[Git][ghc/ghc][master] Fix a QuickLook bug

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
2747cd34 by Simon Peyton Jones at 2024-06-12T12:51:37-04:00
Fix a QuickLook bug

This MR fixes the bug exposed by #24676.  The problem was that
quickLookArg was trying to avoid calling tcInstFun unnecessarily; but
it was in fact necessary.  But that in turn forced me into a
significant refactoring, putting more fields into EValArgQL.

Highlights: see Note [Quick Look overview] in GHC.Tc.Gen.App

* Instantiation variables are now distinguishable from ordinary
  unification variables, by level number = QLInstVar. This is
  treated like "level infinity".  See Note [The QLInstVar TcLevel]
  in GHC.Tc.Utils.TcType.

* In `tcApp`, we don't track the instantiation variables in a set Delta
  any more; instead, we just tell them apart by their level number.

* EValArgQL now much more clearly captures the "half-done" state
  of typechecking an argument, ready for later resumption.
  See Note [Quick Look at value arguments] in GHC.Tc.Gen.App

* Elminated a bogus (never used) fast-path in
  GHC.Tc.Utils.Instantiate.instCallConstraints
  See Note [Possible fast path for equality constraints]

Many other small refactorings.

- - - - -


18 changed files:

- compiler/GHC/Core.hs
- compiler/GHC/Core/DataCon.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Core/TyCo/FVs.hs
- compiler/GHC/Driver/Config/Core/Lint.hs
- compiler/GHC/Tc/Gen/App.hs
- compiler/GHC/Tc/Gen/Expr.hs
- compiler/GHC/Tc/Gen/Head.hs
- compiler/GHC/Tc/Gen/Match.hs
- compiler/GHC/Tc/Gen/Pat.hs
- compiler/GHC/Tc/Solver/InertSet.hs
- compiler/GHC/Tc/Solver/Monad.hs
- compiler/GHC/Tc/Types/Constraint.hs
- compiler/GHC/Tc/Utils/Concrete.hs
- compiler/GHC/Tc/Utils/Instantiate.hs
- compiler/GHC/Tc/Utils/TcMType.hs
- compiler/GHC/Tc/Utils/TcType.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2747cd34e5ae6a9216bacb196d1d45c710c5daff

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2747cd34e5ae6a9216bacb196d1d45c710c5daff
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