Simon Peyton Jones pushed to branch wip/T27466 at Glasgow Haskell Compiler / GHC Commits: 6e381626 by Duncan Coutts at 2026-07-01T22:29:55+01:00 Adjust releaseCapability_ precondition to allow cap->running_task == NULL There are two use cases for releaseCapability_: 1. The current Task (cap->running_task) releases the Capability. The Capability is marked free, and if there is any work to do, an appropriate Task is woken up. 2. There is no current task (cap->task == NULL), and thus the Capability is idle, and we want to wake up an idle Task to animate the Capability. This case uses always_wakeup. Currently, the precondition for releaseCapability_ is cap->running_task != NULL and so the 2nd use cases have to set cap->running_task (which is then immediately overwritten) just to satisfy the precondition. See the use cases in sendMessage and prodCapability. So we can relax the precondition to be: cap->running_task != NULL || always_wakeup so that in the always_wakeup case, we say it is ok for the cap->running_task to be NULL. This lets us simplify sendMessage and prodCapability. In particular it will allow prodCapability to not need a Task parameter. The ulterior motive for all this is that I want to be able to call prodCapability from an OS thread that is not itself a Task, in persuit of issue #27086: disentangle I/O managers from wakeUpRts. The most straightforward way to wake the RTS is using prodCapability, but the context in which we will need to do that are threads that are not Tasks. - - - - - 89404ebc by Duncan Coutts at 2026-07-01T22:29:55+01:00 prodCapability no longer needs to take a Task param Now that releaseCapability_ can accept cap->running_task == NULL then it is no longer necessary for prodCapability to require a Task. - - - - - 4e60c5f6 by Duncan Coutts at 2026-07-01T22:29:56+01:00 Define prodOneCapability There was an existing declaration for this in the header file, but no definition. Similarly, there is a declaration for prodAllCapabilities but no definition, and we don't need it, so remove the declaration. - - - - - 2527026f by Duncan Coutts at 2026-07-01T22:29:56+01:00 Add a wakeUpRtsViaTicker feature to the posix ticker It proxies a call to wakeUpRts, but crucially, this can be called from a signal handler context. It will be used for ctl-c handling. - - - - - aa5a03a5 by Duncan Coutts at 2026-07-01T22:29:56+01:00 Change how wakeUpRts works Previously it would call wakeupIOManager to get a capability to wake up and run. This works but it entangles the I/O managers with unrelated features: ctl-c handling and idle gc (the two features that use wakeUpRts). The reason it used wakeupIOManager is that this action is safe to use from a posix signal handler, since it just posts bytes to a pipe. Otherwise the more direct approach (used e.g. by sendMessage when the target capability is idle) is to use releaseCapability. But that uses condition variables and mutexes, which are not safe to use from within a signal handler. So instead of entangling the (multiple) I/O managers with this, we make wakeUpRts use the direct approach (using prodOneCapability). On win32 the ctl-c console handler can call wakeUpRts directly, since it is called in a proper thread. On posix, to deal with the signal handler problem, we make the signal handler ask the ticker thread to proxy the call to wakeUpRts, since the ticker thread is also a proper thread. This will allow the I/O managers to no longer be concerned with this. This is good because there are many I/O managers (and they're complicated), but there is (on posix) only one ticker implementation. So this is an overall reduction in coupling and complexity. Fixes issue #27086 - - - - - c6d53c16 by sheaf at 2026-07-02T21:35:44-04:00 Test driver: normalise line numbers into libraries When comparing the stdout of tests that print out callstacks, we can't rely on the stability of exact line:column spans pointing into libraries (e.g. ghc-internal), as any change (such as adding a comment) can change them. This commit addresses this by normalising away line:column in callstacks, but only when those point into internal libraries. We don't do this in general, as the exact span might be important to the test (e.g. for a span within the test module itself). Fixes #27387 - - - - - 81ee62e0 by Alan Zimmerman at 2026-07-02T21:36:33-04:00 EPA: Remove LocatedLW from MatchGroup This is the last usage of LocatedLW / SrcSpanAnnLW - - - - - 925959db by Recursion Ninja at 2026-07-04T04:14:12-04:00 Decoupling 'L.H.S' from 'GHC.Hs.Doc' * Migrated 'GHC.Hs.Doc' and 'GHC.Hs.DocString' AST defintions from 'GHC.*' namespace, to new 'Language.Haskell.Syntax.Doc' module in the 'L.H.S' "namespace." * Updated 'HsDocString to be TTG-parameterised as 'HsDocString pass'. * Added 'GHC.Hs.Extension.Pass': splits 'GhcPass'/'Pass' and all 'HsDocString' TTG instances out of 'GHC.Hs.Extension', which re-exports it unchanged (this is backwards compatible and prevents the introduction of a boot file). * Deleted 'GHC.Hs.Doc.hs-boot'; removed all 'L.H.S.*' imports of 'GHC.Hs.Doc'. * Updated 'GHC.Hs.DocString' to be TTG pass-parameterised throughout; moved 'mkHsDocStringChunk'/'unpackHDSC' here (require 'GHC.Utils.Encoding'). * Split 'GHC.Rename.Doc.rnHsDoc' from 'rnHsDocIdentifiersOnly'. * Updated parser, renamer, typechecker, HIE, and exact-print for new types. * Added 'HsDocString' TTG instances for 'DocNameI' to 'Haddock.Types'. * Killed the last module loop between GHC.* and LHS.*. - Only edges from LHS.* to GHC.Data.FastString now! Resolves #26971 - - - - - b7e24044 by mangoiv at 2026-07-04T04:14:56-04:00 ci: retry fetching test metrics Retry fetching test metrics to make the CI not fail if the services is temporarily unavailable - - - - - 4180af3f by Zubin Duggal at 2026-07-04T04:15:38-04:00 Bump semaphore-compat submodule to 2.0.1 This versions includes some cruicial fixes for darwin - - - - - 242d4317 by sheaf at 2026-07-04T04:16:19-04:00 Remove outdated comment in GHC.Data.ShortText There was a long comment in GHC.Data.ShortText about a workaround that was necessary when bootstrapping with GHC 9.2 and below. The actual logic has since been dropped, but the comment remained. This commit removes the vestigial comment. - - - - - 9b714c4c by Zubin Duggal at 2026-07-05T09:40:36+05:30 CorePrep: Don't speculatively evaluate bindings that we have already discovered to be absent In #25924, we segfault because speculation forces a projection out of a RUBBISH dictionary (which we generated because it absent). Solution: Don't speculate on bindings we already know are absent. Fixes 25924 - - - - - 4a59b3ee by Zubin Duggal at 2026-07-05T09:40:36+05:30 Don't make absent fillers for terminating types In #25924 we discovered that we could speculatively evaluate an absent filler for a dictionary, and project a field (a superclass selector) out of it, resulting in segfaults. Solution: Never make an absent filler or rubbish literal for a terminating type like a dictionary. mkAbsentFiller returns Nothing for isTerminatingType, so worker/wrapper and the specialiser keep the real argument instead. Some small metric decreases because we do a little less work in the simplifier now. Metric Decrease: T9872a T9872b T9872c TcPlugin_RewritePerf - - - - - 383ddcd4 by Alan Zimmerman at 2026-07-06T07:08:16-04:00 EPA: Move the 'where' annotation for PatSynBind This allows us to move it out of the MatchGroup exact print annotation too - - - - - ca361003 by Simon Peyton Jones at 2026-07-07T11:42:15+01:00 Update equality-type documenation in GHC.Builtin.Types.Prim Fix #27466 - - - - - 9d413b68 by Simon Peyton Jones at 2026-07-07T11:42:15+01:00 Honour -dsuppress-coercions in GHC.Core.TyCo.pprCo Fixes #27467 - - - - - 115 changed files: - .gitlab/test-metrics.sh - + changelog.d/fix-absent-dict-projection - changelog.d/semaphore-v2 - compiler/GHC/Builtin/Types/Prim.hs - compiler/GHC/Builtin/Utils.hs - compiler/GHC/Core/Make.hs - compiler/GHC/Core/Opt/Specialise.hs - compiler/GHC/Core/Opt/WorkWrap.hs - compiler/GHC/Core/Opt/WorkWrap/Utils.hs - compiler/GHC/Core/Ppr.hs - compiler/GHC/Core/TyCo/Ppr.hs - compiler/GHC/Core/TyCo/Rep.hs - compiler/GHC/CoreToStg/Prep.hs - compiler/GHC/Hs.hs - compiler/GHC/Hs/Binds.hs - compiler/GHC/Hs/Doc.hs - − compiler/GHC/Hs/Doc.hs-boot - compiler/GHC/Hs/DocString.hs - compiler/GHC/Hs/Dump.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/Extension.hs - + compiler/GHC/Hs/Extension/Pass.hs - compiler/GHC/Hs/ImpExp.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Docs.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Annotation.hs - compiler/GHC/Parser/HaddockLex.x - compiler/GHC/Parser/Lexer.x - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Parser/PostProcess/Haddock.hs - compiler/GHC/Parser/Types.hs - compiler/GHC/Rename/Bind.hs - compiler/GHC/Rename/Doc.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/Tc/Errors/Hole.hs - compiler/GHC/Tc/Errors/Hole/FitTypes.hs - compiler/GHC/Tc/Gen/Arrow.hs - compiler/GHC/Tc/Gen/Do.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Gen/Match.hs - compiler/GHC/Tc/Gen/Splice.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/TyCl/PatSyn.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Basic.hs - compiler/GHC/Types/Literal.hs - compiler/Language/Haskell/Syntax.hs - compiler/Language/Haskell/Syntax/Decls.hs - + compiler/Language/Haskell/Syntax/Doc.hs - compiler/Language/Haskell/Syntax/Expr.hs-boot - compiler/Language/Haskell/Syntax/Extension.hs - compiler/Language/Haskell/Syntax/ImpExp.hs - compiler/Language/Haskell/Syntax/Type.hs - − compiler/Language/Haskell/Syntax/Type.hs-boot - compiler/ghc.cabal.in - hadrian/src/Settings/Warnings.hs - libraries/ghc-boot/GHC/Data/ShortText.hs - libraries/semaphore-compat - rts/Capability.c - rts/Capability.h - rts/Messages.c - rts/Schedule.c - rts/Ticker.h - rts/posix/Ticker.c - rts/sm/GC.c - testsuite/driver/testlib.py - testsuite/tests/codeGen/should_compile/T25177.stderr - + testsuite/tests/core-to-stg/T25924/B.hs - + testsuite/tests/core-to-stg/T25924/Main.hs - + testsuite/tests/core-to-stg/T25924/all.T - + testsuite/tests/core-to-stg/T25924a.hs - + testsuite/tests/core-to-stg/T25924a.stdout - testsuite/tests/core-to-stg/all.T - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/dmdanal/should_compile/T18982.stderr - testsuite/tests/ghc-api/exactprint/T22919.stderr - testsuite/tests/ghc-api/exactprint/ZeroWidthSemi.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T24221.stderr - testsuite/tests/module/mod185.stderr - testsuite/tests/numeric/should_compile/T15547.stderr - 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/DumpSemis.stderr - testsuite/tests/parser/should_compile/DumpTypecheckedAst.stderr - testsuite/tests/parser/should_compile/KindSigs.stderr - testsuite/tests/parser/should_compile/T15279.stderr - testsuite/tests/parser/should_compile/T20718.stderr - testsuite/tests/parser/should_compile/T20846.stderr - testsuite/tests/parser/should_compile/T23315/T23315.stderr - testsuite/tests/parser/should_compile/all.T - testsuite/tests/printer/Test20297.stdout - testsuite/tests/printer/Test24533.stdout - testsuite/tests/showIface/DocsInHiFile1.stdout - testsuite/tests/showIface/HaddockSpanIssueT24378.stdout - testsuite/tests/showIface/MagicHashInHaddocks.stdout - testsuite/tests/showIface/NoExportList.stdout - testsuite/tests/simplCore/should_compile/DataToTagFamilyScrut.stderr - testsuite/tests/simplCore/should_compile/T14978.stdout - testsuite/tests/simplCore/should_compile/T18013.stderr - testsuite/tests/simplCore/should_compile/T24229a.stderr - testsuite/tests/simplCore/should_compile/T24229b.stderr - testsuite/tests/simplCore/should_compile/T26615.stderr - utils/check-exact/ExactPrint.hs - utils/check-exact/Utils.hs - utils/haddock/haddock-api/src/Haddock/Interface/Create.hs - utils/haddock/haddock-api/src/Haddock/Interface/LexParseRn.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. 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