-
bee1913d
by Alan Zimmerman at 2026-07-28T16:42:29-04:00
EPA: ClsInstDecl with decls as [LHsDecl GhcPs] in GhcPs
Similar to 4fdfe75731e01dad7d7fa474c2703d0d3965afb1, this commit
changes the as-parsed representation of class instance declarations to
[LHsDecl GhcPs], and only separates them by type from the renamer onward.
This also allows us to remove all the AnnSortKey machinery for exact
printing, as it is now no longer needed.
-
72c55eee
by Cheng Shao at 2026-07-28T16:43:11-04:00
hadrian: implement and use writeFileAtomic to fix race condition
This patch implements `writeFileAtomic` in hadrian and change all
invocations of shake non-atomic `writeFile'` to use `writeFileAtomic`,
to avoid multiple hadrian concurrent invocations overwriting the same
in-tree generated file not in the build root directory. Fixes #27536.
Additional notes:
- `writeFileChanged`/`writeFileChangedBS` cannot be made atomic since
it involves reading the file's older version, so their uses are left
alone. It doesn't affect #27536 given their outputs are contained in
the build root directory.
- It's possible to shrink this patch by only making writes outside the
build root directory atomic. But I think it's not worth the effort
for fine grained distinction here, and atomic writes within the
build root directory should also improve robustness of a hadrian
build.
- In the longer term we do want to make a ghc build only generate
files within the build root directory, though that's a lot of work
and outside the scope of this particular bugfix.
Co-authored-by: Codex <codex@openai.com>
-
46d4f963
by Sylvain Henry at 2026-07-29T06:38:40-04:00
RTS: correctly mark slop bytes when shrinking large arrays (#19048)
Correctly mark slop bytes even when profiling is off so that heap census
doesn't traverse garbage-collected closures.
-
4762a8bf
by Simon Jakobi at 2026-07-29T06:39:23-04:00
Add -XLazyFieldAnnotations (GHC proposal 752)
Unbundle the prefix `~` lazy field annotation syntax from StrictData. The
new LazyFieldAnnotations extension controls whether `~` is accepted on
constructor fields. StrictData (and Strict, transitively) imply the new
extension.
See https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0752-lazy-field-annotations.rst.
Closes #24455.
Assisted-by: Claude Opus 4.8
-
0b6dcc84
by Simon Jakobi at 2026-07-29T06:40:04-04:00
testsuite: Relax T24471 residency tolerance
T24471 peak residency fluctuates enough on i386 to cause spurious
failures. Use the standard residency tolerance while retaining the
existing allocation threshold.
See https://gitlab.haskell.org/ghc/ghc/-/work_items/24471#note_682303.
Assisted-by: gpt-5.6-sol via Codex CLI
-
90e95b34
by Cheng Shao at 2026-07-29T06:40:45-04:00
compiler: fix missing top-level procedure labels in cmm dumps
This patch fixes missing top-level procedure labels in some
intermediate Cmm pass dumps. Fixes #27553.
Co-authored-by: Codex <codex@openai.com>
-
360a5946
by sheaf at 2026-07-29T06:41:35-04:00
Add some type-family-heavy performance tests
FamAppCachePerf stress-tests the performance of lookups in the
type family application cache.
T27336 is a minimisation extracted from the reported reproducer.
SimplCastPerf is a measure of coercion growth due to the simplifier
calling mkTransCo without re-optimising the result.
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3ec9e2b9
by Mike Pilgrem at 2026-07-31T08:21:33-04:00
GHC Guide: Improve docs on response files
-
e5b2a1f7
by sheaf at 2026-07-31T08:22:23-04:00
Disable Core Lint for TcPlugin_RewritePerf
This is a compiler performance test, but the test source hard-coded
-dcore-lint, defeating the measurement.
-------------------------
Metric Decrease:
TcPlugin_RewritePerf
-------------------------
-
85b10c00
by Alan Zimmerman at 2026-07-31T22:09:47+01:00
EPA: Remove LocatedP from OverlapMode
We have
type LocatedP = GenLocated SrcSpanAnnP
type SrcSpanAnnP = EpAnn AnnPragma
As the first step in removing this in favour of LocatedA which only
captures location, comments and trailing annotations, we remove it
from OverlapMode
We do this by moving the AnnPragma into the TTG extension point
instead.
-
c9a34a00
by Viktor Dukhovni at 2026-08-02T04:34:17-04:00
Fix note typo
-
4f2a21f7
by Andreas Klebinger at 2026-08-02T22:46:46-04:00
Apply oneShot Monad trick to STG LintM
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21e4b89d
by Andreas Klebinger at 2026-08-02T22:46:46-04:00
stgLint: Use a single reader env for read only arguments.
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d415f38a
by Alan Zimmerman at 2026-08-02T22:47:27-04:00
EPA: Remove LocatedP from CType
The next step of removing use of LocatedP by moving
the AnnPragma for CType into its TTG extension point
instead.
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8fc6f882
by Simon Jakobi at 2026-08-05T14:53:41-04:00
testsuite: Don't crash on non-UTF-8 test output
read_stdout, read_stderr_for, read_comp_stderr and read_diff decoded
strictly (the first three with UTF-8, read_diff with the locale
encoding), so a test emitting invalid UTF-8 (binary output, or a crash
truncating a multi-byte character) raised UnicodeDecodeError and was
reported as a framework failure instead of its actual result.
Decode with errors='replace', like read_no_crs and safe_print.
Assisted-by: Claude Fable 5
-
56534866
by Simon Jakobi at 2026-08-05T14:53:41-04:00
testsuite: Colorize the test summary, also in CI
The summary headings were plain, and SUMMARY was colored unconditionally,
so the escapes also ended up in the file written by --summary-file.
Color is now decided per output sink via term_color.colored_if; see the
comments in term_color.
CI logs are not a tty, but GitLab's log viewer renders ANSI colors, so
add --force-colors and pass it in .gitlab/ci.sh.
Assisted-by: Claude Opus 5
-
bceb541a
by Simon Jakobi at 2026-08-05T14:53:42-04:00
testsuite: Repeat unexpected failure output in the summary
Finding out why a test failed meant scrolling back through a possibly
very long log to the point where the test ran. The summary now repeats
the captured output of unexpected failures, before the statistics, so
the most interesting part is at the end of the log (#16720).
Output mismatches report their diff instead of the mismatching stream
(see Note [Redundant output in test results]). The repeated output is
bounded per stream, and skipped altogether beyond
MAX_SUMMARY_OUTPUT_TESTS failure blocks. Tests failing identically in
several ways share one block.
Test results now report a source-relative directory, stable regardless
of where the run was started from.
Assisted-by: Claude Fable 5
-
2ab02c57
by Ben Gamari at 2026-08-05T14:54:24-04:00
base: Don't drop exception context in SomeException(toException)
For reasons that are lost to time, the implementation of [CLC #200]
that was merged inappropriately dropped `ExceptionContext` in the
`toException` implementation given to `SomeException`.
Fix this infelicity.
[CLC #200]: https://github.com/haskell/core-libraries-committee/issues/200
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126ce574
by Vladislav Zavialov at 2026-08-05T14:55:05-04:00
Test case for #20902
Starting with GHC 9.14.1 (the first major release to include 51e3ec83),
and from point releases GHC 9.10.2 and GHC 9.12.3 (backports cc4470be68
and b30f25591e), all examples in this ticket are handled as expected.
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b14d8d59
by Alan Zimmerman at 2026-08-05T14:55:46-04:00
EPA: Remove LocatedP, last use in WarningTxt
The last step of removing LocatedP, by moving the AnnPragma for
WarningTxt into its TTG extension point instead.
This also allows us to remove LocatedP and SrcSpanAnnP
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70b58c8f
by Vladislav Zavialov at 2026-08-05T14:56:27-04:00
Test cases for #18725
Starting with GHC 9.4 (the first release to include 268efcc9a4), the program in
this ticket no longer panics. A standalone kind signature breaks the recursive
loop, so the type constructor can be used in a kind within its own group.
T18725a checks that this is accepted with the signature present, while T18725b
confirms it is still rejected without it.
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b18c8dd5
by Zubin Duggal at 2026-08-06T15:51:01-04:00
hie files: Dump the type table when dumping with -ddump-hie
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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
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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
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246d4d72
by Simon Peyton Jones at 2026-08-06T15:52:25-04:00
Documentation only
...driven by my investigation of #27591
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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
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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
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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
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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
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3a552476
by Simon Jakobi at 2026-08-09T15:20:06-04:00
Word64Map: add compareSize
compareSize m c compares the size of a map to an Int, but unlike
compare (size m) c it stops traversing the map once the outcome is
determined.
Based on https://github.com/haskell/containers/pull/1139
Assisted-by: Claude Opus 5
-
6e2c99d8
by Simon Jakobi at 2026-08-09T15:20:06-04:00
Use a pigeonhole sort for deterministic UniqDFM iteration
Deterministic UniqDFM iteration used a list mergesort, allocating O(n
log n) cons cells and contributing significantly to compiler allocations
(#27459).
Use a pigeonhole sort where appropriate, while retaining the mergesort
fallback. See Note [Sorting a UDFM] and Note [Cost of deterministic
iteration].
The peak_megabytes_allocated increase for LinkableUsage02 is probably
due to GC timing noise. See #27613.
-------------------------
Metric Decrease:
InstanceMatching
InstanceMatching1
ManyAlternatives
T12707
T13379
T13719
T24471
T27336
T5321FD
T5321Fun
T783
Metric Increase 'peak_megabytes_allocated':
LinkableUsage02
-------------------------
Assisted-by: gpt-5.6-sol via Codex CLI
-
a938ab12
by sheaf at 2026-08-09T15:20:48-04:00
Testsuite: don't measure max residency for T27336
We really care more about total allocations for this test, so this commit
removes the maximum residency measurement.
-
7d94bb78
by Alan Zimmerman at 2026-08-09T15:21:29-04:00
EPA: Remove LocatedE, replace with LocatedA
This gets rid of one more LocatedXXX occurrence
-
9df24b7e
by sheaf at 2026-08-10T14:28:30-04:00
hie.yaml: use a polyglot shell/batch script
This commit merges hie-bios and hie-bios.bat into a single polyglot
script. This avoids Windows users having to manually update hie.yaml
in order to be able to use HLS.
-
7f75c588
by Alan Zimmerman at 2026-08-10T14:29:11-04:00
EPA: Remove type parameter from AnnList
This is a step towards cutting AnnList down to its core for formatting
lists only
-
e8d1a0d6
by Bernhard M. Wiedemann at 2026-08-10T21:31:23-04:00
driver: Link object files in a deterministic order
The object files handed to the linker come from the HomePackageTable,
which is ordered by the order in which modules finished compiling. With
-j1 that is the build plan order, with -jN it is whatever the scheduler
produced, so the same sources can link to different (but equivalent)
binaries.
The order reaches the output: .text and .rodata contributions are
concatenated in link order, so e.g. building the hdav executable of the
DAV package twice, once with -j1 and once with -j4, yields two binaries
that differ in ~100kB of section contents.
Sort the home modules by module before collecting their linkables,
guarded under `Opt_ObjectDeterminism` .
Fixes #27612
Signed-off-by: Bernhard M. Wiedemann <bwiedemann@suse.de>
-
556db2f3
by sheaf at 2026-08-10T21:32:06-04:00
Reduce SpecConstr threshold in GHC.Tc.Solver.Rewrite
As remarked in #27628, this module currently sits on a knife's edge: if
the body of 'simplifyArgsWorker' is made even a tiny bit smaller, then
SpecConstr suddenly kicks in and causes disastrous reboxing of the
LiftingContext argument.
To make this less likely to happen, this commit lowers the SpecConstr
threshold.
-
4865b2a6
by Zubin Duggal at 2026-08-12T15:58:10+05:30
ghc-internal: annotateSTM should use catchSTM# rather than catch#
A catch# frame inside a transaction breaks retry and async exception
delivery.
Fixes #27657