Wolfgang Jeltsch pushed to branch wip/jeltsch/known-key-removals/lists 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 ------------------------- - - - - - 1d256c44 by Wolfgang Jeltsch at 2025-12-23T22:43:02+02:00 Remove unused known keys and names for list operations This removes the known-key and corresponding name variables for `concat`, `filter`, `zip`, and `(++)`, as they are apparently nowhere used in GHC’s source code. - - - - - 42 changed files: - .gitattributes - compiler/GHC/Builtin/Names.hs - compiler/GHC/Core/DataCon.hs - compiler/GHC/Tc/Errors/Hole.hs - compiler/GHC/Tc/Errors/Hole/FitTypes.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Utils/Unify.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 - − mk/win32-tarballs.md5sum - rts/PrimOps.cmm - testsuite/tests/ghci/scripts/T8353.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/perf/compiler/hard_hole_fits.stderr - testsuite/tests/plugins/test-hole-plugin.stderr - testsuite/tests/th/T15321.stderr - testsuite/tests/typecheck/should_compile/T13050.stderr - testsuite/tests/typecheck/should_compile/T14273.stderr - testsuite/tests/typecheck/should_compile/T14590.stderr - testsuite/tests/typecheck/should_compile/T25180.stderr - testsuite/tests/typecheck/should_compile/abstract_refinement_hole_fits.stderr - testsuite/tests/typecheck/should_compile/constraint_hole_fits.stderr - testsuite/tests/typecheck/should_compile/free_monad_hole_fits.stderr - testsuite/tests/typecheck/should_compile/hole_constraints.stderr - testsuite/tests/typecheck/should_compile/holes.stderr - testsuite/tests/typecheck/should_compile/holes2.stderr - testsuite/tests/typecheck/should_compile/holes3.stderr - testsuite/tests/typecheck/should_compile/refinement_hole_fits.stderr - testsuite/tests/typecheck/should_compile/subsumption_sort_hole_fits.stderr - testsuite/tests/typecheck/should_compile/type_in_type_hole_fits.stderr - testsuite/tests/typecheck/should_compile/valid_hole_fits.stderr - testsuite/tests/typecheck/should_compile/valid_hole_fits_interactions.stderr - testsuite/tests/typecheck/should_fail/T14884.stderr - utils/deriveConstants/Main.hs The diff was not included because it is too large. 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