[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 3 commits: Desugaring, plus -Wincomplete-record-selectors

Sun Oct 13 01:05:43 UTC 2024

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC

Commits:
2c3eb7a3 by Sebastian Graf at 2024-10-12T21:05:34-04:00
Desugaring, plus -Wincomplete-record-selectors

This commit does several related things:

* Major refactor of the handling of applications in the desugarer.
  Now all applications are handled in `dsApp`, `ds_app` and related
  functions.  This dramatically simplifies the code and removes
  complicated cruft that had accumulated.  Hooray.

  Fixes #25281.

* Improve the handling of -Wincomplete-record-selectors.

  We now incorporate the result type of unsaturated record selector
  applications as well as consider long-distance information in
  getField applications.

  Plus, the implmentation now builds the improved `dsApp` stuff
  above, so it is much easier to understand.

  Plus, incorporates improved error message wording suggested
  by Adam Gundry in !12685.

  Fixes #24824, #24891

  See the long Note [Detecting incomplete record selectors]

* Add -Wincomplete-record-selectors to -Wall, as specified in
  GHC Proposal 516.

  To do this, I also had to add -Wno-incomplete-record-selectors
  to the build flags for Cabal in GHC's CI.  See
  hadrian/src/Settings/Warnings.hs.  We can remove this when
  Cabal is updated so that it doesn't trigger the warning:
  https://github.com/haskell/cabal/issues/10402

2.6% decrease in compile time allocation in RecordUpPerf

Metric Decrease:
    RecordUpdPerf

- - - - -
73b3366b by Simon Peyton Jones at 2024-10-12T21:05:35-04:00
Elmininate incomplete record selectors

This patch is a pure refactor of GHC's source code, to avoid the use
of partial record selectors.  It was provoked by adding
-Wincomplete-record-selectors to -Wall (as the GHC Proposal specified),
which in turn showed up lots of places where GHC was using incomplete
record selectors.

This patch does mostly-simple refactoring to make it clear to the pattern
match checker that there is in fact no partiality.

There is one externally-visible change: I changed the data type HoleFit
to split out the two cases

  data HoleFit = TcHoleFit  TcHoleFit | RawHoleFit SDoc
  data TcHoleFit = HoleFit { ...lots of fields }

There are large swathes of code that just deal with `TcHoleFit`, and
having it as a separate data types makes it apparent that `RawHoleFit`
can't occur.

This makes it much better -- but the change is visible in the
HolePlugin interface.  I decided that there are so few clients of this
API that it's worth the change.

I moved several functions from Language.Haskell.Syntax to GHC.Hs.
Reason, when instantiated at (GhcPass _), the extension data construtcor
is guaranteed unused, and that justifies omitted patterns in these
functions.  By putting them in GHC.Hs.X I can specialise the type for
(GhcPass _) and thereby make the function total.

An interesting side-light is that there were a few local function
definitions without a type signature, like this one in GHC.Parser.Header
     convImport (L _ i) = (ideclPkgQual i, reLoc $ ideclName i)
This is fully closed, and so is generalised; but that generalises
it to any old pass, not (GhcPass _), so GHC rightly complains about the
use of the selector `ideclPkgQual`.  I added a type signature to `i`, thus
     convImport (L _ (i::ImportDecl GhcPs))
         = (ideclPkgQual i, reLoc $ ideclName i)
which specialised the function enough to make the record selector complete.
Quite a surprising consequence of local let-generalisation!

- - - - -
787491b7 by Alan Zimmerman at 2024-10-12T21:05:35-04:00
EPA: Remove [AddEpAnn] from IE, Pat and some Tys

EPA: Remove [AddEpAnn] from LazyPat

EPA: Remove [AddEpAnn] from RecordCon/RecordUpd/ConPat

EPA: Remove [AddEpAnn] from HsFieldBind

EPA: Remove [AddEpAnn] from PatSynBind

EPA: Remove [AddEpAnn] from IPBind

EPA: Remove [AddEpAnn] from FixSig

EPA: Remove [AddEpAnn] from activation rules

EPA: Remove [AddEpann] from SpecInstSig

EPA: Remove [AddEpAnn] from MinimalSig

EPA: Remove [AddEpAnn] from SCCFunSig

EPA: Remove [AddEpAnn] from CompleteMatchSig

EPA: Remove [AddEpAnn] from AnnSig, as used in PatSynSig, ClassOpSig, TypeSig

EPA: Remove [AddEpAnn] from IEThingAbs

EPA: Remove [AddEpAnn] from IEThingAll / IEThingWith

EPA: Remove [AddEpAnn] from IEModuleContents

EPA: Remove [AddEpAnn] from HsOpTy

EPA: Remove [AddEpAnn] for various binders

EPA: Remove [AddEpAnn] for HsIParamTy

- - - - -

30 changed files:

- compiler/GHC/CmmToAsm/Dwarf/Types.hs
- compiler/GHC/CmmToAsm/Reg/Graph/Stats.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/ConLike.hs
- compiler/GHC/Core/FVs.hs
- compiler/GHC/Core/LateCC/OverloadedCalls.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/CprAnal.hs
- compiler/GHC/Core/Opt/DmdAnal.hs
- compiler/GHC/Core/Opt/Simplify/Env.hs
- compiler/GHC/Core/Opt/Simplify/Utils.hs
- compiler/GHC/Core/Opt/SpecConstr.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Core/SimpleOpt.hs
- compiler/GHC/Core/Subst.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Core/Utils.hs
- compiler/GHC/CoreToIface.hs
- compiler/GHC/Driver/Flags.hs
- compiler/GHC/Hs/Binds.hs
- compiler/GHC/Hs/Decls.hs
- compiler/GHC/Hs/Dump.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Extension.hs
- compiler/GHC/Hs/ImpExp.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/Hs/Stats.hs
- compiler/GHC/Hs/Type.hs

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8d65871587e59470a707246e8f6b9f76e797419f...787491b7cbcee5f41972afeb5713cabf560b79f6

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8d65871587e59470a707246e8f6b9f76e797419f...787491b7cbcee5f41972afeb5713cabf560b79f6
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