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`
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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.
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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.
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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
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45749c4f by Simon Peyton Jones at 2025-10-22T16:57:52+01:00
Comments only -- remove dangling Note references
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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...
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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/df22e143469528253fa18a104842ac2...
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