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Alan Zimmerman pushed to branch wip/az/exactprint-annotation-rationalisation at Glasgow Haskell Compiler / GHC

Commits:

b18c8dd5

by Zubin Duggal at 2026-08-06T15:51:01-04:00

hie files: Dump the type table when dumping with -ddump-hie

f839d0fb

by Zubin Duggal at 2026-08-06T15:51:01-04:00

hie files: Take evidence for quantified constraints into account when saving evidence terms to the hie ast

Fixes #25709

5753ebaa

by Simon Jakobi at 2026-08-06T15:51:43-04:00

testsuite: fix stale paths for the ghc-config build artifacts

ghc-config.hs moved from testsuite/mk/ to testsuite/ghc-config/ in
6c7a49139c, but the .gitignore entry and the clean rule still referred to
the old location. As a result the compiled ghc-config binary, which
boilerplate.mk rebuilds on every make-driven test run, showed up as an
untracked file and was never cleaned.

Assisted-by: Claude Opus 5

246d4d72

by Simon Peyton Jones at 2026-08-06T15:52:25-04:00

Documentation only

...driven by my investigation of #27591

be69e9df

by Alan Zimmerman at 2026-08-06T15:53:05-04:00

EPA: Replace AnnPragma with individual types

We introduced AnnPragma as a common type for all pragma usages wrapped
in LocatedP / SrcSpanAnnP. Now that those are gone, and the AnnPragma
moved into the TTG points for the given items, we can ensure that each
carries only the annotations it needs.

So we remove AnnPragma, and in its place bring in
  AnnCType
  AnnWarningTxt
  AnnOverlap
  AnnAnnDecl
  AnnPragSCC

0779e12c

by Simon Jakobi at 2026-08-07T12:36:11-04:00

Cmm: print unreachable blocks under -dppr-debug (#27368)

Unreachable blocks linger in a CmmGraph's block map for most of the Cmm
pipeline, but pprCmmGraph only ever printed the blocks reachable from the
entry, so dumps looked consistent while the graph was not. Issues like
 #27368 were hard to debug due to this.

pprCmmGraph now appends the stored-but-unreachable blocks under a
"// unreachable blocks:" heading when -dppr-debug is on.
See Note [unreachable blocks] in GHC.Cmm.Pipeline.

Assisted-by: Claude Opus 5

3a0f9a51

by Simon Peyton Jones at 2026-08-07T12:36:54-04:00

Fix three bugs related to required type args and INLINE pragmas

* `GHC.Core.Opt.Arity.mkEtaForAllMCo` got the visibility flags back to front,
  leading to a Lint error (#27557)

* The arity in an InlineSaturation is the VisArity not the Arity; the
  two can differ when we have "required" type arguments.  This made the
  INLINE pragma argument counting go wrong in `makeCorePair` (#27590).

* When a simple binding has a type signature, we take special path in `tcPolyCheck`,
  leading to an outer `AbsBinds` that has no dictionaries, even when the binding
  is in fact overloaded.  That confused the inline-arity computation in
  `makeCorePair` (#27589).

The latter two are fixed using the new function `GHC.HsToCore.Binds.findSatArity`.
That actually simplifies the API of `makeCorePair`, which is nice.

The first bug is fixed by swapping the visiblity flags in
`GHC.Core.Opt.Arity.mkEtaForAllMCo`

Getting the INLINE behaviour right led to some perf changes:
  * Runtime /halved/ on T7954 due to better specialisation
  * Compile time increased by 6% in T21839c because a bit more inlining
    happened, as it always should have done.
  * For some reason compile-time max-bytes-used dropped by 30% on
    T27336, but only on one build configuration; and it increased
    on LinkableUsage02 by 6% on another configuration

Geometric mean effect on our compile time benchmarks is +0.1%.

Metric Decrease:
    T27336
    T7954
Metric Increase:
    LinkableUsage02
    T21839c

4f985108

by Vladislav Zavialov at 2026-08-07T17:49:50-04:00

Discard type arguments in tcPatToExpr (#27440, #27583)

The builder expression of an implicitly bidirectional pattern synonym must not
mention types written in the RHS:

  * Invisible type arguments led to a panic (#27440)
  * Required type arguments failed with out-of-scope variables (#27583)

Both are now discarded, following the precedent established by pattern
signatures (#9867).

Discarding type arguments takes some care: a type pattern cannot be told from a
value pattern by syntax alone, as the `type` keyword may be omitted. Consider:

    data T a b c where
      MkT :: forall a. forall b c -> a -> T a b c

    pattern P :: x -> T x y z
    pattern P x = MkT @a (type b) c x

In P's right-hand side, `@a` and `type b` are clearly type arguments, but what
about `c` and `x`? We can only tell by matching the patterns against MkT's
type. So tcPatToExpr now runs in TcM and matches the arguments against the
constructor's TyVarBinders using zipPatsBndrs, which is made public for this
purpose. The resulting builder is $bP x = MkT _ _ x.

See Note [Discarding types in the builder expression].

Test cases: T27440a T27440b T27440c T27440d T27440e
            T27583a T27583b T27583c T27583d T27583e T27583f T27583g

Metric Increase: LinkableUsage02
Metric Decrease: T27336

Assisted-by: Claude Opus 5

eb1dcd4d

by sheaf at 2026-08-07T17:50:40-04:00

mkWpFun_FRR: fix ordering of coercion composition

When the subsumption machinery generates an eta-expansion, we must
perform a representation polymorphism check to ensure the lambda binder
it introduces has a fixed runtime representation.
This is done in GHC.Tc.Utils.mkWpFun_FRR.

This check involves composing quite a few coercions, arising from
representation-polymorphism checks on both the actual and expected
argument types. These coercions are then chained using HsWrapper
composition, <.>. The ordering of composition was incorrect, leading to
the Core Lint failure reported in #27639. This commit fixes that.

Fixes #27639

4bbe0b57

by Alan Zimmerman at 2026-08-08T12:16:42+01:00

EPA: Remove LocatedE, replace with LocatedA

This gets rid of one more LocatedXXX occurrence

95b7f1fe