Simon Peyton Jones pushed to branch wip/T23162-spj at Glasgow Haskell Compiler / GHC Commits: 92c0bda2 by Simon Peyton Jones at 2025-10-22T16:47:53+01:00 Improve tracking of rewriter-sets This refactor substantially improves the treatment of so-called "rewriter-sets" in the constraint solver. The story is described in the rewritten Note [Wanteds rewrite Wanteds: rewriter-sets] in GHC.Tc.Types.Constraint Some highlights * Trace the free coercion holes of a filled CoercionHole, in CoercionPlusHoles. See Note [Coercion holes] (COH5) This avoids taking having to take the free coercion variables of a coercion when zonking a rewrriter-set * Many knock on changes * Make fillCoercionHole take CoercionPlusHoles as its argument rather than to separate arguments. * Similarly setEqIfWanted, setWantedE, wrapUnifierAndEmit. * Be more careful about passing the correct CoHoleSet to `rewriteEqEvidence` and friends * Make kickOurAfterFillingCoercionHole more clever. See new Note [Kick out after filling a coercion hole] Smaller matters * Rename RewriterSet to CoHoleSet * Add special-case helper `rewriteEqEvidenceSwapOnly` - - - - - 373492f9 by Simon Peyton Jones at 2025-10-22T16:57:27+01:00 Tidy up constraint solving for foralls * In `can_eq_nc_forall` make sure to track Givens that are used in the nested solve step. * Tiny missing-swap bug-fix in `lookup_eq_in_qcis` * Fix some leftover mess from commit 14123ee646f2b9738a917b7cec30f9d3941c13de Author: Simon Peyton Jones Date: Wed Aug 20 00:35:48 2025 +0100 Solve forall-constraints via an implication, again Specifically, trySolveImplication is now dead. - - - - - ba9616f3 by Simon Peyton Jones at 2025-10-22T16:57:52+01:00 Do not treat CoercionHoles as free variables in coercions This fixes a long-standing wart in the free-variable finder; now CoercionHoles are no longer treated as a "free variable" of a coercion. I got big and unexpected performance regressions when making this change. Turned out that CallArity didn't discover that the free variable finder could be eta-expanded, which gave very poor code. So I re-used Note [The one-shot state monad trick] for Endo, resulting in GHC.Utils.EndoOS. Very simple, big win. - - - - - 026d33b4 by Simon Peyton Jones at 2025-10-22T16:57:52+01:00 Update debug-tracing in CallArity No effect on behaviour, and commented out anyway - - - - - 45749c4f by Simon Peyton Jones at 2025-10-22T16:57:52+01:00 Comments only -- remove dangling Note references - - - - - bea7fbdf by Simon Peyton Jones at 2025-10-22T16:57:52+01:00 Accept error message wibbles - - - - - 39 changed files: - compiler/GHC/Core/Opt/CallArity.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/TyCo/FVs.hs - compiler/GHC/Core/TyCo/Rep.hs - compiler/GHC/Runtime/Eval.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/Sig.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/Irred.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Solver/Rewrite.hs - compiler/GHC/Tc/Solver/Solve.hs - compiler/GHC/Tc/Solver/Solve.hs-boot - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Types/Evidence.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/Tc/Utils/TcType.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Tc/Zonk/TcType.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/Types/Unique/DSM.hs - + compiler/GHC/Utils/EndoOS.hs - compiler/ghc.cabal.in - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/linters/notes.stdout - testsuite/tests/partial-sigs/should_fail/T14584a.stderr - testsuite/tests/quantified-constraints/T15359.hs - testsuite/tests/rep-poly/T13233.stderr - testsuite/tests/rep-poly/T14561b.stderr - testsuite/tests/rep-poly/T19709b.stderr - testsuite/tests/rep-poly/T23903.stderr - testsuite/tests/typecheck/should_compile/T25266a.stderr The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/df22e143469528253fa18a104842ac2... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/df22e143469528253fa18a104842ac2... You're receiving this email because of your account on gitlab.haskell.org.