what = what } -> do { let is_local_given = case what of { LocalInstance -> True; _ -> False } - ; take_shortcut <- tryShortCutSolver is_local_given work_item + ; take_shortcut <- tryShortCutSolver dflags is_local_given work_item ; if take_shortcut then stopWith ev "shortCutSolver worked(2)" else do { insertSafeOverlapFailureTcS what work_item ===================================== compiler/GHC/Tc/Solver/Equality.hs ===================================== @@ -601,7 +601,7 @@ can_eq_nc_forall ev eq_rel s1 s2 -- they are kept alive by `neededEvVars`. Admittedly they are free in `all_co`, -- but only if we zonk it, which `neededEvVars` does not do (see test T7196). ev_binds_var <- getTcEvBindsVar - ; updTcEvBinds ev_binds_var nested_ev_binds_var + ; combineTcEvBinds ev_binds_var nested_ev_binds_var ; setWantedEq orig_dest (CPH { cph_co = all_co, cph_holes = emptyCoHoleSet }) -- emptyCoHoleSet: fully solved, so all_co has no holes ===================================== compiler/GHC/Tc/Solver/InertSet.hs ===================================== @@ -2127,7 +2127,7 @@ solveOneFromTheOther. - For everything else, we want to keep the outermost one. Reason: that makes it more likely that the inner one will turn out to be unused, - and can be reported as redundant. See Note [Tracking redundant constraints] + and can be reported as redundant. See Note [Tracking needed EvIds] in GHC.Tc.Solver. It transpires that using the outermost one is responsible for an @@ -2140,7 +2140,7 @@ solveOneFromTheOther. according to Note [Solving superclass constraints] in GHC.Tc.TyCl.Instance. (b) Prefer constraints that are not superclass selections. See - (TRC3) in Note [Tracking redundant constraints] in GHC.Tc.Solver. + (TRC3) in Note [Tracking needed EvIds] in GHC.Tc.Solver. (c) If both are GivenSCOrigin, chooose the one with the shallower superclass-selection depth, in the hope of identifying more correct ===================================== compiler/GHC/Tc/Solver/Monad.hs ===================================== @@ -15,7 +15,7 @@ module GHC.Tc.Solver.Monad ( failTcS, warnTcS, addErrTcS, wrapTcS, ctLocWarnTcS, runTcSEqualities, nestTcS, nestImplicTcS, tryShortCutTcS, nestFunDepsTcS, - setEvBindsTcS, setTcLevelTcS, updTcEvBinds, + setEvBindsTcS, setTcLevelTcS, selectNextWorkItem, getWorkList, @@ -58,7 +58,7 @@ module GHC.Tc.Solver.Monad ( getInstEnvs, getFamInstEnvs, -- Getting the environments getTopEnv, getGblEnv, getLclEnv, setSrcSpan, getTcEvBindsVar, getTcLevel, - getTcEvTyCoVars, getTcEvBindsMap, setTcEvBindsMap, + getTcEvBindsMap, setTcEvBindsMap, getTcEvBindsState, combineTcEvBinds, tcLookupClass, tcLookupId, tcLookupTyCon, -- Inerts @@ -1140,7 +1140,7 @@ csTraceTcM mk_doc {-# INLINE csTraceTcM #-} -- see Note [INLINE conditional tracing utilities] runTcS :: TcS a -- What to run - -> TcM (a, EvBindMap) + -> TcM (a, EvBindsMap) runTcS tcs = do { ev_binds_var <- TcM.newTcEvBinds ; res <- runTcSWithEvBinds ev_binds_var tcs @@ -1222,7 +1222,7 @@ runTcSWithEvBinds' mode ev_binds_var thing_inside ---------------------------- #if defined(DEBUG) -checkForCyclicBinds :: EvBindMap -> TcM () +checkForCyclicBinds :: EvBindsMap -> TcM () checkForCyclicBinds ev_binds_map | null cycles = return () @@ -1351,7 +1351,7 @@ nestTcS (TcS thing_inside) ; return res } -tryShortCutTcS :: TcS Bool -> TcS Bool +tryShortCutTcS :: TcS WantedConstraints -> TcS Bool -- Like nestTcS, but -- (a) be a no-op if the nested computation returns False -- (b) if (but only if) success, propagate nested bindings to the caller @@ -1380,26 +1380,43 @@ tryShortCutTcS (TcS thing_inside) , tcs_inerts = new_inert_var , tcs_worklist = new_wl_var } - ; TcM.traceTc "tryTcS {" $ + ; TcM.traceTc "tryShortCutTcS {" $ vcat [ text "old_ev_binds:" <+> ppr old_ev_binds_var , text "new_ev_binds:" <+> ppr new_ev_binds_var , ppr old_inerts ] - ; solved <- thing_inside nest_env - ; TcM.traceTc "tryTcS }" (ppr solved) - - ; if not solved - then return False - else do { -- Successfully solved - -- Add the new bindings to the existing ones - ; TcM.updTcEvBinds old_ev_binds_var new_ev_binds_var - - -- Update the existing inert set - ; new_inerts <- TcM.readTcRef new_inert_var - ; TcM.updTcRef inerts_var (`updateInertsWith` new_inerts) - - ; TcM.traceTc "tryTcS update" (ppr (inert_solved_dicts new_inerts)) - - ; return True } } + ; residual <- thing_inside nest_env + ; let solved = isSolvedWC residual + -- NB: isSolvedWC, not isEmptyWC (#26805). We might succeed + -- in fully-solving the constraint but still leave some + -- /solved/ implications in the residual. + -- See (SCS4) in Note [Shortcut solving] + ; TcM.traceTc "tryShortCutTcS }" (ppr solved) + + ; when solved $ -- Successfully solved + do { -- Add the new bindings to the existing ones + ; TcM.combineTcEvBinds old_ev_binds_var new_ev_binds_var + + -- We are discarding some implications; we must add their + -- NeededEvIds to the current bindings, lest we fail to record + -- some needed givens, and then wrongly prune away their bindings + ; TcM.addNeededEvIds old_ev_binds_var $ + foldr add_implic emptyVarSet $ + wc_impl residual + + -- Update the existing inert set + ; new_inerts <- TcM.readTcRef new_inert_var + ; TcM.updTcRef inerts_var (`updateInertsWith` new_inerts) } + + + ; return solved + } + where + add_implic :: Implication -> NeededEvIds -> NeededEvIds + add_implic implic@(Implic { ic_status = status }) needs + | IC_Solved { ics_dm = dm, ics_non_dm = non_dm } <- status + = needs `unionVarSet` dm `unionVarSet` non_dm + | otherwise + = pprPanic "tryShortCutTcS" (ppr implic) updateInertsWith :: InertSet -> InertSet -> InertSet -- Update the current inert set with bits from a nested solve, @@ -1465,21 +1482,21 @@ getTcEvBindsVar = TcS (return . tcs_ev_binds) getTcLevel :: TcS TcLevel getTcLevel = wrapTcS TcM.getTcLevel -getTcEvTyCoVars :: EvBindsVar -> TcS [TcCoercion] -getTcEvTyCoVars ev_binds_var - = wrapTcS $ TcM.getTcEvTyCoVars ev_binds_var +getTcEvBindsState :: EvBindsVar -> TcS EvBindsState +getTcEvBindsState ev_binds_var + = wrapTcS $ TcM.getTcEvBindsState ev_binds_var -getTcEvBindsMap :: EvBindsVar -> TcS EvBindMap +getTcEvBindsMap :: EvBindsVar -> TcS EvBindsMap getTcEvBindsMap ev_binds_var = wrapTcS $ TcM.getTcEvBindsMap ev_binds_var -setTcEvBindsMap :: EvBindsVar -> EvBindMap -> TcS () +setTcEvBindsMap :: EvBindsVar -> EvBindsMap -> TcS () setTcEvBindsMap ev_binds_var binds = wrapTcS $ TcM.setTcEvBindsMap ev_binds_var binds -updTcEvBinds :: EvBindsVar -> EvBindsVar -> TcS () -updTcEvBinds evb nested_evb - = wrapTcS $ TcM.updTcEvBinds evb nested_evb +combineTcEvBinds :: EvBindsVar -> EvBindsVar -> TcS () +combineTcEvBinds evb nested_evb + = wrapTcS $ TcM.combineTcEvBinds evb nested_evb getDefaultInfo :: TcS (DefaultEnv, Bool) getDefaultInfo = wrapTcS TcM.tcGetDefaultTys @@ -2029,12 +2046,9 @@ setWantedDict dest canonical tm HoleDest h -> pprPanic "setWantedEq: HoleDest" (ppr h) fillCoercionHole :: CoercionHole -> CoercionPlusHoles -> TcS () -fillCoercionHole hole co_plus_holes@(CPH { cph_co = co }) +fillCoercionHole hole co_plus_holes = do { ev_binds_var <- getTcEvBindsVar - ; wrapTcS $ do { -- Record usage of the free vars of this coercion - TcM.updTcRef (ebv_tcvs ev_binds_var) (co :) - ; -- Fill the hole - TcM.fillCoercionHole hole co_plus_holes } + ; wrapTcS $ TcM.addTcEvCoBind ev_binds_var hole co_plus_holes ; kickOutAfterFillingCoercionHole hole co_plus_holes } newTcEvBinds :: TcS EvBindsVar ===================================== compiler/GHC/Tc/Solver/Solve.hs ===================================== @@ -33,7 +33,6 @@ import qualified GHC.Tc.Zonk.TcType as TcM import GHC.Core.Predicate import GHC.Core.Reduction import GHC.Core.Coercion -import GHC.Core.TyCo.FVs( coVarsOfCos ) import GHC.Core.Class( classHasSCs ) import GHC.Types.Id( idType ) @@ -432,12 +431,10 @@ solveImplication imp@(Implic { ic_tclvl = tclvl , ic_wanted = final_wanted }) ; evbinds <- TcS.getTcEvBindsMap ev_binds_var - ; tcvs <- TcS.getTcEvTyCoVars ev_binds_var ; traceTcS "solveImplication end }" $ vcat [ text "has_given_eqs =" <+> ppr has_given_eqs , text "res_implic =" <+> ppr res_implic - , text "implication evbinds =" <+> ppr (evBindMapBinds evbinds) - , text "implication tvcs =" <+> ppr tcvs ] + , text "evbinds =" <+> ppr evbinds ] ; return res_implic } @@ -460,30 +457,27 @@ setImplicationStatus :: Implication -> TcS Implication -- * Prune unnecessary evidence bindings -- * Prune unnecessary child implications -- Precondition: the ic_status field is not already IC_Solved -setImplicationStatus implic@(Implic { ic_status = old_status - , ic_info = info - , ic_wanted = wc }) - = assertPpr (not (isSolvedStatus old_status)) (ppr info) $ - -- Precondition: we only set the status if it is not already solved - do { traceTcS "setImplicationStatus {" (ppr implic) - - ; let solved = isSolvedWC wc - ; new_implic <- neededEvVars implic - ; bad_telescope <- if solved then checkBadTelescope implic - else return False - - ; let new_status | insolubleWC wc = IC_Insoluble - | not solved = IC_Unsolved - | bad_telescope = IC_BadTelescope - | otherwise = IC_Solved { ics_dead = dead_givens } - dead_givens = findRedundantGivens new_implic - new_wc = pruneImplications wc - - final_implic = new_implic { ic_status = new_status - , ic_wanted = new_wc } - - ; traceTcS "setImplicationStatus }" (ppr final_implic) - ; return final_implic } +setImplicationStatus implic@(Implic { ic_wanted = wc }) + | insolubleWC wc + = do { traceTcS "setImplicationStatus:insoluble" (ppr implic) + ; return (implic { ic_status = IC_Insoluble }) } + + | not (isSolvedWC wc) + = -- Precondition: we only set the status if it is not /already/ solved + do { traceTcS "setImplicationStatus:in progress" (ppr implic) + ; return (implic { ic_status = IC_Unsolved }) } + + | otherwise -- The Wanteds are all solved + = do { traceTcS "setImplicationStatus:solved" (ppr implic) + ; bad_telescope <- checkBadTelescope implic + ; if bad_telescope + then return (implic { ic_status = IC_BadTelescope }) + else + + do { solved_status <- computeSolvedStatus implic + ; let pruned_wc = pruneImplications wc + ; return (implic { ic_status = solved_status + , ic_wanted = pruned_wc }) } } pruneImplications :: WantedConstraints -> WantedConstraints -- We have now recorded the `ic_need` variables of the child @@ -502,44 +496,6 @@ pruneImplications wc@(WC { wc_impl = implics }) | otherwise = True -- Otherwise, keep it -findRedundantGivens :: Implication -> [EvVar] -findRedundantGivens (Implic { ic_info = info, ic_need = need, ic_given = givens }) - | not (warnRedundantGivens info) -- Don't report redundant constraints at all - = [] -- See (TRC4) of Note [Tracking redundant constraints] - - | not (null unused_givens) -- Some givens are literally unused - = unused_givens - - -- Only try this if unused_givens is empty: see (TRC2a) - | otherwise -- All givens are used, but some might - = redundant_givens -- still be redundant e.g. (Eq a, Ord a) - - where - in_instance_decl = case info of { InstSkol {} -> True; _ -> False } - -- See Note [Redundant constraints in instance decls] - - unused_givens = filterOut is_used givens - - needed_givens_ignoring_default_methods = ens_fvs need - is_used given = is_type_error given - || given `elemVarSet` needed_givens_ignoring_default_methods - || (in_instance_decl && is_improving (idType given)) - - minimal_givens = mkMinimalBySCs evVarPred givens -- See (TRC2) - - is_minimal = (`elemVarSet` mkVarSet minimal_givens) - redundant_givens - | in_instance_decl = [] - | otherwise = filterOut is_minimal givens - - -- See #15232 - is_type_error id = containsUserTypeError False (idType id) - -- False <=> do not look under ty-fam apps, AppTy etc. - -- See (UTE1) in Note [Custom type errors in constraints]. - - is_improving pred -- (transSuperClasses p) does not include p - = any isImprovementPred (pred : transSuperClasses pred) - warnRedundantGivens :: SkolemInfoAnon -> Bool warnRedundantGivens (SigSkol ctxt _ _) = case ctxt of @@ -549,7 +505,7 @@ warnRedundantGivens (SigSkol ctxt _ _) warnRedundantGivens (InstSkol from _) -- Do not report redundant constraints for quantified constraints - -- See (TRC4) in Note [Tracking redundant constraints] + -- See (TRC4) in Note [Tracking needed EvIds] -- Fortunately it is easy to spot implications constraints that arise -- from quantified constraints, from their SkolInfo = case from of @@ -611,113 +567,142 @@ checkBadTelescope (Implic { ic_info = info | otherwise = go (later_skols `extendVarSet` one_skol) earlier_skols -neededEvVars :: Implication -> TcS Implication --- Find all the evidence variables that are "needed", --- /and/ delete dead evidence bindings +computeSolvedStatus :: Implication -> TcS ImplicStatus +-- Given a fully-solved implication, +-- - Figure out the right IC_Solved fields +-- - Delete unused evidence bindings -- --- See Note [Tracking redundant constraints] +-- See Note [Tracking needed EvIds] -- See Note [Delete dead Given evidence bindings] --- --- - Start from initial_seeds (from nested implications) --- --- - Add free vars of RHS of all Wanted evidence bindings --- and coercion variables accumulated in tcvs (all Wanted) --- --- - Generate 'needed', the needed set of EvVars, by doing transitive --- closure through Given bindings --- e.g. Needed {a,b} --- Given a = sc_sel a2 --- Then a2 is needed too --- --- - Prune out all Given bindings that are not needed - -neededEvVars implic@(Implic { ic_info = info +computeSolvedStatus (Implic { ic_info = info , ic_binds = ev_binds_var - , ic_wanted = WC { wc_impl = implics } - , ic_need_implic = old_need_implic -- See (TRC1) - }) - = do { ev_binds <- TcS.getTcEvBindsMap ev_binds_var - ; used_cos <- TcS.getTcEvTyCoVars ev_binds_var - - ; let -- Find the variables needed by `implics` - new_need_implic@(ENS { ens_dms = dm_seeds, ens_fvs = other_seeds }) - = foldr add_implic old_need_implic implics - -- Start from old_need_implic! See (TRC1) - - -- Get the variables needed by the solved bindings - -- (It's OK to use a non-deterministic fold here - -- because add_wanted is commutative.) - used_covars = coVarsOfCos used_cos - seeds_w = nonDetStrictFoldEvBindMap add_wanted used_covars ev_binds - - need_ignoring_dms = findNeededGivenEvVars ev_binds (other_seeds `unionVarSet` seeds_w) - need_from_dms = findNeededGivenEvVars ev_binds dm_seeds - need_full = need_ignoring_dms `unionVarSet` need_from_dms - - -- `need`: the Givens from outer scopes that are used in this implication - -- is_dm_skol: see (TRC5) - need | is_dm_skol info = ENS { ens_dms = trim ev_binds need_full - , ens_fvs = emptyVarSet } - | otherwise = ENS { ens_dms = trim ev_binds need_from_dms - , ens_fvs = trim ev_binds need_ignoring_dms } - - -- Delete dead Given evidence bindings + , ic_given = givens + , ic_wanted = WC { wc_impl = implics } }) + = do { ev_binds_state <- TcS.getTcEvBindsState ev_binds_var + + ; let EBS { ebs_binds = ev_binds, ebs_needs = local_needs } = ev_binds_state + + -- Gather the raw needed EvIds, from the + -- current evidence bindings `local_needs`, and the `implics` + (need_dm, need_non_dm) = foldr add_implic (emptyVarSet, local_needs) implics + + -- Do transitive closure through the evidence bindings + -- and delete all EvIds bound by the bindings + need_dm1 = findNeededGivenEvVars ev_binds need_dm + need_non_dm1 = findNeededGivenEvVars ev_binds need_non_dm + + -- Compute the redundant Givens + dead_givens = findRedundantGivens info need_non_dm1 givens + + -- Delete variables bound by ev_binds or by givens + need_dm2 = trim_needs need_dm1 + need_non_dm2 = trim_needs need_non_dm1 + + trim_needs :: NeededEvIds -> NeededEvIds + trim_needs needs = (needs `varSetMinusEvBindsMap` ev_binds) + `delVarSetList` givens + + -- Prune dead Given evidence bindings -- See Note [Delete dead Given evidence bindings] - ; let live_ev_binds = filterEvBindMap (needed_ev_bind need_full) ev_binds - ; TcS.setTcEvBindsMap ev_binds_var live_ev_binds - - ; traceTcS "neededEvVars" $ - vcat [ text "old_need_implic:" <+> ppr old_need_implic - , text "new_need_implic:" <+> ppr new_need_implic - , text "used_covars:" <+> ppr used_covars - , text "need_ignoring_dms:" <+> ppr need_ignoring_dms - , text "need_from_dms:" <+> ppr need_from_dms - , text "need:" <+> ppr need + ; let need_full = need_dm1 `unionVarSet` need_non_dm1 + pruned_ev_binds = filterEvBindsMap (keep_ev_bind need_full) ev_binds + ; TcS.setTcEvBindsMap ev_binds_var pruned_ev_binds + + ; traceTcS "computeSolvedStatus" $ + vcat [ text "local_needs:" <+> ppr local_needs + , text "need_dm:" <+> ppr need_dm + , text "need_non_dm:" <+> ppr need_non_dm + , text "need_dm1:" <+> ppr need_dm1 + , text "need_non_dm1:" <+> ppr need_non_dm1 + , text "need_dm2:" <+> ppr need_dm2 + , text "need_non_dm2:" <+> ppr need_non_dm2 , text "ev_binds:" <+> ppr ev_binds - , text "live_ev_binds:" <+> ppr live_ev_binds ] - ; return (implic { ic_need = need - , ic_need_implic = new_need_implic }) } - where - trim :: EvBindMap -> VarSet -> VarSet - -- Delete variables bound by Givens or bindings - trim ev_binds needs = needs `varSetMinusEvBindMap` ev_binds + , text "deleted ev_binds:" + <+> ppr (filterEvBindsMap (not . keep_ev_bind need_full) ev_binds) ] + + ; if is_dm_skol info + then return (IC_Solved { ics_dead = dead_givens + , ics_dm = need_dm2 `unionVarSet` need_non_dm2 + , ics_non_dm = emptyVarSet }) - add_implic :: Implication -> EvNeedSet -> EvNeedSet - add_implic (Implic { ic_given = givens, ic_need = need }) acc - = (need `delGivensFromEvNeedSet` givens) `unionEvNeedSet` acc + else return (IC_Solved { ics_dead = dead_givens + , ics_dm = need_dm2 + , ics_non_dm = need_non_dm2 }) } + where + add_implic :: Implication -> (NeededEvIds, NeededEvIds) -> (NeededEvIds, NeededEvIds) + add_implic (Implic { ic_status = status}) (dm2, non_dm2) + | IC_Solved { ics_dm = dm1, ics_non_dm = non_dm1 } <- status + = (dm1 `unionVarSet` dm2, non_dm1 `unionVarSet` non_dm2) + | otherwise + = pprPanic "computeSolvedStatus" (ppr implics) - needed_ev_bind needed (EvBind { eb_lhs = ev_var, eb_info = info }) + keep_ev_bind :: NeededEvIds -> EvBind -> Bool + -- False => we can discard this unused Given evidence binding + -- We always keep all the Wanted bindings + keep_ev_bind needed (EvBind { eb_lhs = ev_var, eb_info = info }) | EvBindGiven{} <- info = ev_var `elemVarSet` needed | otherwise = True -- Keep all wanted bindings - add_wanted :: EvBind -> VarSet -> VarSet - add_wanted (EvBind { eb_info = info, eb_rhs = rhs }) needs - | EvBindGiven{} <- info = needs -- Add the rhs vars of the Wanted bindings only - | otherwise = nestedEvIdsOfTerm rhs `unionVarSet` needs - is_dm_skol :: SkolemInfoAnon -> Bool is_dm_skol (MethSkol _ is_dm) = is_dm is_dm_skol _ = False -findNeededGivenEvVars :: EvBindMap -> VarSet -> VarSet +findRedundantGivens :: SkolemInfoAnon -> NeededEvIds -> [EvVar] -> [EvVar] +findRedundantGivens info need givens + | not (warnRedundantGivens info) -- Don't report redundant constraints at all + = [] -- See (TRC4) of Note [Tracking needed EvIds] + + | not (null unused_givens) -- Some givens are literally unused + = unused_givens + + -- Only try this if unused_givens is empty: see (TRC2a) + | otherwise -- All givens are used, but some might + = redundant_givens -- still be redundant e.g. (Eq a, Ord a) + + where + in_instance_decl = case info of { InstSkol {} -> True; _ -> False } + -- See Note [Redundant constraints in instance decls] + + unused_givens = filterOut is_used givens + + is_used given = is_type_error given + || given `elemVarSet` need + || (in_instance_decl && is_improving (idType given)) + + minimal_givens = mkMinimalBySCs evVarPred givens -- See (TRC2) + + is_minimal = (`elemVarSet` mkVarSet minimal_givens) + redundant_givens + | in_instance_decl = [] + | otherwise = filterOut is_minimal givens + + -- See #15232 + is_type_error id = containsUserTypeError False (idType id) + -- False <=> do not look under ty-fam apps, AppTy etc. + -- See (UTE1) in Note [Custom type errors in constraints]. + + is_improving pred -- (transSuperClasses p) does not include p + = any isImprovementPred (pred : transSuperClasses pred) + +findNeededGivenEvVars :: EvBindsMap -> NeededEvIds -> NeededEvIds -- Find all the Given evidence needed by seeds, -- looking transitively through bindings for Givens (only) findNeededGivenEvVars ev_binds seeds = transCloVarSet also_needs seeds where - also_needs :: VarSet -> VarSet - also_needs needs = nonDetStrictFoldUniqSet add emptyVarSet needs - -- It's OK to use a non-deterministic fold here because we immediately - -- forget about the ordering by creating a set - - add :: Var -> VarSet -> VarSet - add v needs - | Just ev_bind <- lookupEvBind ev_binds v - , EvBind { eb_info = EvBindGiven, eb_rhs = rhs } <- ev_bind - -- Look at Given bindings only - = nestedEvIdsOfTerm rhs `unionVarSet` needs - | otherwise - = needs + also_needs :: VarSet -> VarSet + also_needs needs = nonDetStrictFoldUniqSet add emptyVarSet needs + -- It's OK to use a non-deterministic fold here because we immediately + -- forget about the ordering by creating a set + + add :: Var -> VarSet -> VarSet + add v needs + | Just ev_bind <- lookupEvBind ev_binds v + , EvBind { eb_info = EvBindGiven, eb_rhs = rhs } <- ev_bind + -- Look at Given bindings only + = nestedEvIdsOfTerm rhs `unionVarSet` needs + | otherwise + = needs ------------------------------------------------- simplifyDelayedErrors :: Bag DelayedError -> TcS (Bag DelayedError) @@ -837,26 +822,80 @@ from TypeHole in HoleSort. See also Note [Extra-constraint holes in partial type signatures] in GHC.Tc.Gen.HsType. -Note [Tracking redundant constraints] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -With Opt_WarnRedundantConstraints, GHC can report which constraints of a type -signature (or instance declaration) are redundant, and can be omitted. Here is -an overview of how it works. +Note [Tracking needed EvIds] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The solver has some careful footwork to track: + + Which Given EvIds are in fact needed + +The relevant type is NeededEvIds, which is just a VarSet; it may be a mixture +of DictIds and CoVars. + +The NeededEvIds are used for two related purposes: -This is all tested in typecheck/should_compile/T20602 (among others). +* Redundant Givens. With Opt_WarnRedundantConstraints, GHC can report which + constraints of a type signature (or instance declaration) are redundant, and + can be omitted. We report this by computing which of the Implication's + `ic_givens` are not in the `NeededIds` for that Implication. -How tracking works: + See `findRedundantGivens` -* We maintain the `ic_need` field in an implication: - ic_need: the set of Given evidence variables that are needed somewhere - inside this implication; and are bound either by this implication - or by an enclosing one. +* Pruning useless evidence bindings. The solver creates lots of superclass + bindings, in the EvBinds of an Implication, just in case they are needed. So + we might get + \ (d::Ord a). let d2:Eq a = sc_sel d in ... + That `d2` binding may or may not be needed. For fully-solved implications, + GHC prunes away the un-needed bindings simply to reduce clutter; less to zonk, + less to desugar etc. -* `setImplicationStatus` does all the work: - - When the constraint solver finishes solving all the wanteds in - an implication, it sets its status to IC_Solved + See Note [Delete dead Given evidence bindings] + and the pruning code in `computeSolvedStatus` + +The tracking works like this: + +* An `Implication` has `ic_binds :: EvBindVar`. + +* That EvBindsVar holds a mutable reference to an `EvBindsState`. + +* That `EvBindsState` is a pair of + * ebs_binds :: EvBindsMap The evidence bindings themselves + * ebs_needs :: NeededEvIds The free EvIds of the Wanted `ebs_binds` + NB: only the Wanted ones! + + When we add a new binding to `ebs_binds` we also add to `ebs_needs` the free + EvIds of the RHS, iff the binding is Wanted. Why Wanted only? Each Wanted + binding solves a Wanted constraint, so we want them all. But Given bindings + are speculative; we work them out in `findNeededGivenEvVars`. + + See `GHC.Tc.Utils.Monad.addTcEvBind` and `addTcCoBind` + +* When an implication is fully Solved, we give it an `ic_status` of IC_Solved, + in `setImplicationStatus`: + data ImplicStatus + = ... + | IC_Solved { ics_dead :: [EvVar] + , ics_dm :: NeededEvIds + , ics_non_dm :: NeededEvIds } + The `ics_dead` field records the `ic_given` EvVars that are unused. + The other two fields record the NeededEvIds bound by /enclosing/ Implications; + that is, the `ic_given` from /this/ implication have been removed. + + Why two fields? See (TRC5) below. + +* `computeSolvedStatus` does all the work of computing these fields. + + - It combines the NeededEvIds from the sub-implications, plus + those from the bindings. + + - It uses a transitive closure algorithm across the Given bindings + so find the transitive needs. E.g. suppose the bindings are + [G] d2 = sc_sel d1 + [G] d3 = sc_sel d2 + [W] w1 = d3 + The `ebs_needs` for these bindings will be {d3} (free var of the RHS + of the Wanted bindings). But needing d3 needs d2 and needing d2 needs + d1. Hence the transitive closure in `findNeededGivenEvVars`. - - `neededEvVars`: computes which evidence variables are needed by an implication in `setImplicationStatus`. A variable is needed if a) It is in the ic_need field of this implication, computed in @@ -884,15 +923,13 @@ How tracking works: Wrinkles: -(TRC1) `pruneImplications` drops any sub-implications of an Implication - that are irrelevant for error reporting: - - no unsolved wanteds - - no sub-implications - - no redundant givens to report - But in doing so we must not lose track of the variables that those implications - needed! So we track the ic_needs of all child implications in `ic_need_implics`. - Crucially, this set includes things need by child implications that have been - discarded by `pruneImplications`. +(TRC1) In `setImplicationStatus`, for a fully-solved Implication, we take + the opportunity to discard any fully-solved child implications, using + `pruneImplications`. We can't drop /all/ fully-solved children; we can + drop a sub-implication only if: + - it has empty `ics_dead` (if not, keep the Implication so we can report the + redundant givens later + - it itself has no sub-implications (presumably with redundant givens) (TRC2) A Given can be redundant because it is implied by other Givens f :: (Eq a, Ord a) => blah -- Eq a unnecessary @@ -914,6 +951,7 @@ Wrinkles: the one from the user-written Eq a, not the superclass selection. This means we report the Ord a as redundant with -Wredundant-constraints, not the Eq a. Getting this wrong was #20602. + See Note [Replacement vs keeping] in GHC.Tc.Solver.InertSet (TRC4) We don't compute redundant givens for *every* implication; only for those which reply True to `warnRedundantGivens`: @@ -949,7 +987,7 @@ Wrinkles: and because of the degnerate instance for `Show (T a)`, we don't need the `Eq a` constraint. But we don't want to report it as redundant! -(TRC5) Consider this (#25992), where `op2` has a default method +(TRC5) Default methods. Consider this (#25992), where `op2` has a default method class C a where { op1, op2 :: a -> a ; op2 = op1 . op1 } instance C a => C [a] where @@ -960,17 +998,22 @@ Wrinkles: $dmop2 = op1 . op1 $fCList :: forall a. C a => C [a] - $fCList @a (d::C a) = MkC (\(x:a).x) ($dmop2 @a d) + $fCList @a (d::C a) = MkC (\(x:a).x) + ($dmop2 @[a] ($fCList @a d)) + + Notice that `d` gets passed (indirectly) to `$dmop`: it appears to be + "needed". But it's only /really/ needed if some /other/ method or + superclass (in this case `op1`) uses it. - Notice that `d` gets passed to `$dmop`: it is "needed". But it's only - /really/ needed if some /other/ method (in this case `op1`) uses it. + So, in IC_Solved rather than one set of NeededEvIds we have /two/: + ics_dm: needed /only/ by default-method calls + ics_non_dm: needed by something other than a default-method call + Then: + - For tracking redundant Givens we use only ics_non_dm + - For pruning evidence bindings we use the union of the two - So, rather than one set of "needed Givens" we use `EvNeedSet` to track - a /pair/ of sets: - ens_dms: needed /only/ by default-method calls - ens_fvs: needed by something other than a default-method call It's a bit of a palaver, but not really difficult. - All the logic is localised in `neededEvVars`. + All the logic is localised in `computeSolvedStatus`. But NOTE that this only applies to /vanilla/ default methods. For /generic/ default methods, like @@ -979,26 +1022,26 @@ Wrinkles: the (Eq a) constraint really is needed (e.g. class NFData and #25992). Hence the `Bool` field of `MethSkol` indicates a /vanilla/ default method. ------ Examples +----- Examples of reporting redundant Givens f, g, h :: (Eq a, Ord a) => a -> Bool f x = x == x g x = x > x h x = x == x && x > x - All of f,g,h will discover that they have two [G] Eq a constraints: one as - given and one extracted from the Ord a constraint. They will both discard - the latter; see (TRC3). +All of f,g,h will discover that they have two [G] Eq a constraints: one as +given and one extracted from the Ord a constraint. They will both discard +the latter; see (TRC3). - The body of f uses the [G] Eq a, but not the [G] Ord a. It will report a - redundant Ord a. +* The body of f uses the [G] Eq a, but not the [G] Ord a. It will report a + redundant Ord a. - The body of g uses the [G] Ord a, but not the [G] Eq a. It will report a - redundant Eq a. +* The body of g uses the [G] Ord a, but not the [G] Eq a. It will report a + redundant Eq a. - The body of h uses both [G] Ord a and [G] Eq a; each is used in a solved - Wanted evidence binding. But (TRC2) kicks in and discovers the Eq a - is redundant. +* The body of h uses both [G] Ord a and [G] Eq a; each is used in a solved + Wanted evidence binding. But (TRC2) kicks in and discovers the Eq a + is redundant. ----- Shortcomings @@ -1010,10 +1053,10 @@ Shortcoming 1. Consider k :: (Eq a, b ~ a) => a -> Bool k x = x == x -Currently (Nov 2021), j issues no warning, while k says that b ~ a -is redundant. This is because j uses the a ~ b constraint to rewrite -everything to be in terms of b, while k does none of that. This is -ridiculous, but I (Richard E) don't see a good fix. +Currently (Nov 2021), j issues no warning, while k says that b ~ a is +redundant. This is because j uses the a ~ b constraint to rewrite everything to +be in terms of b, while k does none of that. This is ridiculous, but I (Richard +E) don't see a good fix. Shortcoming 2. Removing a redundant constraint can cause clients to fail to compile, by making the function more polymorphic. Consider (#16154) @@ -1645,10 +1688,12 @@ solveWantedQCI mode ct@(CQuantCan (QCI { qci_ev = ev, qci_tvs = tvs -- carrying a record of which evidence variables are used -- See Note [Free vars of EvFun] in GHC.Tc.Types.Evidence do { setWantedDict dest EvCanonical $ - EvFun { et_tvs = skol_tvs, et_given = given_ev_vars + EvFun { et_tvs = skol_tvs + , et_given = given_ev_vars , et_binds = TcEvBinds ev_binds_var - , et_body = wantedCtEvEvId wanted_ev } + , et_body = wantedCtEvEvId wanted_ev } + ; traceTcS "solveWantedQCI" (ppr imp') ; return (Right imp') } } ===================================== compiler/GHC/Tc/TyCl/Instance.hs ===================================== @@ -1481,8 +1481,7 @@ Notice that implication for the whole instance declaration, with the expected skolems and givens. We need this to get the correct "redundant constraint" warnings, gathering all the uses from all the methods - and superclasses. See GHC.Tc.Solver Note [Tracking redundant - constraints] + and superclasses. See GHC.Tc.SolverSolve Note [Tracking needed EvIds] * The given constraints in the outer implication may generate evidence, notably by superclass selection. Since the method and @@ -1947,7 +1946,7 @@ tcMethods _skol_info dfun_id clas tyvars dfun_ev_vars inst_tys mismatched_meths = bind_nms `minusList` cls_meth_nms is_vanilla_dm :: DefMethSpec ty -> Bool - -- See (TRC5) in Note [Tracking redundant constraints] + -- See (TRC5) in Note [Tracking needed EvIds] -- in GHC.Tc.Solver.Solve is_vanilla_dm VanillaDM = True is_vanilla_dm (GenericDM {}) = False @@ -2022,7 +2021,7 @@ Instead, we take the following approach: ------------------------ tcMethodBody :: Bool -- True <=> This is a vanilla default method - -- See (TRC5) in Note [Tracking redundant constraints] + -- See (TRC5) in Note [Tracking needed EvIds] -- in GHC.Tc.Solver.Solve -> Class -> [TcTyVar] -> [EvVar] -> [TcType] -> TcEvBinds -> Bool ===================================== compiler/GHC/Tc/Types/Constraint.hs ===================================== @@ -65,7 +65,6 @@ module GHC.Tc.Types.Constraint ( ImplicStatus(..), isInsolubleStatus, isSolvedStatus, UserGiven, getGivensFromImplics, HasGivenEqs(..), checkImplicationInvariants, - EvNeedSet(..), emptyEvNeedSet, unionEvNeedSet, extendEvNeedSet, delGivensFromEvNeedSet, -- CtLocEnv CtLocEnv(..), setCtLocEnvLoc, setCtLocEnvLvl, getCtLocEnvLoc, getCtLocEnvLvl, ctLocEnvInGeneratedCode, @@ -1055,6 +1054,13 @@ mkImplicWC :: Bag Implication -> WantedConstraints mkImplicWC implic = emptyWC { wc_impl = implic } +-- | `isEmptyWC` sees if a `WantedConstraints` is truly empty, including +-- having no implications. +-- +-- It's possible that it might have /solved/ implications, which are left around +-- just so we can report unreachable code. So: +-- isEmptyWC implies isSolvedWC +-- but not vice versa isEmptyWC :: WantedConstraints -> Bool isEmptyWC (WC { wc_simple = f, wc_impl = i, wc_errors = errors }) = isEmptyBag f && isEmptyBag i && isEmptyBag errors @@ -1557,45 +1563,9 @@ data Implication ic_binds :: EvBindsVar, -- Points to the place to fill in the -- abstraction and bindings. - -- The ic_need fields keep track of which Given evidence - -- is used by this implication or its children - -- See Note [Tracking redundant constraints] - -- NB: these sets include stuff used by fully-solved nested implications - -- that have since been discarded - ic_need :: EvNeedSet, -- All needed Given evidence, from this implication - -- or outer ones - -- That is, /after/ deleting the binders of ic_binds, - -- but /before/ deleting ic_givens - - ic_need_implic :: EvNeedSet, -- Union of of the ic_need of all implications in ic_wanted - -- /including/ any fully-solved implications that have been - -- discarded by `pruneImplications`. This discarding is why - -- we need to keep this field in the first place. - ic_status :: ImplicStatus } -data EvNeedSet = ENS { ens_dms :: VarSet -- Needed only by default methods - , ens_fvs :: VarSet -- Needed by things /other than/ default methods - -- See (TRC5) in Note [Tracking redundant constraints] - } - -emptyEvNeedSet :: EvNeedSet -emptyEvNeedSet = ENS { ens_dms = emptyVarSet, ens_fvs = emptyVarSet } - -unionEvNeedSet :: EvNeedSet -> EvNeedSet -> EvNeedSet -unionEvNeedSet (ENS { ens_dms = dm1, ens_fvs = fv1 }) - (ENS { ens_dms = dm2, ens_fvs = fv2 }) - = ENS { ens_dms = dm1 `unionVarSet` dm2, ens_fvs = fv1 `unionVarSet` fv2 } - -extendEvNeedSet :: EvNeedSet -> Var -> EvNeedSet -extendEvNeedSet ens@(ENS { ens_fvs = fvs }) v = ens { ens_fvs = fvs `extendVarSet` v } - -delGivensFromEvNeedSet :: EvNeedSet -> [Var] -> EvNeedSet -delGivensFromEvNeedSet (ENS { ens_dms = dms, ens_fvs = fvs }) givens - = ENS { ens_dms = dms `delVarSetList` givens - , ens_fvs = fvs `delVarSetList` givens } - implicationPrototype :: CtLocEnv -> Implication implicationPrototype ct_loc_env = Implic { -- These fields must be initialised @@ -1612,14 +1582,21 @@ implicationPrototype ct_loc_env , ic_given = [] , ic_wanted = emptyWC , ic_given_eqs = MaybeGivenEqs - , ic_status = IC_Unsolved - , ic_need = emptyEvNeedSet - , ic_need_implic = emptyEvNeedSet } + , ic_status = IC_Unsolved } data ImplicStatus = IC_Solved -- All wanteds in the tree are solved, all the way down - { ics_dead :: [EvVar] } -- Subset of ic_given that are not needed - -- See Note [Tracking redundant constraints] in GHC.Tc.Solver + { ics_dead :: [EvVar] -- Subset of ic_given that are not needed + + , ics_dm :: NeededEvIds -- Enclosing Given EvIds that are needed by + -- calls to default methods (typically empty) + + , ics_non_dm :: NeededEvIds -- Enclosing Given EvIds that are needed, other than + -- calls to default methods + } + -- Reporting redundant givens: use ics_non_dm + -- Pruning evidence bindings: use ics_dm `union` ics_non_dm + -- See Note [Tracking needed EvIds] in GHC.Tc.Solver.Solve | IC_Insoluble -- At least one insoluble Wanted constraint in the tree @@ -1708,7 +1685,6 @@ instance Outputable Implication where , ic_given = given, ic_given_eqs = given_eqs , ic_wanted = wanted, ic_status = status , ic_binds = binds - , ic_need = need, ic_need_implic = need_implic , ic_info = info }) = hang (text "Implic" <+> lbrace) 2 (sep [ text "TcLevel =" <+> ppr tclvl @@ -1718,21 +1694,17 @@ instance Outputable Implication where , hang (text "Given =") 2 (pprEvVars given) , hang (text "Wanted =") 2 (ppr wanted) , text "Binds =" <+> ppr binds - , text "need =" <+> ppr need - , text "need_implic =" <+> ppr need_implic , pprSkolInfo info ] <+> rbrace) -instance Outputable EvNeedSet where - ppr (ENS { ens_dms = dms, ens_fvs = fvs }) - = text "ENS" <> braces (sep [text "ens_dms =" <+> ppr dms - , text "ens_fvs =" <+> ppr fvs]) - instance Outputable ImplicStatus where ppr IC_Insoluble = text "Insoluble" ppr IC_BadTelescope = text "Bad telescope" ppr IC_Unsolved = text "Unsolved" - ppr (IC_Solved { ics_dead = dead }) - = text "Solved" <+> (braces (text "Dead givens =" <+> ppr dead)) + ppr (IC_Solved { ics_dead = dead, ics_dm = dm, ics_non_dm = non_dm }) + = text "Solved" <> (braces $ + vcat [ text "Dead givens =" <+> ppr dead + , text "need_dm =" <+> ppr dm + , text "need_non_dm =" <+> ppr non_dm ]) checkTelescopeSkol :: SkolemInfoAnon -> Bool -- See Note [Checking telescopes] ===================================== compiler/GHC/Tc/Types/Evidence.hs ===================================== @@ -14,14 +14,15 @@ module GHC.Tc.Types.Evidence ( optSubTypeHsWrapper, -- * Evidence bindings - TcEvBinds(..), EvBindsVar(..), - EvBindMap(..), emptyEvBindMap, extendEvBinds, unionEvBindMap, + TcEvBinds(..), EvBindsVar(..), NeededEvIds, + EvBindsState(..), emptyEvBindsState, unionEvBindsState, addNeededEvIdsEBS, + EvBindsMap(..), emptyEvBindsMap, extendEvBinds, unionEvBindsMap, lookupEvBind, evBindMapBinds, - foldEvBindMap, nonDetStrictFoldEvBindMap, - filterEvBindMap, - isEmptyEvBindMap, + foldEvBindsMap, nonDetStrictFoldEvBindsMap, + filterEvBindsMap, + isEmptyEvBindsMap, evBindMapToVarSet, - varSetMinusEvBindMap, + varSetMinusEvBindsMap, EvBindInfo(..), EvBind(..), emptyTcEvBinds, isEmptyTcEvBinds, mkGivenEvBind, mkWantedEvBind, evBindVar, isCoEvBindsVar, @@ -725,30 +726,45 @@ data EvBindsVar ebv_uniq :: Unique, -- The Unique is for debug printing only - ebv_binds :: IORef EvBindMap, + ebv_binds :: IORef EvBindsState -- The main payload: the value-level evidence bindings -- (dictionaries etc) - -- Some Given, some Wanted - - ebv_tcvs :: IORef [TcCoercion] - -- When we solve a Wanted by filling in a CoercionHole, it is as - -- if we were adding an evidence binding - -- co_hole := coercion - -- We keep all these RHS coercions in a list, alongside `ebv_binds`, - -- so that we can report unused given constraints, - -- in GHC.Tc.Solver.neededEvVars - -- See Note [Tracking redundant constraints] in GHC.Tc.Solver - -- Also: we garbage-collect unused bindings in `neededEvVars`, - -- so this matters for correctness too. + -- Some Given, some Wanted; this is tracked in the `eb_info` + -- field of the `EvBind`. } | CoEvBindsVar { -- See Note [Coercion evidence only] -- See above for comments on ebv_uniq, ebv_tcvs - ebv_uniq :: Unique, - ebv_tcvs :: IORef [TcCoercion] + ebv_uniq :: Unique, + ebv_needs :: IORef NeededEvIds } +type NeededEvIds = VarSet + +data EvBindsState = EBS { ebs_binds :: EvBindsMap + , ebs_needs :: NeededEvIds } + +emptyEvBindsState :: EvBindsState +emptyEvBindsState = EBS { ebs_binds = emptyEvBindsMap + , ebs_needs = emptyVarSet } + +unionEvBindsState :: EvBindsState -> EvBindsState -> EvBindsState +unionEvBindsState (EBS { ebs_binds = bs1, ebs_needs = n1 }) + (EBS { ebs_binds = bs2, ebs_needs = n2 }) + = EBS { ebs_binds = bs1 `unionEvBindsMap` bs2 + , ebs_needs = n1 `unionVarSet` n2 } + +addNeededEvIdsEBS :: NeededEvIds -> EvBindsState -> EvBindsState +addNeededEvIdsEBS n1 ebs@(EBS { ebs_needs = n2 }) + = ebs { ebs_needs = n1 `unionVarSet` n2 } + +instance Outputable EvBindsState where + ppr (EBS { ebs_binds = bs, ebs_needs = needs }) + = text "EBS" <> (braces $ + sep [ text "needs =" <+> ppr needs + , text "binds =" <+> ppr bs ]) + instance Data.Data TcEvBinds where -- Placeholder; we can't traverse into TcEvBinds toConstr _ = abstractConstr "TcEvBinds" @@ -778,8 +794,8 @@ isCoEvBindsVar (CoEvBindsVar {}) = True isCoEvBindsVar (EvBindsVar {}) = False ----------------- -newtype EvBindMap - = EvBindMap { +newtype EvBindsMap + = EvBindsMap { ev_bind_varenv :: DVarEnv EvBind } -- Map from evidence variables to evidence terms -- We use @DVarEnv@ here to get deterministic ordering when we @@ -801,56 +817,56 @@ newtype EvBindMap -- See Note [Deterministic UniqFM] in GHC.Types.Unique.DFM for explanation why -- @UniqFM@ can lead to nondeterministic order. -emptyEvBindMap :: EvBindMap -emptyEvBindMap = EvBindMap { ev_bind_varenv = emptyDVarEnv } +emptyEvBindsMap :: EvBindsMap +emptyEvBindsMap = EvBindsMap { ev_bind_varenv = emptyDVarEnv } -extendEvBinds :: EvBindMap -> EvBind -> EvBindMap +extendEvBinds :: EvBindsMap -> EvBind -> EvBindsMap extendEvBinds bs ev_bind - = EvBindMap { ev_bind_varenv = extendDVarEnv (ev_bind_varenv bs) + = EvBindsMap { ev_bind_varenv = extendDVarEnv (ev_bind_varenv bs) (eb_lhs ev_bind) ev_bind } -- | Union two evidence binding maps -unionEvBindMap :: EvBindMap -> EvBindMap -> EvBindMap -unionEvBindMap (EvBindMap env1) (EvBindMap env2) = - EvBindMap { ev_bind_varenv = plusDVarEnv env1 env2 } +unionEvBindsMap :: EvBindsMap -> EvBindsMap -> EvBindsMap +unionEvBindsMap (EvBindsMap env1) (EvBindsMap env2) = + EvBindsMap { ev_bind_varenv = plusDVarEnv env1 env2 } -isEmptyEvBindMap :: EvBindMap -> Bool -isEmptyEvBindMap (EvBindMap m) = isEmptyDVarEnv m +isEmptyEvBindsMap :: EvBindsMap -> Bool +isEmptyEvBindsMap (EvBindsMap m) = isEmptyDVarEnv m -lookupEvBind :: EvBindMap -> EvVar -> Maybe EvBind +lookupEvBind :: EvBindsMap -> EvVar -> Maybe EvBind lookupEvBind bs = lookupDVarEnv (ev_bind_varenv bs) -evBindMapBinds :: EvBindMap -> Bag EvBind -evBindMapBinds = foldEvBindMap consBag emptyBag +evBindMapBinds :: EvBindsMap -> Bag EvBind +evBindMapBinds = foldEvBindsMap consBag emptyBag -foldEvBindMap :: (EvBind -> a -> a) -> a -> EvBindMap -> a -foldEvBindMap k z bs = foldDVarEnv k z (ev_bind_varenv bs) +foldEvBindsMap :: (EvBind -> a -> a) -> a -> EvBindsMap -> a +foldEvBindsMap k z bs = foldDVarEnv k z (ev_bind_varenv bs) -- See Note [Deterministic UniqFM] to learn about nondeterminism. -- If you use this please provide a justification why it doesn't introduce -- nondeterminism. -nonDetStrictFoldEvBindMap :: (EvBind -> a -> a) -> a -> EvBindMap -> a -nonDetStrictFoldEvBindMap k z bs = nonDetStrictFoldDVarEnv k z (ev_bind_varenv bs) +nonDetStrictFoldEvBindsMap :: (EvBind -> a -> a) -> a -> EvBindsMap -> a +nonDetStrictFoldEvBindsMap k z bs = nonDetStrictFoldDVarEnv k z (ev_bind_varenv bs) -filterEvBindMap :: (EvBind -> Bool) -> EvBindMap -> EvBindMap -filterEvBindMap k (EvBindMap { ev_bind_varenv = env }) - = EvBindMap { ev_bind_varenv = filterDVarEnv k env } +filterEvBindsMap :: (EvBind -> Bool) -> EvBindsMap -> EvBindsMap +filterEvBindsMap k (EvBindsMap { ev_bind_varenv = env }) + = EvBindsMap { ev_bind_varenv = filterDVarEnv k env } -evBindMapToVarSet :: EvBindMap -> VarSet -evBindMapToVarSet (EvBindMap dve) = unsafeUFMToUniqSet (mapUFM evBindVar (udfmToUfm dve)) +evBindMapToVarSet :: EvBindsMap -> VarSet +evBindMapToVarSet (EvBindsMap dve) = unsafeUFMToUniqSet (mapUFM evBindVar (udfmToUfm dve)) -varSetMinusEvBindMap :: VarSet -> EvBindMap -> VarSet -varSetMinusEvBindMap vs (EvBindMap dve) = vs `uniqSetMinusUDFM` dve +varSetMinusEvBindsMap :: VarSet -> EvBindsMap -> VarSet +varSetMinusEvBindsMap vs (EvBindsMap dve) = vs `uniqSetMinusUDFM` dve -instance Outputable EvBindMap where - ppr (EvBindMap m) = ppr m +instance Outputable EvBindsMap where + ppr (EvBindsMap m) = ppr m -data EvBindInfo - = EvBindGiven { -- See Note [Tracking redundant constraints] in GHC.Tc.Solver - } - | EvBindWanted { ebi_canonical :: CanonicalEvidence -- See Note [Desugaring non-canonical evidence] - } +data EvBindInfo -- See Note [Tracking needed EvIds] in GHC.Tc.Solver.Solve + = EvBindGiven + | EvBindWanted + { ebi_canonical :: CanonicalEvidence } + -- See Note [Desugaring non-canonical evidence] ----------------- -- All evidence is bound by EvBinds; no side effects @@ -1334,7 +1350,7 @@ can just squeeze by. Here's how. * Each EvBindsVar in an et_binds field of an EvFun is /also/ in the ic_binds field of an Implication * So we can track usage via the processing for that implication, - (see Note [Tracking redundant constraints] in GHC.Tc.Solver). + (see Note [Tracking needed EvIds] in GHC.Tc.Solver). We can ignore usage from the EvFun altogether. * /After/ typechecking `evTermFVs` is used by `GHC.Iface.Ext.Ast`, but by ===================================== compiler/GHC/Tc/Types/Origin.hs ===================================== @@ -94,7 +94,7 @@ data UserTypeCtxt -- Also used for types in SPECIALISE pragmas Name -- Name of the function ReportRedundantConstraints - -- See Note [Tracking redundant constraints] in GHC.Tc.Solver + -- See Note [Tracking needed EvIds] in GHC.Tc.Solver -- This field is usually 'WantRCC', but 'NoRCC' for -- * Record selectors (not important here) -- * Class and instance methods. Here the code may legitimately @@ -285,7 +285,7 @@ data SkolemInfoAnon | MethSkol Name Bool -- Bound by the type of class method op -- True <=> it's a vanilla default method -- False <=> it's a user-written, or generic-default, method - -- See (TRC5) in Note [Tracking redundant constraints] + -- See (TRC5) in Note [Tracking needed EvIds] -- in GHC.Tc.Solver.Solve | FamInstSkol -- Bound at a family instance decl ===================================== compiler/GHC/Tc/Utils/Monad.hs ===================================== @@ -104,9 +104,10 @@ module GHC.Tc.Utils.Monad( -- * Type constraints newTcEvBinds, newNoTcEvBinds, cloneEvBindsVar, - addTcEvBind, addTcEvBinds, addTopEvBinds, - getTcEvBindsMap, setTcEvBindsMap, updTcEvBinds, - getTcEvTyCoVars, chooseUniqueOccTc, + addTcEvCoBind, addTcEvBind, addTopEvBinds, + getTcEvBindsMap, getTcEvBindsState, + setTcEvBindsMap, combineTcEvBinds, addNeededEvIds, + chooseUniqueOccTc, getConstraintVar, setConstraintVar, emitConstraints, emitSimple, emitSimples, emitImplication, emitImplications, ensureReflMultiplicityCo, @@ -118,6 +119,7 @@ module GHC.Tc.Utils.Monad( getLclTypeEnv, setLclTypeEnv, traceTcConstraints, emitNamedTypeHole, IsExtraConstraint(..), emitAnonTypeHole, + fillCoercionHole, -- * Template Haskell context recordThUse, recordThNeededRuntimeDeps, @@ -187,12 +189,13 @@ import GHC.Unit.Module.Warnings import GHC.Unit.Home.PackageTable import GHC.Core.UsageEnv - import GHC.Core.Coercion ( isReflCo ) import GHC.Core.Multiplicity import GHC.Core.InstEnv import GHC.Core.FamInstEnv import GHC.Core.Type( mkNumLitTy ) +import GHC.Core.TyCo.Rep( CoercionHole(..) ) +import GHC.Core.TyCo.FVs( coVarsOfCo ) import GHC.Core.TyCon ( TyCon ) import GHC.Driver.Env @@ -230,6 +233,7 @@ import GHC.Types.SafeHaskell import GHC.Types.Id import GHC.Types.TypeEnv import GHC.Types.Var.Env +import GHC.Types.Var.Set import GHC.Types.SrcLoc import GHC.Types.Name.Env import GHC.Types.Name.Set @@ -1660,6 +1664,105 @@ tryTcDiscardingErrs' validate recover_invalid recover_error thing_inside recover_error } +{- Note [Constraints and errors] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider this (#12124): + + foo :: Maybe Int + foo = return (case Left 3 of + Left -> 1 -- Hard error here! + _ -> 0) + +The call to 'return' will generate a (Monad m) wanted constraint; but +then there'll be "hard error" (i.e. an exception in the TcM monad), from +the unsaturated Left constructor pattern. + +We'll recover in tcPolyBinds, using recoverM. But then the final +tcSimplifyTop will see that (Monad m) constraint, with 'm' utterly +un-filled-in, and will emit a misleading error message. + +The underlying problem is that an exception interrupts the constraint +gathering process. Bottom line: if we have an exception, it's best +simply to discard any gathered constraints. Hence in 'attemptM' we +capture the constraints in a fresh variable, and only emit them into +the surrounding context if we exit normally. If an exception is +raised, simply discard the collected constraints... we have a hard +error to report. So this capture-the-emit dance isn't as stupid as it +looks :-). + +However suppose we throw an exception inside an invocation of +captureConstraints, and discard all the constraints. Some of those +constraints might be "variable out of scope" Hole constraints, and that +might have been the actual original cause of the exception! For +example (#12529): + f = p @ Int +Here 'p' is out of scope, so we get an insoluble Hole constraint. But +the visible type application fails in the monad (throws an exception). +We must not discard the out-of-scope error. + +It's distressingly delicate though: + +* If we discard too /many/ constraints we may fail to report the error + that led us to interrupt the constraint gathering process. + + One particular example "variable out of scope" Hole constraints. For + example (#12529): + f = p @ Int + Here 'p' is out of scope, so we get an insoluble Hole constraint. But + the visible type application fails in the monad (throws an exception). + We must not discard the out-of-scope error. + + Also GHC.Tc.Solver.simplifyAndEmitFlatConstraints may fail having + emitted some constraints with skolem-escape problems. + +* If we discard too /few/ constraints, we may get the misleading + class constraints mentioned above. + + We may /also/ end up taking constraints built at some inner level, and + emitting them (via the exception catching in `tryCaptureConstraints`) at some + outer level, and then breaking the TcLevel invariants See Note [TcLevel + invariants] in GHC.Tc.Utils.TcType + +So `dropMisleading` has a horridly ad-hoc structure: + +* It keeps only /insoluble/ flat constraints (which are unlikely to very visibly + trip up on the TcLevel invariant) + +* But it keeps all /implication/ constraints (except the class constraints + inside them). The implication constraints are OK because they set the ambient + level before attempting to solve any inner constraints. + +Ugh! I hate this. But it seems to work. + +Other wrinkles + +(CERR1) Note that freshly-generated constraints like (Int ~ Bool), or + ((a -> b) ~ Int) are all CNonCanonical, and hence won't be flagged as + insoluble. The constraint solver does that. So they'll be discarded. + That's probably ok; but see th/5358 as a not-so-good example: + t1 :: Int + t1 x = x -- Manifestly wrong + + foo = $(...raises exception...) + We report the exception, but not the bug in t1. Oh well. Possible + solution: make GHC.Tc.Utils.Unify.uType spot manifestly-insoluble constraints. + +(CERR2) In #26015 I found that from the constraints + [W] alpha ~ Int -- A class constraint + [W] F alpha ~# Bool -- An equality constraint + we were dropping the first (because it's a class constraint) but not the + second, and then getting a misleading error message from the second. As + #25607 shows, we can get not just one but a zillion bogus messages, which + conceal the one genuine error. Boo. + + For now I have added an even more ad-hoc "drop class constraints except + equality classes (~) and (~~)"; see `dropMisleading`. That just kicks the can + down the road; but this problem seems somewhat rare anyway. The code in + `dropMisleading` hasn't changed for years. + +It would be great to have a more systematic solution to this entire mess. +-} + {- ************************************************************************ * * @@ -1854,108 +1957,113 @@ debugTc thing addTopEvBinds :: Bag EvBind -> TcM a -> TcM a addTopEvBinds new_ev_binds thing_inside - =updGblEnv upd_env thing_inside + = updGblEnv upd_env thing_inside where upd_env tcg_env = tcg_env { tcg_ev_binds = tcg_ev_binds tcg_env `unionBags` new_ev_binds } newTcEvBinds :: TcM EvBindsVar -newTcEvBinds = do { binds_ref <- newTcRef emptyEvBindMap - ; tcvs_ref <- newTcRef [] +newTcEvBinds = do { binds_ref <- newTcRef emptyEvBindsState ; uniq <- newUnique ; traceTc "newTcEvBinds" (text "unique =" <+> ppr uniq) ; return (EvBindsVar { ebv_binds = binds_ref - , ebv_tcvs = tcvs_ref , ebv_uniq = uniq }) } -- | Creates an EvBindsVar incapable of holding any bindings. It still --- tracks covar usages (see comments on ebv_tcvs in "GHC.Tc.Types.Evidence"), thus +-- tracks covar usages (see comments on ebv_needs in "GHC.Tc.Types.Evidence"), thus -- must be made monadically newNoTcEvBinds :: TcM EvBindsVar newNoTcEvBinds - = do { tcvs_ref <- newTcRef [] + = do { tcvs_ref <- newTcRef emptyVarSet ; uniq <- newUnique ; traceTc "newNoTcEvBinds" (text "unique =" <+> ppr uniq) - ; return (CoEvBindsVar { ebv_tcvs = tcvs_ref - , ebv_uniq = uniq }) } + ; return (CoEvBindsVar { ebv_needs = tcvs_ref + , ebv_uniq = uniq }) } cloneEvBindsVar :: EvBindsVar -> TcM EvBindsVar -- Clone the refs, so that any binding created when -- solving don't pollute the original cloneEvBindsVar ebv@(EvBindsVar {}) - = do { binds_ref <- newTcRef emptyEvBindMap - ; tcvs_ref <- newTcRef [] - ; return (ebv { ebv_binds = binds_ref - , ebv_tcvs = tcvs_ref }) } + = do { binds_ref <- newTcRef emptyEvBindsState + ; uniq <- newUnique + ; return (ebv { ebv_uniq = uniq + , ebv_binds = binds_ref }) } cloneEvBindsVar ebv@(CoEvBindsVar {}) - = do { tcvs_ref <- newTcRef [] - ; return (ebv { ebv_tcvs = tcvs_ref }) } + = do { tcvs_ref <- newTcRef emptyVarSet + ; return (ebv { ebv_needs = tcvs_ref }) } -getTcEvTyCoVars :: EvBindsVar -> TcM [TcCoercion] -getTcEvTyCoVars ev_binds_var - = readTcRef (ebv_tcvs ev_binds_var) +getTcEvBindsMap :: EvBindsVar -> TcM EvBindsMap +getTcEvBindsMap ebv = do { EBS { ebs_binds = bs } <- getTcEvBindsState ebv + ; return bs } -getTcEvBindsMap :: EvBindsVar -> TcM EvBindMap -getTcEvBindsMap (EvBindsVar { ebv_binds = ev_ref }) +getTcEvBindsState :: EvBindsVar -> TcM EvBindsState +getTcEvBindsState (EvBindsVar { ebv_binds = ev_ref }) = readTcRef ev_ref -getTcEvBindsMap (CoEvBindsVar {}) - = return emptyEvBindMap - -setTcEvBindsMap :: EvBindsVar -> EvBindMap -> TcM () -setTcEvBindsMap (EvBindsVar { ebv_binds = ev_ref }) binds - = writeTcRef ev_ref binds -setTcEvBindsMap v@(CoEvBindsVar {}) ev_binds - | isEmptyEvBindMap ev_binds - = return () - | otherwise - = pprPanic "setTcEvBindsMap" (ppr v $$ ppr ev_binds) - -updTcEvBinds :: EvBindsVar -> EvBindsVar -> TcM () -updTcEvBinds (EvBindsVar { ebv_binds = old_ebv_ref, ebv_tcvs = old_tcv_ref }) - (EvBindsVar { ebv_binds = new_ebv_ref, ebv_tcvs = new_tcv_ref }) +getTcEvBindsState (CoEvBindsVar { ebv_needs = needs_ref }) + = do { needs <- readTcRef needs_ref + ; return (EBS { ebs_binds = emptyEvBindsMap, ebs_needs = needs }) } + +setTcEvBindsMap :: EvBindsVar -> EvBindsMap -> TcM () +setTcEvBindsMap (EvBindsVar { ebv_binds = ev_ref }) ev_binds + = updTcRef ev_ref (\ebs -> ebs { ebs_binds = ev_binds }) +setTcEvBindsMap (CoEvBindsVar {}) ev_binds + = assertPpr (isEmptyEvBindsMap ev_binds) (ppr ev_binds) $ + return () + +combineTcEvBinds :: EvBindsVar -> EvBindsVar -> TcM () +combineTcEvBinds (EvBindsVar { ebv_binds = old_ebv_ref }) + (EvBindsVar { ebv_binds = new_ebv_ref }) = do { new_ebvs <- readTcRef new_ebv_ref - ; updTcRef old_ebv_ref (`unionEvBindMap` new_ebvs) - ; new_tcvs <- readTcRef new_tcv_ref - ; updTcRef old_tcv_ref (new_tcvs ++) } -updTcEvBinds (EvBindsVar { ebv_tcvs = old_tcv_ref }) - (CoEvBindsVar { ebv_tcvs = new_tcv_ref }) + ; updTcRef old_ebv_ref (`unionEvBindsState` new_ebvs) } +combineTcEvBinds (EvBindsVar { ebv_binds = old_tcv_ref }) + (CoEvBindsVar { ebv_needs = new_tcv_ref }) = do { new_tcvs <- readTcRef new_tcv_ref - ; updTcRef old_tcv_ref (new_tcvs ++) } -updTcEvBinds (CoEvBindsVar { ebv_tcvs = old_tcv_ref }) - (CoEvBindsVar { ebv_tcvs = new_tcv_ref }) + ; updTcRef old_tcv_ref (addNeededEvIdsEBS new_tcvs) } +combineTcEvBinds (CoEvBindsVar { ebv_needs = old_tcv_ref }) + (CoEvBindsVar { ebv_needs = new_tcv_ref }) = do { new_tcvs <- readTcRef new_tcv_ref - ; updTcRef old_tcv_ref (new_tcvs ++) } -updTcEvBinds old_var new_var - = pprPanic "updTcEvBinds" (ppr old_var $$ ppr new_var) + ; updTcRef old_tcv_ref (unionVarSet new_tcvs) } +combineTcEvBinds old_var new_var + = pprPanic "combineTcEvBinds" (ppr old_var $$ ppr new_var) -- Terms inside types, no good +addNeededEvIds :: EvBindsVar -> NeededEvIds -> TcM () +addNeededEvIds (EvBindsVar { ebv_binds = bs_ref }) needed + = updTcRef bs_ref (addNeededEvIdsEBS needed) +addNeededEvIds (CoEvBindsVar { ebv_needs = need_ref }) needed + = updTcRef need_ref (unionVarSet needed) + +addTcEvCoBind :: EvBindsVar -> CoercionHole -> CoercionPlusHoles -> TcM () +addTcEvCoBind ebv hole co_plus_holes@(CPH { cph_co = co }) + = do { fillCoercionHole hole co_plus_holes + -- Record usage of the free vars of this coercion + ; addNeededEvIds ebv (coVarsOfCo co) } + addTcEvBind :: EvBindsVar -> EvBind -> TcM () -- Add a binding to the TcEvBinds by side effect -addTcEvBind (EvBindsVar { ebv_binds = ev_ref, ebv_uniq = u }) ev_bind - = do { bnds <- readTcRef ev_ref - ; let bnds' = extendEvBinds bnds ev_bind +addTcEvBind (EvBindsVar { ebv_binds = ev_ref, ebv_uniq = u }) + ev_bind@(EvBind { eb_info = info, eb_rhs = rhs }) + = do { EBS { ebs_binds = bnds, ebs_needs = needs } <- readTcRef ev_ref + ; let bnds' = extendEvBinds bnds ev_bind + needs' = case info of + EvBindWanted {} -> nestedEvIdsOfTerm rhs + `unionVarSet` needs + EvBindGiven {} -> needs + ; traceTc "addTcEvBind" $ vcat [ text "EvBindsVar:" <+> ppr u , text "ev_bind:" <+> ppr ev_bind , text "bnds:" <+> ppr bnds - , text "bnds':" <+> ppr bnds' ] - ; writeTcRef ev_ref bnds' } + , text "bnds':" <+> ppr bnds' + , text "needs" <+> ppr needs + , text "needs'" <+> ppr needs' ] + + ; writeTcRef ev_ref $ + EBS { ebs_binds = bnds', ebs_needs = needs' } } + addTcEvBind (CoEvBindsVar { ebv_uniq = u }) ev_bind = pprPanic "addTcEvBind CoEvBindsVar" (ppr ev_bind $$ ppr u) -addTcEvBinds :: EvBindsVar -> EvBindMap -> TcM () --- ^ Add a collection of binding to the TcEvBinds by side effect -addTcEvBinds _ new_ev_binds - | isEmptyEvBindMap new_ev_binds - = return () -addTcEvBinds (EvBindsVar { ebv_binds = ev_ref, ebv_uniq = u }) new_ev_binds - = do { traceTc "addTcEvBinds" $ ppr u $$ - ppr new_ev_binds - ; old_bnds <- readTcRef ev_ref - ; writeTcRef ev_ref (old_bnds `unionEvBindMap` new_ev_binds) } -addTcEvBinds (CoEvBindsVar { ebv_uniq = u }) new_ev_binds - = pprPanic "addTcEvBinds CoEvBindsVar" (ppr new_ev_binds $$ ppr u) - chooseUniqueOccTc :: (OccSet -> OccName) -> TcM OccName chooseUniqueOccTc fn = do { env <- getGblEnv @@ -2137,111 +2245,22 @@ emitNamedTypeHole (name, tv) where occ = nameOccName name -{- Note [Constraints and errors] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Consider this (#12124): - - foo :: Maybe Int - foo = return (case Left 3 of - Left -> 1 -- Hard error here! - _ -> 0) - -The call to 'return' will generate a (Monad m) wanted constraint; but -then there'll be "hard error" (i.e. an exception in the TcM monad), from -the unsaturated Left constructor pattern. - -We'll recover in tcPolyBinds, using recoverM. But then the final -tcSimplifyTop will see that (Monad m) constraint, with 'm' utterly -un-filled-in, and will emit a misleading error message. - -The underlying problem is that an exception interrupts the constraint -gathering process. Bottom line: if we have an exception, it's best -simply to discard any gathered constraints. Hence in 'attemptM' we -capture the constraints in a fresh variable, and only emit them into -the surrounding context if we exit normally. If an exception is -raised, simply discard the collected constraints... we have a hard -error to report. So this capture-the-emit dance isn't as stupid as it -looks :-). - -However suppose we throw an exception inside an invocation of -captureConstraints, and discard all the constraints. Some of those -constraints might be "variable out of scope" Hole constraints, and that -might have been the actual original cause of the exception! For -example (#12529): - f = p @ Int -Here 'p' is out of scope, so we get an insoluble Hole constraint. But -the visible type application fails in the monad (throws an exception). -We must not discard the out-of-scope error. - -It's distressingly delicate though: +-- | Put a value in a coercion hole +fillCoercionHole :: CoercionHole -> CoercionPlusHoles -> TcM () +fillCoercionHole (CH { ch_ref = ref, ch_co_var = cv }) co + = do { when debugIsOn $ + do { cts <- readTcRef ref + ; whenIsJust cts $ \old_co -> + pprPanic "Filling a filled coercion hole" (ppr cv $$ ppr co $$ ppr old_co) } + ; traceTc "Filling coercion hole" (ppr cv <+> text ":=" <+> ppr co) + ; writeTcRef ref (Just co) } -* If we discard too /many/ constraints we may fail to report the error - that led us to interrupt the constraint gathering process. - One particular example "variable out of scope" Hole constraints. For - example (#12529): - f = p @ Int - Here 'p' is out of scope, so we get an insoluble Hole constraint. But - the visible type application fails in the monad (throws an exception). - We must not discard the out-of-scope error. - - Also GHC.Tc.Solver.simplifyAndEmitFlatConstraints may fail having - emitted some constraints with skolem-escape problems. - -* If we discard too /few/ constraints, we may get the misleading - class constraints mentioned above. - - We may /also/ end up taking constraints built at some inner level, and - emitting them (via the exception catching in `tryCaptureConstraints` at some - outer level, and then breaking the TcLevel invariants See Note [TcLevel - invariants] in GHC.Tc.Utils.TcType - -So `dropMisleading` has a horridly ad-hoc structure: - -* It keeps only /insoluble/ flat constraints (which are unlikely to very visibly - trip up on the TcLevel invariant - -* But it keeps all /implication/ constraints (except the class constraints - inside them). The implication constraints are OK because they set the ambient - level before attempting to solve any inner constraints. - -Ugh! I hate this. But it seems to work. - -Other wrinkles - -(CERR1) Note that freshly-generated constraints like (Int ~ Bool), or - ((a -> b) ~ Int) are all CNonCanonical, and hence won't be flagged as - insoluble. The constraint solver does that. So they'll be discarded. - That's probably ok; but see th/5358 as a not-so-good example: - t1 :: Int - t1 x = x -- Manifestly wrong - - foo = $(...raises exception...) - We report the exception, but not the bug in t1. Oh well. Possible - solution: make GHC.Tc.Utils.Unify.uType spot manifestly-insoluble constraints. - -(CERR2) In #26015 I found that from the constraints - [W] alpha ~ Int -- A class constraint - [W] F alpha ~# Bool -- An equality constraint - we were dropping the first (becuase it's a class constraint) but not the - second, and then getting a misleading error message from the second. As - #25607 shows, we can get not just one but a zillion bogus messages, which - conceal the one genuine error. Boo. - - For now I have added an even more ad-hoc "drop class constraints except - equality classes (~) and (~~)"; see `dropMisleading`. That just kicks the can - down the road; but this problem seems somewhat rare anyway. The code in - `dropMisleading` hasn't changed for years. - -It would be great to have a more systematic solution to this entire mess. - - -************************************************************************ +{- ********************************************************************* * * Template Haskell context * * -************************************************************************ --} +********************************************************************* -} recordThUse :: TcM () recordThUse = do { env <- getGblEnv; writeTcRef (tcg_th_used env) True } ===================================== compiler/GHC/Tc/Utils/TcMType.hs ===================================== @@ -341,31 +341,13 @@ newImplication (implicationPrototype (mkCtLocEnv env)) { ic_warn_inaccessible = warn_inaccessible && not in_gen_code } -{- -************************************************************************ -* * - Coercion holes -* * -************************************************************************ --} - newCoercionHole :: TcPredType -> TcM CoercionHole -- For the Bool, see (EIK2) in Note [Equalities with heterogeneous kinds] newCoercionHole pred_ty = do { co_var <- newEvVar pred_ty ; traceTc "New coercion hole:" (ppr co_var <+> dcolon <+> ppr pred_ty) ; ref <- newMutVar Nothing - ; return $ CoercionHole { ch_co_var = co_var, ch_ref = ref } } - --- | Put a value in a coercion hole -fillCoercionHole :: CoercionHole -> CoercionPlusHoles -> TcM () -fillCoercionHole (CoercionHole { ch_ref = ref, ch_co_var = cv }) co - = do { when debugIsOn $ - do { cts <- readTcRef ref - ; whenIsJust cts $ \old_co -> - pprPanic "Filling a filled coercion hole" (ppr cv $$ ppr co $$ ppr old_co) } - ; traceTc "Filling coercion hole" (ppr cv <+> text ":=" <+> ppr co) - ; writeTcRef ref (Just co) } + ; return $ CH { ch_co_var = co_var, ch_ref = ref } } {- ********************************************************************** * ===================================== compiler/GHC/Tc/Utils/Unify.hs ===================================== @@ -418,7 +418,8 @@ Some examples: -} tcSkolemiseGeneral - :: DeepSubsumptionFlag + :: HasDebugCallStack + => DeepSubsumptionFlag -> UserTypeCtxt -> TcType -> TcType -- top_ty and expected_ty -- Here, top_ty is the type we started to skolemise; used only in SigSkol @@ -446,15 +447,16 @@ tcSkolemiseGeneral ds_flag ctxt top_ty expected_ty thing_inside ; skol_info <- mkSkolemInfo sig_skol } ; let skol_tvs = map (binderVar . snd) tv_prs - ; traceTc "tcSkolemiseGeneral" (pprUserTypeCtxt ctxt <+> ppr skol_tvs <+> ppr given) + ; traceTc "tcSkolemiseGeneral {" (pprUserTypeCtxt ctxt <+> ppr skol_tvs <+> ppr given) ; (ev_binds, result) <- checkConstraints sig_skol skol_tvs given $ thing_inside tv_prs rho_ty + ; traceTc "tcSkolemiseGeneral }" (ppr ev_binds $$ traceCallStackDoc) ; return (wrap <.> mkWpLet ev_binds, result) } -- The ev_binds returned by checkConstraints is very -- often empty, in which case mkWpLet is a no-op -tcSkolemiseCompleteSig :: TcCompleteSig +tcSkolemiseCompleteSig :: HasDebugCallStack => TcCompleteSig -> ([ExpPatType] -> TcRhoType -> TcM result) -> TcM (HsWrapper, result) -- ^ The wrapper has type: spec_ty ~~> expected_ty @@ -471,7 +473,7 @@ tcSkolemiseCompleteSig (CSig { sig_bndr = poly_id, sig_ctxt = ctxt, sig_loc = lo tcExtendNameTyVarEnv (map (fmap binderVar) tv_prs) $ thing_inside (map (mkInvisExpPatType . snd) tv_prs) rho_ty } -tcSkolemiseExpectedType :: TcSigmaType +tcSkolemiseExpectedType :: HasDebugCallStack => TcSigmaType -> ([ExpPatType] -> TcRhoType -> TcM result) -> TcM (HsWrapper, result) -- Just like tcSkolemiseCompleteSig, except that we don't have a user-written @@ -483,14 +485,15 @@ tcSkolemiseExpectedType exp_ty thing_inside = tcSkolemiseGeneral Shallow GenSigCtxt exp_ty exp_ty $ \tv_prs rho_ty -> thing_inside (map (mkInvisExpPatType . snd) tv_prs) rho_ty -tcSkolemise :: DeepSubsumptionFlag -> UserTypeCtxt -> TcSigmaType +tcSkolemise :: HasDebugCallStack => DeepSubsumptionFlag -> UserTypeCtxt -> TcSigmaType -> (TcRhoType -> TcM result) -> TcM (HsWrapper, result) tcSkolemise ds_flag ctxt expected_ty thing_inside = tcSkolemiseGeneral ds_flag ctxt expected_ty expected_ty $ \_ rho_ty -> thing_inside rho_ty -checkConstraints :: SkolemInfoAnon +checkConstraints :: HasDebugCallStack + => SkolemInfoAnon -> [TcTyVar] -- Skolems -> [EvVar] -- Given -> TcM result @@ -504,14 +507,16 @@ checkConstraints skol_info skol_tvs given thing_inside ; if implication_needed then do { (tclvl, wanted, result) <- pushLevelAndCaptureConstraints thing_inside ; (implics, ev_binds) <- buildImplicationFor tclvl skol_info skol_tvs given wanted - ; traceTc "checkConstraints" (ppr tclvl $$ ppr skol_tvs) + ; traceTc "checkConstraints A" (ppr tclvl $$ ppr skol_tvs $$ traceCallStackDoc) ; emitImplications implics ; return (ev_binds, result) } else -- Fast path. We check every function argument with tcCheckPolyExpr, -- which uses tcTopSkolemise and hence checkConstraints. -- So this fast path is well-exercised - do { res <- thing_inside + do { traceTc "checkConstraints B" (ppr skol_tvs $$ ppr given $$ ppr skol_info $$ + traceCallStackDoc) + ; res <- thing_inside ; return (emptyTcEvBinds, res) } } checkTvConstraints :: SkolemInfo ===================================== compiler/GHC/Tc/Zonk/TcType.hs ===================================== @@ -236,7 +236,7 @@ zonkCo :: Coercion -> ZonkM Coercion , tcm_tycon = zonkTcTyCon } where hole :: () -> CoercionHole -> ZonkM Coercion - hole _ hole@(CoercionHole { ch_ref = ref, ch_co_var = cv }) + hole _ hole@(CH { ch_ref = ref, ch_co_var = cv }) = do { contents <- readTcRef ref ; case contents of Just (CPH { cph_co = co }) @@ -617,7 +617,7 @@ instance Monoid UnfilledCoercionHoleMonoid where -- | Is a coercion hole filled in? isFilledCoercionHole :: CoercionHole -> ZonkM Bool -isFilledCoercionHole (CoercionHole { ch_ref = ref }) +isFilledCoercionHole (CH { ch_ref = ref }) = isJust <$> readTcRef ref -- | Retrieve the contents of a coercion hole. Panics if the hole @@ -631,7 +631,7 @@ unpackCoercionHole hole -- | Retrieve the contents of a coercion hole, if it is filled unpackCoercionHole_maybe :: CoercionHole -> ZonkM (Maybe CoercionPlusHoles) -unpackCoercionHole_maybe (CoercionHole { ch_ref = ref }) = readTcRef ref +unpackCoercionHole_maybe (CH { ch_ref = ref }) = readTcRef ref {- ===================================== compiler/GHC/Tc/Zonk/Type.hs ===================================== @@ -485,7 +485,7 @@ zonkCoVarOcc cv _ -> mkCoVarCo <$> (lift $ liftZonkM $ zonkCoVar cv) } zonkCoHole :: CoercionHole -> ZonkTcM Coercion -zonkCoHole hole@(CoercionHole { ch_ref = ref, ch_co_var = cv }) +zonkCoHole hole@(CH { ch_ref = ref, ch_co_var = cv }) = do { contents <- readTcRef ref ; case contents of Just (CPH { cph_co = co }) @@ -1910,8 +1910,9 @@ zonk_tc_ev_binds (EvBinds bs) = zonkEvBinds bs zonkEvBindsVar :: EvBindsVar -> ZonkBndrTcM (Bag EvBind) zonkEvBindsVar (EvBindsVar { ebv_binds = ref }) - = do { bs <- readTcRef ref + = do { EBS { ebs_binds = bs } <- readTcRef ref ; zonkEvBinds (evBindMapBinds bs) } + zonkEvBindsVar (CoEvBindsVar {}) = return emptyBag zonkEvBinds :: Bag EvBind -> ZonkBndrTcM (Bag EvBind) ===================================== compiler/GHC/Types/Var.hs ===================================== @@ -176,7 +176,7 @@ type KindVar = Var -- Definitely a kind variable -- See Note [Evidence: EvIds and CoVars] -- | Evidence Identifier -type EvId = Id -- Term-level evidence: DictId, IpId, or EqVar +type EvId = Id -- Term-level evidence: DictId, IpId, or CoVar -- | Evidence Variable type EvVar = EvId -- ...historical name for EvId ===================================== compiler/GHC/Utils/Trace.hs ===================================== @@ -11,6 +11,7 @@ module GHC.Utils.Trace , warnPprTraceM , pprTraceUserWarning , trace + , traceCallStackDoc ) where ===================================== testsuite/tests/simplCore/should_compile/T26805.hs ===================================== @@ -0,0 +1,29 @@ +{-# LANGUAGE GADTs #-} +{-# LANGUAGE ImpredicativeTypes #-} +{-# LANGUAGE TypeData #-} +module T26805( interpret ) where + +import Data.Kind (Type) + +data Phantom (sh :: Type) = Phantom -- newtype fails to specialise as well + +instance Show (Phantom sh) where + show Phantom = "show" + +type Foo r = (forall sh. Show (Phantom sh), Num r) +-- this specialises fine: +-- type Foo r = (Num r) + +type data TK = TKScalar Type + +data AstTensor :: TK -> Type where + AstInt :: Int -> AstTensor (TKScalar Int) + AstPlus :: Foo r => AstTensor (TKScalar r) -> AstTensor (TKScalar r) + +plusConcrete :: Foo r => r -> r +plusConcrete = (+ 1) + +interpret :: AstTensor (TKScalar Int) -> Int +interpret v0 = case v0 of + AstInt n -> n + AstPlus u -> plusConcrete (interpret u) ===================================== testsuite/tests/simplCore/should_compile/T26805.stderr ===================================== @@ -0,0 +1 @@ + \ No newline at end of file ===================================== testsuite/tests/simplCore/should_compile/all.T ===================================== @@ -578,3 +578,4 @@ test('T26615', [grep_errmsg(r'fEqList')], multimod_compile, ['T26615', '-O -fsp # T26722: there should be no reboxing in $wg test('T26722', [grep_errmsg(r'SPEC')], compile, ['-O -dno-typeable-binds']) +test('T26805', [grep_errmsg(r'fromInteger')], compile, ['-O -dno-typeable-binds -ddump-simpl -dsuppress-uniques']) ===================================== testsuite/tests/typecheck/should_compile/T26805a.hs ===================================== @@ -0,0 +1,38 @@ +{-# LANGUAGE ScopedTypeVariables #-} +{-# LANGUAGE UndecidableSuperClasses #-} +{-# LANGUAGE QuantifiedConstraints #-} +{-# LANGUAGE TypeApplications #-} +{-# LANGUAGE RoleAnnotations #-} + +-- This is a cut-down version of the failure found in !15389 +-- when compiling the `constraints` package. +-- We got a Lint error because the NeededEvIds stuff in the +-- constraint solver forgot some needed variables. + +module T26805a where + +import GHC.Exts (Constraint) +import Data.Kind + +data Dict :: Constraint -> Type where + Dict :: a => Dict a + +newtype a :- b = Sub (a => Dict b) +type role (:-) nominal nominal + +-- | Instantiate a quantified @'ForallF' p f@ constraint at type @a@. +instF :: forall p f a . ForallF p f :- p (f a) +instF = Sub @(ForallF p f) @(p (f a)) + (case inst :: Forall (ComposeC p f) :- ComposeC p f a of + Sub Dict -> Dict) + +class Forall (ComposeC p f) => ForallF (p :: k2 -> Constraint) (f :: k1 -> k2) + +class p (f a) => ComposeC (p :: k2 -> Constraint) (f :: k1 -> k2) (a :: k1) + +class (forall a. p a) => Forall (p :: k -> Constraint) +instance (forall a. p a) => Forall (p :: k -> Constraint) + +inst :: forall p a. Forall p :- p a +inst = Sub Dict + ===================================== testsuite/tests/typecheck/should_compile/all.T ===================================== @@ -959,3 +959,5 @@ test('T26451', normal, compile, ['']) test('T26582', normal, compile, ['']) test('T26746', normal, compile, ['']) test('T26737', normal, compile, ['']) +test('T26805a', normal, compile, ['']) + View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3ff419a9fa70b975f74e20a65fe398b… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/3ff419a9fa70b975f74e20a65fe398b… You're receiving this email because of your account on gitlab.haskell.org.

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