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Rodrigo Mesquita pushed to branch wip/romes/25636 at Glasgow Haskell Compiler / GHC

Commits:

55eab80d

by Sylvain Henry at 2025-11-20T17:33:13-05:00

Build external interpreter program on demand (#24731)

This patch teaches GHC how to build the external interpreter program
when it is missing. As long as we have the `ghci` library, doing this is
trivial so most of this patch is refactoring for doing it sanely.

08bbc028

by Rodrigo Mesquita at 2025-11-20T17:33:54-05:00

Add tests for #23973 and #26565

These were fixed by 4af4f0f070f83f948e49ad5d7835fd91b8d3f0e6 in !10417

6b42232c

by sheaf at 2025-11-20T17:34:35-05:00

Mark T26410_ffi as fragile on Windows

As seen in #26595, this test intermittently fails on Windows.
This commit marks it as fragile, until we get around to fixing it.

b7b7c049

by Andrew Lelechenko at 2025-11-21T21:04:01+00:00

Add nubOrd / nubOrdBy to Data.List and Data.List.NonEmpty

As per https://github.com/haskell/core-libraries-committee/issues/336

352d5462

by Marc Scholten at 2025-11-22T10:33:03-05:00

Fix haddock test runner to handle UTF-8 output

xhtml 3000.4.0.0 now produces UTF-8 output instead of escaping non-ASCII characters.

When using --test-accept it previously wrote files in the wrong encoding
because they have not been decoded properly when reading the files.

48a3ed57

by Simon Peyton Jones at 2025-11-25T15:33:54+00:00

Add a fast-path for args=[] to occAnalApp

In the common case of having not arguments, occAnalApp
was doing redundant work.

951e5ed9

by Simon Peyton Jones at 2025-11-25T15:33:54+00:00

Fix a performance hole in the occurrence analyser

As #26425 showed, the clever stuff in

   Note [Occurrence analysis for join points]

does a lot of duplication of usage details.  This patch
improved matters with a little fancy footwork.  It is
described in the new (W4) of the same Note.

Compile-time allocations go down slightly. Here are the changes
of +/- 0.5% or more:

    T13253(normal)    329,369,244    326,395,544  -0.9%
T13253-spj(normal)     66,410,496     66,095,864  -0.5%
    T15630(normal)    129,797,200    128,663,136  -0.9%
   T15630a(normal)    129,212,408    128,027,560  -0.9%
    T16577(normal)  6,756,706,896  6,723,028,512  -0.5%
    T18282(normal)    128,462,070    125,808,584  -2.1% GOOD
   T18698a(normal)    208,418,305    202,037,336  -3.1% GOOD
    T18730(optasm)    136,981,756    136,208,136  -0.6%
    T18923(normal)     58,103,088     57,745,840  -0.6%
    T19695(normal)  1,386,306,272  1,365,609,416  -1.5%
    T26425(normal)  3,344,402,957  2,457,811,664 -26.5% GOOD
     T6048(optasm)     79,763,816     79,212,760  -0.7%
     T9020(optasm)    225,278,408    223,682,440  -0.7%
     T9961(normal)    303,810,717    300,729,168  -1.0% GOOD

         geo. mean                                -0.5%
         minimum                                 -26.5%
         maximum                                  +0.4%

Metric Decrease:
    T18282
    T18698a
    T26425
    T9961

f1959dfc

by Simon Peyton Jones at 2025-11-26T11:58:07+00:00

Remove a quadratic-cost assertion check in mkCoreApp

See the new Note [Assertion checking in mkCoreApp]

98fa0d36

by Simon Hengel at 2025-11-27T17:54:57-05:00

Fix typo in docs/users_guide/exts/type_families.rst

5b97e5ce
by Simon Hengel at 2025-11-27T17:55:37-05:00
```
Fix broken RankNTypes example in user's guide
```

fa2aaa00

by Simon Peyton Jones at 2025-11-27T17:56:18-05:00

Switch off specialisation in ExactPrint

In !15057 (where we re-introduced -fpolymoprhic-specialisation) we found
that ExactPrint's compile time blew up by a factor of 5.  It turned out
to be caused by bazillions of specialisations of `markAnnotated`.

Since ExactPrint isn't perf-critical, it does not seem worth taking
the performance hit, so this patch switches off specialisation in
this one module.

1fd25987

by Simon Peyton Jones at 2025-11-27T17:56:18-05:00

Switch -fpolymorphic-specialisation on by default

This patch addresses #23559.

Now that !10479 has landed and #26329 is fixed, we can switch on
polymorphic specialisation by default, addressing a bunch of other
tickets listed in #23559.

Metric changes:
  * CoOpt_Singleton: +4% compiler allocations: we just get more
    specialisations

  * info_table_map_perf: -20% decrease in compiler allocations.
    This is caused by using -fno-specialise in ExactPrint.hs
    Without that change we get a 4x blow-up in compile time;
    see !15058 for details

Metric Decrease:
    info_table_map_perf
Metric Increase:
    CoOpt_Singletons

b7fe7445

by Matthew Pickering at 2025-11-27T17:56:59-05:00

rts: Fix a deadlock with eventlog flush interval and RTS shutdown

The ghc_ticker thread attempts to flush at the eventlog tick interval, this requires
waiting to take all capabilities.

At the same time, the main thread is shutting down, the schedule is
stopped and then we wait for the ticker thread to finish.

Therefore we are deadlocked.

The solution is to use `newBoundTask/exitMyTask`, so that flushing can
cooperate with the scheduler shutdown.

Fixes #26573

1d4a1229

by sheaf at 2025-11-27T17:58:02-05:00

SimpleOpt: don't subst in pushCoercionIntoLambda

It was noticed in #26589 that the change in 15b311be was incorrect:
the simple optimiser carries two different substitution-like pieces of
information: 'soe_subst' (from InVar to OutExpr) and 'soe_inl'
(from InId to InExpr). It is thus incorrect to have 'pushCoercionIntoLambda'
apply the substitution from 'soe_subst' while discarding 'soe_inl'
entirely, which is what was done in 15b311be.

Instead, we change back pushCoercionIntoLambda to take an InScopeSet,
and optimise the lambda before calling 'pushCoercionIntoLambda' to avoid
mixing InExpr with OutExpr, or mixing two InExpr with different
environments. We can then call 'soeZapSubst' without problems.

Fixes #26588 #26589

84a087d5

by Sylvain Henry at 2025-11-28T17:35:28-05:00

Fix PIC jump tables on Windows (#24016)

Avoid overflows in jump tables by using a base label closer to the jump
targets. See added Note [Jump tables]

82db7042

by Zubin Duggal at 2025-11-28T17:36:10-05:00

rts/linker/PEi386: Copy strings before they are inserted into LoadedDllCache. The original strings are temporary and might be freed at an arbitrary point.

Fixes #26613

ff3f0d09

by Ben Gamari at 2025-11-29T18:34:28-05:00

gitlab-ci: Run ghcup-metadata jobs on OpenCape runners

This significantly reduces our egress traffic
and makes the jobs significantly faster.

ef0dc33b

by Matthew Pickering at 2025-11-29T18:35:10-05:00

Use 'OsPath' in getModificationTimeIfExists

This part of the compiler is quite hot during recompilation checking in
particular since the filepaths will be translated to a string. It is
better to use the 'OsPath' native function, which turns out to be easy
to do.

fa3bd0a6
by Georgios Karachalias at 2025-11-29T18:36:05-05:00
```
Use OsPath in PkgDbRef and UnitDatabase, not FilePath
```

0d7c05ec

by Ben Gamari at 2025-12-01T03:13:46-05:00

hadrian: Place user options after package arguments

This makes it easier for the user to override the default package
arguments with `UserSettings.hs`.

Fixes #25821.

-------------------------
Metric Decrease:
    T14697
-------------------------

3b2c4598

by Vladislav Zavialov at 2025-12-01T03:14:29-05:00

Namespace-specified wildcards in import/export lists (#25901)

This change adds support for top-level namespace-specified wildcards
`type ..` and `data ..` to import and export lists.

Examples:
  import M (type ..) -- imports all type and class constructors from M
  import M (data ..) -- imports all data constructors and terms from M
  module M (type .., f) where
    -- exports all type and class constructors defined in M,
    -- plus the function 'f'

The primary intended usage of this feature is in combination with module
aliases, allowing namespace disambiguation:
  import Data.Proxy as T (type ..)  -- T.Proxy is unambiguously the type constructor
  import Data.Proxy as D (data ..)  -- D.Proxy is unambiguously the data constructor

The patch accounts for the interactions of wildcards with:
* Imports with `hiding` clauses
* Import warnings -Wunused-imports, -Wdodgy-imports
* Export warnings -Wduplicate-exports, -Wdodgy-exports

Summary of the changes:

1. Move the NamespaceSpecifier type from GHC.Hs.Binds to GHC.Hs.Basic,
   making it possible to use it in more places in the AST.

2. Extend the AST (type: IE) with a representation of `..`, `type ..`,
   and `data ..` (constructor: IEWholeNamespace). Per the proposal, the
   plain `..` is always rejected with a dedicated error message.

3. Extend the grammar in Parser.y with productions for `..`, `type ..`,
   and `data ..` in both import and export lists.

4. Implement wildcard imports by updating the `filterImports` function
   in GHC.Rename.Names; the logic for IEWholeNamespace is roughly
   modeled after the Nothing (no explicit import list) case.

5. Implement wildcard exports by updating the `exports_from_avail`
   function in GHC.Tc.Gen.Export; the logic for IEWholeNamespace is
   closely modeled after the IEModuleContents case.

6. Refactor and extend diagnostics to report the new warnings and
   errors. See PsErrPlainWildcardImport, DodgyImportsWildcard,
               PsErrPlainWildcardExport, DodgyExportsWildcard,
               TcRnDupeWildcardExport.

Note that this patch is specifically about top-level import/export
items. Subordinate import/export items are left unchanged.

c71faa76

by Luite Stegeman at 2025-12-01T03:16:05-05:00

rts: Handle overflow of ELF section header string table

If the section header string table is stored in a section greater
than or equal to SHN_LORESERVE (0xff00), the 16-bit field e_shstrndx
in the ELF header does not contain the section number, but rather
an overflow value SHN_XINDEX (0xffff) indicating that we need to look
elsewhere.

This fixes the linker by not using e_shstrndx directly but calling
elf_shstrndx, which correctly handles the SHN_XINDEX value.

Fixes #26603

ab20eb54

by Mike Pilgrem at 2025-12-01T22:46:55+00:00

Re CLC issue 292 Warn GHC.Internal.List.{init,last} are partial

Also corrects the warning for `tail` to refer to `Data.List.uncons` (like the existing warning for `head`).

In module `Settings.Warnings`, applies `-Wno-x-partial` to the `filepath`, and `parsec` packages (outside GHC's repository).

Also bumps submodules.

fc1d7f79

by Jade Lovelace at 2025-12-02T11:04:09-05:00

docs: fix StandaloneKindSignatures in DataKinds docs

These should be `type` as otherwise GHC reports a duplicate definition
error.

beae879b

by Rodrigo Mesquita at 2025-12-03T15:42:37+01:00

task: Substitute some datatypes for newtypes

* Substitutes some data type declarations for newtype declarations
* Adds comment to `LlvmConfigCache`, which must decidedly not be a
  newtype.

Fixes #23555

3bd7dd44

by mangoiv at 2025-12-04T04:36:45-05:00

Renamer: reinstate the template haskell level check in notFound

Out-of-scope names might be caused by a staging error, as is explained by
Note [Out of scope might be a staging error] in GHC.Tc.Utils.Env.hs.
This logic was assumed to be dead code after 217caad1 and has thus been
removed. This commit reintroduces it and thus fixes issue #26099.

0318010b

by Zubin Duggal at 2025-12-04T04:37:27-05:00

testlib: Optionally include the way name in the expected output file

This allows us to have different outputs for different ways.

6d945fdd

by Zubin Duggal at 2025-12-04T04:37:27-05:00

testsuite: Accept output of tests failing in ext-interp way due to differing compilation requirements

Fixes #26552

0ffc5243

by Cheng Shao at 2025-12-04T04:38:09-05:00

devx: minor fixes for compile_flags.txt

This patch includes minor fixes for compile_flags.txt to improve
developer experience when using clangd as language server to hack on
RTS C sources:

- Ensure `-fPIC` is passed and `__PIC__` is defined, to be coherent
  with `-DDYNAMIC` and ensure the `__PIC__` guarded code paths are
  indexed
- Add the missing `-DRtsWay` definition, otherwise a few source files
  like `RtsUtils.c` and `Trace.c` would produce clangd errors

e36a5fcb

by Matthew Pickering at 2025-12-05T16:25:57-05:00

Add support for building bytecode libraries

A bytecode library is a collection of bytecode files (.gbc) and a
library which combines together additional object files.

A bytecode library is created by invoking GHC with the `-bytecodelib`
flag.

A library can be created from in-memory `ModuleByteCode` linkables or
by passing `.gbc` files as arguments on the command line.

Fixes #26298

8f9ae339

by Matthew Pickering at 2025-12-05T16:25:57-05:00

Load bytecode libraries to satisfy package dependencies

This commit allows you to use a bytecode library to satisfy a package
dependency when using the interpreter.

If a user enables `-fprefer-byte-code`, then if a package provides a
bytecode library, that will be loaded and used to satisfy the
dependency.

The main change is to separate the relevant parts of the `LoaderState`
into external and home package byte code. Bytecode is loaded into either
the home package or external part (similar to HPT/EPS split), HPT
bytecode can be unloaded. External bytecode is never unloaded.

The unload function has also only been called with an empty list of
"stable linkables" for a long time. It has been modified to directly
implement a complete unloading of the home package bytecode linkables.

At the moment, the bytecode libraries are found in the "library-dirs"
field from the package description. In the future when `Cabal`
implements support for "bytecode-library-dirs" field, we can read the
bytecode libraries from there. No changes to the Cabal submodule are
necessary at the moment.

Four new tests are added in testsuite/tests/cabal, which generate fake
package descriptions and test loading the libraries into GHCi.

Fixes #26298

54458ce4

by mangoiv at 2025-12-05T16:26:50-05:00

ExplicitLevelImports: improve documentation of the code

- more explicit names for variable names like `flg` or `topLevel`
- don't pass the same value twice to functions
- some explanations of interesting but undocumented code paths
- adjust comment to not mention non-existent error message

c7061392

by mangoiv at 2025-12-05T16:27:42-05:00

driver: don't expect nodes to exist when checking paths between them

In `mgQueryZero`, previously node lookups were expected to never fail,
i.e. it was expected that when calculating the path between two nodes in
a zero level import graph, both nodes would always exist. This is not
the case, e.g. in some situations involving exact names (see the
test-case). The fix is to first check whether the node is present in the
graph at all, instead of panicking, just to report that there is no
path.

Closes #26568

d6cf8463

by Peng Fan at 2025-12-06T11:06:28-05:00

NCG/LA64: Simplify genCCall into two parts

genCCall is too long, so it's been simplified into two parts:
genPrim and genLibCCall.

Suggested by Andreas Klebinger

9d371d23

by Matthew Pickering at 2025-12-06T11:07:09-05:00

hadrian: Use a response file to invoke GHC for dep gathering.

In some cases we construct an argument list too long for GHC to
handle directly on windows. This happens when we generate
the dependency file because the command line will contain
references to a large number of .hs files.

To avoid this we now invoke GHC using a response file when
generating dependencies to sidestep length limitations.

Note that we only pass the actual file names in the dependency
file. Why? Because this side-steps #26560

0043bfb0

by Marc Scholten at 2025-12-06T11:08:03-05:00

update xhtml to 3000.4.0.0

haddock-api: bump xhtml bounds

haddock-api: use lazy text instead of string to support xhtml 3000.4.0.0

Bumping submodule xhtml to 3000.4.0.0

add xhtml to stage0Packages

remove unused import of writeUtf8File

Remove redundant import

Update haddock golden files for xhtml 3000.4.0.0

Metric Decrease:
    haddock.Cabal
    haddock.base

fc958fc9

by Julian Ospald at 2025-12-06T11:08:53-05:00

rts: Fix object file format detection in loadArchive

Commit 76d1041dfa4b96108cfdd22b07f2b3feb424dcbe seems to
have introduced this bug, ultimately leading to failure of
test T11788. I can only theorize that this test isn't run
in upstream's CI, because they don't build a static GHC.

The culprit is that we go through the thin archive, trying
to follow the members on the filesystem, but don't
re-identify the new object format of the member. This pins
`object_fmt` to `NotObject` from the thin archive.

Thanks to @angerman for spotting this.

0f297f6e

by mangoiv at 2025-12-06T11:09:44-05:00

users' guide: don't use f strings in the python script to ensure compatibility with python 3.5

3bfe7aa2

by Matthew Pickering at 2025-12-07T12:18:57-05:00

ci: Try using multi repl in ghc-in-ghci test

This should be quite a bit faster than the ./hadrian/ghci command as it
doesn't properly build all the dependencies.

2ef1601a

by Rodrigo Mesquita at 2025-12-07T12:19:38-05:00

Stack.Decode: Don't error on bitmap size 0

A RET_BCO may have a bitmap with no payload.
In that case, the bitmap = 0.

One can observe this by using -ddump-bcos and interpreting

```
main = pure ()
```

Observe, for instance, that the BCO for this main function has size 0:

```
ProtoBCO Main.main#0:
   \u []
       break<main:Main,0>() GHC.Internal.Base.pure
                                GHC.Internal.Base.$fApplicativeIO GHC.Internal.Tuple.()
   bitmap:  0 []
   BRK_FUN <breakarray> main:Main 0 <cc>
   PACK     () 0
   PUSH_G   GHC.Internal.Base.$fApplicativeIO
   PUSH_APPLY_PP
   PUSH_G   GHC.Internal.Base.pure
   ENTER
```

Perhaps we never tried to decode a stack in which a BCO like this was
present. However, for the debugger, we want to decode stacks of threads
stopped at breakpoints, and these kind of BCOs do get on a stack under
e.g. `stg_apply_interp_info` frames.

See the accompanying test in the next commit for an example to trigger
the bug this commit fixes.

Fixes #26640

747153d2
by Rodrigo Mesquita at 2025-12-07T12:19:38-05:00
```
Add test for #26640
```
d4b1e353
by Simon Hengel at 2025-12-10T00:00:02-05:00
```
Fix syntax error in gadt_syntax.rst
```

91cc8be6

by Cheng Shao at 2025-12-10T00:00:43-05:00

ci: fix "ci.sh clean" to address frequent out of space error on windows runners

This patch fixes the `ci.sh clean` logic to address frequent out of
space error on windows runners; previously it didn't clean up the
inplace mingw blobs, which is the largest source of space leak on
windows runners. See added comment for detailed explanation.

fe2b79f4

by Recursion Ninja at 2025-12-10T08:34:18-05:00

Narrow before optimising MUL/DIV/REM into shifts

The MUL/DIV/REM operations can be optimised into shifts when one of the
operands is a constant power of 2. However, as literals in Cmm are
stored as 'Integer', for this to be correct we first need to narrow the
literal to the appropriate width before checking whether the literal is
a power of 2.

Fixes #25664

06c2349c

by Recursion Ninja at 2025-12-10T08:34:58-05:00

Decouple 'Language.Haskell.Syntax.Type' from 'GHC.Utils.Panic'

  - Remove the *original* defintion of 'hsQTvExplicit' defined within 'Language.Haskell.Syntax.Type'

  - Redefine 'hsQTvExplicit' as 'hsq_explicit' specialized to 'GhcPass' exported by 'GHC.Utils.Panic'

  - Define 'hsQTvExplicitBinders' as 'hsq_explicit' specialized to 'DocNameI' exported by 'Haddock.GhcUtils'.

  - Replace all call sites of the original 'hsQTvExplicit' definition with either:
    1. 'hsQTvExplicit' updated definition
    2. 'hsQTvExplicitBinders'

All call sites never entered the 'XLHsQTyVars' constructor branch, but a call to 'panic' existed on this code path because the type system was not strong enought to guarantee that the 'XLHsQTyVars' construction was impossible.
These two specialized functions provide the type system with enough information to make that guarantee, and hence the dependancy on 'panic' can be removed.

ac0815d5

by sheaf at 2025-12-10T23:39:57-05:00

Quantify arg before mult in function arrows

As noted in #23764, we expect quantification order to be left-to-right,
so that in a type such as

  a %m -> b

the inferred quantification order should be [a, m, b] and not [m, a, b].

This was addressed in commit d31fbf6c, but that commit failed to update
some other functions such as GHC.Core.TyCo.FVs.tyCoFVsOfType.

This affects Haddock, as whether we print an explicit forall or not
depends on whether the inferred quantification order matches the actual
quantification order.

2caf796e

by sheaf at 2025-12-10T23:39:57-05:00

Haddock: improvements to ty-var quantification

This commit makes several improvements to how Haddock deals with the
quantification of type variables:

  1. In pattern synonyms, Haddock used to jumble up universal and
     existential quantification. That is now fixed, fixing #26252.

     Tested in the 'PatternSyns2' haddock-html test.

  2. The logic for computing whether to use an explicit kind annotation
     for a type variable quantified in a forall was not even wrong.
     This commit improves the heuristic, but it will always remain an
     imperfect heuristic (lest we actually run kind inference again).
     In the future (#26271), we hope to avoid reliance on this heuristic.

b14bdd59

by Teo Camarasu at 2025-12-10T23:40:38-05:00

Add explicit export list to GHC.Num

Let's make clear what this module exports to allow us to easily deprecate and remove some of these in the future. Resolves https://gitlab.haskell.org/ghc/ghc/-/issues/26625

d99f8326

by Cheng Shao at 2025-12-11T19:14:18-05:00

compiler: remove unused CPP code in foreign stub

This patch removes unused CPP code in the generated foreign stub:

- `#define IN_STG_CODE 0` is not needed, since `Rts.h` already
  includes this definition
- The `if defined(__cplusplus)` code paths are not needed in the `.c`
  file, since we don't generate C++ stubs and don't include C++
  headers in our stubs. But it still needs to be present in the `.h`
  header since it might be later included into C++ source files.

46c9746f

by Cheng Shao at 2025-12-11T19:14:57-05:00

configure: bump LlvmMaxVersion to 22

This commit bumps LlvmMaxVersion to 22; 21.x releases have been
available since Aug 26th, 2025 and there's no regressions with 21.x so
far. This bump is also required for updating fedora image to 43.

96fce8d0