Simon Peyton Jones pushed to branch wip/T23162-spj at Glasgow Haskell Compiler / GHC

Commits:

• 2842aa8a
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Big increment in rewriter tracking
  
  Needs more documentation
  
  More tidying up of rewriter sets
  

• 087641b7
  by Simon Peyton Jones at 2025-10-22T09:20:06+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.
  

• 5728c534
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Fix buglet in solving equalities from QCIs
  

• 6fb8ad25
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Improve equality checking for foralls a bit
  
  ...by re-using the TcEvBindsVar
  

• fed02e8e
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Update debug-tracing in CallArity
  
  No effect on behaviour, and commented out anyway
  

• 50ee09d4
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Wibble Endo
  

• ba99fc22
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Wibble CoercionHole free vars
  

• 2d13e782
  by Simon Peyton Jones at 2025-10-22T09:20:06+01:00

  Wibble improve forall
  

• ddcd5a28
  by Simon Peyton Jones at 2025-10-22T09:20:07+01:00

  Comments only -- remove dangling Note references
  

• 7da8daaf
  by Simon Peyton Jones at 2025-10-22T13:10:48+01:00

  Accept error message wibbles
  

• df22e143
  by Simon Peyton Jones at 2025-10-22T13:11:02+01:00

  More rewriter-set refactoring
  
  * Introduce and use CoercionPlusHoles
  * More documentation
  

36 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/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/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/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.