Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 716274a5 by Simon Peyton Jones at 2025-08-29T17:27:12-04:00 Fix deep subsumption again This commit fixed #26255: commit 56b32c5a2d5d7cad89a12f4d74dc940e086069d1 Author: sheaf Date: Mon Aug 11 15:50:47 2025 +0200 Improve deep subsumption This commit improves the DeepSubsumption sub-typing implementation in GHC.Tc.Utils.Unify.tc_sub_type_deep by being less eager to fall back to unification. But alas it still wasn't quite right for view patterns: #26331 This MR does a generalisation to fix it. A bit of a sledgehammer to crack a nut, but nice. * Add a field `ir_inst :: InferInstFlag` to `InferResult`, where ``` data InferInstFlag = IIF_Sigma | IIF_ShallowRho | IIF_DeepRho ``` * The flag says exactly how much `fillInferResult` should instantiate before filling the hole. * We can also use this to replace the previous very ad-hoc `tcInferSigma` that was used to implement GHCi's `:type` command. - - - - - 27206c5e by sheaf at 2025-08-29T17:28:14-04:00 Back-compat for TH SpecialiseP data-con of Pragma This commit improves the backwards-compatibility story for the SpecialiseP constructor of the Template Haskell 'Pragma' datatype. Instead of keeping the constructor but deprecating it, this commit makes it into a bundled pattern synonym of the Pragma datatype. We no longer deprecate it; it's useful for handling old-form specialise pragmas. - - - - - 7f6daa8b by fendor at 2025-08-29T17:59:31-04:00 Move stack decoding logic from ghc-heap to ghc-internal The stack decoding logic in `ghc-heap` is more sophisticated than the one currently employed in `CloneStack`. We want to use the stack decoding implementation from `ghc-heap` in `base`. We cannot simply depend on `ghc-heap` in `base` due do bootstrapping issues. Thus, we move the code that is necessary to implement stack decoding to `ghc-internal`. This is the right location, as we don't want to add a new API to `base`. Moving the stack decoding logic and re-exposing it in ghc-heap is insufficient, though, as we have a dependency cycle between. * ghc-heap depends on stage1:ghc-internal * stage0:ghc depends on stage0:ghc-heap To fix this, we remove ghc-heap from the set of `stage0` dependencies. This is not entirely straight-forward, as a couple of boot dependencies, such as `ghci` depend on `ghc-heap`. Luckily, the boot compiler of GHC is now >=9.10, so we can migrate `ghci` to use `ghc-internal` instead of `ghc-heap`, which already exports the relevant modules. However, we cannot 100% remove ghc's dependency on `ghc-heap`, since when we compile `stage0:ghc`, `stage1:ghc-internal` is not yet available. Thus, when we compile with the boot-compiler, we still depend on an older version of `ghc-heap`, and only use the modules from `ghc-internal`, if the `ghc-internal` version is recent enough. ------------------------- Metric Increase: T24602_perf_size T25046_perf_size_gzip T25046_perf_size_unicode T25046_perf_size_unicode_gzip size_hello_artifact size_hello_artifact_gzip size_hello_unicode size_hello_unicode_gzip ------------------------- These metric increases are unfortunate, they are most likely caused by the larger (literally in terms of lines of code) stack decoder implementation that are now linked into hello-word binaries. On linux, it is almost a 10% increase, which is considerable. - - - - - 6d49482c by fendor at 2025-08-29T17:59:31-04:00 Implement `decode` in terms of `decodeStackWithIpe` Uses the more efficient stack decoder implementation. - - - - - e70c9b9e by fendor at 2025-08-29T17:59:31-04:00 Remove stg_decodeStackzh - - - - - ee00dc74 by Simon Peyton Jones at 2025-08-29T17:59:35-04:00 Fix a long standing bug in the coercion optimiser We were mis-optimising ForAllCo, leading to #26345 Part of the poblem was the tricky tower of abstractions leading to the dreadful GHC.Core.TyCo.Subst.substForAllCoTyVarBndrUsing This function was serving two masters: regular substitution, but also coercion optimsation. So tricky was it that it did so wrong. In this MR I locate all the fancy footwork for coercion optimisation in GHC.Core.Coercion.Opt, where it belongs. That leaves substitution free to be much simpler. - - - - - 80 changed files: - compiler/GHC/ByteCode/Types.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Core/Coercion/Opt.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/Core/Type.hs - compiler/GHC/Runtime/Heap/Inspect.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Bind.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Gen/Expr.hs-boot - compiler/GHC/Tc/Gen/Head.hs - compiler/GHC/Tc/Gen/HsType.hs - compiler/GHC/Tc/Gen/Match.hs - compiler/GHC/Tc/Gen/Pat.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/Tc/Utils/TcType.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/ThToHs.hs - compiler/ghc.cabal.in - hadrian/src/Rules/ToolArgs.hs - hadrian/src/Settings/Default.hs - libraries/base/src/GHC/Stack/CloneStack.hs - libraries/ghc-boot-th/GHC/Boot/TH/Ppr.hs - libraries/ghc-heap/GHC/Exts/Heap/ClosureTypes.hs - libraries/ghc-heap/GHC/Exts/Heap/Closures.hs - + libraries/ghc-heap/GHC/Exts/Heap/Constants.hs - + libraries/ghc-heap/GHC/Exts/Heap/InfoTable.hs - + libraries/ghc-heap/GHC/Exts/Heap/InfoTable/Types.hs - + libraries/ghc-heap/GHC/Exts/Heap/InfoTableProf.hs - libraries/ghc-heap/GHC/Exts/Heap/ProfInfo/Types.hs - + libraries/ghc-heap/GHC/Exts/Stack/Constants.hs - libraries/ghc-heap/GHC/Exts/Stack/Decode.hs - libraries/ghc-heap/ghc-heap.cabal.in - libraries/ghc-heap/cbits/HeapPrim.cmm → libraries/ghc-internal/cbits/HeapPrim.cmm - libraries/ghc-heap/cbits/Stack.cmm → libraries/ghc-internal/cbits/Stack.cmm - libraries/ghc-internal/cbits/StackCloningDecoding.cmm - libraries/ghc-heap/cbits/Stack_c.c → libraries/ghc-internal/cbits/Stack_c.c - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/jsbits/base.js - libraries/ghc-internal/src/GHC/Internal/Exception/Backtrace.hs - + libraries/ghc-internal/src/GHC/Internal/Heap/Closures.hs - libraries/ghc-heap/GHC/Exts/Heap/Constants.hsc → libraries/ghc-internal/src/GHC/Internal/Heap/Constants.hsc - libraries/ghc-heap/GHC/Exts/Heap/InfoTable.hsc → libraries/ghc-internal/src/GHC/Internal/Heap/InfoTable.hsc - libraries/ghc-heap/GHC/Exts/Heap/InfoTable/Types.hsc → libraries/ghc-internal/src/GHC/Internal/Heap/InfoTable/Types.hsc - libraries/ghc-heap/GHC/Exts/Heap/InfoTableProf.hsc → libraries/ghc-internal/src/GHC/Internal/Heap/InfoTableProf.hsc - + libraries/ghc-internal/src/GHC/Internal/Heap/ProfInfo/Types.hs - libraries/ghc-internal/src/GHC/Internal/Stack/CloneStack.hs - libraries/ghc-heap/GHC/Exts/Stack/Constants.hsc → libraries/ghc-internal/src/GHC/Internal/Stack/Constants.hsc - + libraries/ghc-internal/src/GHC/Internal/Stack/Decode.hs - libraries/ghc-internal/src/GHC/Internal/TH/Syntax.hs - libraries/ghc-heap/tests/stack-annotation/Makefile → libraries/ghc-internal/tests/stack-annotation/Makefile - libraries/ghc-heap/tests/stack-annotation/TestUtils.hs → libraries/ghc-internal/tests/stack-annotation/TestUtils.hs - libraries/ghc-heap/tests/stack-annotation/all.T → libraries/ghc-internal/tests/stack-annotation/all.T - libraries/ghc-heap/tests/stack-annotation/ann_frame001.hs → libraries/ghc-internal/tests/stack-annotation/ann_frame001.hs - libraries/ghc-heap/tests/stack-annotation/ann_frame001.stdout → libraries/ghc-internal/tests/stack-annotation/ann_frame001.stdout - libraries/ghc-heap/tests/stack-annotation/ann_frame002.hs → libraries/ghc-internal/tests/stack-annotation/ann_frame002.hs - libraries/ghc-heap/tests/stack-annotation/ann_frame002.stdout → libraries/ghc-internal/tests/stack-annotation/ann_frame002.stdout - libraries/ghc-heap/tests/stack-annotation/ann_frame003.hs → libraries/ghc-internal/tests/stack-annotation/ann_frame003.hs - libraries/ghc-heap/tests/stack-annotation/ann_frame003.stdout → libraries/ghc-internal/tests/stack-annotation/ann_frame003.stdout - libraries/ghc-heap/tests/stack-annotation/ann_frame004.hs → libraries/ghc-internal/tests/stack-annotation/ann_frame004.hs - libraries/ghc-heap/tests/stack-annotation/ann_frame004.stdout → libraries/ghc-internal/tests/stack-annotation/ann_frame004.stdout - libraries/ghci/GHCi/Message.hs - libraries/ghci/ghci.cabal.in - libraries/template-haskell/Language/Haskell/TH/Lib.hs - libraries/template-haskell/Language/Haskell/TH/Syntax.hs - libraries/template-haskell/changelog.md - rts/CloneStack.c - rts/CloneStack.h - rts/RtsSymbols.c - 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/template-haskell-exports.stdout - + testsuite/tests/patsyn/should_compile/T26331.hs - + testsuite/tests/patsyn/should_compile/T26331a.hs - testsuite/tests/patsyn/should_compile/all.T - + testsuite/tests/typecheck/should_compile/T26345.hs - testsuite/tests/typecheck/should_compile/all.T The diff was not included because it is too large. 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