[Git][ghc/ghc][wip/io-manager-deadlock-detection] 179 commits: Add type family performance test for #26426

16 Jul 2026

      Duncan Coutts pushed to branch wip/io-manager-deadlock-detection at Glasgow Haskell Compiler / GHC

Commits:
40764930 by sheaf at 2026-06-12T14:54:43-04:00
Add type family performance test for #26426

Some GHC versions produced large numbers of coercions after typechecking
and desugaring when compiling the program in #26426:

Version | Typechecker time | Typechecker allocations | Coercions
-------:|-----------------:|------------------------:|---------:
9.6     |   47 ms          |  48 MB                  |    110k
9.8     | 1000 ms          | 486 MB                  | 10,437k
9.10    |  922 ms          | 489 MB                  | 10,436k
9.12    |  906 ms          | 482 MB                  | 10,437k
9.14    |   63 ms          |  55 MB                  |    333k
10.0    |   47 ms          |  64 MB                  |     35k

The improvement 9.12 -> 9.14 was due to commit 22d11fa818fae2c95c494fc0fac1f8cb4c6e7cb6,
while the improvement 9.14 -> 10.0 was due to commit 0b7df6db9e46df40e86fbff1a66dc10440b99db5.

As the behaviour of GHC seems better than it's ever been on this program,
we declare victory, adding this performance test to ensure we don't
regress on this program.

On the way, we update Note [Combining equalities] in GHC.Tc.SolveR.Equality
with the explanation of the 9.12 -> 9.14 improvement (getting rid of an
exponential blowup in coercion sizes), and we update
Note [Exploiting closed type families] in GHC.Tc.Solver.FunDeps with
the explanation of the 9.14 -> 10.0 improvement (bringing down coercion
size growth from cubic to quadratic).

- - - - -
0f3d0a71 by Zubin Duggal at 2026-06-12T14:55:30-04:00
compiler: mark tool messages as errors/warnings depending on the exit code

Fixes #27370

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d9ea2d76 by mangoiv at 2026-06-13T04:41:51-04:00
libraries/process: bump submodule to v1.6.30.0

- bump the submodule to the appropriate tag
- suppress benign warning resulting from the change

- - - - -
6ebaaba3 by David Eichmann at 2026-06-13T04:42:37-04:00
ghc-toolchain: don't throw when candidate executables are not found

Fixes #27369

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6c65e1e1 by David Eichmann at 2026-06-13T04:43:23-04:00
CI: lint-changelog checks for no-changelog label in script instead of rules

- - - - -
bab37cc6 by konsumlamm at 2026-06-13T19:10:21+02:00
Implement CLC proposal #378

Add `Data.Double` and `Data.Float` modules
Document that GHC uses IEEE 754

- - - - -
fb5246ad by fendor at 2026-06-15T18:07:23-04:00
Drop `preloadClosure` from `UnitState`

It is always hard-coded to the same value.

Backpack Unit instantiation isn't using it any more.
Allows us to simplify the API and get rid of `improveUnit`.

- - - - -
291ce3aa by ARATA Mizuki at 2026-06-15T18:08:26-04:00
RISC-V NCG: Zero-extend the result of castFloatToWord32

According to the ISA manual, FMV.X.W sign-extends the result.
We need to truncate the result to avoid creating an exotic Word32 value.

Fixes #27300

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011be91f by ARATA Mizuki at 2026-06-15T18:08:26-04:00
RISC-V NCG: Treat d28-d31 (ft8-ft11) as caller-saved

According to the calling convention, the registers d28-d31 (ft8-ft11) are caller-saved.

Fixes #27306

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e8a54713 by ARATA Mizuki at 2026-06-15T18:08:26-04:00
RISC-V NCG: Set rounding mode when emitting `truncate`

If we omit the rounding mode for `fcvt`, `dyn` will be used.
We do not want that for `truncate`, so we set `rtz`.
In other places, we set `rne` because we do not use the dynamic rounding mode.

Fixes #27303

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9438bec7 by Zubin Duggal at 2026-06-15T18:09:11-04:00
rts: fix validate build with gcc 16. `__attribute__((regparm(1)))` is ignored on x86_64 and now
gcc warns that it is ignored:

rts/sm/Evac.h:35:1: error:
     error: ‘regparm’ attribute ignored [-Werror=attributes]

See https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=ccead81bbc39668376eb5cf47066ac...

Fixes #27366

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893e6133 by Andrew Lelechenko at 2026-06-15T23:55:36+01:00
base: more NonEmpty zips

CLC proposal: https://github.com/haskell/core-libraries-committee/issues/409

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1314f2fd by David Eichmann at 2026-06-16T05:46:52-04:00
Hadrian: fix ghc-internal .def file name

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7f72bcb3 by mangoiv at 2026-06-16T05:47:39-04:00
compiler: ignore camelCase and Eta reduce hlint hints

These do not cohere with the style used in GHC. After disabling them,
hlint lints are much less noisy again.

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842bef9f by Alan Zimmerman at 2026-06-16T05:48:25-04:00
EPA: Use standard type family declaration for Anno

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f6d30767 by Wolfgang Jeltsch at 2026-06-16T15:32:34-04:00
Fix two issues in the documentation of pipeline interruption

One issue is a typo (“interreuptible”), the other one the lack of an end
of a sentence, which has been reconstructed from the message of
633bbc1fd4762a2bb73ba1c5b9e0c279f1dd3c40, the commit that introduced
said documentation.

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a3fa10e0 by Christian Georgii at 2026-06-16T15:33:26-04:00
Find plugins in sibling home units in multiple-home-unit sessions

In a multiple-home-unit session (e.g. `cabal repl --enable-multi-repl` or HLS), enabling a plugin with -fplugin that is defined in (or reexported by) another home unit failed with a "hidden package" error. The plugin module finder only searched the current home unit and the registered external packages, never the sibling home units.

findPluginModuleNoHsc now searches the home units that the current home unit depends on, following module reexports and respecting hidden modules, exactly as ordinary import resolution does in findImportedModuleNoHsc. To avoid two divergent copies of this logic, the shared home-unit search (the current home unit first, then its dependencies in priority order, with the accompanying ordering invariant) is extracted into findHomeModuleAmongDeps, which both findImportedModuleNoHsc and findPluginModuleNoHsc now call.

Add testsuite/tests/driver/multipleHomeUnits/plugin01, which loads a plugin as byte-code from a sibling home unit, and plugin02, in which the consumer enables a plugin reexported by a sibling home unit without depending on the plugin's own home unit directly.

Fixes #27349

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d216412b by Ian-Woo Kim at 2026-06-16T20:25:57-04:00
Make the order of usages deterministic

It has been observed that the ordering of usages can be non-determinstic
in parallel builds. Therefore, this contribution introduces sorting of
usages based on a platform- and race-independent sorting criterion.

Resolves #26877.

Co-authored-by: Wolfgang Jeltsch <wolfgang@well-typed.com>

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8e1cc105 by Wolfgang Jeltsch at 2026-06-16T20:25:57-04:00
Change the descriptions of two existing changelog entries

The descriptions now describe the changes in a user-friendly manner, as
opposed to describing the contributions that led to these changes in a
developer-friendly manner.

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636c1c7a by Ian Duncan at 2026-06-16T20:26:50-04:00
AArch64: use SXTH, not SXTW, for W32 signExtendReg

signExtendReg was using SXTH (sign-extend halfword, 16-bit) for
W32-to-W64 sign extension. This should be SXTW (sign-extend word,
32-bit). SXTH only sign-extends the lower 16 bits, producing wrong
results for 32-bit values whose bit 15 differs from bit 31.

Other fixes:

  - At sub-W64, code gen for MO_S_Mul2 should use W32 registers for
    SMULL source operands as per the ARM spec (SMULL Xd, Wn, Wm),
    and not W64.

  - Ensure signExtendReg uses the source width for the source operand
    in SXTW/SXTH/SXTB instructions. GNU as requires sxtw Xd,Wn (not
    sxtw Xd,Xn), while LLVM's integrated assembler on macOS is lenient.

  - Fix overflow flag computation for `MO_S_Mul2`. The overflow bit
    was exactly inverted for sub-W64 operands.

Fixes #26978 and #27047

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b734c75d by Igor Ranieri at 2026-06-16T20:27:32-04:00
haddock: Update CONTRIBUTING with missing step, add missing test
dependency

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7fe4f2ec by Luite Stegeman at 2026-06-17T05:35:09-04:00
tag inference: don't confuse functions with their return values

inferTagRhs was mixing up taggedness for closures and return values
for function closures. We really shouldn't assign TagTuple to a
properly tagged function returning a tuple.

We fix this by keeping track of functions (TagFun) separately from
values (TagVal) and keeping track of their return value. TagFun is
also used for join points.

fixes #27005

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4671c126 by Sebastian Graf at 2026-06-17T05:35:55-04:00
Seed the simplifier's in-scope set for open expressions

simplifyExpr simplifies expressions typed at the GHCi prompt and the
results of Template Haskell splices. Such an expression may be open: at a
GHCi debugger breakpoint its free variables include RuntimeUnk skolems
standing for as-yet-unknown types.

The simplifier began with an in-scope set holding only the wildcard
binder, so when it instantiated the unsafeCoerce# wrapper that GHCi
builds around a result, it formed a substitution whose range mentioned a
free skolem that was not in scope. That breaks the substitution invariant
and, in a compiler built with assertions, trips substTy's sanity check.

Seed the initial in-scope set with the free variables of the expression.
For a closed expression this adds nothing.

See Note [Seed the in-scope set for open expressions].

Fixes #17833 and its duplicate #21118.

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67d41299 by Sebastian Graf at 2026-06-18T05:18:24-04:00
Desugar a `case` scrutinee only once (#27383, #20251)

In `dsExpr` for `HsCase` we desugared the scrutinee /twice/: once to
build the Core `case` itself, and again inside `matchWrapper`, which
re-desugared the source scrutinee (via `addHsScrutTmCs`) purely to
record long-distance information for the pattern-match checker.

For a single `case` that is merely wasteful.  But for nested cases it
is catastrophic.  Consider

    case (case (case e of ... ) of ... ) of ...

Desugaring the outer scrutinee desugars the middle `case` twice, each
of which desugars the inner `case` twice, and so on.  The work doubles
at every level, so desugaring takes O(2^n) time in the nesting depth.
That is the blowup reported in #27383; it is also what makes the
machine-generated program in #20251 take an age to compile.

The fix is simple.  `matchWrapper` is handed the scrutinee anyway, so
we give it the Core expression we have /already/ desugared, and record
the long-distance term constraint with `addCoreScrutTmCs` instead of
re-desugaring from source.  This is just what `matchSinglePatVar`
already does for single-pattern matches.

So:

* `matchWrapper` now takes `Maybe [CoreExpr]` rather than
  `Maybe [LHsExpr GhcTc]`.

* The `HsCase` equation of `dsExpr` passes the already-desugared
  `core_discrim`; the arrow desugarer passes its match variables.

* `addHsScrutTmCs` had no other use, so it is gone.

Desugaring is now linear in the nesting depth.  (The coverage checker
still runs `simpleOptExpr` over each scrutinee, which leaves the total
at O(n^2); that is ample.)  The long-distance information itself is
unchanged: the checker sees precisely the Core that backs the
generated code.

Test: deSugar/should_compile/T27383

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fa5defde by Rodrigo Mesquita at 2026-06-18T05:19:11-04:00
fix: Save FastStrings in the PMC

There is no point in adding the unique to the occurrence FastString we
create, since it is part of the Id anyway.

Adding it to the FastString, meant each FastString was unique
unnecessarily!

In a separate branch, running the compiler on test `InstanceMatching`
observed 30000 `FastString`s created by this code path.

Plus, `fsLit "pm"` follows the existing pattern in `mkPmId`.

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4efb4a66 by Alan Zimmerman at 2026-06-18T14:41:14-04:00
TTG: Add extension points to HsConDetails

Extend HsConDetails as

    data HsConDetails p arg rec
      = PrefixCon !(XPrefixCon p) [arg]    -- C @t1 @t2 p1 p2 p3
      | RecCon    !(XRecCon p)    rec      -- C { x = p1, y = p2 }
      | InfixCon  !(XInfixCon p)  arg arg  -- p1 `C` p2
      | XHsConDetails !(XXHsConDetails p)

    type family XPrefixCon      p
    type family XRecCon         p
    type family XInfixCon       p
    type family XXHsConDetails  p

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c8d27dd4 by Simon Jakobi at 2026-06-18T14:41:59-04:00
CI: quiet submodule clean output in after_script and setup

The clean and cleanup_submodules functions ran 'git submodule foreach
git clean -xdf', flooding the job log with 'Entering ...' and
'Removing ...' lines. Pass --quiet to 'git submodule' and -q to 'git
clean' to drop the success output; errors are still reported.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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09326ca6 by Matthew Pickering at 2026-06-20T23:41:12+02:00
Add missing req_interp modifier to T18441fail3 and T18441fail19

These tests require the interpreter but they were failing in a different
way with the javascript backend because the interpreter was disabled and
stderr is ignored by the test.

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521e55bf by Matthew Pickering at 2026-06-20T23:41:13+02:00
hadrian: Fill in more of the default.host toolchain file

When you are building a cross compiler this file will be used to build
stage1 and it's libraries, so we need enough information here to work
accurately. There is still more work to be done (see for example, word
size is still fixed).

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23c9b6c3 by Matthew Pickering at 2026-06-20T23:42:52+02:00
hadrian: Build stage 2 cross compilers

* Most of hadrian is abstracted over the stage in order to remove the
  assumption that the target of all stages is the same platform. This
  allows the RTS to be built for two different targets for example.
* Abstracts the bindist creation logic to allow building either normal
  or cross bindists. Normal bindists use stage 1 libraries and a stage 2
  compiler. Cross bindists use stage 2 libararies and a stage 2
  compiler.
* hadrian: Make binary-dist-dir the default build target. This allows us
  to have the logic in one place about which libraries/stages to build
  with cross compilers. Fixes #24192

New hadrian target:

* `binary-dist-dir-cross`: Build a cross compiler bindist (compiler =
  stage 1, libraries = stage 2)

This commit also contains various changes to make stage2 compilers
feasible.

-------------------------
Metric Decrease:
    LinkableUsage02
    ManyAlternatives
    ManyConstructors
    MultiComponentModulesRecomp
    MultiLayerModulesRecomp
    RecordUpdPerf
    T10421
    T12150
    T12227
    T12425
    T12707
    T13035
    T13379
    T13820
    T15703
    T16577
    T18140
    T18282
    T18698a
    T18698b
    T18923
    T1969
    T20049
    T21839c
    T3294
    T4801
    T5030
    T5321FD
    T5321Fun
    T5631
    T5642
    T6048
    T783
    T9020
    T9198
    T9233
    T9630
    T9872d
    T9961
    parsing001
    T3064

Metric Increase:
    T26989
    hard_hole_fits
-------------------------

Co-authored-by: Sven Tennie <sven.tennie@gmail.com>

- - - - -
26fed8ab by Matthew Pickering at 2026-06-20T23:42:52+02:00
ci: Test cross bindists

We remove the special logic for testing in-tree cross
compilers and instead test cross compiler bindists, like we do for all
other platforms.

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80c8910e by Matthew Pickering at 2026-06-20T23:42:52+02:00
ci: Introduce CROSS_STAGE variable

In preparation for building and testing stage3 bindists we introduce the
CROSS_STAGE variable which is used by a CI job to determine what kind of
bindist the CI job should produce.

At the moment we are only using CROSS_STAGE=2 but in the future we will
have some jobs which set CROSS_STAGE=3 to produce native bindists for a
target, but produced by a cross compiler, which can be tested on by
another CI job on the native platform.

CROSS_STAGE=2: Build a normal cross compiler bindist
CROSS_STAGE=3: Build a stage 3 bindist, one which is a native compiler and library for the target

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8215573d by Sven Tennie at 2026-06-20T23:42:52+02:00
ci: Increase timeout for emulators

Test runs with emulators naturally take longer than on native machines.

Generate jobs.yml

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5acb7dbc by Matthew Pickering at 2026-06-20T23:42:52+02:00
ci: Javascript don't set CROSS_EMULATOR

There is no CROSS_EMULATOR needed to run javascript binaries, so we
don't set the CROSS_EMULATOR to some dummy value.

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48345343 by Sven Tennie at 2026-06-20T23:42:52+02:00
Javascript skip T23697

See #22355 about how HSC2HS and the Javascript target don't play well
together.

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5e44fd05 by Sven Tennie at 2026-06-20T23:42:52+02:00
Mark T24602 as fragile

It was skipped before (due to CROSS_EMULATOR being set, which changed
for JS), so we don't make things worse by marking it as fragile.

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ab349ec2 by Sven Tennie at 2026-06-20T23:42:52+02:00
Fix T22744 for GHCJS

In fact, this test needs Template Haskell, not necessarily an
interpreter.

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c73352d8 by Sven Tennie at 2026-06-20T23:42:52+02:00
haddock-test: fix GHCJS haddock test failures

Add --ghc-pkg-path flag support so haddock test runner can find
cross-prefixed ghc-pkg (e.g. javascript-unknown-ghcjs-ghc-pkg) which
is not on $PATH in cross install directories.

Skip haddockHtmlTest on GHCJS: Threaded.hs uses forkOS in a TH splice,
which GHCJS RTS doesn't support. Mark with js_skip in all.T.

- - - - -
5e814e76 by Andreas Klebinger at 2026-06-22T23:00:24-04:00
compiler: Deduplicate hscTidy

This function was accidentally duplicated during a refactor.

Fixes #27351

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473b97eb by sheaf at 2026-06-22T23:01:22-04:00
Avoid mkTick in Core Prep breaking ANF (part II)

Hotfix for 2f9579765f55b3920ceb2e04995ff41a9d0e2d4e fixing a small
oversight in the call to tickTickedExpr from mkTick, in which we
improperly recursively called mkTick without passing on the preserve_anf
flag.

Fixes #27386

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9284a1f7 by Simon Hengel at 2026-06-23T05:55:33-04:00
Don't use global variables to address concurrency bugs! (fixes #27234)

This was originally introduce with
88f38b03025386f0f1e8f5861eed67d80495168a to address #17922.

In this specific case a better fix would have been to synchronize on
stderr:

    withHandle_ "stderrSupportsAnsiColors" stderr $ \ _ -> do
      ...

But apparently the dependency on `terminfo` was removed in
32ab07bf3d6ce45e8ea5b55e8095174a6b42a7f0, preventing #17922 in the first
place.

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44309cd3 by Alan Zimmerman at 2026-06-23T05:56:20-04:00
EPA: remove LocatedL / SrcSpanAnnL and  LocatedLI / SrcSpanAnnLI

This is part of a refactor towards only having LocatedA / SrcSpanAnnA

It removes the stated items, but has to add back one for BooleanFormula,
LocatedBF / SrcSpanAnnBF

This commit also use the HsConDetails RecCon extension point to
capture the braces in a record constructor

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2f6a5534 by Simon Jakobi at 2026-06-23T15:46:20+02:00
Add -dstable-core-dump-order for stable Core dump ordering (#27296)

The order of top-level bindings in Core dumps (-ddump-simpl etc.) is the
compiler's Unique-sensitive internal processing order, so an unrelated
upstream change can reorder them and defeat a textual diff of two dumps.

This adds an opt-in flag -dstable-core-dump-order that reorders the
top-level bindings of dumps routed through dumpPassResult into a stable,
Unique-independent order, so two dumps line up across rebuilds. See
Note [Stable Core dump order] in GHC.Core.Ppr for the sort key and its
rationale.

Adds tests T27296 (binders GHC emits in non-source order by default,
asserted to come out stably ordered under the flag) and T27296b (an
untidied -ddump-float-out dump pinning the ordering of the anonymous lvl
floats by literal value).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

- - - - -
141986e3 by mangoiv at 2026-06-24T15:51:14-04:00
compiler: refactor error reporting code for ExplicitLevelImports

Refactors error reporting code for ExplicitLevelImports to pass in a
RdrName and a GlobalReaderElt to be able to report errors that are
faithful to the source and to more precisely distinguish between names
that are in scope from different qualifications.

Fixes #27385 and #26616

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aa7df6b6 by Simon Hengel at 2026-06-24T15:52:18-04:00
Set GHC_VERSION when calling custom pre-processors (see #25952)

(so that pre-processors can emit backwards compatible code)

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a9e494f2 by Simon Hengel at 2026-06-24T15:54:08-04:00
Add a flag to control GHCi specific error hints (close #27409)

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a805b2a2 by Simon Hengel at 2026-06-24T15:55:20-04:00
Reference correct package in error messages for reexported modules

(fixes #27417)

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f235d183 by Simon Jakobi at 2026-06-25T05:51:18-04:00
Add explicit setBit/clearBit/complementBit for instance Bits Integer (#21176)

The default setBit, clearBit, and complementBit methods allocate
intermediate Integers per call. Define them explicitly via the new
integerSetBit[#], integerClearBit[#] and integerComplementBit[#], built
on the BigNat# primitives, which avoid those allocations. Allocation is not
eliminated entirely -- the negative (IN) cases would need in-place mutation,
which is left as future work.

The default methods constant-folded on literal arguments via the
integerOr/integerAnd/integerXor rules, which fold literal Integers of any
size. The explicit functions have no such rule, so they (their Word-argument
wrappers, and the Bits Integer methods) are marked INLINE to expose the
underlying primops to the simplifier; see Note [INLINE for constant folding
of bit operations]. This restores folding only on the small-int (IS) path --
large literal Integers (IP/IN) are no longer constant-folded, a minor
regression for that case. T8832 covers the IS-path folding.

The new golden-output test T21176 checks all three operations against the
default implementations across the sign/size boundaries, recording each
result plus its integerCheck validity. The base and ghc-bignum interface-
stability export goldens gain the new functions.

The main changelog entry lives in changelog.d under a new ghc-internal
section (renamed from ghc-prim).

CLC proposal: https://github.com/haskell/core-libraries-committee/issues/423

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

- - - - -
202ed264 by Marc Scholten at 2026-06-25T05:52:21-04:00
haddock: use Text in documentation pipeline

This patch moves Haddock's documentation pipeline from String to Text
where the data is already textual. It avoids repeated conversions while
keeping the existing decoding behavior for invalid UTF-8 docstring
chunks.

The main changes are:

* Render and carry docstrings as Text in Haddock-facing paths.
* Use the Binary Text instance from GHC.Utils.Binary for Haddock
  interface files, and bump the Haddock binary interface version.
* Add a FastString HTML instance so XHTML rendering avoids
  intermediate String allocation.
* Keep HsDocStringChunk decoding lenient, matching the previous
  unpackHDSC behavior on invalid UTF-8 input.
* Update the xhtml submodule to 3000.4.1.0, which contains the
  apostrophe escaping fix used by the Haddock test output.

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Assisted-by: Codex <codex@openai.com>

- - - - -
a72ff58f by mangoiv at 2026-06-25T05:53:07-04:00
compiler: rename ZonkAny to UnusedType and add pretty printing logic

ZonkAny is a hard to understand name for users who do not know how the
compiler works internally. Additionally, it is confusing that ZonkAny,
while being a concrete type *represents* a meta variable, espeically in
the compiler output.
This patch changes the name of ZonkAny to UnusedType which is closer to
its intended semantics and adds special pretty printing logic to display
this type in the same fashion the compiler displays meta variables in
other places, whenever they leak from the implementation to the user.
It also exports the type from ghc-internal:GHC.Internal.Types in order
to expose documentation.

Fixes #27390

Co-Authored-By: Sam Derbyshire <sam.derbyshire@gmail.com>

- - - - -
6813f002 by Simon Jakobi at 2026-06-26T04:51:47-04:00
Reg.Linear: drop Platform argument from most FR (FreeRegs) methods

The FR class has one instance per CPU architecture, so any
architecture-constant information its methods derived from the Platform
argument can instead be baked into the instance. This removes the now
needless Platform argument from frAllocateReg, frGetFreeRegs and
frReleaseReg.

frInitFreeRegs keeps its Platform argument: the initial allocatable set is
genuinely platform-dependent, see Note [Aarch64 Register x18 at Darwin and
Windows].

Fixes #26665

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

- - - - -
3b2a9409 by Zubin Duggal at 2026-06-26T04:52:39-04:00
testsuite: Report fragile failures as skipped in JUnit output

- - - - -
27463426 by Rodrigo Mesquita at 2026-06-26T20:54:58-04:00
perf: Share Module in Iface Symbol Table

This commit modifies the structure of the serialized `SymbolTable Name`
to then re-use and share the `Module` (both on disk and in memory) across
all `Name`s from the same module.

The new structure looks like:

  <total name count>
  $modules.size
  for (mod, names) in $modules:
    $mod
    $names.size
    for table_ix, occ in $names
      $table_ix
      $occ

i.e. we put the module just once, followed by all names in that module.
When deserializing, we deserialize the module just once, and all the
following `Name`s are constructed with a pointer to that same decoded
`Module`.

In `hoogle-test`, we must use `DNameEnv` rather than `Map Name`,
otherwise the output fixities order was susceptible to changes in the
uniques assigned to each Names, which is not stable.

Fixes #27401

-------------------------
Metric Decrease:
    InstanceMatching
    LinkableUsage01
    LinkableUsage02
    hard_hole_fits
-------------------------

- - - - -
412f1675 by Simon Hengel at 2026-06-26T20:55:41-04:00
Rename `MCDiagnostic` to `InternalMCDiagnostic`

`MCDiagnostic` is meant to be used for compiler diagnostics.

Any code that creates `MCDiagnostic` directly, without going through
`GHC.Driver.Errors.printMessage`, sidesteps `-fdiagnostics-as-json` (see
e.g. !14616, !14475, !14492 !14548).

To avoid this in the future, this change more narrowly controls who
creates `MCDiagnostic` (see #24113).

- - - - -
6f212121 by Facundo Domínguez at 2026-06-26T20:56:27-04:00
Encapsulate options of occurAnalysePgm in a record

- - - - -
adfbb179 by Facundo Domínguez at 2026-06-26T20:56:27-04:00
Allow to configure the occurrence analyser to retain some dead bindings

This is needed by plugins that are the only consumers of a binding which
is otherwise unused in the program.

See Note [Controlling elimination of dead bindings in occurrence analysis]
added in this commit, or
https://gitlab.haskell.org/ghc/ghc/-/issues/27240 for more discussion.

- - - - -
c745b11f by Copilot at 2026-06-26T20:56:27-04:00
Address documentation feedback

- - - - -
2c2a4a2a by Copilot at 2026-06-26T20:56:27-04:00
Keep the imp_rules parameter of occurPgmAnalysePgm and add occ_opts to OccEnv

- - - - -
e2262b0e by Copilot at 2026-06-26T20:56:27-04:00
Strengthen T27240.hs with a binding that should be removed

- - - - -
5f9d9268 by Copilot at 2026-06-26T20:56:27-04:00
Move the reference #27240 to a related paragraph

- - - - -
d86d2644 by Simon Hengel at 2026-06-26T20:57:10-04:00
Remove deprecated flag `-ddump-json` (see #24113)

This was first deprecated in 9.10.1.

- - - - -
3b15ff03 by Simon Jakobi at 2026-06-27T18:48:34+02:00
Tweak mk_mod_usage_info

* Use O(log n) `elemModuleEnv` instead of O(n) `elem` to filter the
  direct imports.
* Use `nonDetModuleEnvKeys` to avoid sorting the ent_map keys twice.
* Prepend the presumably shorter list when creating all_mods with
  `(++)`. Actually this eliminates the `(++)` entirely, as it seems to
  fuse with the `filter` expression.

As a result there is a tiny speed-up when generating the .hi-files for
modules with many imports.

None of the changes affect compilation determinism as the module list
is explicitly sorted to ensure a canonical order.

- - - - -
2d0fd154 by Alan Zimmerman at 2026-06-29T11:44:00-04:00
EPA: Remove LocatedC / SrcSpanAnnC

This is part of a cleanup of the zoo of
SrcSpanAnnXXX types for exact print annotations.

This one removes SrcSpanAnnC used for storing exact print annotations
for contexts. It replaces it with an explicit `HsContext` data type
that carries the annotations and the context.

So, replace

  type HsContext pass = [LHsType pass]

with

  type HsContext pass = HsContextDetails pass (LHsType pass)

  data HsContextDetails pass arg
    = HsContext
      { hsc_ext  :: !(XHsContext pass)
      , hsc_ctxt :: [arg]
      }
    | XHsContextDetails !(XXHsContextDetails pass)

We need the parameterised HsContextDetails because it is used both for
HsQual carrying 'LHsExpr p' and "normal" contexts carrying 'LHsType p'.

- - - - -
cca0d589 by Luite Stegeman at 2026-06-30T13:33:40-04:00
rts: handle large AP closures in compacting GC

The function update_fwd_large in the compacting GC could run into
an unexpected object with the following error:

  internal error: update_fwd_large: unknown/strange object  24

Closure type 24 is the AP closure, which was not handled in
upd_fwd_large. This patch adds handling them.

fixes #27434

- - - - -
42935858 by Luite Stegeman at 2026-06-30T13:33:40-04:00
testsuite: use compacting_gc way instead of hardcoding +RTS -c

- - - - -
bf7b5ce6 by Alan Zimmerman at 2026-06-30T13:34:23-04:00
EPA: Remove LocatedLW from LStmtLR

HsDo already had its XDo extension point for an
AnnList, which also appeared in LocatedLW.
So we remove the redundant one and use the one inside HsDo
as originally intended.

Also delete LocatedLC/LocatedLS as they were unused

- - - - -
d7cfea49 by Recursion Ninja at 2026-06-30T21:37:12-04:00
Decoupling 'L.H.S' from 'GHC.Types.SourceText'

  * Migrated 'IntegralLit'   to 'L.H.S.Lit'.
  * Migrated 'FractionalLit' to 'L.H.S.Lit'.
  * Migrated 'StringLiteral' to 'L.H.S.Lit'.
  * Added TTG extension points to the types above.
  * Added nice export list to 'GHC.Hs.Lit'.
  * Added 'rnOverLitVal' and 'tcOverLitVal' functions to 'GHC.Hs.Lit'.
  * Added instance 'Anno (StringLiteral (GhcPass p)) = SrcSpanAnnN'
  * Moved [Notes] about 'SourceText' from 'L.H.S.*' to 'GHC.*'.
  * Removed all references to 'SourceText' from 'L.H.S'.
  * Removed the trailing comma record field from  'StringLiteral'
  * Renamed exported functions for nomenclature consistency.
  * Deprecated the renamed functions

Fixes #26953

- - - - -
a1f2558b by Recursion Ninja at 2026-06-30T21:37:12-04:00
Monomorphising GHC pass parameters where appropriate

- - - - -
7bf9e3c5 by Teo Camarasu at 2026-06-30T21:38:03-04:00
Make Q abstract

This patch aims to clearly demarcate the internal and external interfaces
of Q.
In the past the `Quasi` typeclass was both part of the external,
public-facing interface, and was used to give the implementation of `Q`.

Now we separate out these two distinct roles. `Quasi` continues to exist
in the public interface, but we introduce a new `MetaHandlers` type,
which is equivalent to `Dict Quasi`.

`Q a` is now defined to be `MetaHandlers -> IO a`, and, crucially,
the constructor and the new `MetaHandlers` type are not exposed from the
public interface.

This gives us the ability to vary the interface on the GHC side without
forcing a breaking change on the `template-haskell` side.
Similarly `template-haskell` has more freedom to change the `Quasi`
typeclass without needing any changes in `lib:ghc`.

Implements https://github.com/ghc-proposals/ghc-proposals/pull/700

Resolves #27341

- - - - -
4262af36 by L0neGamer at 2026-06-30T21:38:56-04:00
generically defines mconcat in terms of internal type's Semigroup instance

add changelog entry

use simpler definition for mconcat

`nonEmpty` isn't available yet; inline branches in case

add test case

fixup generically defines mconcat in terms of internal type's Semigroup instance

add comment on Generically and deriving mishaps

swap mconcat to foldr version

add some strictness testing for mconcat

add to `base` changelog entry

- - - - -
e22ad997 by Cheng Shao at 2026-06-30T21:39:43-04:00
hadrian/rts: fix unregisterised build for gcc 15+

This patch fixes unregisterised build for gcc 15+:

- Pass -optc-Wno-error in hadrian when +werror enables -optc-Werror,
  see added comment for details.
- For RTS functions that the codegen would emit calls, ensure their
  real prototype is hidden when the header is included in .hc fies
  (IN_STG_CODE), and the dummy prototype is provided to match the EFF_
  convention.

In the future we should get rid of EFF_ (#14647) and remove these
hacks, but for now this patch makes unregisterised work again on newer
toolchains. Fixes #27404.

Co-authored-by: Codex <codex@openai.com>

- - - - -
3f00f234 by Cheng Shao at 2026-06-30T21:40:32-04:00
compiler: fix missing handling of CmmUnsafeForeignCall node in LayoutStack

This patch fixes missing handling of `CmmUnsafeForeignCall` middle
node in the `LayoutStack` pass.

Before proc-points splitting, this pass computes liveliness of local
registers, and spills those alive across a Cmm native call onto the
stack. It need to traverse all middle nodes in each block and check
whether a local register is an assignee, if so then the previous
mapping in `sm_regs` is invalidated and needs to be dropped. However,
it didn't handle `CmmUnsafeForeignCall` node which may also assign to
a local register. When proc-points splitting is enabled, this can
produce an invalid basic block that doesn't properly backup the
updated local register to the stack before doing a Cmm call, resulting
in completely invalid runtime behavior.

The patch also adds a `T27447` regression test. With no-TNTC or with
LLVM backend, without the fix the test case would output a stale
0x1111111111111111 value, instead of the expected 0x2222222222222222
output.

Fixes #27447.

Co-authored-by: Codex <codex@openai.com>

- - - - -
701088db by Ben Gamari at 2026-07-01T10:34:03-04:00
gitlab-ci: Drop vestigial references to make build system

- - - - -
62d54a53 by Ben Gamari at 2026-07-01T10:34:03-04:00
gitlab-ci: Add support for running specifying a job's testsuite ways

- - - - -
7f97ac2c by Ben Gamari at 2026-07-01T10:34:03-04:00
gitlab-ci: Run llvm testsuite ways in llvm jobs

Addresses #25762.

- - - - -
7ea75116 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Add normalise_ddump_deriv setup function

Some tests check the result of -ddump-deriv, which may contain INLINE pragmas depending on optimization flags.
With normalise_ddump_deriv setup function, INLINE pragmas are stripped off.

- - - - -
c7a8199f by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Use -dsuppress-idinfo to make tests more robust

Previously, T18052a and T21755 were failing on 'optasm' and 'optllvm' ways because of visibility of unfoldings.

- - - - -
a12122e5 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Use a trick to keep large objects alive

Previously, T17574 and T19381 were failing on 'optasm' and 'optllvm' ways because of compiler optimizations.
Change them to use NOINLINE to prevent unwanted optimizations.

- - - - -
1a95b327 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Only run T24224 in 'normal' way

This test is a frontend-only one and breaks if optimizations are enabled.

- - - - -
8abea737 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Ignore T18118's stderr

When optimizations are enabled, the compiler emits a warning (You cannot SPECIALISE ...).
The message is not important, so ignore it.

- - - - -
9453a722 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Mark T816 and tc216 broken with optimizations

These tests are about type checking, so we should not care too much if they are broken with optimizations.

See #26952

- - - - -
0aef9ec0 by Ben Gamari at 2026-07-01T10:34:03-04:00
testsuite: ds014 is not longer broken

It now appears to pass in the ways it was marked as broken in.

Closes #14901.

- - - - -
4692d1e4 by Ben Gamari at 2026-07-01T10:34:03-04:00
testsuite: Only run stack cloning tests in the normal way

These are too dependent upon code generation specifics to pass in most
other ways.

- - - - -
c154df26 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Update options_ghc_fbyte-code

The `-fbyte-code` option used to be overriden by `-fllvm` but it is no longer true since !14872 was merged.

I updated the test to accept the new behavior.

Closes #27049

- - - - -
5d8bb7b5 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Only run T22744 in 'normal' way

This test takes a long time on optimized ways.

- - - - -
d1e74c8e by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Disable tests that use -finfo-table-map on llvm ways

Currently, -finfo-table-map does not work with -fllvm. See #26435

- - - - -
3bf38c84 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Don't run T24726 on optimized ways

If optimizations are enabled, the rewrite rule just fires and -drule-check will report nothing.

- - - - -
e4eef116 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Use -fno-unoptimized-core-for-interpreter when running LinkableUsage01/02

Optimizations for the bytecode interpreter are considered experimental, and need a flag to be enabled.

- - - - -
234a9872 by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Suppress unwanted optimizations on T25284

- - - - -
99a2af2f by ARATA Mizuki at 2026-07-01T10:34:03-04:00
testsuite: Don't run stack_big_ret with optimizations

Stack layout may change with optimizations enabled.

- - - - -
04c836df by ARATA Mizuki at 2026-07-01T10:34:04-04:00
testsuite: Mark memo001 broken on optimized ways

See #27396

- - - - -
1a8a24f4 by ARATA Mizuki at 2026-07-01T10:34:04-04:00
testsuite: Mark syn-perf broken on optimized ways

See #27398

- - - - -
40412093 by Duncan Coutts at 2026-07-01T10:34:50-04:00
Add a test for thread scheduler fairness

It also tests that the interval timer and context switching works.
We also test that fairness is lost when the context switching interval
is too coarse for the duration of the test.

We add this test before doing surgery on the interval timer, so we have
decent coverage.

- - - - -
3f34d557 by Duncan Coutts at 2026-07-01T10:34:50-04:00
Make exported stop/startTimer no-ops, and rename internal functions

Specifically, internally rename:
stop/startTimer to pause/unpauseTimer
stop/startTicker to pause/unpauseTicker

and keep stop/startTimer as exported functions, but now as no-ops.

In the past the stop/startTicker actions were used incorrectly as if
they were synchronous, which they are not. See issue #27105. We now
document pause/unpackTicker as being async and not to be used for the
purpose of concurrency safety.

The existing stop/startTimer (note Timer not Ticker, the Timer calls the
Ticker!) are also exported from the RTS as a public API. This was
historically because the ticker used signals and it was important to
suspend the timer signel over a process fork. So these functions were
exported to be used by the process and unix libraries.

We cannot just remove the RTS exports, but we now make them no-ops, and
they can be removed from the process and unix library later. This
was already documented in a changelog.d entry no-more-timer-signal but
due to changes during the MR process the change to make stop/startTicker
into no-ops didn't make it into the earlier MR.

- - - - -
02e84e5f by Duncan Coutts at 2026-07-01T10:34:51-04:00
Make exitTicker/exitTimer unconditionally synchronous

We never use them asynchronously, and we should never need to do so.

And update some related comments.

- - - - -
13db6a72 by Duncan Coutts at 2026-07-01T10:34:51-04:00
posix ticker: update and improve comments on (un)pause and exit

Clarify what is async vs sync.

- - - - -
43d9a07d by Duncan Coutts at 2026-07-01T10:34:51-04:00
posix ticker: split out ppoll/select helper functions

Move the #ifdefs out of the main code body by introducing local helper
functions and types, which themselves have two implementations (with a
common API) based on ppoll or select.

This helps improve clarity/readability.

- - - - -
a5491baa by Duncan Coutts at 2026-07-01T10:34:51-04:00
posix ticker: improve the implementation

The existing implementation supported pausing and exiting, with the
implementation of pausing reling on a mutex and condition variable.
It needed to check the pause and stop shared variables on every
iteration. It relies on ppoll or select, to wait on the timeout and also
wait on an interrupt fd. The interrupt fd was only used for prompt
exit/shutdown, and not for pausing or other notification. The pause only
needed a lock and a memory operation, but the pause was not prompt. The
resume used a lock, and signaling a cond var.

The new implementation uses a somewhat more regular design: every
notification is done by setting a shared variable and
interrupting/notifying the ticker via the fd. The ticker thread does not
need to check any shared variables on normal timer expiry, only when it
recevies notification. This may be a micro-optimisation, but the tick
occurs 100 times a second by default so any improvements in the hot path
are amplified. When the ticker thread does receive notification it can
check the various shared variables and update its local state. The
blocking relies on using ppoll/select but without a timeout. This avoids
the condition var and also allows further notifications when paused
(also used for unpausing).

This design can be extended with further notification types if needed by
using and checking further shared vars (or making existing shared vars
an enum or counter). This may be used in future for additional
notifications to the ticker thread. This will likely be used to proxy
wakeUpRts from a single handler context for example. And this approach,
avoiding mutexes, is compatible with use from signal handlers.

So overall, it's:
 * slightly simpler / more regular;
 * easier to extend with additional notifications;
 * probably slightly more efficient (but a micro-optimisation);
 * and supports calling notification from signal handlers

- - - - -
5b20821e by Duncan Coutts at 2026-07-01T10:34:51-04:00
posix ticker: further minor local renaming for code clarity

Improve the clarity with better choice of names for several local vars
and function.

- - - - -
1f3ec5e0 by Duncan Coutts at 2026-07-01T10:34:51-04:00
win32 ticker: split out local helper functions

- - - - -
596e7307 by Duncan Coutts at 2026-07-01T10:34:51-04:00
win32 ticker: provide guarantee about concurrency and idempotency

Use a lock to ensure pause/unpause can be used concurrently. Use a
paused variable, protected by the lock, to ensure that pause and unpause
are both idempotent. This is what the portable API expects.

- - - - -
1870edd7 by Duncan Coutts at 2026-07-01T10:34:51-04:00
win32 ticker: make the initial tick be after one wait interval

There is no need to tick immediately. This is consistent with the
posix implementation.

- - - - -
7c15ab5b by Duncan Coutts at 2026-07-01T10:34:51-04:00
ticker: remove now-unnecessary layer of enable/disable

There was an atomic variable used to block *part* of the actions of the
tick handler. This still did not make stopTimer synchronous, even for
the part of the the handle_tick actions it covered. It also added a more
expensive (sequentuially consistent) atomic operation in the hot path
for the handle_tick action, whereas our new design requires no atomic
ops at all.

Now that we have eliminate the need for synchronous stop/startTicker,
we don't need this not-quite-working-anyway atomic protocol. The new
pause/unpauseTicker is explicitly asynchronous and idempotent.

- - - - -
8585f8cb by Duncan Coutts at 2026-07-01T10:34:51-04:00
ticker: add TODOs about issue #27250: too much being done from handle_tick

The handle_tick should not perform I/O, block, perform long-running
operations or call arbitrary user code. Unfortunately, everything to
do with the eventlog (at the moment) falls into all those categories.

- - - - -
6e381626 by Duncan Coutts at 2026-07-01T22:29:55+01:00
Adjust releaseCapability_ precondition to allow cap->running_task == NULL

There are two use cases for releaseCapability_:

1. The current Task (cap->running_task) releases the Capability.
   The Capability is marked free, and if there is any work to do,
   an appropriate Task is woken up.

2. There is no current task (cap->task == NULL), and thus the
   Capability is idle, and we want to wake up an idle Task to animate
   the Capability. This case uses always_wakeup.

Currently, the precondition for releaseCapability_ is
  cap->running_task != NULL
and so the 2nd use cases have to set cap->running_task (which is then
immediately overwritten) just to satisfy the precondition. See the
use cases in sendMessage and prodCapability.

So we can relax the precondition to be:
  cap->running_task != NULL || always_wakeup
so that in the always_wakeup case, we say it is ok for the
cap->running_task to be NULL.

This lets us simplify sendMessage and prodCapability. In particular it
will allow prodCapability to not need a Task parameter.

The ulterior motive for all this is that I want to be able to call
prodCapability from an OS thread that is not itself a Task, in persuit
of issue #27086: disentangle I/O managers from wakeUpRts. The most
straightforward way to wake the RTS is using prodCapability, but the
context in which we will need to do that are threads that are not Tasks.

- - - - -
89404ebc by Duncan Coutts at 2026-07-01T22:29:55+01:00
prodCapability no longer needs to take a Task param

Now that releaseCapability_ can accept cap->running_task == NULL then it
is no longer necessary for prodCapability to require a Task.

- - - - -
4e60c5f6 by Duncan Coutts at 2026-07-01T22:29:56+01:00
Define prodOneCapability

There was an existing declaration for this in the header file, but no
definition.

Similarly, there is a declaration for prodAllCapabilities but no
definition, and we don't need it, so remove the declaration.

- - - - -
2527026f by Duncan Coutts at 2026-07-01T22:29:56+01:00
Add a wakeUpRtsViaTicker feature to the posix ticker

It proxies a call to wakeUpRts, but crucially, this can be called from
a signal handler context. It will be used for ctl-c handling.

- - - - -
aa5a03a5 by Duncan Coutts at 2026-07-01T22:29:56+01:00
Change how wakeUpRts works

Previously it would call wakeupIOManager to get a capability to wake up
and run. This works but it entangles the I/O managers with unrelated
features: ctl-c handling and idle gc (the two features that use wakeUpRts).

The reason it used wakeupIOManager is that this action is safe to use
from a posix signal handler, since it just posts bytes to a pipe.
Otherwise the more direct approach (used e.g. by sendMessage when the
target capability is idle) is to use releaseCapability. But that uses
condition variables and mutexes, which are not safe to use from within a
signal handler.

So instead of entangling the (multiple) I/O managers with this, we make
wakeUpRts use the direct approach (using prodOneCapability). On win32
the ctl-c console handler can call wakeUpRts directly, since it is
called in a proper thread. On posix, to deal with the signal handler
problem, we make the signal handler ask the ticker thread to proxy the
call to wakeUpRts, since the ticker thread is also a proper thread.

This will allow the I/O managers to no longer be concerned with this.
This is good because there are many I/O managers (and they're
complicated), but there is (on posix) only one ticker implementation. So
this is an overall reduction in coupling and complexity.

Fixes issue #27086

- - - - -
c6d53c16 by sheaf at 2026-07-02T21:35:44-04:00
Test driver: normalise line numbers into libraries

When comparing the stdout of tests that print out callstacks, we can't
rely on the stability of exact line:column spans pointing into libraries
(e.g. ghc-internal), as any change (such as adding a comment) can change
them.

This commit addresses this by normalising away line:column in callstacks,
but only when those point into internal libraries. We don't do this in
general, as the exact span might be important to the test (e.g. for a
span within the test module itself).

Fixes #27387

- - - - -
81ee62e0 by Alan Zimmerman at 2026-07-02T21:36:33-04:00
EPA: Remove LocatedLW from MatchGroup

This is the last usage of LocatedLW / SrcSpanAnnLW

- - - - -
925959db by Recursion Ninja at 2026-07-04T04:14:12-04:00
Decoupling 'L.H.S' from 'GHC.Hs.Doc'

  * Migrated 'GHC.Hs.Doc' and 'GHC.Hs.DocString' AST defintions from 'GHC.*' namespace,
    to new 'Language.Haskell.Syntax.Doc' module in the 'L.H.S' "namespace."
  * Updated 'HsDocString to be TTG-parameterised as 'HsDocString pass'.
  * Added 'GHC.Hs.Extension.Pass': splits 'GhcPass'/'Pass' and all 'HsDocString'
    TTG instances out of 'GHC.Hs.Extension', which re-exports it unchanged
    (this is backwards compatible and prevents the introduction of a boot file).
  * Deleted 'GHC.Hs.Doc.hs-boot'; removed all 'L.H.S.*' imports of 'GHC.Hs.Doc'.
  * Updated 'GHC.Hs.DocString' to be TTG pass-parameterised throughout; moved
    'mkHsDocStringChunk'/'unpackHDSC' here (require 'GHC.Utils.Encoding').
  * Split 'GHC.Rename.Doc.rnHsDoc' from 'rnHsDocIdentifiersOnly'.
  * Updated parser, renamer, typechecker, HIE, and exact-print for new types.
  * Added 'HsDocString' TTG instances for 'DocNameI' to 'Haddock.Types'.
  * Killed the last module loop between GHC.* and LHS.*.
        - Only edges from LHS.* to GHC.Data.FastString now!

Resolves #26971

- - - - -
b7e24044 by mangoiv at 2026-07-04T04:14:56-04:00
ci: retry fetching test metrics

Retry fetching test metrics to make the CI not fail if the services is
temporarily unavailable

- - - - -
4180af3f by Zubin Duggal at 2026-07-04T04:15:38-04:00
Bump semaphore-compat submodule to 2.0.1

This versions includes some cruicial fixes for darwin

- - - - -
242d4317 by sheaf at 2026-07-04T04:16:19-04:00
Remove outdated comment in GHC.Data.ShortText

There was a long comment in GHC.Data.ShortText about a workaround that
was necessary when bootstrapping with GHC 9.2 and below. The actual
logic has since been dropped, but the comment remained. This commit
removes the vestigial comment.

- - - - -
9b714c4c by Zubin Duggal at 2026-07-05T09:40:36+05:30
CorePrep: Don't speculatively evaluate bindings that we have already discovered to be absent

In #25924, we segfault because speculation forces a projection out of a RUBBISH dictionary
(which we generated because it absent).

Solution: Don't speculate on bindings we already know are absent.

Fixes 25924

- - - - -
4a59b3ee by Zubin Duggal at 2026-07-05T09:40:36+05:30
Don't make absent fillers for terminating types

In #25924 we discovered that we could speculatively evaluate an absent filler
for a dictionary, and project a field (a superclass selector) out of it,
resulting in segfaults.

Solution: Never make an absent filler or rubbish literal for a terminating type
like a dictionary. mkAbsentFiller returns Nothing for isTerminatingType, so
worker/wrapper and the specialiser keep the real argument instead.

Some small metric decreases because we do a little less work in the
simplifier now.

Metric Decrease:
    T9872a
    T9872b
    T9872c
    TcPlugin_RewritePerf

- - - - -
383ddcd4 by Alan Zimmerman at 2026-07-06T07:08:16-04:00
EPA: Move the 'where' annotation for PatSynBind

This allows us to move it out of the MatchGroup exact print annotation
too

- - - - -
66d1a5d5 by fendor at 2026-07-07T16:57:56-04:00
Add 'backendInfoTableMapValidity' backend predicate

Check whether the backend supports the `-finfo-table-map` flag and
ignore it otherwise.

Improve by-design documentation of `backendCodeOutput`.

`Backend` is **abstract by design**. Make this clearer in
`backendCodeOutput` which is incorrectly being used as a proxy for
`Backend`.

Instead, define the desired property predicates in GHC.Driver.Backend
In the process, make `backendCodeOutput` total.

- - - - -
74f1071d by fendor at 2026-07-07T16:57:56-04:00
Add failing test for `-finfo-table-map` and bytecode backend

If you compile a module using the bytecode backend, with
-finfo-table-map, then the info table map doesn't get populated for the
module.

This is because the -finfo-table-map code path is implemented mostly in
the StgToCmm phase which isn't run when creating bytecode.

Ticket #27039

- - - - -
28d63bca by mangoiv at 2026-07-07T16:59:16-04:00
ci: don't fail nightly if there have been no changes that night

Fixes #27127

- - - - -
4ebfc478 by Rodrigo Mesquita at 2026-07-08T04:47:53-04:00
ttg: Using ShortText over FastString in the AST

To make the AST independent of GHC, this commit replaces usages of
`FastString` with `HText` in the AST, killing the last edge from
Language.Haskell.* to GHC.* modules.

Even though we /do/ want to use FastStrings in general -- critically in
Names or Ids -- there is no particular reason for the FastStrings that
occur in the AST proper to be FastStrings. Strings in the AST are
typically unique and don't benefit particularly from being interned
FastStrings with Uniques for fast comparison.

`HText` is a type synonym for `ShortText` which uses GHC's Modified
UTF-8 encoding exclusively.

Modified UTF-8 must be used to represent the Haskell AST because the
Haskell Report allows surrogate code points. `Data.Text.Text` functions
use Standard UTF-8 which replace surrogates with a placeholder value,
thus `Data.Text.Text` is unsuitable for AST strings. See the
`Language.Haskell.Syntax.Text` module header for more details.

Final progress towards #21592

Closes #21628

- - - - -
d910b353 by Simon Peyton Jones at 2026-07-08T04:48:36-04:00
Update equality-type documenation in GHC.Builtin.Types.Prim

Fix #27466

- - - - -
b2530542 by Simon Peyton Jones at 2026-07-08T04:48:36-04:00
Honour -dsuppress-coercions in GHC.Core.TyCo.pprCo

Fixes #27467

- - - - -
9a73179a by Facundo Domínguez at 2026-07-08T04:49:26-04:00
Add item to MR checklist asking to squash fixup commits after approval

The checklist has an item that reads

    All commits are either individually buildable or squashed.

This item could be checked immediately after sending the merge request
though. If reviewers ask for amends later on, and the author amends
the merge request, there was no item that would remind the contributors
to squash the fixup commits before landing.

This commit adds a new item

    After all approvals and before landing: all fixup commits are squashed with their originating commits.

which should be harder to mark as done before approvals have been given.

- - - - -
ed09895d by Andreas Klebinger at 2026-07-08T16:53:27-04:00
Fix a profiling race condition resulting in segfaults.

StgToCmm: Don't assume tagged FUN closures in closureCodeBody.
When entering a closure the self/node pointer might not be tagged in
some situations when a thunk is evaluated by multiple threads.
So we most AND away the tag bits rather than subtracting an expected tag.

Apply.cmm: Fix a race condition occuring when a thunk is mutated during GC.

In stg_ap_0_fast when might need to run GC before entering a thunk. If this happens
another thread or the GC itself might mutate the closure making entering it no longer
valid. We now check for this.

Add test and changelog for #27123 fixes.

- - - - -
67c03eb2 by Cheng Shao at 2026-07-08T16:54:09-04:00
ghc-heap: fix invalid srtlen returned by peekItbl when no-TNTC

This patch fixes the no-TNTC code path of `peekItbl` so that it looks
at the right memory address when reading the `srt` field from the
`StgInfoTable_` struct. Also adds a `T27465` regression test that
reproduces the bug on no-TNTC builds before the fix. Fixes #27465.

Co-authored-by: Codex <codex@openai.com>

- - - - -
2ecabb4f by Zubin Duggal at 2026-07-09T09:23:25-04:00
hadrian: binary-dist-dir should not be the default target

Revert behaviour to pre 23c9b6c392f52ec9d7a8618b204ff6b885f5fba2

In 23c9b6c392f52ec9d7a8618b204ff6b885f5fba2, we applied the following behaviour change:

```
hadrian: Build stage 2 cross compilers
...
* hadrian: Make binary-dist-dir the default build target. This allows us
  to have the logic in one place about which libraries/stages to build
  with cross compilers. Fixes #24192
```

This is a major regression to development experience, a plain hadrian/build
--freeze1 now takes ages because we rebuild all docs (which need to go in the
binary dist dir).

`binary-dist-dir` is the wrong default target for regular GHC development work

Fixes #27445

- - - - -
e16388e3 by Zubin Duggal at 2026-07-09T09:23:25-04:00
.gitignore: Add the hadrian system.config introduced by commit 23c9b6c392f52ec9d7a8618b204ff6b885f5fba2

Since

commit 23c9b6c392f52ec9d7a8618b204ff6b885f5fba2
Author: Matthew Pickering <matthewtpickering@gmail.com>
Date:   Thu Dec 21 16:17:41 2023 +0000

    hadrian: Build stage 2 cross compilers

./configure produces /hadrian/cfg/system.config.{host,target}

Add these to .gitignore

- - - - -
7e8abf41 by Alan Zimmerman at 2026-07-09T09:24:12-04:00
EPA: Replace AnnListItem with simply [TrailingAnn]

Remove the unnecessary wrapper around a single field.

- - - - -
29032f17 by Zubin Duggal at 2026-07-09T09:24:58-04:00
testsuite: Keep real reason for fragile test failures

- - - - -
c34e03a7 by Zubin Duggal at 2026-07-09T09:24:58-04:00
testsuite: Fall back to the failure reason for empty JUnit bodies

- - - - -
409d40f0 by Zubin Duggal at 2026-07-09T09:24:58-04:00
testsuite: Show output diffs in JUnit output

Also refactor compare_outputs to return essentially a `Maybe Diff`
(`CompareOutput`) instead of a bool, but more pythonic. This
allows us to pass the diff through nice.

- - - - -
06fee1ab by Zubin Duggal at 2026-07-09T09:24:58-04:00
perf notes: include stat deviation and acceptance window in notes so they show up in gitlab

- - - - -
57c0f32c by mangoiv at 2026-07-10T11:08:38-04:00
driver: enable -finter-module-far-jumps by default

this fixes a compatibility bug with certain binutils/gcc versions where
we were seeing jump offset overflow errors.
This commit can probably reverted if we stop supporting the problematic
binutils/gcc verions (2.44 and 14.2, respectively)

Reolves #26994

- - - - -
4396a6f2 by Andrea Vezzosi at 2026-07-10T11:09:25-04:00
[Fix #27287] preserve ModBreaks in ModIface

- - - - -
ed261a7e by Cheng Shao at 2026-07-14T17:59:38-04:00
hadrian: fix HLS support

This patch fixes hadrian's HLS support so one can rely on HLS when
working on the hadrian codebase. Fixes #27480.

Not building/linking shared libraries for hadrian is a severely
premature optimization; this top-level setting in `cabal.project` only
affects home packages while the dependencies in the cabal store are
built with vanilla/dynamic anyway, and even adding dynamic builds to
home packages would not be costly due to cabal's usage of
`-dynamic-too`.

- - - - -
eee8ec5b by Cheng Shao at 2026-07-14T18:00:20-04:00
compiler: fix miscompiled %load_relaxed, add missing %store_relaxed

This patch fixes the %load_relaxed cmm primop compilation logic to
correctly use relaxed memory ordering, and adds the missing
%store_relaxed primop. Parsing logic of %load/%store with explicit
ordering is covered in the AtomicFetch test case. Fixes #27483.

Co-authored-by: Codex <codex@openai.com>

- - - - -
1718230f by Alan Zimmerman at 2026-07-14T18:01:06-04:00
EPA: Keep binds and sigs together in HsValBindsLR

We combine them into a single list for GhcPs, wrapped in the
ValBind data type, which is the bind equivalent of ValD, having
constructors for binds and sigs.

This simplifies exact print processing, especially when using it to
update the contents of local binds, as we no longer need AnnSortKey
BindTag

- - - - -
6bd1ad2a by Andreas Klebinger at 2026-07-14T18:01:49-04:00
Bump nofib submodule to account for MonoLocalBinds.

New versions of GHC enable MonoLocalBinds by default.
This breaks some of the benchmarks. I've fixed this and
this bump pulls in that fix.

- - - - -
7eb0f1c9 by Cheng Shao at 2026-07-14T18:02:31-04:00
testsuite: fix bytecodeIPE test under +ipe flavours

This patch fixes the bytecodeIPE test under +ipe flavours. It used to
fail under +ipe because the RTS is built with IPE info, then
stg_AP_info in RTS carries IPE info, so whereFrom wouldn't return
Nothing. Now the test checks IPE info of a datacon in the ghci-loaded
module which is not affected by whether the RTS is built with IPE info
or not. Fixes #27498.

Co-authored-by: Codex <codex@openai.com>

- - - - -
ef038aae by cydparser at 2026-07-15T04:35:41-04:00
Reduce bytes allocated for `capabilities` in RTS (fixes #27487)

In rts/Capability.c, `capabilities` is an array of pointers, but it was allocated as if it were an
array of Capability's.

- - - - -
d377e83e by Cheng Shao at 2026-07-15T04:36:27-04:00
rts: fix missing UNTAG in stg_readTVarIOzh

This patch fixes missing UNTAG on the current value closure read from
StgTVar. UNTAG is a no-op when it's stg_TREC_HEADER_info which is word
aligned; it may be a tagged closure, and reading info table from the
tagged address is an unaligned load which may cause issues on
platforms with strict alignment requirements.

Co-authored-by: Codex <codex@openai.com>

- - - - -
8ed03842 by Cheng Shao at 2026-07-15T04:36:27-04:00
rts: fix missing UNTAG in stg_control0zh_ll

This patch fixes missing UNTAG on the cont closure returned by
captureContinuationAndAbort. In case it's not NULL,
captureContinuationAndAbort returns a tagged StgContinuation closure,
in which case it must be untagged before accessing the
apply_mask_frame field.

In the past it worked out of luck: when apply_mask_frame was NULL then
mask_frame_offset is also 0 so the control flow didn't diverge to a
wrong path. Still, this is horribly wrong and will crash once
StgContinuation struct is refactored and fields are shuffled around.

Co-authored-by: Codex <codex@openai.com>

- - - - -
5aa7000a by Cheng Shao at 2026-07-15T04:37:08-04:00
compiler: fix redundant AP thunk codegen when not using -ticky-ap-thunk

This patch fixes a double negation confusion in !7525 that results in
some redundant AP thunk code generation when not using
-ticky-ap-thunk. Now, we use `stgToCmmUseStdApThunk` to indicate
whether precomputed AP thunks in the RTS should be used, which
defaults to `True`, unless `-ticky-ap-thunk` is passed.
`-finfo-table-map` now also implies `-ticky-ap-thunk`, since when
doing IPE profiling we want the generated AP thunks to be unique.
Fixes #27502.

-------------------------
Metric Decrease:
    T3064
-------------------------

Co-authored-by: Codex <codex@openai.com>

- - - - -
d43a7b7a by Brian McKenna at 2026-07-15T20:10:04+02:00
Strip ticks when desugaring bool guards

The special `considerAccessible` pattern was broken when compiling
with debug info. Compiling with debug info wraps expressions with
`SourceNote` ticks, which broke the internals of the
`desugarBoolGuard` function. Ticks are now ignored within this
function.

Fixes #27360

- - - - -
ede4b17b by Ben Gamari at 2026-07-15T22:59:53-04:00
base: Display ExceptionContext in WhileHandling's textual description

As originally-implemented the implementation for
`WhileHandling(displayExceptionAnnotation)` would display the
`ExceptionContext` of the exception which it carries (as this was the
behavior of `displayException`, in terms of which
`displayExceptionAnnotation` was implemented).

However, in 284ffab3 the definition of `SomeException(displayException)`
was changed to exclude the `ExceptionContext`. This means that
`WhileHandling(displayExceptionAnnotation)` fails to describe the
provenance of the exception which it captures, greatly limiting its
utility.

Return the implementation to its originally-specified behavior by
implementing `WhileHandling(displayExceptionAnnotation)` in terms of
`displayExceptionWithInfo`.

Fixes #27456.

- - - - -
4f54bcc1 by Duncan Coutts at 2026-07-16T09:14:38+01:00
Move THREADED_RTS-conditional struct members to end of Capability

Accessing members of the Capability struct from CMM code rely on
accessor macros. (The macros are generated by deriveConstants).

These macros have a single definition. This means that the offsets of
all struct members must *not* vary based on THREADED_RTS vs
!THREADED_RTS. This requires that any struct members that are
conditional on THREADED_RTS must occur after the unconditional struct
members. Hence we move all the ones that are conditional on
THREADED_RTS to the end.

Add a deriveConstants entry for the iomgr member of the Capability
struct, which was the motivation for this change.

Add warning messages to help our future selves. Debugging this took me
a couple hours in gdb!

- - - - -
74adf094 by Duncan Coutts at 2026-07-16T09:14:38+01:00
Make the IOManager API use CapIOManager rather than Capability

This makes the API somewhat more self-contained and more consistent.
Now the IOManager API and each of the backends takes just the I/O
manager structure. Previously we had a bit of a mixture, depending on
whether the function needed access to the Capability or just the
CapIOManager.

We still need access to the cap, so we introduce a back reference to
reach the capability, via iomgr->cap.

Convert all uses in select and poll backends, but not win32 ones.
Convert callers in the scheduler and elsewhere.

Also convert the three CMM primops that call IOManager APIs. They just
need to use Capability_iomgr(MyCapability()).

- - - - -
7ef31daf by Duncan Coutts at 2026-07-16T09:14:38+01:00
Split posix/MIO.c out of posix/Signals.c

The MIO I/O manager was secretly living inside the Signals file.

Now it gets its own file, like any other self-respecting I/O manager.

- - - - -
12382f85 by Duncan Coutts at 2026-07-16T09:14:38+01:00
Rationalise some scheduler run queue utilities

Move them all to the same place in the file.

Make some static that were used only internally.

Also remove a redundant assignment after calling truncateRunQueue that
is already done within truncateRunQueue.

- - - - -
87367a1d by Duncan Coutts at 2026-07-16T09:14:38+01:00
Rename initIOManager{AfterFork} to {re}startIOManager

These are more accurate names, since these actions happen after
initialisation and are really about starting (or restarting) background
threads.

- - - - -
e7326bb0 by Duncan Coutts at 2026-07-16T09:14:38+01:00
Free per-cap I/O managers during shutdown and forkProcess

Historically this was not strictly necessary. The select and win32
legacy I/O managers did not maintain any dynamically allocated
resources. The new poll one does (an auxillary table), and so this
should be freed.

After forkProcess, all threads get deleted. This includes threads
waiting on I/O or timers. So as of this patch, resetting the I/O
manager is just about tidying things up. For example, for the poll
I/O manager this will reset the size of the AIOP table (which
otherwise grows but never shrinks).

In future however the re-initialising will become neeecessary for
functionality, since some I/O managers will need to re-initialise
wakeup fds that are set CLOEXEC.

- - - - -
76125f45 by Duncan Coutts at 2026-07-16T09:14:38+01:00
Add a TODO to the MIO I/O manager

The direction of travel is to make I/O managers per-capability and have
all their state live in the struct CapIOManager. The MIO I/O manager
however still has a number of global variables.

It's not obvious how handle these globals however.

- - - - -
73ddbe67 by Duncan Coutts at 2026-07-16T09:14:38+01:00
Add a FIXME note in the Poll I/O manager

- - - - -
3feb9efe by Duncan Coutts at 2026-07-16T09:14:39+01:00
Add missing updateRemembSetPushClosure in poll I/O manager

For the non-moving GC.

- - - - -
d4932eb6 by Duncan Coutts at 2026-07-16T09:14:39+01:00
Minor doc improvement to struct StgAsyncIOOp member outcome

Mention the enumeration names, as well as their numeric values. The rest
of the code uses the enum names.

- - - - -
a9bff207 by Duncan Coutts at 2026-07-16T09:14:39+01:00
Minor doc improvements for StgTSOBlockInfo

Clarify that certain union members are used only by certain legacy
I/O managers. Hopefully we will be able to remove these at some point.

- - - - -
06e132fd by Duncan Coutts at 2026-07-16T09:14:39+01:00
Avoid exporting various win32-specific rts symbols

The BeginPrivate.h / EndPrivate.h scheme works perfectly well on
Windows, but all of the rts/win32/*.h files were not using it.

- - - - -
bc110400 by Duncan Coutts at 2026-07-16T09:14:39+01:00
Remove wakeupIOManager, ioManagerWakeup and setIOManagerWakeupFd

We no longer need wakeupIOManager for the threaded RTS case, so we can
remove it and the bits only needed to support it. This includes the
pipe/eventfd fd shared between the RTS and the in-library I/O manager
used for waking up the I/O manager thread. The pipe/eventfd still
exists, but it no longer has to be communicated to the RTS, since the
RTS no longer needs to use it.

So we remove the RTS API export setIOManagerWakeupFd, and remove uses of
it within the I/O managers in ghc-internal.

- - - - -
d41446b8 by Duncan Coutts at 2026-07-16T09:14:39+01:00
Add a new interruptIOManager API for the I/O managers

It will be used to interrupt awaitCompletedTimeoutsOrIO. Also update the
return type and docs for awaitCompletedTimeoutsOrIO to have it return
false when it gets interrupted, and have no useful post condition in
that case.

- - - - -
991324b1 by Duncan Coutts at 2026-07-16T09:14:39+01:00
Add interruptIOManager support for select I/O manager

Uses the FdWakup mechanism.

- - - - -
ba470b5a by Duncan Coutts at 2026-07-16T09:14:39+01:00
Add interruptIOManager support for poll I/O manager

Uses the FdWakup mechanism.

A quirk we have to cope with is that we now need to poll one more fd --
the wakeup_fd_r -- but this fd has no corresponding entry in the
aiop_table. This is awkward since we have set up our aiop_poll_table to
be an auxilliary table with matching indicies.

The solution this patch uses (and described in the comments) is to have
two tables: struct pollfd *aiop_poll_table, *full_poll_table;
and to have the aiop_poll_table alias the tail of the full_poll_table.
The head entry in the full_poll_table is the extra fd. So we poll the
full_poll_table, while the aiop_poll_table still has matching indicies
with the aiop_table.

Hurrah for C aliasing rules.

- - - - -
6197fecf by Duncan Coutts at 2026-07-16T09:14:39+01:00
Add interruptIOManager support for win32 legacy I/O manager

And remove unused related helper resetAbandonRequestWait. It is not
called because the event is created in auto-reset mode, so never needs
to be reset manually.

- - - - -
c0393a7c by Duncan Coutts at 2026-07-16T09:14:39+01:00
Note lack of interruptIOManager support for WinIO I/O manager

Though there's a plausible design, we can't sanely test it at the moment
due to related WinIO bugs. Filed as issue #27403.

- - - - -
e6ee1c89 by Duncan Coutts at 2026-07-16T09:36:44+01:00
Make signal handling be a respondibility of the I/O manager(s)

Previously it was scattered between I/O managers and the scheduler, and
especially the scheduler's deadlock detection.

Previously the scheduler would poll for pending signals each iteration
of the scheduler loop. The scheduler also had some hairy signal
functionality in the deadlock detection: in the non-threaded RTS (only)
if there were still no threads running after deadlock detection then it
would block waiting for signals.

But signals can and (in my opinion) should be thought of as just a funny
kind of I/O, and thus should be a responsibility of the I/O manager.

So now we have the I/O managers poll for signals when they are polling
for I/O completion (and removing the separate poll in the scheduler).
And when I/O managers block waiting for I/O then they now also start
signal handlers if they get interrupted by a signal. Crucially, if there
is no pending I/O or timers, the awaitCompletedTimeoutsOrIO will still
block waiting for signals.

This patch puts us into an intermediate state: it temporarily breaks
deadlock detection in the non-threaded RTS. The waiting on I/O currently
happens before deadlock detection. This means we'll now wait forever on
signals before doing deadlock detection. We need to move waiting after
deadlock detection. We'll do that in a later patch.

- - - - -
68a22a05 by Duncan Coutts at 2026-07-16T09:36:44+01:00
Clean up the RTS internal signal handling API

Now that the I/O manager is responsible for signals, we can simplify the
API we present for signal handling.

We now just need startPendingSignalHandlers, which is called from the
I/O managers. We can get rid of awaitUserSignals. We also don't need
RtsSignals.h to re-export the platform-specific posix/Signals.h or
win32/ConsoleHandler.h

We can also hide more of the implementation of signals. Less has to be
exposed in posix/Signals.h or win32/ConsoleHandler.h. Indeed,
posix/Signals.h becomes empty and we remove it. Partly this is because
we don't need inline functions (or macros) in the interface.

Also remove signal_handlers from RTS ABI exported symbols list. It does
not appear to have any users in the core libs, and its really an
internal implementation detail. It should not be exposed unless it's
really necessary.

- - - - -
f566aac9 by Duncan Coutts at 2026-07-16T09:36:44+01:00
In the scheduler, move I/O blocking after deadlock detection

To make deadlock detection effective in the non-threaded RTS when there
are deadlocked threads and other unrelated threads waiting on I/O, we
need to arrange to do deadlock detection before we block in scheduler
to wait on I/O.

The solution is to:

1. adjust scheduleFindWork, which runs before deadlock detection, to
   only poll for I/O and not block; and
2. add a step after deadlock detection to wait on I/O if there are
   still no threads to run (and there's any I/O or timeouts outstanding)

The scheduleCheckBlockedThreads is now so simple that it made more sense
to inline it into scheduleFindWork.

- - - - -
fe408939 by Duncan Coutts at 2026-07-16T09:36:44+01:00
Remove bogus anyPendingTimeoutsOrIO guard from scheduleDetectDeadlock

The deadlock detection was only invoked if both of these conditions
hold:
1. the run queue is empty
2. there is no pending I/O or timeouts

The second condition is unnecessary. The deadlock detection mechanism
can find deadlocks even if there are other threads waiting on I/O or
timers. Having this extra condition means that we fail to detect
blocked threads if there are any threads waiting on I/O or timers.

Part of fixing issue #26408

- - - - -
ec5706a0 by Duncan Coutts at 2026-07-16T09:36:44+01:00
Don't consider pending I/O for early context switch optimisation

Context switches are normally initiated by the timer signal. If however
the user specifies "context switch as often as possible", with +RTS -C0
then the scheduler arranges for an early context switch (when it's just
about to run a Haskell thread).

Context switching very often is expensive, so as an optimisation there
cases where we do not arrange an early context switch:
1. if there's no other threads to run
2. if there is no pending I/O or timers

This patch eliminates case 2, leaving only case 1.

The rationale is as follows. The use of this was inconsistent across
platforms and threaded/non-threaded RTS ways. It only worked on the
non-threaded RTS and on Windows only worked for the win32-legacy I/O
manager. On all other combinations anyPendingTimeoutsOrIO would always
return false. The fact that nobody noticed and complained about this
inconsistency suggests that the feature is not relied upon.

If however it turns out that applications do rely on this, then the
proper thing to do is not to restore this check, but to add a new I/O
manager hint function that returns if there is any pending events that
are likely to happen *soon*: for example timeouts expiring within one
timeslice, or I/O waits on things likely to complete soon like disk I/O,
but not for example socket/pipe I/O.

The motivation to avoid this use of anyPendingTimeoutsOrIO is to
allow us to eliminate anyPendingTimeoutsOrIO entirely. All other uses
of this are just guards on {await,poll}CompletedTimeoutsOrIO and
the guards can safely be folded into those functions. This will better
cope with some I/O managers having no proper implementation of
anyPendingTimeoutsOrIO.

Ultimately this will let us simplify the scheduler which currently has
to have special #ifdef mingw32_HOST_OS cases to cope with the lack of a
working anyPendingTimeoutsOrIO for some Windows I/O managers

- - - - -
df340a0f by Duncan Coutts at 2026-07-16T09:36:44+01:00
Remove anyPendingTimeoutsOrIO guarding {poll,await}CompletedTimeoutsOrIO

Previously the API of the I/O manager used a two step process: check
anyPendingTimeoutsOrIO and then call {poll,await}CompletedTimeoutsOrIO.
This was primarily there as a performance thing, to cheaply check if we
need to do anything.

And then because anyPendingTimeoutsOrIO existed, it was used for other
things too. We have now eliminated the other uses, and are just left
with the performance pattern.

But this was problematic because not all I/O managers correctly
implement anyPendingTimeoutsOrIO (specifically the win32 ones), and now
that we also make I/O managers responsible for signals then we need to
poll/await even if there is no pending I/O or timeouts. If there is no
pending I/O or timeouts then poll/await needs to degenerate to just
waiting forever for any signals.

- - - - -
11dde2c6 by Duncan Coutts at 2026-07-16T09:36:44+01:00
Remove anyPendingTimeoutsOrIO, it is no longer used

And this avoids the problems arising from the win32 I/O managers having
had a bogus implementation.

- - - - -
99037204 by Duncan Coutts at 2026-07-16T09:36:44+01:00
Remove second scheduler call to awaitCompletedTimeoutsOrIO

Previously awaitCompletedTimeoutsOrIO was called both before and after
deadlock detection in the scheduler. The reason for that was that the
win32 I/O managers had a bogus implementation of anyPendingTimeoutsOrIO
and this was used to guard the call of awaitCompletedTimeoutsOrIO prior
to deadlock detection. This meant the first call site was never actually
called when using the win32 I/O managers. This was the reason for the
second call: the first one was never used. What a mess.

So now we have a simple design in the scheduler:
1. poll for completed I/O, timers or signals
2. if no runnable threads: do deadlock detection
3. if still no runnable threads: block waiting for I/O, timers or
   signals.

- - - - -
ccbe220a by Duncan Coutts at 2026-07-16T09:36:45+01:00
Lift emptyRunQueue guard out of scheduleDetectDeadlock

this improved the clarity of the logic when reading the scheduler code.

- - - - -
748bf4d9 by Duncan Coutts at 2026-07-16T09:36:45+01:00
Make non-threaded deadlock detection also rely on idle GC

Only do deadlock detection GC when idle GC kicks in. This also relies on
using wakeUpRts, so now do this unconditionally. Previously wakeUpRts
was for the threaded rts only.

- - - - -
490d8fe3 by Duncan Coutts at 2026-07-16T09:36:45+01:00
Enable idle GC by default on non-threaded RTS.

The behaviour is now uniform between threaded and non-threaded. The
deadlock detection now relies on idle GC for both threaded and
non-threaded ways. Previously deadlock detection did not rely on idle
GC for the non-threaded way.

- - - - -
e08746e0 by Duncan Coutts at 2026-07-16T09:36:45+01:00
Add a long Note [Deadlock detection]

It describes the historical and modern designs and their trade-offs.

The point is we've now unified the code for deadlock detection between
the threaded and non-threaded ways, by changing the non-threaded to
follow the same design as the threaded.

- - - - -
dee3a735 by Duncan Coutts at 2026-07-16T09:36:45+01:00
Add a test for deadlock detection, issue #26408

- - - - -
1120a867 by Duncan Coutts at 2026-07-16T09:36:45+01:00
Update the user guide with the revised idle GC behaviour

i.e. it's now not just for the threaded RTS, but general.

Also document the fact that disabling idle GC also disables deadlock
detection.

And add a changelog entry.

- - - - -

750 changed files:

- .gitignore
- .gitlab-ci.yml
- .gitlab/ci.sh
- .gitlab/generate-ci/gen_ci.hs
- .gitlab/jobs.yaml
- .gitlab/merge_request_templates/Default.md
- .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py
- .gitlab/test-metrics.sh
- + changelog.d/26616
- + changelog.d/AbstractQ
- + changelog.d/T17833
- + changelog.d/T21176
- + changelog.d/T21628
- + changelog.d/T26978
- + changelog.d/T27047
- + changelog.d/T27123.md
- + changelog.d/T27308
- + changelog.d/T27360
- + changelog.d/T27386
- + changelog.d/T27456
- + changelog.d/add_can_drop_to_occurence_analyser
- changelog.d/config
- + changelog.d/deterministic-usage-order
- + changelog.d/fix-absent-dict-projection
- + changelog.d/fix-cmm-atomic-load-store
- + changelog.d/fix-compacting-gc-ap-27434
- + changelog.d/fix-exponential-case-desugar-27383
- + changelog.d/fix-layout-stack-fcall
- + changelog.d/fix-peekitbl-no-tntc
- + changelog.d/fix-plugin-finder-multi-home-unit.md
- + changelog.d/fix-unreg
- + changelog.d/fix-use-std-ap-thunk
- + changelog.d/generically-mconcat
- + changelog.d/idle-gc-and-deadlock-detection
- + changelog.d/inter-module-far-jumps-aarch64-default
- + changelog.d/interactive-error-hints
- changelog.d/module-graph-reuse-in-downsweep
- changelog.d/more-efficient-home-unit-imports-finding
- + changelog.d/pp-set-ghc-version
- + changelog.d/reexported-module-errors
- + changelog.d/remove-ddump-json-flag
- changelog.d/semaphore-v2
- + changelog.d/stable-core-dump-order-27296
- + changelog.d/stage2-cross-compilers
- + changelog.d/tag-inference-27005
- + changelog.d/tool-messages-27370
- + changelog.d/unused-type
- compiler/.hlint.yaml
- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Builtin/Types.hs
- compiler/GHC/Builtin/Types/Prim.hs
- compiler/GHC/Builtin/Utils.hs
- compiler/GHC/ByteCode/Breakpoints.hs
- compiler/GHC/ByteCode/Types.hs
- compiler/GHC/Cmm/CLabel.hs
- compiler/GHC/Cmm/LayoutStack.hs
- compiler/GHC/Cmm/Parser.y
- compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
- compiler/GHC/CmmToAsm/AArch64/Instr.hs
- compiler/GHC/CmmToAsm/AArch64/Ppr.hs
- compiler/GHC/CmmToAsm/RV64/CodeGen.hs
- compiler/GHC/CmmToAsm/RV64/Instr.hs
- compiler/GHC/CmmToAsm/RV64/Ppr.hs
- compiler/GHC/CmmToAsm/RV64/Regs.hs
- compiler/GHC/CmmToAsm/Reg/Linear.hs
- compiler/GHC/CmmToAsm/Reg/Linear/FreeRegs.hs
- compiler/GHC/CmmToAsm/Reg/Linear/JoinToTargets.hs
- compiler/GHC/CmmToAsm/Reg/Linear/X86.hs
- compiler/GHC/CmmToAsm/Reg/Linear/X86_64.hs
- compiler/GHC/CmmToAsm/X86/RegInfo.hs
- compiler/GHC/CmmToAsm/X86/Regs.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Make.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Core/Opt/Simplify.hs
- compiler/GHC/Core/Opt/Specialise.hs
- compiler/GHC/Core/Opt/WorkWrap.hs
- compiler/GHC/Core/Opt/WorkWrap/Utils.hs
- compiler/GHC/Core/Ppr.hs
- compiler/GHC/Core/SimpleOpt.hs
- compiler/GHC/Core/TyCo/Ppr.hs
- compiler/GHC/Core/TyCo/Rep.hs
- compiler/GHC/Core/TyCon.hs
- compiler/GHC/Core/Utils.hs
- compiler/GHC/CoreToStg/Prep.hs
- compiler/GHC/Data/BooleanFormula.hs
- compiler/GHC/Data/FastString.hs
- compiler/GHC/Data/IOEnv.hs
- compiler/GHC/Data/List/NonEmpty.hs
- compiler/GHC/Data/StringBuffer.hs
- compiler/GHC/Driver/Backend.hs
- compiler/GHC/Driver/Backpack.hs
- compiler/GHC/Driver/CodeOutput.hs
- compiler/GHC/Driver/Config.hs
- compiler/GHC/Driver/Config/StgToCmm.hs
- compiler/GHC/Driver/DynFlags.hs
- compiler/GHC/Driver/Errors.hs
- compiler/GHC/Driver/Errors/Ppr.hs
- compiler/GHC/Driver/Flags.hs
- compiler/GHC/Driver/Main/Compile.hs
- compiler/GHC/Driver/Main/Hsc.hs
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- compiler/GHC/Driver/Main/Passes.hs
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- compiler/GHC/Hs.hs
- compiler/GHC/Hs/Binds.hs
- compiler/GHC/Hs/Decls.hs
- compiler/GHC/Hs/Doc.hs
- − compiler/GHC/Hs/Doc.hs-boot
- compiler/GHC/Hs/DocString.hs
- compiler/GHC/Hs/Dump.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Extension.hs
- + compiler/GHC/Hs/Extension/Pass.hs
- compiler/GHC/Hs/ImpExp.hs
- compiler/GHC/Hs/Instances.hs
- compiler/GHC/Hs/Lit.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/Hs/Stats.hs
- compiler/GHC/Hs/Type.hs
- compiler/GHC/Hs/Utils.hs
- compiler/GHC/HsToCore.hs
- compiler/GHC/HsToCore/Arrows.hs
- compiler/GHC/HsToCore/Breakpoints.hs
- + compiler/GHC/HsToCore/Breakpoints/Types.hs
- compiler/GHC/HsToCore/Docs.hs
- compiler/GHC/HsToCore/Errors/Types.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/HsToCore/Foreign/C.hs
- compiler/GHC/HsToCore/Foreign/JavaScript.hs
- compiler/GHC/HsToCore/Foreign/Wasm.hs
- compiler/GHC/HsToCore/Match.hs
- compiler/GHC/HsToCore/Match.hs-boot
- compiler/GHC/HsToCore/Match/Constructor.hs
- compiler/GHC/HsToCore/Match/Literal.hs
- compiler/GHC/HsToCore/Monad.hs
- compiler/GHC/HsToCore/Pmc.hs
- compiler/GHC/HsToCore/Pmc/Desugar.hs
- compiler/GHC/HsToCore/Pmc/Solver.hs
- compiler/GHC/HsToCore/Pmc/Solver/Types.hs
- compiler/GHC/HsToCore/Quote.hs
- compiler/GHC/HsToCore/Ticks.hs
- compiler/GHC/HsToCore/Usage.hs
- compiler/GHC/Iface/Binary.hs
- compiler/GHC/Iface/Errors.hs
- compiler/GHC/Iface/Errors/Ppr.hs
- compiler/GHC/Iface/Errors/Types.hs
- compiler/GHC/Iface/Ext/Ast.hs
- compiler/GHC/Iface/Load.hs
- compiler/GHC/Iface/Make.hs
- compiler/GHC/Iface/Recomp.hs
- compiler/GHC/Iface/Syntax.hs
- compiler/GHC/Iface/Type.hs
- compiler/GHC/Iface/Warnings.hs
- compiler/GHC/Parser.y
- compiler/GHC/Parser/Annotation.hs
- compiler/GHC/Parser/Errors/Ppr.hs
- compiler/GHC/Parser/HaddockLex.x
- compiler/GHC/Parser/Lexer.x
- compiler/GHC/Parser/PostProcess.hs
- compiler/GHC/Parser/PostProcess/Haddock.hs
- compiler/GHC/Parser/Types.hs
- compiler/GHC/Platform/Ways.hs
- compiler/GHC/Rename/Bind.hs
- compiler/GHC/Rename/Doc.hs
- compiler/GHC/Rename/Env.hs
- compiler/GHC/Rename/Expr.hs
- compiler/GHC/Rename/HsType.hs
- compiler/GHC/Rename/Lit.hs
- compiler/GHC/Rename/Module.hs
- compiler/GHC/Rename/Names.hs
- compiler/GHC/Rename/Pat.hs
- compiler/GHC/Rename/Splice.hs
- compiler/GHC/Rename/Splice.hs-boot
- compiler/GHC/Rename/Unbound.hs
- compiler/GHC/Rename/Utils.hs
- compiler/GHC/Runtime/Eval.hs
- compiler/GHC/Stg/EnforceEpt.hs
- compiler/GHC/Stg/EnforceEpt/Rewrite.hs
- compiler/GHC/Stg/EnforceEpt/TagSig.hs
- compiler/GHC/Stg/EnforceEpt/Types.hs
- compiler/GHC/StgToByteCode.hs
- compiler/GHC/StgToCmm/Bind.hs
- compiler/GHC/StgToCmm/Config.hs
- compiler/GHC/StgToCmm/Foreign.hs
- compiler/GHC/StgToCmm/Prim.hs
- compiler/GHC/StgToJS/FFI.hs
- compiler/GHC/SysTools/Process.hs
- compiler/GHC/SysTools/Tasks.hs
- compiler/GHC/SysTools/Terminal.hs
- compiler/GHC/Tc/Deriv.hs
- compiler/GHC/Tc/Deriv/Generate.hs
- compiler/GHC/Tc/Deriv/Generics.hs
- compiler/GHC/Tc/Errors.hs
- compiler/GHC/Tc/Errors/Hole.hs
- compiler/GHC/Tc/Errors/Hole/FitTypes.hs
- compiler/GHC/Tc/Errors/Ppr.hs
- compiler/GHC/Tc/Errors/Types.hs
- compiler/GHC/Tc/Gen/App.hs
- compiler/GHC/Tc/Gen/Arrow.hs
- compiler/GHC/Tc/Gen/Bind.hs
- compiler/GHC/Tc/Gen/Do.hs
- compiler/GHC/Tc/Gen/Export.hs
- compiler/GHC/Tc/Gen/Expr.hs
- compiler/GHC/Tc/Gen/Head.hs
- compiler/GHC/Tc/Gen/HsType.hs
- compiler/GHC/Tc/Gen/Match.hs
- compiler/GHC/Tc/Gen/Pat.hs
- compiler/GHC/Tc/Gen/Sig.hs
- compiler/GHC/Tc/Gen/Splice.hs
- compiler/GHC/Tc/Gen/Splice.hs-boot
- compiler/GHC/Tc/Instance/Class.hs
- compiler/GHC/Tc/Module.hs
- compiler/GHC/Tc/Solver/Dict.hs
- compiler/GHC/Tc/Solver/Equality.hs
- compiler/GHC/Tc/Solver/FunDeps.hs
- compiler/GHC/Tc/TyCl.hs
- compiler/GHC/Tc/TyCl/PatSyn.hs
- compiler/GHC/Tc/TyCl/Utils.hs
- compiler/GHC/Tc/Types.hs
- compiler/GHC/Tc/Types/Origin.hs
- compiler/GHC/Tc/Utils/Backpack.hs
- compiler/GHC/Tc/Utils/Env.hs
- compiler/GHC/Tc/Utils/Instantiate.hs
- compiler/GHC/Tc/Utils/Monad.hs
- compiler/GHC/Tc/Utils/TcMType.hs
- compiler/GHC/Tc/Utils/TcType.hs
- compiler/GHC/Tc/Validity.hs
- compiler/GHC/Tc/Zonk/Type.hs
- compiler/GHC/ThToHs.hs
- compiler/GHC/Types/Basic.hs
- compiler/GHC/Types/Error.hs
- − compiler/GHC/Types/Error.hs-boot
- compiler/GHC/Types/FieldLabel.hs
- compiler/GHC/Types/ForeignCall.hs
- compiler/GHC/Types/Hint/Ppr.hs
- compiler/GHC/Types/Literal.hs
- compiler/GHC/Types/Name/Reader.hs
- compiler/GHC/Types/PkgQual.hs
- compiler/GHC/Types/SourceError.hs
- compiler/GHC/Types/SourceText.hs
- compiler/GHC/Unit.hs
- compiler/GHC/Unit/Finder.hs
- compiler/GHC/Unit/Finder/Types.hs
- compiler/GHC/Unit/Module/Deps.hs
- compiler/GHC/Unit/Module/Env.hs
- compiler/GHC/Unit/Module/ModGuts.hs
- compiler/GHC/Unit/Module/ModIface.hs
- compiler/GHC/Unit/Module/Warnings.hs
- compiler/GHC/Unit/Module/WholeCoreBindings.hs
- compiler/GHC/Unit/State.hs
- compiler/GHC/Unit/Types.hs
- compiler/GHC/Utils/Binary.hs
- compiler/GHC/Utils/Error.hs
- compiler/GHC/Utils/Logger.hs
- compiler/GHC/Utils/Outputable.hs
- compiler/Language/Haskell/Syntax.hs
- compiler/Language/Haskell/Syntax/Basic.hs
- compiler/Language/Haskell/Syntax/Binds.hs
- compiler/Language/Haskell/Syntax/Binds/InlinePragma.hs
- compiler/Language/Haskell/Syntax/Decls.hs
- compiler/Language/Haskell/Syntax/Decls/Foreign.hs
- + compiler/Language/Haskell/Syntax/Doc.hs
- compiler/Language/Haskell/Syntax/Expr.hs
- compiler/Language/Haskell/Syntax/Expr.hs-boot
- compiler/Language/Haskell/Syntax/Extension.hs
- compiler/Language/Haskell/Syntax/ImpExp.hs
- compiler/Language/Haskell/Syntax/Lit.hs
- compiler/Language/Haskell/Syntax/Module/Name.hs
- compiler/Language/Haskell/Syntax/Pat.hs
- + compiler/Language/Haskell/Syntax/Text.hs
- compiler/Language/Haskell/Syntax/Type.hs
- − compiler/Language/Haskell/Syntax/Type.hs-boot
- compiler/ghc.cabal.in
- configure.ac
- distrib/configure.ac.in
- docs/users_guide/bugs.rst
- docs/users_guide/debugging.rst
- docs/users_guide/ghci.rst
- docs/users_guide/phases.rst
- docs/users_guide/runtime_control.rst
- docs/users_guide/using-optimisation.rst
- ghc/GHCi/UI.hs
- ghc/GHCi/UI/Exception.hs
- ghc/Main.hs
- hadrian/README.md
- hadrian/bindist/config.mk.in
- hadrian/cabal.project
- hadrian/cfg/default.host.target.in
- + hadrian/cfg/system.config.host.in
- hadrian/cfg/system.config.in
- + hadrian/cfg/system.config.target.in
- hadrian/hadrian.cabal
- hadrian/src/Base.hs
- + hadrian/src/BindistConfig.hs
- hadrian/src/Builder.hs
- hadrian/src/Context.hs
- hadrian/src/Expression.hs
- hadrian/src/Flavour.hs
- hadrian/src/Flavour/Type.hs
- hadrian/src/Hadrian/Builder.hs
- hadrian/src/Hadrian/Haskell/Hash.hs
- hadrian/src/Hadrian/Oracles/TextFile.hs
- hadrian/src/Main.hs
- hadrian/src/Oracles/Flag.hs
- hadrian/src/Oracles/Flavour.hs
- hadrian/src/Oracles/Setting.hs
- hadrian/src/Oracles/TestSettings.hs
- hadrian/src/Packages.hs
- hadrian/src/Rules.hs
- hadrian/src/Rules/BinaryDist.hs
- hadrian/src/Rules/CabalReinstall.hs
- hadrian/src/Rules/Changelog.hs
- hadrian/src/Rules/Compile.hs
- hadrian/src/Rules/Documentation.hs
- hadrian/src/Rules/Generate.hs
- hadrian/src/Rules/Gmp.hs
- hadrian/src/Rules/Library.hs
- hadrian/src/Rules/Program.hs
- hadrian/src/Rules/Register.hs
- hadrian/src/Rules/Rts.hs
- hadrian/src/Rules/Test.hs
- hadrian/src/Settings.hs
- hadrian/src/Settings/Builders/Cabal.hs
- hadrian/src/Settings/Builders/Common.hs
- hadrian/src/Settings/Builders/Configure.hs
- hadrian/src/Settings/Builders/DeriveConstants.hs
- hadrian/src/Settings/Builders/Ghc.hs
- hadrian/src/Settings/Builders/Hsc2Hs.hs
- hadrian/src/Settings/Builders/RunTest.hs
- hadrian/src/Settings/Builders/SplitSections.hs
- hadrian/src/Settings/Default.hs
- hadrian/src/Settings/Flavours/GhcInGhci.hs
- hadrian/src/Settings/Flavours/Performance.hs
- hadrian/src/Settings/Flavours/QuickCross.hs
- hadrian/src/Settings/Packages.hs
- hadrian/src/Settings/Program.hs
- hadrian/src/Settings/Warnings.hs
- libraries/base/base.cabal.in
- libraries/base/changelog.md
- + libraries/base/src/Data/Double.hs
- + libraries/base/src/Data/Float.hs
- libraries/base/src/Data/List/NonEmpty.hs
- libraries/base/src/GHC/Base.hs
- libraries/base/src/GHC/Exts.hs
- libraries/base/tests/T15349.stderr
- libraries/base/tests/all.T
- libraries/ghc-bignum/changelog.md
- libraries/ghc-boot/GHC/Data/ShortText.hs
- libraries/ghc-experimental/src/GHC/PrimOps.hs
- + libraries/ghc-heap/tests/T27465.hs
- + libraries/ghc-heap/tests/T27465.stdout
- libraries/ghc-heap/tests/all.T
- libraries/ghc-internal/src/GHC/Internal/Bignum/Integer.hs
- libraries/ghc-internal/src/GHC/Internal/Bits.hs
- libraries/ghc-internal/src/GHC/Internal/Event/Control.hs
- libraries/ghc-internal/src/GHC/Internal/Event/Manager.hs
- libraries/ghc-internal/src/GHC/Internal/Event/TimerManager.hs
- libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs
- libraries/ghc-internal/src/GHC/Internal/Float.hs
- libraries/ghc-internal/src/GHC/Internal/Generics.hs
- libraries/ghc-internal/src/GHC/Internal/Heap/InfoTable.hsc
- libraries/ghc-internal/src/GHC/Internal/Heap/InfoTableProf.hsc
- libraries/ghc-internal/src/GHC/Internal/TH/Lib.hs
- libraries/ghc-internal/src/GHC/Internal/TH/Monad.hs
- libraries/ghc-internal/src/GHC/Internal/Types.hs
- libraries/ghc-internal/tests/backtraces/T14532b.stdout
- libraries/ghci/GHCi/TH.hs
- libraries/process
- libraries/semaphore-compat
- libraries/template-haskell/Language/Haskell/TH/Syntax.hs
- libraries/xhtml
- m4/fp_find_nm.m4
- m4/prep_target_file.m4
- nofib
- rts/Apply.cmm
- rts/Capability.c
- rts/Capability.h
- rts/ContinuationOps.cmm
- rts/IOManager.c
- rts/IOManager.h
- rts/IOManagerInternals.h
- rts/Linker.c
- rts/Messages.c
- rts/PrimOps.cmm
- rts/RaiseAsync.c
- rts/RtsFlags.c
- rts/RtsSignals.h
- rts/RtsStartup.c
- rts/RtsSymbols.c
- rts/Schedule.c
- rts/Schedule.h
- rts/Ticker.h
- rts/Timer.c
- rts/Timer.h
- rts/include/rts/IOInterface.h
- rts/include/rts/NonMoving.h
- rts/include/rts/Timer.h
- rts/include/rts/storage/Closures.h
- rts/include/rts/storage/TSO.h
- rts/include/stg/MiscClosures.h
- rts/posix/FdWakeup.h
- + rts/posix/MIO.c
- rts/posix/Signals.h → rts/posix/MIO.h
- rts/posix/Poll.c
- rts/posix/Poll.h
- rts/posix/Select.c
- rts/posix/Select.h
- rts/posix/Signals.c
- rts/posix/Ticker.c
- rts/posix/Timeout.c
- rts/posix/Timeout.h
- rts/rts.cabal
- rts/sm/Compact.c
- rts/sm/Evac.h
- rts/sm/GC.c
- rts/win32/AsyncMIO.c
- rts/win32/AsyncMIO.h
- rts/win32/AsyncWinIO.h
- rts/win32/AwaitEvent.c
- rts/win32/AwaitEvent.h
- rts/win32/ConsoleHandler.c
- rts/win32/ConsoleHandler.h
- rts/win32/MIOManager.h
- rts/win32/ThrIOManager.h
- rts/win32/Ticker.c
- rts/win32/WorkQueue.h
- rts/win32/veh_excn.h
- testsuite/driver/junit.py
- testsuite/driver/perf_notes.py
- testsuite/driver/testglobals.py
- testsuite/driver/testlib.py
- testsuite/driver/testutil.py
- testsuite/ghc-config/ghc-config.hs
- testsuite/tests/annotations/should_fail/annfail03.stderr
- testsuite/tests/annotations/should_fail/annfail04.stderr
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- utils/haddock/haddock-api/src/Haddock/Interface/AttachInstances.hs
- utils/haddock/haddock-api/src/Haddock/Interface/Create.hs
- utils/haddock/haddock-api/src/Haddock/Interface/Json.hs
- utils/haddock/haddock-api/src/Haddock/Interface/LexParseRn.hs
- utils/haddock/haddock-api/src/Haddock/Interface/ParseModuleHeader.hs
- utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs
- utils/haddock/haddock-api/src/Haddock/Interface/RenameType.hs
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- utils/haddock/haddock-api/src/Haddock/Options.hs
- utils/haddock/haddock-api/src/Haddock/Parser.hs
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- utils/haddock/haddock-api/src/Haddock/Utils/Json.hs
- utils/haddock/haddock-api/src/Haddock/Utils/Json/Parser.hs
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- utils/haddock/haddock-library/src/Documentation/Haddock/Doc.hs
- utils/haddock/haddock-library/src/Documentation/Haddock/Markup.hs
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- utils/haddock/haddock-library/src/Documentation/Haddock/Parser/Util.hs
- utils/haddock/haddock-library/src/Documentation/Haddock/Types.hs
- utils/haddock/haddock-library/test/Documentation/Haddock/ParserSpec.hs
- utils/haddock/haddock-test/haddock-test.cabal
- utils/haddock/haddock-test/src/Test/Haddock/Config.hs
- utils/haddock/html-test/ref/Hash.html
- utils/haddock/html-test/ref/Test.html
- utils/haddock/html-test/ref/TypeFamilies3.html

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f2345a091ec10e68e25ea8355a4d2f7...

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Duncan Coutts (＠dcoutts)

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