[Git][ghc/ghc][wip/T23162-part2] 11 commits: Do deep subsumption when computing valid hole fits

Simon Peyton Jones pushed to branch wip/T23162-part2 at Glasgow Haskell Compiler / GHC Commits: db1ce858 by sheaf at 2025-12-22T17:11:17-05:00 Do deep subsumption when computing valid hole fits This commit makes a couple of improvements to the code that computes "valid hole fits": 1. It uses deep subsumption for data constructors. This matches up the multiplicities, as per Note [Typechecking data constructors]. This fixes #26338 (test: LinearHoleFits). 2. It now suggests (non-unidirectional) pattern synonyms as valid hole fits. This fixes #26339 (test: PatSynHoleFit). 3. It uses 'stableNameCmp', to make the hole fit output deterministic. ------------------------- Metric Increase: hard_hole_fits ------------------------- - - - - - 72ee9100 by sheaf at 2025-12-22T17:11:17-05:00 Speed up hole fits with a quick pre-test This speeds up the machinery for valid hole fits by doing a small check to rule out obviously wrong hole fits, such as: 1. A hole fit identifier whose type has a different TyCon at the head, after looking through foralls and (=>) arrows, e.g.: hole_ty = Int cand_ty = Maybe a or hole_ty = forall a b. a -> b cand_ty = forall x y. Either x y 2. A hole fit identifier that is not polymorphic when the hole type is polymorphic, e.g. hole_ty = forall a. a -> a cand_ty = Int -> Int ------------------------- Metric Decrease: hard_hole_fits ------------------------- - - - - - 30e513ba by Cheng Shao at 2025-12-22T17:12:00-05:00 configure: remove unused win32-tarballs.md5sum This patch removes the unused `win32-tarballs.md5sum` file from the tree. The current mingw tarball download logic in `mk/get-win32-tarballs.py` fetches and checks against `SHA256SUM` from the same location where the tarballs are fetched, and this file has been unused for a few years. - - - - - a2d52b3b by Wolfgang Jeltsch at 2025-12-23T04:47:33-05:00 Add an operation `System.IO.hGetNewlineMode` This commit also contains some small code and documentation changes for related operations, for the sake of consistency. - - - - - b26d134a by Cheng Shao at 2025-12-23T04:48:15-05:00 rts: opportunistically reclaim slop space in shrinkMutableByteArray# Previously, `shrinkMutableByteArray#` shrinks a `MutableByteArray#` in-place by assigning the new size to it, and zeroing the extra slop space. That slop space is not reclaimed and wasted. But it's often the case that we allocate a `MutableByteArray#` upfront, then shrink it shortly after, so the `MutableByteArray#` closure sits right at the end of a nursery block; this patch identifies such chances, and also shrink `bd->free` if possible, reducing heap space fragmentation. Co-authored-by: Codex ------------------------- Metric Decrease: T10678 ------------------------- - - - - - 81c413c4 by Simon Peyton Jones at 2025-12-23T16:11:24+00:00 Improved fundeps for closed type families The big payload of this commit is to execute the plan suggested in #23162, by improving the way that we generate functional dependencies for closed type families. It is all described in Note [Exploiting closed type families] Most of the changes are in GHC.Tc.Solver.FunDeps Other small changes * GHC.Tc.Solver.bumpReductionDepth. This function brings together the code that * Bumps the depth * Checks for overflow Previously the two were separated, sometimes quite widely. * GHC.Core.Unify.niFixSubst: minor improvement, removing an unnecessary itraetion in the base case. * GHC.Core.Unify: no need to pass an InScopeSet to tcUnifyTysForInjectivity. It can calculate one for itself; and it is never inspected anyway so it's free to do so. * GHC.Tc.Errors.Ppr: slight impovement to the error message for reduction-stack overflow, when a constraint (rather than a type) is involved. * GHC.Tc.Solver.Monad.wrapUnifier: small change to the API - - - - - dd279145 by Simon Peyton Jones at 2025-12-23T16:11:24+00:00 Add missing (KK4) to kick-out criteria There was a missing case in kick-out that meant we could fail to solve an eminently-solvable constraint. See the new notes about (KK4) - - - - - 028e57df by Simon Peyton Jones at 2025-12-23T16:11:24+00:00 Some small refactorings of error reporting in the typechecker This is just a tidy-up commit. * Add ei_insoluble to ErrorItem, to cache insolubility. Small tidy-up. * Remove `is_ip` and `mkIPErr` from GHC.Tc.Errors; instead enhance mkDictErr to handle implicit parameters. Small refactor. - - - - - f328b01e by Simon Peyton Jones at 2025-12-23T16:11:24+00:00 Better fundeps for type-family Givens This commit addresses #22652, by recording when the fundeps for a constraint are definitely insoluble. That in turn improves the perspicacity of the pattern-match overlap checker. See Note [Insoluble fundeps] - - - - - 24c59428 by Simon Peyton Jones at 2025-12-23T16:11:24+00:00 Fix a buglet in niFixSubst The MR of which this is part failed an assertion check extendTvSubst because we extended the TvSubst with a CoVar. Boo. This tiny patch fixes it, and adds the regression test from #13882 that showed it up. - - - - - 0cc9db43 by Simon Peyton Jones at 2025-12-23T16:11:24+00:00 More on insolubility - - - - - 103 changed files: - .gitattributes - compiler/GHC/Core/DataCon.hs - compiler/GHC/Core/FamInstEnv.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/Core/TyCon.hs - compiler/GHC/Core/Unify.hs - compiler/GHC/HsToCore/Monad.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Hole.hs - compiler/GHC/Tc/Errors/Hole/FitTypes.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Splice.hs - compiler/GHC/Tc/Solver.hs - compiler/GHC/Tc/Solver/Default.hs - compiler/GHC/Tc/Solver/Dict.hs - compiler/GHC/Tc/Solver/Equality.hs - compiler/GHC/Tc/Solver/FunDeps.hs - compiler/GHC/Tc/Solver/InertSet.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Solver/Rewrite.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Types/CtLoc.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Types/TyThing.hs - docs/users_guide/9.16.1-notes.rst - libraries/base/changelog.md - libraries/base/src/System/IO.hs - libraries/ghc-internal/src/GHC/Internal/IO/Handle.hs - libraries/ghc-internal/src/GHC/Internal/System/IO.hs - linters/lint-codes/LintCodes/Static.hs - − mk/win32-tarballs.md5sum - rts/PrimOps.cmm - testsuite/tests/ghci/scripts/T8353.stderr - testsuite/tests/indexed-types/should_compile/CEqCanOccursCheck.hs - testsuite/tests/indexed-types/should_fail/T12522a.hs - testsuite/tests/indexed-types/should_fail/T26176.stderr - 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/overloadedrecflds/should_fail/DRFHoleFits.stderr - testsuite/tests/parser/should_fail/RecordDotSyntaxFail10.stderr - testsuite/tests/parser/should_fail/RecordDotSyntaxFail13.stderr - testsuite/tests/perf/compiler/hard_hole_fits.stderr - testsuite/tests/plugins/test-hole-plugin.stderr - testsuite/tests/pmcheck/should_compile/T15753c.hs - + testsuite/tests/pmcheck/should_compile/T15753c.stderr - testsuite/tests/pmcheck/should_compile/T15753d.hs - + testsuite/tests/pmcheck/should_compile/T15753d.stderr - + testsuite/tests/pmcheck/should_compile/T22652.hs - + testsuite/tests/pmcheck/should_compile/T22652a.hs - testsuite/tests/pmcheck/should_compile/all.T - + testsuite/tests/polykinds/T13882.hs - testsuite/tests/polykinds/all.T - testsuite/tests/quantified-constraints/T15316A.stderr - testsuite/tests/quantified-constraints/T17267.stderr - testsuite/tests/quantified-constraints/T17267a.stderr - testsuite/tests/quantified-constraints/T17267b.stderr - testsuite/tests/quantified-constraints/T17267c.stderr - testsuite/tests/quantified-constraints/T17267e.stderr - testsuite/tests/quantified-constraints/T17458.stderr - testsuite/tests/th/T15321.stderr - testsuite/tests/typecheck/should_compile/T13050.stderr - 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testsuite/tests/typecheck/should_fail/ContextStack1.stderr - testsuite/tests/typecheck/should_fail/FD3.stderr - testsuite/tests/typecheck/should_fail/FunDepOrigin1b.stderr - testsuite/tests/typecheck/should_fail/T13506.stderr - testsuite/tests/typecheck/should_fail/T14884.stderr - testsuite/tests/typecheck/should_fail/T15767.stderr - testsuite/tests/typecheck/should_fail/T19415.stderr - testsuite/tests/typecheck/should_fail/T19415b.stderr - testsuite/tests/typecheck/should_fail/T22924b.stderr - + testsuite/tests/typecheck/should_fail/T23162b.hs - + testsuite/tests/typecheck/should_fail/T23162b.stderr - + testsuite/tests/typecheck/should_fail/T23162c.hs - + testsuite/tests/typecheck/should_fail/T23162d.hs - testsuite/tests/typecheck/should_fail/T5236.stderr - testsuite/tests/typecheck/should_fail/T5978.stderr - testsuite/tests/typecheck/should_fail/T9612.stderr - testsuite/tests/typecheck/should_fail/TcCoercibleFail.stderr - testsuite/tests/typecheck/should_fail/all.T - testsuite/tests/typecheck/should_fail/tcfail143.stderr - utils/deriveConstants/Main.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs The diff was not included because it is too large. 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