Simon Peyton Jones pushed to branch wip/T23162-part2 at Glasgow Haskell Compiler / GHC

Commits:

• 115702e2
  by Simon Peyton Jones at 2025-12-24T09:27:56+00:00

  Improve recording of insolubility for fundeps
  
  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]
  

• 906abe13
  by Simon Peyton Jones at 2025-12-24T09:27:56+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.
  

39 changed files:

• compiler/GHC/Core/TyCo/Subst.hs
• compiler/GHC/Core/Unify.hs
• compiler/GHC/Tc/Errors.hs
• compiler/GHC/Tc/Errors/Ppr.hs
• compiler/GHC/Tc/Errors/Types.hs
• compiler/GHC/Tc/Solver.hs
• compiler/GHC/Tc/Solver/FunDeps.hs
• compiler/GHC/Tc/Solver/Monad.hs
• compiler/GHC/Tc/Types/Constraint.hs
• compiler/GHC/Tc/Utils/Monad.hs
• docs/users_guide/9.16.1-notes.rst
• testsuite/tests/indexed-types/should_fail/T26176.stderr
• testsuite/tests/parser/should_fail/RecordDotSyntaxFail10.stderr
• testsuite/tests/parser/should_fail/RecordDotSyntaxFail13.stderr
• testsuite/tests/parser/should_fail/T20654a.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/typecheck/should_compile/T16188.hs
• testsuite/tests/typecheck/should_fail/FD3.stderr
• testsuite/tests/typecheck/should_fail/FDsFromGivens2.stderr
• testsuite/tests/typecheck/should_fail/FunDepOrigin1b.stderr
• testsuite/tests/typecheck/should_fail/T13506.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/T25325.stderr
• testsuite/tests/typecheck/should_fail/T5236.stderr
• testsuite/tests/typecheck/should_fail/T5246.stderr
• testsuite/tests/typecheck/should_fail/T5978.stderr
• testsuite/tests/typecheck/should_fail/T9612.stderr
• testsuite/tests/typecheck/should_fail/all.T
• testsuite/tests/typecheck/should_fail/tcfail143.stderr

The diff was not included because it is too large.