GitLab

Simon Peyton Jones pushed to branch wip/T26330 at Glasgow Haskell Compiler / GHC

Commits:

9e857171

by Brandon Chinn at 2025-08-20T11:47:46-04:00

Don't warn unused-imports with used generated imports

Fixes #21730

* The old notion of "implicit" import has been renamed to "generated". See Note [Generated imports] in GHC.Hs.ImpExp.

* ImportMap now keeps track of generated and user-written imports separately. This avoids the fake SrcSpan we used to give the implicit Prelude import, and the hack that went with it.

* -ddump-minimal-imports now considers generated imports (but still only
  warns on + prints user-written imports)

* bestImport considers generated imports to take priority over user-written imports.

9fb3bad4

by Ben Gamari at 2025-08-20T11:48:31-04:00

mailmap: Use ben@well-typed.com more liberally

Nearly all of this work was done while working for Well-Typed.

774fec37

by Ben Gamari at 2025-08-20T11:49:15-04:00

Add primop to annotate the call stack with arbitrary data

We introduce a new primop `annotateStack#` which allows us to push
arbitrary data onto the call-stack.
This allows us to extract the data later when decoding the stack, for
example when an exception is thrown, showing more information to the
user without having to annotate the full call-stack with `HasCallStack`
constraints.

A new stack frame value is introduced `AnnFrame`, which consists of
nothing but a generic payload.

The primop has a small wrapper API that allows users to annotate their
call-stack in programs.
There is a pure API and an IO-based one. The former is a little bit
dubious, as it affects the evaluation of a program, so use with care.
The latter is "safe", as it doesn't change the evaluation of the
program.

The stack annotation mechanism is similarly implemented to the
`ExceptionAnnotation` and `Exception`, there is a typeclass to indicate
something can be pushed onto the call-stack and all values are wrapped
in the existential `SomeStackAnnotation`, which recover the type of the
annotation payload.

There is currently no builtin way to show the stack annotations when
`Backtraces` are displayed (i.e., when showing stack traces to the user),
which we will address in a follow-up MR.

-------------------------
Metric Increase:
    ghc_experimental_so
-------------------------

We increase the size of the package, so this is not unreasonable.

Co-Authored-By: fendor <fendor@posteo.de>
Co-Authored-By: Ben Gamari <bgamari.foss@gmail.com>

fdfa3892
by Ben Gamari at 2025-08-20T11:49:57-04:00
```
testsuite: Add regression test for #24606
```

39b2e382

by Cheng Shao at 2025-08-20T11:50:40-04:00

compiler: only use `Name` instead of `Id` in `SptEntry`

As a part of #26298, this patch refactors `SptEntry` to only carry a
`Name` instead of `Id`: we do not care about extra information like
caffyness or type at all in any static pointer related codegen logic.
This is necessary to make `SptEntry` serializable, as a part of the
grand plan of serializable bytecode.

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

276f8ea8
by Vekhir -- at 2025-08-20T11:51:35-04:00
```
Bump Cabal dependency
```

0b9c7437

by Zubin Duggal at 2025-08-20T11:52:18-04:00

ci: Teach ci.sh to fetch FreeBSD artifacts from ghcup unofficial bindists and bootstrap compiler on FreeBSD to 9.10.1

Also refactor fetch_ghc logic in ci.sh, renaming the GHC_VERSION enviorment configuration variable to FETCH_GHC_VERSION,
making it clear that it is intended for use on platforms like Windows and FreeBSD where we don't want to use the GHC
excecutable from the platform environment and instead need to download and install GHC-$FETCH_GHC_VERSION from a release
bindist.

Fixes #26296

b2914797

by Cheng Shao at 2025-08-20T11:53:00-04:00

driver: use UniqSet for hiddenModules in DynFlags/FinderOpts

This patch replaces Set ModuleName with UniqSet ModuleName in
DynFlags.hiddenModules and FinderOpts.finder_hiddenModules for
improved efficiency.

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

0335d899

by Cheng Shao at 2025-08-20T11:53:00-04:00

driver: use UniqMap ModuleName in the finder

This patch replaces Map ModuleName with UniqMap ModuleName in the
finder for improved efficiency.

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

91f4faaa

by Cheng Shao at 2025-08-20T11:53:43-04:00

configure: check python3 version and require minimal 3.7

Since !9515, the testsuite driver requires python3 version to be at
least 3.7, though this has never been checked by configure logic. This
patch implements the version check. Fixes #23234.

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

df4ee9b4

by Cheng Shao at 2025-08-20T11:54:25-04:00

compiler: use zero cost coerce in GHC.CmmToAsm.CFG.loopInfo

This patch refactors GHC.CmmToAsm.CFG.loopInfo to use zero cost coerce
and thus addresses the TODO. For coerce to work, constructors of
Label/LabelMap/LabelSet from GHC.Cmm.Dataflow.Label are exposed,
though I believe it's a worthy tradeoff to avoid unnecessary runtime
cost without using unsafeCoerce, since the latter could be a landmine
for future refactoring.

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

ccda188d

by Simon Peyton Jones at 2025-08-20T11:55:07-04:00

Start with empty inerts in shortcut solving

When short-cut solving we were starting with an inert set that had
unsolved Wanteds.  This caused an infinite loop (#26314), because a
typechecker plugin kept being given that unsolved Wanted.

It's better just to start with an empty inert set

c8882ed7

by Ben Gamari at 2025-08-20T11:55:49-04:00

configure: Bump minimal bootstrap GHC version to 9.8

f0a19d74

by fendor at 2025-08-20T19:55:00-04:00

Remove deprecated functions from the ghci package

ebeb991b

by fendor at 2025-08-20T19:55:00-04:00

base: Remove unstable heap representation details from GHC.Exts

e368e247

by Rodrigo Mesquita at 2025-08-20T19:55:42-04:00

bytecode: Use 32bits for breakpoint index

Fixes #26325

42724462

by Simon Hengel at 2025-08-21T17:52:11-04:00

Serialize wired-in names as external names when creating HIE files

Note that the domain of de-serialized names stays the same.
Specifically, for known-key names, before `lookupKnownKeyName` was used,
while now this is handled by `lookupOrigNameCache` which captures the
same range provided that the OrigNameCache has been initialized with
`knownKeyNames` (which is the case by default).

(fixes #26238)

6a43f8ec

by Cheng Shao at 2025-08-21T17:52:52-04:00

compiler: fix closure C type in SPT init code

This patch fixes the closure C type in SPT init code to StgClosure,
instead of the previously incorrect StgPtr. Having an incorrect C type
makes SPT init code not compatible with other foreign stub generation
logic, which may also emit their own extern declarations for the same
closure symbols and thus will clash with the incorrect prototypes in
SPT init code.

5b5d9d47

by Ben Gamari at 2025-08-25T14:29:35-04:00

Revert "STM: don't create a transaction in the rhs of catchRetry# (#26028)"

This reverts commit 0a5836891ca29836a24c306d2a364c2e4b5377fd

10f06163

by Cheng Shao at 2025-08-25T14:30:16-04:00

wasm: ensure setKeepCAFs() is called in ghci

This patch is a critical bugfix for #26106, see comment and linked
issue for details.

bedc1004

by Cheng Shao at 2025-08-26T09:31:18-04:00

compiler: use zero cost coerce in hoopl setElems/mapToList

This patch is a follow-up of !14680 and changes setElems/mapToList in
GHC/Cmm/Dataflow/Label to use coerce instead of mapping mkHooplLabel
over the keys.

13250d97

by Ryan Scott at 2025-08-26T09:31:59-04:00

Reject infix promoted data constructors without DataKinds

In the rename, make sure to apply the same `DataKinds` checks for both
`HsTyVar` (for prefix promoted data constructors) and `HsOpTy` (for infix
promoted data constructors) alike.

Fixes #26318.

37655c46

by Teo Camarasu at 2025-08-26T15:24:51-04:00

tests: disable T22859 under LLVM

This test was failing under the LLVM backend since the allocations
differ from the NCG.

Resolves #26282

2cbba9d6

by Teo Camarasu at 2025-08-26T15:25:33-04:00

base-exports: update version numbers

As the version of the compiler has been bumped, a lot of the embedded
version numbers will need to be updated if we ever run this test with
`--test-accept` so let's just update them now, and keep future diffs
clean.

f9f2ffcf

by Alexandre Esteves at 2025-08-27T07:19:14-04:00

Import new name for 'utimbuf' on windows to fix #26337

Fixes an `-Wincompatible-pointer-types` instance that turns into an error on
recent toolchains and surfaced as such on nixpkgs when doing linux->ucrt cross.

This long-standing warning has been present at least since 9.4:

```
C:\GitLabRunner\builds\0\1709189\tmp\ghc16652_0\ghc_4.c:26:115: error:
     warning: incompatible pointer types passing 'struct utimbuf *' to parameter of type 'struct _utimbuf *' [-Wincompatible-pointer-types]
   |
26 | HsInt32 ghczuwrapperZC9ZCbaseZCSystemziPosixziInternalsZCzuutime(char* a1, struct utimbuf* a2) {return _utime(a1, a2);}

   |                                                                                                                   ^
HsInt32 ghczuwrapperZC9ZCbaseZCSystemziPosixziInternalsZCzuutime(char* a1, struct utimbuf* a2) {return _utime(a1, a2);}
                                                                                                                  ^~

C:\GitLabRunner\builds\0\1709189\_build\stage0\lib\..\..\mingw\x86_64-w64-mingw32\include\sys\utime.h:109:72: error:
     note: passing argument to parameter '_Utimbuf' here
    |
109 | __CRT_INLINE int __cdecl _utime(const char *_Filename,struct _utimbuf *_Utimbuf) {
    |                                                                        ^
__CRT_INLINE int __cdecl _utime(const char *_Filename,struct _utimbuf *_Utimbuf) {
```

ae89f000

by Hassan Al-Awwadi at 2025-08-27T07:19:56-04:00

Adds the fucnction addDependentDirectory to Q, resolving issue #26148.

This function adds a new directory to the list of things a module depends upon. That means that when the contents of the directory change, the recompilation checker will notice this and the module will be recompiled. Documentation has also been added for addDependentFunction and addDependentDirectory in the user guide.

00478944
by Simon Peyton Jones at 2025-08-27T16:48:30+01:00
```
Comments only
```

a7884589

by Simon Peyton Jones at 2025-08-28T11:08:23+01:00

Type-family occurs check in unification

The occurs check in `GHC.Core.Unify.uVarOrFam` was inadequate in dealing
with type families.

Better now.  See Note [The occurs check in the Core unifier].

As I did this I realised that the whole apartness thing is trickier than I
thought: see the new Note [Shortcomings of the apartness test]

8adfc222

by sheaf at 2025-08-28T19:47:17-04:00

Fix orientation in HsWrapper composition (<.>)

This commit fixes the order in which WpCast HsWrappers are composed,
fixing a bug introduced in commit 56b32c5a2d5d7cad89a12f4d74dc940e086069d1.

Fixes #26350

eb2ab1e2

by Oleg Grenrus at 2025-08-29T11:00:53-04:00

Generalise thNameToGhcName by adding HasHscEnv

There were multiple single monad-specific `getHscEnv` across codebase.
HasHscEnv is modelled on HasDynFlags.

My first idea was to simply add thNameToGhcNameHsc and
thNameToGhcNameTc, but those would been exactly the same
as thNameToGhcName already.

Also add an usage example to thNameToGhcName and mention that it's
recommended way of looking up names in GHC plugins

2d575a7f

by fendor at 2025-08-29T11:01:36-04:00

configure: Bump minimal bootstrap GHC version to 9.10

716274a5

by Simon Peyton Jones at 2025-08-29T17:27:12-04:00

Fix deep subsumption again

This commit fixed #26255:

    commit 56b32c5a2d5d7cad89a12f4d74dc940e086069d1
    Author: sheaf <sam.derbyshire@gmail.com>
    Date:   Mon Aug 11 15:50:47 2025 +0200

        Improve deep subsumption

        This commit improves the DeepSubsumption sub-typing implementation
        in GHC.Tc.Utils.Unify.tc_sub_type_deep by being less eager to fall back
        to unification.

But alas it still wasn't quite right for view patterns: #26331

This MR does a generalisation to fix it.  A bit of a sledgehammer to crack
a nut, but nice.

* Add a field `ir_inst :: InferInstFlag` to `InferResult`, where
  ```
  data InferInstFlag = IIF_Sigma | IIF_ShallowRho | IIF_DeepRho
  ```

* The flag says exactly how much `fillInferResult` should instantiate
  before filling the hole.

* We can also use this to replace the previous very ad-hoc `tcInferSigma`
  that was used to implement GHCi's `:type` command.

27206c5e

by sheaf at 2025-08-29T17:28:14-04:00

Back-compat for TH SpecialiseP data-con of Pragma

This commit improves the backwards-compatibility story for the
SpecialiseP constructor of the Template Haskell 'Pragma' datatype.

Instead of keeping the constructor but deprecating it, this commit makes
it into a bundled pattern synonym of the Pragma datatype. We no longer
deprecate it; it's useful for handling old-form specialise pragmas.

26dbcf61

by fendor at 2025-08-30T05:10:08-04:00

Move stack decoding logic from ghc-heap to ghc-internal

The stack decoding logic in `ghc-heap` is more sophisticated than the one
currently employed in `CloneStack`. We want to use the stack decoding
implementation from `ghc-heap` in `base`.
We cannot simply depend on `ghc-heap` in `base` due do bootstrapping
issues.
Thus, we move the code that is necessary to implement stack decoding to
`ghc-internal`. This is the right location, as we don't want to add a
new API to `base`.

Moving the stack decoding logic and re-exposing it in ghc-heap is
insufficient, though, as we have a dependency cycle between.

* ghc-heap depends on stage1:ghc-internal
* stage0:ghc depends on stage0:ghc-heap

To fix this, we remove ghc-heap from the set of `stage0` dependencies.

This is not entirely straight-forward, as a couple of boot dependencies,
such as `ghci` depend on `ghc-heap`.
Luckily, the boot compiler of GHC is now >=9.10, so we can migrate `ghci`
to use `ghc-internal` instead of `ghc-heap`, which already exports the
relevant modules.

However, we cannot 100% remove ghc's dependency on `ghc-heap`, since
when we compile `stage0:ghc`, `stage1:ghc-internal` is not yet
available.
Thus, when we compile with the boot-compiler, we still depend on an
older version of `ghc-heap`, and only use the modules from `ghc-internal`,
if the `ghc-internal` version is recent enough.

-------------------------
Metric Increase:
    T24602_perf_size
    T25046_perf_size_gzip
    T25046_perf_size_unicode
    T25046_perf_size_unicode_gzip
    size_hello_artifact
    size_hello_artifact_gzip
    size_hello_unicode
    size_hello_unicode_gzip
-------------------------

These metric increases are unfortunate, they are most likely caused by
the larger (literally in terms of lines of code) stack decoder implementation
that are now linked into hello-word binaries.

On linux, it is almost a 10% increase, which is considerable.

bd80bb70

by fendor at 2025-08-30T05:10:08-04:00

Implement `decode` in terms of `decodeStackWithIpe`

Uses the more efficient stack decoder implementation.

24441165
by fendor at 2025-08-30T05:10:08-04:00
```
Remove stg_decodeStackzh
```

fb9cc882

by Simon Peyton Jones at 2025-08-30T05:10:51-04:00

Fix a long standing bug in the coercion optimiser

We were mis-optimising ForAllCo, leading to #26345

Part of the poblem was the tricky tower of abstractions leading to
the dreadful
   GHC.Core.TyCo.Subst.substForAllCoTyVarBndrUsing
This function was serving two masters: regular substitution, but also
coercion optimsation.  So tricky was it that it did so wrong.

In this MR I locate all the fancy footwork for coercion optimisation
in GHC.Core.Coercion.Opt, where it belongs.   That leaves substitution
free to be much simpler.

6c78de2d

by Sylvain Henry at 2025-09-01T08:46:19-04:00

Driver: substitute virtual Prim module in --make mode too

When we build ghc-internal with --make (e.g. with cabal-install), we
need to be careful to substitute the virtual interface file for
GHC.Internal.Prim:
- after code generation (we generate code for an empty module, so we get
  an empty interface)
- when we try to reload its .hi file

26e0db16

by fendor at 2025-09-01T08:47:01-04:00

Expose Stack Annotation frames in IPE backtraces by default

When decoding the Haskell-native call stack and displaying the IPE information
for the stack frames, we print the `StackAnnotation` of the `AnnFrame` by default.

This means, when an exception is thrown, any intermediate stack annotations will
be displayed in the `IPE Backtrace`.

Example backtrace:
```
Exception: ghc-internal:GHC.Internal.Exception.ErrorCall:

Oh no!

IPE backtrace:
  annotateCallStackIO, called at app/Main.hs:48:10 in backtrace-0.1.0.0-inplace-server:Main
  annotateCallStackIO, called at app/Main.hs:46:13 in backtrace-0.1.0.0-inplace-server:Main
  Main.handler (app/Main.hs:(46,1)-(49,30))
  Main.liftIO (src/Servant/Server/Internal/Handler.hs:30:36-42)
  Servant.Server.Internal.Delayed.runHandler' (src/Servant/Server/Internal/Handler.hs:27:31-41)
  Control.Monad.Trans.Resource.runResourceT (./Control/Monad/Trans/Resource.hs:(192,14)-(197,18))
  Network.Wai.Handler.Warp.HTTP1.processRequest (./Network/Wai/Handler/Warp/HTTP1.hs:195:20-22)
  Network.Wai.Handler.Warp.HTTP1.processRequest (./Network/Wai/Handler/Warp/HTTP1.hs:(195,5)-(203,31))
  Network.Wai.Handler.Warp.HTTP1.http1server.loop (./Network/Wai/Handler/Warp/HTTP1.hs:(141,9)-(157,42))
HasCallStack backtrace:
  error, called at app/Main.hs:48:32 in backtrace-0.1.0.0-inplace-server:Main
```

The first two entries have been added by `annotateCallStackIO`, defined in `annotateCallStackIO`.

a1567efd

by Sylvain Henry at 2025-09-01T23:01:35-04:00

RTS: rely less on Hadrian for flag setting (#25843)

Hadrian used to pass -Dfoo command-line flags directly to build the rts.
We can replace most of these flags with CPP based on cabal flags.
It makes building boot libraries with cabal-install simpler (cf #25843).

ca5b0283

by Sergey Vinokurov at 2025-09-01T23:02:23-04:00

Remove unnecessary irrefutable patterns from Bifunctor instances for tuples

Implementation of https://github.com/haskell/core-libraries-committee/issues/339

Metric Decrease:
    mhu-perf

2da84b7a

by sheaf at 2025-09-01T23:03:23-04:00

Only use active rules when simplifying rule RHSs

When we are simplifying the RHS of a rule, we make sure to only apply
rewrites from rules that are active throughout the original rule's
range of active phases.

For example, if a rule is always active, we only fire rules that are
themselves always active when simplifying the RHS. Ditto for inline
activations.

This is achieved by setting the simplifier phase to a range of phases,
using the new SimplPhaseRange constructor. Then:

  1. When simplifying the RHS of a rule, or of a stable unfolding,
     we set the simplifier phase to a range of phases, computed from
     the activation of the RULE/unfolding activation, using the
     function 'phaseFromActivation'.

     The details are explained in Note [What is active in the RHS of a RULE?]
     in GHC.Core.Opt.Simplify.Utils.

  2. The activation check for other rules and inlinings is then:
     does the activation of the other rule/inlining cover the whole
     phase range set in sm_phase? This continues to use the 'isActive'
     function, which now accounts for phase ranges.

On the way, this commit also moves the exact-print SourceText annotation
from the Activation datatype to the ActivationAnn type. This keeps the
main Activation datatype free of any extra cruft.

Fixes #26323

79816cc4