-
5fab2238
by Wolfgang Jeltsch at 2026-05-12T21:24:27+03:00
Introduce a cache of home module name providers
This contribution introduces to the module graph a cache that maps home
module names to sets of units providing them and changes the finder to
use that cache. This is a performance optimization, especially for
multi-home-unit builds.
The particular changes are as follows:
* In `GHC.Unit.Module.Graph`, `ModuleGraph` is extended with a new
field `mg_home_module_name_providers_map`, exposed as
`mgHomeModuleNameProvidersMap`. This is a cache that assigns to each
home module name the set of IDs of home units that define it.
Operations that construct module graphs are updated such that this
cache stays synchronized.
* In `GHC.Unit.Finder`, `findImportedModule` is changed to pull
`mgHomeModuleNameProvidersMap` from `hsc_mod_graph` and pass it to
`findImportedModuleNoHsc`, which now does not search home units in
arbitrary order but prioritizes those units that the cache mentions
as potential providers of the requested module.
In addition, this contribution adds variants of the two multi-component
compiler performance tests that use 100 units instead of 20, because
with just 20 units the benefits from caching of home module name
providers are still negligible.
The following table shows the total time needed for running both
multi-component tests before and after this contribution and with
different numbers of units:
| # of units | Before | After |
|-----------:|-------:|------:|
| 20 | 0:12 | 0:12 |
| 100 | 0:47 | 0:42 |
| 200 | 3:05 | 2:08 |
Note that there seems to be a general overhead of 12 seconds that is not
attributable to the actual tests, so that the real running times should
be 12 seconds smaller than shown above.
Resolves #27055.
Metric Decrease:
MultiComponentModules
MultiComponentModulesRecomp
Co-authored-by: Matthew Pickering <matthewtpickering@gmail.com>
Co-authored-by: Fendor <fendor@posteo.de>
-
38b76b2f
by Cheng Shao at 2026-05-13T17:48:48-04:00
testsuite: mark T22159 as fragile
This patch marks T22159 as fragile on Windows for issue described in #27248.
Before we get to the bottom of those failures, this unblocks newer
Windows runners.
-
50188615
by Ian Duncan at 2026-05-14T13:45:07+02:00
AArch64: use ASR not LSR for MO_U_Shr at W8/W16
The unsigned right shift (MO_U_Shr) for sub-word widths (W8, W16)
with a variable shift amount was emitting ASR (arithmetic/signed shift
right) after zero-extending with UXTB/UXTH. This should be LSR
(logical/unsigned shift right). After zero-extension the upper bits
happen to be 0 so ASR produces the same result, but it is semantically
wrong and would break if the zero-extension were ever optimized away.
Includes assembly output test (grep for lsr) and runtime test
verifying unsigned right shift of Word8 and Word16 values.
-
28666fbf
by Vladislav Zavialov at 2026-05-19T12:44:05-04:00
Add type families: Tuple, Constraints, Tuple#, Sum# (#27179)
These type families map tuples of types to the corresponding Tuple<N>,
Tuple<N>#, CTuple<N>, and Sum<N># types. Some examples at N=2:
Tuple (Int, Bool) = Tuple2 Int Bool
Constraints (Show a, Eq a) = CTuple2 (Show a) (Eq a)
Tuple# (Int#, Float#) = Tuple2# Int# Float#
Sum# (Int#, Float#) = Sum2# Int# Float#
See GHC Proposal #145 "Non-punning list and tuple syntax".
To make the Sum# instance at N=64 possible, this patch also introduces
the Sum64# constructor declaration and bumps mAX_SUM_SIZE from 63 to 64.
Metric Increase:
ghc_experimental_dir
-
41c2448b
by Wen Kokke at 2026-05-19T12:44:53-04:00
rts: Add IPE event class for -l
This commit adds a new IPE event class to the -l RTS flag.
Previously, IPE events were enabled unconditionally.
However, the IPE events can easily grow to hundreds or thousands of megabytes.
With the new event class you can pass, e.g., -l-I to disable IPE events.
-
62536551
by Wen Kokke at 2026-05-19T12:44:53-04:00
ghc-internal: Add TraceFlags.traceIPE
-
e45312d1
by Wen Kokke at 2026-05-19T12:44:53-04:00
testsuite: Add test for TraceFlags.traceIpe
-
4768d9aa
by Wen Kokke at 2026-05-19T12:44:53-04:00
ghc-internal: Add DebugFlags.ipe
-
bc1b5c69
by Wen Kokke at 2026-05-19T12:44:53-04:00
testsuite: Add test for DebugFlags.ipe
-
0da1543f
by Duncan Coutts at 2026-05-19T12:45:37-04:00
Document removal of the signal-based interval timer
Update mentions within the RTS section of the users guide.
Add a changelog entry.
-
b2911514
by Duncan Coutts at 2026-05-19T12:45:37-04:00
Fix section for an recent changelog entry
-
d6d76a7a
by David Eichmann at 2026-05-19T12:46:19-04:00
ghc-toolchain: implement llvm program versioning logic
-
2dd36fa3
by Wolfgang Jeltsch at 2026-05-20T04:49:52-04:00
Turn `Trustworthy` into `Safe` in `base` where possible
-
f4399dd1
by Wolfgang Jeltsch at 2026-05-20T04:50:37-04:00
Make the current `base` buildable with GHC 10.0
-
1a7de232
by Duncan Coutts at 2026-05-20T12:26:25-04:00
Hadrian: remove legacy rts .so symlinks
For compatibility with the old makefile based build system, hadrian had
rules to generate symlinks from unversioned to versioned names for the
rts .so/.dynlib file, like libHSrts-ghcx.y.so -> libHSrts-1.0.3-ghcx.y.so
We no longer need these symlinks since the makefile build system has
been retired some time ago. The need for these symlinks is awkward on
windows where we cannot (in practice) create symlinks. So rather than
make them conditional (non-windows), just remove them entirely.
-
286f1adf
by fendor at 2026-05-20T12:27:09-04:00
Fix regression T27202: `:load` and `:add` work in GHCi
To fix the regression there are conceptually two major things that we
fix:
* We don't remove the `importDirs` from `interactive-session`
* When `:add`ing a module, we don't try to find them via PackageImports
* The PackageImport is wrong as we can't know the package-name at
this stage in ghc/UI.hs
What does it mean to not remove the `importDirs` from
`interactive-session`?
It means that, given some initial `DynFlags`, we will use those
`importDirs` in `interactive-session`.
The initial `DynFlags`, however, depend on how you initialise the GHC
session.
For a simple session, initialised by
ghc -isrc -this-unit-id main
It is simple, just use the `DynFlags` given on the cli.
Thus, `main` and `interactive-session` will have the same `DynFlags`,
except for the `homeUnitId` and `interactive-session` depends on `main`
by construction of the GHCi session.
What about a multiple home unit session, though?
ghc -unit @unit1 -unit @unit2
What are the `DynFlags` in this cli invocation? It shouldn't be either
`@unti1` nor `@unit2`, as the order shouldn't matter or any other
implicit condition.
For consistency, we decide that the initial `DynFlags` are the top
`DynFlags` on the cli, ignoring `-unit` flags.
Thus, in this example, there are no `importsDirs` regardless of what we
might find in `@unit1` and `@unit2`.
But in this invocation:
ghc -isrc -unit @unit1 -unit @unit2
The `interactive-session` will have the `importsDirs` `src`.
Note, `-isrc` will be inherited in `@unit1` and `@unit2`, so you need to
explicitly use `-i` to clear the `importsDirs`, in order to avoid
accidentally adding `src` as an import directory to all other home
units.
This fix has been made possible by the improvements introduced in
!15888, which avoids ambiguity when a home unit shares the `importsDirs`
with the `interactive-session`, on top of being much faster for multiple
home units.
Adds regression tests for T27202 for `:load`ing and `:add`ing modules
that are located in import directories.
-
728662de
by fendor at 2026-05-20T12:27:09-04:00
Use home unit package db stacks in GHCi prompt and session unit
In order to import modules from home unit dependencies (e.g., `Data.Map`),
the ghci prompt unit needs to populate its `UnitState`.
This is tricky to handle correctly, which `PackageDBFlag`s should we use
to populate the `UnitState`?
We decide, the most intuitive solution for users is to depend on all
`PackageDBFlag`s, so that any dependency can be imported in GHCi.
This assumes consistency in the `PackageDBFlag`s, so no two home units
specify `PackageDBFlag`s that are inconsistent with each other.
We could simply concat all the `PackageDBFlag`s of the existing home
units, but later `PackageDBFlag`s shadow earlier ones, leading to the
last processed home units' `PackageDBFlag`s to shadow the earlier ones.
This is hard to fix, we need to give users the capability to provide ghc
options for the ghci prompt home unit.
However, as this is considerably more work, we decided on an
approximation that should work out most of the time.
Package Db stacks in cabal and stack follow a certain structure:
-no-user-package-db > -package-db $cabal-store > -package-db $local-db
The first two arguments are always the same, namely the
`-no-user-package-db` and `-package-db`.
We compute the longest common prefix over all home units, and use that
as the start of the package db stack. Then, over the rest of the
`PackageDBFlag`s, we simply take the union and append them to our
initial stack.
We assume, that the rest of package dbs only defines very few, "local"
units that are usually not shadowing each other.
This allows us to get a relatively consistent package database stack for
the ghci prompt home unit.
Similar reasoning applies to the session unit in order to add modules to
the session and have dependencies available in the module.
We do something similar for `-package` flags, to make sure only the
correct units are actually visible in the ghci session.
This time, we simply take the union of all `PackageFlag`s, allowing us
to import modules from the home unit dependencies.
In the future, it would be beneficial to allow the user to provide the
exact ghc options to control the visibilities. For now, this will have
to do.
-
740d89a0
by Simon Peyton Jones at 2026-05-20T17:20:44-04:00
Do not use mkCast during typechecking
This commit fixes #27219. The problem was that the typechecker was using
`mkCast`, whose assertion checks legitimately fail when applied to types
that contain unification variables.
-
a50fdb06
by Simon Peyton Jones at 2026-05-20T17:20:45-04:00
Major refactor of the Simplifier
The main payload of this patch is to refactor the Simplifer to avoid
repeated simplification when using Plan (AFTER) for rule rewrites.
The need for this was shown up by #26989.
See Note [Avoid repeated simplification] in GHC.Core.Opt.Simplify.Iteration.
Related refactoring:
* Refactor the two fields `sc_dup` and `sc_env` in `ApplyToVal` into one, `sc_env`.
Reason: the envt is irrelevant in the "simplified" case, so the data type describes
the possiblitiies much more accurately now.
* Some refactoring in `knownCon` to split off `wrapDataConFloats`.
* Refactor `lookupRule` and its auxiliary functions to return `RuleMatch`,
a new data type. See Note [data RuleMatch] in GHC.Core. Ditto for BuiltinRule.
This RuleMatch returns fragments of the target in rm_args and rm_floats,
leaving `rm_rhs` to be the stuff from the RULE itself.
Doing this has routine consequences in GHC.Core.Opt.ConstantFold. Many changes
there but all routine.
* When doing occurrence analysis on RULEs, make the occ-info on the rule
binders relate just to the RHS, not the LHS. See (OUR1) in
Note Note [OccInfo in unfoldings and rules]
This means that Lint must not complain about the fact that the patterns
in the RULE mentions binders that are marked dead.
See Note [Dead occurrences] in GHC.Core.Lint.
I changed the Core pretty-printer so that it didn't suppress dead binders,
else I can't see those binders in RULEs. That led to quite a lot of testsuite wibbles.
* Refactor FloatBinds, so that it is used both by
`exprIsConApp_mabye` and by `lookupRule`
* Move the definition of FloatBinds out of GHc.Core.Make, into GHC.Core.
* Add FloatTick as an extra constructor.
* Refactor `lookupRule` to use `FloatBinds` instead of `BindWrapper`.
This refactor just shares more code.
(Rename GHC.Core.Opt.FloatOut.FloatBinds to FloatLets, to avoid gratuitious
name clash with GHC.Core.FloatBinds.)
Corecion optimisation
* In simpleOpt, when composing coercions, call new function `optTransCo`.
This is much lighter weight than full blown coercion optimisation.
* Make `GHC.Core.Opt.Arity.pushCoValArg` and `pushCoTyArg` return the
coercionLKind of the coercion. This saves recomputing that coercionLKind
at the key call sites in GHC.Core.Opt.Simplify.Iteration.pushCast.
* Rename `addCoerce` in GHC.Core.Simplify.Iteration to become `pushCast`.
* In the `ApplyToVal` case of `pushCast` we had a very unsavoury call to `simplArg`.
I eliminated it by adding a field `sc_cast` to `ApplyToVal` that records any
pending casts. Much nicer now. See Note [The sc_cast field of ApplyToVal].
* Don't optimise coercions if the type-substitution is empty.
See Note [Optimising coercions] in GHC.Core.Opt.Simplify.Iteration.
The fix for #26838 is dramatic. For the test in perf/compiler/T26839 we have
Compiler allocs: Before: 7,363M
After: 688M
Compile time goes down generally. Here are compiler-alloc changes
over 0.5%:
CoOpt_Read(normal) 729,184,920 -0.7%
CoOpt_Singletons(normal) 666,916,960 -4.6% GOOD
LargeRecord(normal) 1,227,056,876 +1.1%
T12227(normal) 256,827,604 -4.6% GOOD
T12425(optasm) 76,879,410 -0.8%
T12545(normal) 787,826,918 -10.8% GOOD
T12707(normal) 775,186,464 -0.9%
T13253(normal) 318,599,596 -0.8%
T14766(normal) 685,857,320 -1.0%
T15304(normal) 1,123,333,422 -2.2%
T15630(normal) 123,142,330 -2.6%
T15630a(normal) 123,092,100 -2.6%
T15703(normal) 299,751,682 -2.9% GOOD
T17516(normal) 964,072,280 +1.0%
T18223(normal) 367,016,820 -6.2% GOOD
T18730(optasm) 130,643,770 -3.3% GOOD
T20261(normal) 535,608,584 -0.7%
T21839c(normal) 340,340,436 -0.9%
T24984(normal) 85,568,392 -1.9%
T3064(normal) 174,631,992 -1.2%
T3294(normal) 1,215,886,432 -0.7%
T5030(normal) 141,449,704 -17.2% GOOD
T5321Fun(normal) 258,484,744 -1.9%
T8095(normal) 770,532,232 -2.7%
T9630(normal) 858,423,408 -14.5% GOOD
T9872c(normal) 1,591,709,448 +0.7%
info_table_map_perf(normal) 19,700,614,458 -1.3%
geo. mean -0.7%
minimum -17.2%
maximum +1.1%
However, strangely there seems to be a 5.0% increase in CoOpt_Read in
the x86_64-linux-fedora43-validate+debug_info+ubsan job, although
there generally a /decrease/ in this test in other builds. The baseline
value looks strange. Anyway I'll just accept it.
Metric Decrease:
CoOpt_Singletons
T12227
T12545
T12707
T15703
T18223
T18730
T21839c
T5030
T9630
Metric Increase:
CoOpt_Read
-
834623d4
by Mrjtjmn at 2026-05-20T17:21:41-04:00
users-guide: Fix weird notation in "Summary of stolen syntax"
-
6f9d7c71
by Markus Läll at 2026-05-21T15:25:34-04:00
Use "grimily" instead of "grimly"
Fixes https://gitlab.haskell.org/ghc/ghc/-/issues/27221
-
50e999ca
by fendor at 2026-05-21T15:26:18-04:00
Speed up 'closure' computation in `ghc-pkg`
Cache the set of already seen `UnitId`s and use `Set` operations to
speed up 'closure' computation.
Further simplify the implementation of 'closure' to account for the
actual usage.
As a consequence, we rename 'closure' to 'brokenPackages' to reflect its
purpose better after the simplification.
-
7ecc6184
by sheaf at 2026-05-21T15:27:10-04:00
TcMPluginHandling: be more lenient when no plugins
This change ensures that, if a function such as 'typecheckModule' was
invoked with 'NoTcMPlugins', GHC doesn't spuriously complain about TcM
plugins having already been stopped, as there were none to start with.
-
72c8de5c
by Simon Jakobi at 2026-05-23T18:41:42-04:00
Implement List.elem via foldr
...in order to allow specialization to Eq instances.
The implementation of notElem is updated for consistency.`
Corresponding CLC proposal:
https://github.com/haskell/core-libraries-committee/issues/412
Addresses #27096.
-
3268c610
by Alan Zimmerman at 2026-05-23T18:42:30-04:00
EPA: Fix span for qualified multiline string
Fix the span for a qualified multiline string like
Text."""
I'm a multiline
Text value
!
"""
to extend to the end of the entire string, not just the first line.
Closes #27274
-
1f096790
by Alan Zimmerman at 2026-05-23T18:43:20-04:00
EPA: Fix exact printing namespace-specified wildcards
Ensures correct printing of imports of the form
import Data.Bool (data True(data ..))
import Data.Bool (data True(type ..))
Closes #27291
-
56ada7c0
by Mrjtjmn at 2026-05-23T18:44:19-04:00
Fix ambiguous syntax of BangPatterns in users guide
Update documentation for the BangPatterns extension to specify
how surrounding whitespace affects interpretation of `!`.
* Only when there is whitespace before `!` and no whitespace after,
it is recognized as a BangPattern.
* Other cases `⟨varid⟩!⟨varid⟩`, `⟨varid⟩ ! ⟨varid⟩`, `⟨varid⟩! ⟨varid⟩`
are treated as infix operators.
-
579aa0b7
by Simon Jakobi at 2026-05-25T16:31:26-04:00
Ensure that SetOps.{minusList,unionListsOrd} can be specialized
...by marking them INLINABLE. Haddock allocates 0.1–0.3% less as a
result.
This also removes some redundant constraints on unionListsOrd.
-
cccf45da
by Cheng Shao at 2026-05-25T16:32:13-04:00
wasm: ensure post-linker output is synchronous ESM
This patch fixes wasm backend's post-linker output script to ensure
it's synchronous ESM and doesn't use top-level await, which doesn't
work in ServiceWorkers. Fixes #27257.
-
8db331a3
by Zubin Duggal at 2026-05-26T04:54:03-04:00
Update to semaphore-compat 2.0.0 using v2 of the protocol
On Linux and other POSIX platforms, GHC's -jsem jobserver client now
speaks v2 of the semaphore-compat protocol, which uses Unix domain
sockets in place of POSIX named semaphores. This avoids the libc-ABI
issues that affected the old implementation. Windows is unaffected
and continues to use the v1 protocol (Win32 named semaphores); its
reported protocol version remains v1.
When GHC receives a -jsem name whose protocol version it does not
support, it emits a -Wsemaphore-version-mismatch warning and falls
back to -j<N> rather than crashing. ghc --info exposes the supported
version in a new "Semaphore version" entry so cabal-install can detect
a mismatch before invoking GHC.
Users on a cabal-install that predates the v2 update will continue to
build successfully on Linux/POSIX, but will lose the cross-process
-jsem coordination and fall back to -j<N> per GHC invocation. Users
must upgrade to a cabal-install that supports protocol v2 to recover
full parallelism.
Also fix a leak in cleanupSem (#27253): cleanupSem used to snapshot
heldTokens and release them before killing the loop, while the loop's
in-flight acquire/release children could still be mutating it.
Cleanup now runs inside the loop's own exit handler, after draining
the active child via a new activeChild TVar, so the snapshot has no
concurrent mutator.
See also:
- GHC proposal amendment: https://github.com/ghc-proposals/ghc-proposals/pull/673
- cabal-install patch: https://github.com/haskell/cabal/pull/11628
- semaphore-compat MR: https://gitlab.haskell.org/ghc/semaphore-compat/-/merge_requests/8
Bump semaphore-compat submodule to 2.0.0
Fixes #25087 and #27253
-
17be4f1f
by Alan Zimmerman at 2026-05-26T04:54:52-04:00
EPA: Record semicolons in HsModifier
Ensure the semi colons are captured in the ParsedSource for code like
%True;; %False;
instance C D
It makes HsModifier (and hence HsModifierOf) LocatedA, so the semi
colons can be recorded as [TrailingAnn]
Also rename pprHsModifiers to pprLHsModifiers to match.
Closes #27294
-
8f991755
by fendor at 2026-05-26T11:02:52-04:00
Revert prog003 acceptance
We thought the commit 286f1adff3e78d775ff325caff71d0cee25d710b fixed the
test, but due to changes to ghci, modules loaded during the GHCi
session, the test was actually no longer testing what it set out to do,
"fixing" the broken test.
As modules are added to the `interactive-session` home unit, the object code needs
to be compiled with `-this-unit-id interactive-session`, otherwise the
object code won't be used.
Once this has been fixed in the test, the test fails as expected again.
-
277a3687
by mangoiv at 2026-05-26T11:03:40-04:00
libraries/process: bump submodule to v1.6.29.0
This submodule bump resolves a segfault on macos 15.
Fixes #27144
-
6779bb0c
by mangoiv at 2026-05-26T11:03:40-04:00
libraries/unix: in submodule, don't pick branch 2.7
The 2.7 branch is outdated and the module has been advanced far beyond
it anyway, so remove that line.
-
4a645683
by Simon Peyton Jones at 2026-05-27T21:41:59-04:00
Trim the continuation in mkDupableContWithDmds
When there are no remaining argument demands, it means the application
is bottoming. In this case, we can trim the continuation to avoid the
panic that was observed in #27261.
See Note [Trimming the continuation for bottoming functions] in
GHC.Core.Opt.Simplify.Iteration.
-
8ab506ff
by Cheng Shao at 2026-05-27T21:42:47-04:00
ghci: fix module name string lifetime in hs_hpc_module invocation
This patch makes hpcAddModule pass a properly malloced module name
string to hs_hpc_module, instead of using useAsCString which causes
use-after-free of module name string. Fixes #27297.
Co-authored-by: Codex <codex@openai.com>
-
b0233814
by sheaf at 2026-05-27T21:43:31-04:00
Relax acceptance threshold for T10421
As seen in #27289, the 1% acceptance threshold for this text was
overly narrow, resulting in spurious test failures. This commit widens
the acceptance threshold to 2%. Fixes #27289.
-
63ce5770
by Luite Stegeman at 2026-05-28T12:23:35-04:00
Fixes for black holes
- suspend duplicate work for eager black holes
- detect eager black holes in checkBlockingQueues
- don't overwrite existing black holes even if they're not
in an eager blackhole frame
- don't deadlock on self when thunk is already blackholed
Fixes #26936
-
037a80dc
by Tom McLaughlin at 2026-05-28T12:24:36-04:00
Event/Windows.hsc: rethrow exceptions in overlapped IO
This prevents the WinIO manager from swallowing exceptions in overlapped IO. It
was added to make WinIO support possible in the `network` library. See
https://gitlab.haskell.org/ghc/ghc/-/issues/27283.
We also bump __IO_MANAGER_WINIO__ to 2 so libraries can gate on this using CPP.
-
2d53bcdb
by Wolfgang Jeltsch at 2026-05-28T12:25:21-04:00
Allow `downsweep` to use nodes of an existing module graph
To this end, `downsweep` has not been able to use the nodes of a module
graph obtained from a previous downsweeping round. In some GHC API
applications, downsweeping is performed somewhat incrementally and
therefore could profit from reusing such existing results. This
contribution makes this possible.
Resolves #27054.
Co-authored-by: Matthew Pickering <matthewtpickering@gmail.com>
-
f4fbb583
by Simon Jakobi at 2026-05-28T12:26:04-04:00
Add regression test for T11226
Closes #11226.
-
ed29a5e6
by Sven Tennie at 2026-05-28T17:30:36-04:00
Add optional config setting for LibDir (#19174)
Previously, the `libDir` was derived from `topDir`. This won't work for
inplace stage2 cross-compilers where binaries and libraries are in
different stage dirs (`_build/stage1/` for executables and
`_build/stage2` for libraries).
`LibDir` is set in the inplace `settings` files. For bindists, we
generate a new `settings` file with no `LibDir` entry. GHC then defaults
to use `topDir` as `libDir` again. This keeps the bindist relocatable.
If `LibDir` is a relative path, it is interpreted relatively to
`topDir`.
The global package db is part of the `lib/` folder. If we want to point
for inplace cross-compilers to the succeeding stage's folder, this is
done by setting `LibDir`. Thus, the global package db must be found
relative to `libDir`` (which may default to `topDir` or be set by
`LibDir`).
The complexity of settings becomes scary. So, add a test to ensure
`LibDir` works as expected.
-
8339cf8f
by Sven Tennie at 2026-05-28T17:30:36-04:00
Add Haddock to FileSettings
Helping to understand the fields' meanings without deeper analyses.
-
4ce251e4
by Sylvain Henry at 2026-05-28T17:31:39-04:00
foundation test: skip signed minBound `quot` (-1) (#27222)
`minBound `quot` (-1)` for fixed-width signed integers is platform
dependent: the mathematical result -minBound is not representable in
the type. On x86, IDIV traps; LLVM's sdiv is undefined behaviour in
this case; on AArch64/RISC-V, SDIV wraps to minBound.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
-
b8ba7e61
by Simon Jakobi at 2026-05-28T17:32:23-04:00
Prevent dictionary-passing in checkTyEqRhs
...by pre-specializing it to TcM.
Previously, wherever checkTyEqRhs was used in other modules, the
Core showed dictionary passing ($fMonadIOEnv). The added SPECIALIZE
pragma prevents this.
-
d603477f
by David Eichmann at 2026-05-29T13:17:12-04:00
Hadrian: create a ghc-internal .def file per ghc-internal dll
The .def file generated from rts/win32/libHSghc-internal.def.in contains
the name of the ghc-internal dll. The correct dll name differs based
on if the dll is inplace/final and if using the Dynamic way. Previously,
this was not accounted for and inconsistent dlls names where used. That
led to failure when loading dlls at runtime in experiments with windows
dynamic linking.
-
1fc21753
by Sylvain Henry at 2026-05-29T13:18:14-04:00
ghc-bignum: copy backend interface haddocks to Native backend (#27305)
The haddock comments documenting the BigNat backend interface (function
contracts, expected MutableWordArray# sizes, return-value semantics, etc.)
were attached to the FFI backend module. Copy them to the Native backend
so they remain in tree once the FFI backend is removed.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
-
717059df
by Sylvain Henry at 2026-05-29T13:18:14-04:00
ghc-bignum: remove FFI backend (#27305)
The FFI backend of ghc-bignum (now part of ghc-internal) had no known
users and is easy to recreate by relinking ghc-internal with a custom
backend. Remove the backend module, the bignum-ffi cabal flag, and the
ffi option from Hadrian's --bignum selector. The backend interface
documentation now lives in the Native backend module.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
-
4bb3b1d8
by Sylvain Henry at 2026-05-29T13:18:14-04:00
ghc-bignum: remove Check backend (#27305)
The Check backend of ghc-bignum (now part of ghc-internal) compared the
selected backend's output against the Native backend for validation.
It had no known users. Remove the backend module, the bignum-check
cabal flag, the bignumCheck Hadrian flavour field, and the check-
prefix in Hadrian's --bignum selector.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
-
6b3044a0
by David Eichmann at 2026-05-30T11:58:48-04:00
Add code comments to allocator code
-
f4e04210
by Matthew Pickering at 2026-05-30T11:59:34-04:00
hadrian: Refactor system-cxx-std-lib rules
I noticed a few things wrong with the hadrian rules for
`system-cxx-std-lib` rules.
* For `text` there is an ad-hoc check to depend on `system-cxx-std-lib`
outside of `configurePackage`.
* The `system-cxx-std-lib` dependency is not read from cabal files.
* Recache is not called on the packge database after the `.conf` file is
generated, a more natural place for this rule is `registerRules`.
Treating this uniformly like other packages is complicated by it not
having any source code or a cabal file. However we can do a bit better
by reporting the dependency firstly in `PackageData` and then needing
the `.conf` file in the same place as every other package in
`configurePackage`.
This commit increases the `shakeVersion`, to provide backwards
compatibility to previous builds with different PackageData.
Fixes #25303
Co-authored-by: Sven Tennie <sven.tennie@gmail.com>
-
576987d0
by Simon Jakobi at 2026-06-02T04:53:36-04:00
compiler: use nubOrd from containers
Address #27103 by replacing GHC.Utils.Misc.ordNub[On] with
Data.Containers.ListUtils.nubOrd[On].
Note that nubOrd suffers from a small inefficiency, a fix for which
will be included in the next containers release:
https://github.com/haskell/containers/issues/1202
-
deea53c3
by David Eichmann at 2026-06-02T04:54:22-04:00
Hadrian: disable response files for GHC/Haddock builders on non-Windows
This makes debugging build errors easier on non-windows hosts.
See issue #27230
-
f2f5c6ba
by Nikita Efremov at 2026-06-02T16:04:54+00:00
fix typo : compete with performance, not complete
-
5524ea0e
by Wolfgang Jeltsch at 2026-06-03T08:01:26-04:00
Make the current `base` buildable with GHC 9.14
This comprises the following changes:
* Disable some imports into `GHC.Base` for GHC 9.14
* Disable some imports into `Prelude` for GHC 9.14
* Disable separate `ArrowLoop` import for GHC 9.14
* Disable `GHC.Internal.STM` import for GHC 9.14
* Disable `GHC.Internal.Unicode.Version` import for GHC 9.14
* Disable `GHC.Internal.TH.Monad` import for GHC 9.14
* Add alternative `fixIO` import for GHC 9.14
* Add alternative `unsafeCodeCoerce` import for GHC 9.14
* Disable hiding of imported SIMD operations for GHC 9.14
* Disable use of GHC 9.14’s `printToHandleFinalizerExceptionHandler`
* Enable use of `getFileHash` from `ghc-internal` for GHC 9.14
* Make `thenA` available for GHC 9.14
* Make `thenM` available for GHC 9.14
* Disable translation of `IoManagerFlagPoll` for GHC 9.14
* Add `hGetNewlineMode` for GHC 9.14
-
d3438055
by Enrico Maria De Angelis at 2026-06-03T08:02:17-04:00
Fix #27067 - Clarify haddocks on `minusNaturalMaybe`
-
f9bcfac2
by sheaf at 2026-06-03T14:47:19-04:00
Avoid mkTick in Core Prep breaking ANF
As discovered in #27182, mkTick can break ANF. This patch introduces a
variant of mkTick that skips the single optimisation that could break
ANF. This is preferrable over switching to the raw Tick constructor,
as the latter may introduce spurious cost centres in profiling reports.
This is a temporary measure until we more thoroughly refactor how
mkTick works (see #27141).
See Note [mkTick breaks ANF] in GHC.CoreToStg.Prep.
Fixes #27182
-
cf1fd661
by Artem Pelenitsyn at 2026-06-03T14:48:09-04:00
clarify comment for getSizeofMutableByteArray#: we get the size in bytes, not "elements"
-
a3b431f3
by David Eichmann at 2026-06-04T10:10:19+00:00
Hadrian: convert env variable ACLOCAL_PATH to unix paths.
Convert ACLOCAL_PATH to a unix style path when invoking autoreconf.
Autoreconf doesn't handle windows paths.
See Note [Autoreconf unix paths from ACLOCAL_PATH].
Fixes #27311
-
18f6138a
by Simon Jakobi at 2026-06-04T20:20:31-04:00
testsuite: Deduplicate --only test names
config.only is assumed to be a set, but supplying --only overwrote it
with the (list) argparse result, which can contain duplicates. When a
test ran, config.only.remove(name) dropped only the first occurrence,
so a duplicated name lingered and was later misreported as a
"test not found" framework failure. Store it as a set instead.
Fixes #27322
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
-
2f3cc9ff
by Simon Jakobi at 2026-06-08T07:55:49-04:00
testsuite: detect fast bignum via ghc-internal, not removed ghc-bignum
The ghc-bignum package was merged into ghc-internal, so the BIGNUM_GMP
probe in test.mk ran `ghc-pkg field ghc-bignum exposed-modules`, which
fails with "cannot find package ghc-bignum". That error went to stderr
and leaked into the captured stderr of every makefile_test, causing
spurious [bad stderr] failures across the suite. The probe also silently
returned empty, so config.have_fast_bignum was wrongly False even on GMP
builds.
Probe ghc-internal's extra-libraries for the gmp library instead: the
GMP backend module is an other-module (not exposed), but GMP_LIBS adds
gmp to extra-libraries only on a GMP build, so this distinguishes the
backends. Redirect stderr to keep any future missing-package error off
the harness's stderr.
This also removes a stale comment as per suggestion from hsyl20.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
-
eb3bf6e7
by Alan Zimmerman at 2026-06-08T07:56:32-04:00
EPA: Rename Transform.anchorEof to addModuleCommentOrigDeltas
This now matches what it actually does.
-
498bb21a
by David Eichmann at 2026-06-09T18:02:39-04:00
Hadrian: avoid response files when command line is short enough
This replaces the logic of always using response files on Windows.
With the new condition based on command line lenght, reponse files
can be avoided in many more cases (on windows).
Now that response files are only used in a small number of cases,
response files are always kept and the -r / --keep-response-files
command line options have been removed
The response file paths are nolonger randomized. They are placed in the
`_build/rsp` directory. This ensures they are ignored by git and we
that Hadrian reuses response file paths when rebuilding rather than
leaving stale response files around.
Update user guide putting response files in its own section
-
87f510a5
by Simon Hengel at 2026-06-09T18:03:25-04:00
Don't use non-breaking spaces
-
41a19379
by David Eichmann at 2026-06-09T18:04:11-04:00
Hadrian: remove unused wrapper scripts from windows bindist
These wrapper scripts are only installed on non-relocatable builds
which are not generally supported on windows.
-
ce01ccb6
by sheaf at 2026-06-10T05:08:48-04:00
Don't drop ticks around variables of type `IO ()`
GHC.Core.Utils.mkTick is responsible for placing a tick on a Core
expression. It contains logic for dropping SCCs (non-counting profiling
ticks) around non-function variables, as such variables cannot
meaningfully contribute to profiles. However, the logic for what counts
as a function was incorrect: it used `isFunTy` which returns 'False' for
types such as 'IO ()' where the function arrow is hidden under a
newtype.
We now use 'mightBeFunTy' instead of 'isFunTy'. This ensures we don't
drop ticks in cases we aren't sure.
On the way, we improve the documentation of 'isFunTy', 'isPiTy' and
'mightBeFunTy', and update the latter's implementation to consistently
handle unary classes.
Fixes #27225
-------------------------
Metric Decrease:
T5642
-------------------------
-
d311c4f1
by Simon Jakobi at 2026-06-10T05:09:32-04:00
testsuite: Add regression test for #4081
Check that a strict constructor field is unboxed once outside an
enclosing loop, not re-inspected each iteration (the float-out
case-floating from 9cb20b488). Uses simonpj's `data T a = T !a` example
from the ticket; T4081.stderr captures the expected Core.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
-
333df444
by sheaf at 2026-06-10T05:10:25-04:00
Check for cabal-install >= 3.12 upfront
Starting with commit 8cb99552f607f6bc4000e45ab32532d50c8bb996, Hadrian
requires cabal-install >= 3.12 in order to use the 'cabal path' command
that was introduced in version 3.12, as per
https://github.com/haskell/cabal/blob/a51c4ee1556d816ad86e90db7e6330dd51b0b6e7/release-notes/cabal-install-3.12.1.0.md?plain=1#L45
This was not reflected in the Hadrian build script, causing a delayed
build failure instead of enforcing the version requirement upfront,
which this patch does.
Fixes #27317
-
98c20394
by sheaf at 2026-06-10T05:11:09-04:00
Fix crash in Data.Data instance for HsCtxt
The Data.Data instance for HsCtxt contained an error for the 'toConstr'
method, which could trigger for example when looking at -ddump-tc-ast
traces. Replace it with the 'abstractConstr' pattern used in the rest of
the codebase.
-
5ac9ce7d
by Zubin Duggal at 2026-06-10T21:26:32+05:30
hadrian: Remove old package.conf files when generating new ones
Old package.conf files might exists with different hashes, causing issues like #26661
Fixes #26661
-
c9015f09
by sheaf at 2026-06-11T12:40:28-04:00
Fix AArch64 clobbering bug for MUL2
On AArch64, the code generator could clobber one of the input operands
when computing the lower bits of a MUL2 operation. This rendered invalid
the subsequent computation of the high bits.
This commit fixes that by using a temporary register. The register
allocator can remove the redundant move in the common case when the
registers do not conflict.
Fixes #27046
-
7ab90288
by Rodrigo Mesquita at 2026-06-11T12:41:11-04:00
fix: make T27131 less flaky
It seems that T27131 fails flakily in a race where we check the flag
before the capability had the chance to process the mailbox which sets
the flag. This seemingly should only happen if the capability ends up
being the same for setting and checking the flag.
-
8965cb76
by Marc Scholten at 2026-06-12T04:53:22-04:00
haddock: render modules concurrently
-
8cc0b64a
by Duncan Coutts at 2026-06-12T04:54:06-04:00
Promote HAVE_PREEMPTION from Timer.c to OSThreads.h
We will want to know about HAVE_PREEMPTION in more places.
HAVE_PREEMPTION tells us that we do have OS threads available,
irrespective of whether THREADED is defined. In particular,
HAVE_PREEMPTION is defined on all proper OSs, but not on WASM (and
hyopthetically may not be true on some other platforms like
micro-controllers, RTOSs, VM hypervisors etc).
-
cce574ed
by Duncan Coutts at 2026-06-12T04:54:06-04:00
Define ACQUIRE_LOCK_ALWAYS and friends
Fix issue #27335
Like the atomic _ALWAYS variants, these lock actions are always defined,
rather than being dependent on whether we are in the THREADED case. All
the "normal" LOCK macros are defined to be no-ops when !THREADED.
The use case for the _ALWAYS variants is where we are using OS threads
even in the non-threaded RTS. This includes everything to do with the
timer/ticker thread, which is used in the non-threaded RTS too.
In particular, we will want to use this for eventlog things, because the
timer thread performs eventlogging concurrently with the main
capability, even in the non-threaded RTS.
-
1f28d1f6
by Duncan Coutts at 2026-06-12T04:54:06-04:00
Use ACQUIRE/RELEASE_LOCK_ALWAYS with eventBufMutex
Even in the non-threaded RTS the eventBufMutex is needed by both the
main capability and the timer/ticker thread, so always use the mutex.
This should fix #25165 which is about the main capability and the timer
thread posting events to the eventlog buffer concurrently and thereby
corrupting the buffer data.
-
0ff29782
by Duncan Coutts at 2026-06-12T04:54:06-04:00
Expose eventBufMutex in the EventLog interface/header
We will need it in forkProcess to ensure we don't write to the global
eventlog buffer concurrently with trying to flush eventlog buffers and
do the fork().
-
7a688395
by Duncan Coutts at 2026-06-12T04:54:07-04:00
Split flushAllCapsEventsBufs into safe and unlocked version
Following the convention that unlocked versions have a trailing _
underscore in their name. This one requires the caller to hold the
eventlog global buffer mutex. We will need this in forkProcess.
-
341ed474
by Duncan Coutts at 2026-06-12T04:54:07-04:00
Remove redundant use of stopTimer in setNumCapabilities
Historically, the comment here was:
We must stop the interval timer while we are changing the
capabilities array lest handle_tick may try to context switch
an old capability. See #17289.
and
We must disable the timer while we do this since the tick handler may
call contextSwitchAllCapabilities, which may see the capabilities array
as we free it.
What this refers to is that historically, when changing the number of
capabilities, the array of capabilities was reallocated to a new size,
allocating new ones and freeing the old ones, thus invalidating all
existing capbility pointers.
Strangely, for good measure the code used to call stopTimer twice (hence
the two similar comments above).
However, since commit a3eccf06292dd666b24606251a52da2b466a9612, the
capabilities array is no longer reallocated. Instead the array is
allcoated once on RTS startup to the maximum size it could ever be
allowed to be, and then capabilities get enabled/disabled at runtime. So
the capability pointers never become invalid anymore. At worst, they may
point to capabilities that are disabled.
Thus we no longer need to stop the timer (twice) while we change the
number of enabled capabilities. This also partially solves issue #27105,
which notes that stopTimer is being used as if it were synchronous, when
it is not. At least for this case, the solution is that stopTimer is not
needed at all!
-
674858e3
by Duncan Coutts at 2026-06-12T04:54:07-04:00
Remove redundant use of stopTimer in forkProcess
but replace it with taking the eventlog buffer lock during the fork.
Fixes issue #27105
The original reason to block the timer during a fork was that
historically the timer was implemented using a periodic timer signal,
and the signal itself would interrupt the fork system call (returning
EINTR). For large processes (where fork() takes a while) this could
permanently livelock: the timer always would go off before the fork
could complete, which got retried in a loop forever.
The timer is no longer implemented as a unix signal, but uses threads.
Thus the original problem no longer exists. The only remaining reason to
block the timer tick is to prevent actions taken by the tick from
interfering with the delicate process involved in fork (taking a load of
locks and pausing everything).
The only thing we need to do is to prevent the eventlog from being
written to or flushed while the fork is taking place. To achieve this
all we need to do is hold the mutex for the global eventlog buffer.
This removes the last use of stopTimer that expects stopTimer to work
synchronously (which it was not) and thus solves issue #27105. To be
clear, we solve issue #27105 not by making stopTimer synchronous, but by
eliminating the use sites that expected it to be synchronous.
-
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
-
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
-
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
-
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
-
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
-
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=ccead81bbc39668376eb5cf47066acb446cc43f3
Fixes #27366
-
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
-
1314f2fd
by David Eichmann at 2026-06-16T05:46:52-04:00
Hadrian: fix ghc-internal .def file name
-
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.
-
842bef9f
by Alan Zimmerman at 2026-06-16T05:48:25-04:00
EPA: Use standard type family declaration for Anno
-
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.
-
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
-
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>
-
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.
-
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
-
b734c75d
by Igor Ranieri at 2026-06-16T20:27:32-04:00
haddock: Update CONTRIBUTING with missing step, add missing test
dependency
-
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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6009c460
by Simon Hengel at 2026-06-22T04:21:10+07:00
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.