GitLab

Sven Tennie pushed to branch wip/supersven/riscv-fix-switch-jump-tables at Glasgow Haskell Compiler / GHC

Commits:

44bf5fa1

by Matthew Pickering at 2025-03-07T13:48:18+00:00

iface: Store flags in interface files

When reporting the reason why a module is recompiled (using
`-dump-hi-diffs`), it is much more informative to inform the user about
which flag exactly has changed, rather than just an opaque reference to
a hash.

Now, when the user enables `-fwrite-if-self-recomp-flags`
there is a difference the precise part of the flags is
reported:

```
codegen flags changed:
before: [Opt_NoTypeableBinds, Opt_OmitYields]
after: [Opt_NoTypeableBinds, Opt_OmitYields, Opt_DictsStrict]
```

Fixes #25571

324222bd

by Oleg Grenrus at 2025-03-08T08:50:18-05:00

Run fix-whitespace on compiler/

https://hackage.haskell.org/package/fix-whitespace

IMO this should be included into lint suite

1e53277a

by sheaf at 2025-03-08T16:32:25-05:00

Allow defaulting of representational equalities

This commit generalises the defaulting of equality constraints that
was introduced in 663daf8d (with follow-up in 6863503c) to allow
the defaulting of *representational* equality constraints.

Now we default a representational equality

  ty1 ~R# ty2

by unifying ty1 ~# ty2.

This allows the following defaulting to take place:

  - Coercible alpha[tau] Int ==> alpha := Int
  - Coercible (IO beta[tau]) (IO Char) ==> beta := Char

See Note [Defaulting representational equalities] in GHC.Tc.Solver.Default
for more details.

Fixes #21003

d6c40afc

by Andreas Klebinger at 2025-03-08T16:33:02-05:00

Revert "Use `Infinite` in unique generation, and clean up some other partial uni patterns as well."

This reverts commit 643dd3d86968c527ba07ece9cc337728dbdfe2a0.

As described in #25817 this commit introduced a subtle bug in AArch64
code generation. So for the time being I will simply revert it
wholesale.

68310e11

by Andreas Klebinger at 2025-03-08T16:33:39-05:00

Properly describe acceptance window for stat tests.

The relative metric is already in %, so no need to multiply by 100.

cca68421

by Cheng Shao at 2025-03-08T22:04:42-05:00

wasm: do not use wasm type reflection in dyld

The wasm dynamic linker used to depend on v8's experimental wasm type
reflection support to generate stub functions when treating GOT.func
items that aren't exported by any loaded library yet. However, as we
work towards wasm ghci browser mode (#25399), we need to ensure the
wasm dyld logic is portable across browsers. So this commit removes
the usage of wasm type reflection in wasm dyld, and it shall only be
added many months later when this feature is widely available in
browsers.

75fcc5c9

by Cheng Shao at 2025-03-08T22:05:19-05:00

wasm: don't create a wasm global for dyld poison

There's a much more efficient way to convert an unsigned i32 to a
signed one. Thanks, o3-mini-high.

fd40eaa1

by Cheng Shao at 2025-03-08T22:05:19-05:00

wasm: revamp JSFFI internal implementation and documentation

This patch revamps the wasm backend's JSFFI internal implementation
and documentation:

- `JSValManager` logic to allocate a key is simplified to simple
  bumping. According to experiments with all major browsers, the
  internal `Map` would overflow the heap much earlier before we really
  exhaust the 32-bit key space, so there's no point in the extra
  complexity.
- `freeJSVal` is now idempotent and safe to call more than once. This
  is achieved by attaching the `StablePtr#` to the `JSVal#` closure
  and nullifying it when calling `freeJSVal`, so the same stable
  pointer cannot be double freed.
- `mkWeakJSVal` no longer exposes the internal `Weak#` pointer and
  always creates a new `Weak#` on the fly. Otherwise by finalizing
  that `Weak#`, user could accidentally drop the `JSVal`, but
  `mkWeakJSVal` is only supposed to create a `Weak` that observes the
  `JSVal`'s liveliness without actually interfering it.
- `PromisePendingException` is no longer exported since it's never
  meant to be caught by user code; it's a severe bug if it's actually
  raised at runtime.
- Everything exported by user-facing `GHC.Wasm.Prim` now has proper
  haddock documentation.
- Note [JSVal representation for wasm] has been updated to reflect the
  new JSVal# memory layout.

cbae3708
by Ben Gamari at 2025-03-11T06:09:58-04:00
```
users guide: Fix typo
```

1951eb7a

by Ben Gamari at 2025-03-11T06:10:35-04:00

testsuite: Don't count fragile passes as failures in JUnit output

As noted in #25806, the testsuite driver's JUnit output
previously considered passes of fragile tests to be failures. Fix this.

Closes #25806.

589f40b9

by Matthew Pickering at 2025-03-11T06:11:11-04:00

Use panic rather than error in expectJust

Otherwise, we would not get a callstack printed out when the exception
occurs.

Fixes #25829

d450e88e

by sheaf at 2025-03-11T06:42:59-04:00

Solve Wanted quantified constraints from Givens

This commit ensures we directly solve Wanted quantified constraints from
matching inert Given quantified constraints,instead of going through the
trouble of emitting an implication constraint and processing that.

This is not just an optimisation; it makes our lives easier when
generating RULEs for specialisation.
See Note [Solving Wanted QCs from Given QCs] for details

Fixes #25758

48daaf53
by Ben Gamari at 2025-03-11T06:42:59-04:00
```
testsuite: Add testcase for #25577
```

d2ffb0ce

by Ben Gamari at 2025-03-11T06:42:59-04:00

testsuite/ghc-api: Eliminate Makefile usage from various GHC API tests

These tests can be expressed perfectly well using the testsuite driver
itself.

2275b642

by Ben Gamari at 2025-03-11T06:42:59-04:00

rts/linker/MachO: Assert that GOT relocations have GOT entries

In #25577 we found that some GOT relocation types were not being given
relocation entries. Add assertions to catch this sort of failure in the
future.

8c96bcb4

by Ben Gamari at 2025-03-11T06:42:59-04:00

rts/linker/MachO: Account for internal GOT references in GOT construction

Previously we failed to give GOT slots to symbols which were referred to
by GOT relocations in the same module. This lead to #25577.

Fix this by explicitly traversing relocation lists and maintaining a
`needs_got` flag for each symbol.

Fixes #25577.

7b84c588

by Vladislav Zavialov at 2025-03-11T06:43:02-04:00

One list in ConPat (part of #25127)

This patch changes PrefixCon to use one list instead of two:

	-data HsConDetails tyarg arg rec
	-  = PrefixCon [tyarg] [arg]
	+data HsConDetails arg rec
	+  = PrefixCon [arg]
	   | RecCon    rec
	   | InfixCon  arg arg

The [tyarg] list is now gone. To understand the effect of this change,
recall that there are three instantiations of HsConDetails:

1. type HsConPatDetails p =
      HsConDetails (HsConPatTyArg (NoGhcTc p))  -- tyarg
                   (LPat p)                     -- arg
                   (HsRecFields p (LPat p))     -- rec

2. type HsConDeclH98Details pass =
      HsConDetails Void                              -- tyarg
                   (HsScaled pass (LBangType pass))  -- arg
                   (XRec pass [LConDeclField pass])  -- rec

3. type HsPatSynDetails pass =
      HsConDetails Void                     -- tyarg
                   (LIdP pass)              -- arg
                   [RecordPatSynField pass] -- rec

In cases (2) and (3), tyarg was instantiated to Void, so the [tyarg]
list was always empty. Its removal is basically a no-op.

The interesting case is (1), which is used in ConPat to represent
pattern matching of the form (MkE @tp1 @tp2 p1 p2).
With this patch, its representation is changed as follows:

  ConPat "MkE" [tp1, tp2] [p1, p2]               -- old
  ConPat "MkE" [InvisP tp1, InvisP tp2, p1, p2]  -- new

The new mixed-list representation is consintent with lambdas, where
InvisP is already used to deal with \ @tp1 @tp2 p1 p2 -> body.

The immediate effect of the new representation is an improvement to
error messages. Consider the pattern (Con x @t y). Previously it
resulted in a parse error because @t could not occur after x. Now it is
reported as [GHC-14964]. Test case: TyAppPat_MisplacedApplication.

In the long term, this is intended as preparation for #18389 and #25127,
which would make (Con x @t y) potentially valid, e.g. if its type is
  Con :: forall a -> forall b. (a, b) -> T

The TH AST is left unchanged for the moment to avoid breakage.

cce869ea

by Vladislav Zavialov at 2025-03-11T06:43:02-04:00

Error message with EmptyCase and RequiredTypeArguments (#25004)

Fix a panic triggered by a combination of \case{} and forall t ->

  ghci> let f :: forall (xs :: Type) -> (); f = \case {}
  panic! (the 'impossible' happened)
    GHC version 9.10.1:
          Util: only

The new error message looks like this:

  ghci> let f :: forall (xs :: Type) -> (); f = \case {}
  <interactive>:5:41: error: [GHC-48010]
      • Empty list of alternatives in \case expression
        checked against a forall-type: forall xs -> ...

This is achieved as follows:

* A new data type, BadEmptyCaseReason, is now used to describe
  why an empty case has been rejected. Used in TcRnEmptyCase.

* HsMatchContextRn is passed to tcMatches, so that the type checker
  can attach the syntactic context to the error message.

* tcMatches now rejects type arguments if the list of alternatives is
  empty. This is what fixes the bug.

37d8b50b

by sheaf at 2025-03-11T06:43:06-04:00

user's guide: consolidate defaulting documentation

This commit adds a new section on defaulting, which consolidates various
parts of documentation surrounding defaulting into one central place.

It explains type class defaulting in detail, extensions to it with
OverloadedStrings, NamedDefaults and ExtendedDefaultRules, as well
as other defaulting mechanisms (e.g. kind-based defaulting such as
RuntimeRep defaulting, and defaulting of equalities).

0c9fd8d4

by sheaf at 2025-03-11T06:43:06-04:00

user's guide: flesh out XOverloadedStrings docs

This commit extends the documentation of the OverloadedStrings extension
with some usage information, in particular suggestions to:

  - use default declarations, such as `default (Text)` or
    `default IsString(Text)` (with the NamedDefaults extension),

  - enable the ExtendedDefaultRules extension to relax the requirement
    that a defaultable type variable must only appear in unary standard
    classes

Fixes #23388

2df171d4

by sheaf at 2025-03-11T06:43:06-04:00

user's guide: NamedDefaults vs ExtendedDefaultRules

This commit clarifies the defaulting rules with NamedDefaults,
in particular in situations where a type variable appears in other
constraints than standard/unary constraints.

77df05d0

by Matthew Pickering at 2025-03-11T06:43:07-04:00

Take into account all flags when computing iface_hash

The "interface hash" should contain a hash of everything in the
interface file. We are not doing that yet but at least a start is to
include a hash of everything in `mi_self_recomp`, rather than just
`mi_src_hash` and `mi_usages`.

In particular, this fixes #25837, a bug where we should recompile a
`dyn_hi` file but fail to do so.

48b8f110

by Matthew Pickering at 2025-03-11T06:43:07-04:00

Pass -fPIC to dynamicToo001 test to avoid platform dependence issues

On darwin platforms, `-fPIC` is always enabled but on linux it is only
enabled in the dynamic flavour. This can cause a difference in
interface files (see #25836).

The purpose of this test isn't to test module A recompilation, so we
avoid this platform dependency by always passing `-fPIC`.

03c72f01

by Matthew Pickering at 2025-03-11T06:43:07-04:00

Remove mi_used_th field from interface files

In the distant past, recompilation checking was disabled for interfaces which used
TemplateHaskell, but for several years now recompilation checking has
been more fine-grained. This has rendered this field unused and
lingering in an interface file.

6bb0e261

by Matthew Pickering at 2025-03-11T06:43:07-04:00

Remove mi_hpc field from interface files

The `mi_hpc` field is not used for anything as far as I can discern so
there is no reason to record in the private interface of a module that
there are modules in the transitive closure which use `hpc`.

You can freely mix modules which use `-fhpc` and ones which don't.

Whether to recompile a module due to `-fhpc` being passed to the module
itself is determined in `fingerprintDynFlags`.

b6d5b091

by Simon Peyton Jones at 2025-03-11T22:39:23-04:00

We can't UNPACK multi-constructor GADTs

This MR fixes #25672

See Note [Unpacking GADTs and existentials] in GHC.Types.Id.Make

8eae151d

by Teo Camarasu at 2025-03-11T22:40:00-04:00

template-haskell: Add explicit exports lists to all remaining modules

db621b58

by Teo Camarasu at 2025-03-11T22:40:00-04:00

template-haskell: fix haddocks

It seems that we need a direct dependency on ghc-internal, otherwise
Haddock cannot find our haddocks

The bug seems to be caused by Hadrian because if I rebuild with
cabal-install (without this extra dependency) then I get accurate
Haddocks.

Resolves #25705

64ea68d9

by Ben Gamari at 2025-03-12T07:11:51-04:00

mk-ghcup-metadata: Clean up and add type annotations

Getting this file right has historically been quite painful as it is a
dynamically-typed script running only late in the release pipeline.

b3f80b07

by Ben Gamari at 2025-03-12T07:12:27-04:00

rts: Drop imports of pthreads functions in cmm sources

These are no longer used. I noticed these while looking for uses of
__PIC__ in Cmm sources.

915a6781

by Matthew Pickering at 2025-03-13T01:46:41-04:00

interfaces: Ensure that forceModIface deeply forces a ModIface

A ModIface is the result of compilation that we keep for a long time in
memory. Therefore, it's very important to manage what we are going to
retain and remove any external references to things which we might have
captured compilation.

If storing your ModIface in memory uses too much space, then store
less things or make it use a more efficient representation.

In the past there have been many space leak bugs by not sufficiently
forcing a ModIface (#15111)

This patch adds all the missing NFData instances for all the places I
could find where we weren't deeply forcing the structure.

24d373a6
by Matthew Craven at 2025-03-13T01:47:18-04:00
```
Add interface-stability test for ghc-prim
```

0cb1db92

by sheaf at 2025-03-14T13:11:44-04:00

Don't report used duplicate record fields as unused

This commit fixes the bug reported in #24035 in which the import of a
duplicate record field could be erroneously reported as unused.

The issue is that an import of the form "import M (fld)" can import
several different 'Name's, and we should only report an error if ALL
of those 'Name's are unused, not if ANY are.

Note [Reporting unused imported duplicate record fields]
in GHC.Rename.Names explains the solution to this problem.

Fixes #24035

f1830d74

by Matthew Pickering at 2025-03-14T13:12:21-04:00

binary: Directly copy ShortByteString to buffer rather than go via ByteString

This avoids allocating an intermediate bytestring. I just noticed on a
profile that `putFS` was allocating, and it seemed strange to me why
since it should just copy the contents of the FastString into the
already allocated buffer. It turned out we were going indirectly via a
ByteString.

Fixes #25861

b15fca2b

by Matthew Pickering at 2025-03-15T05:36:40-04:00

iface: Store logical parts of ModIface together

The ModIface structure is divided into several logical parts:

1. mi_mod_info: Basic module metadata (name, version, etc.)

2. mi_public: The public interface of the module (the ABI), which includes:
   - Exports, declarations, fixities, warnings, annotations
   - Class and type family instances
   - Rewrite rules and COMPLETE pragmas
   - Safe Haskell and package trust information
   - ABI hashes for recompilation checking

4. mi_self_recomp: Information needed for self-recompilation checking
   (see Note [Self recompilation information in interface files])

5. mi_simplified_core: Optional simplified Core for bytecode generation
   (only present when -fwrite-if-simplified-core is enabled)

6. mi_docs: Optional documentation (only present when -haddock is enabled)

7. mi_top_env: Information about the top-level environment of the original source

8. mi_ext_fields: Additional fields for extensibility

This structure helps organize the interface data according to its purpose and usage
patterns. Different parts of the compiler use different fields. By separating them
logically in the interface we can arrange to only deserialize the fields that are needed.

This patch also enforces the invariant that the fields of ModIface are
lazy. If you are keeping a ModIface on disk, then force it using
`forceModIface`. Otherwise, when the `ModIface` is read from disk, only
the parts which are needed from the interface will be deserialised.

In a follow-up patch I will tackle follow-up issues:

* Recompilation checking doesn't take into account exported named defaults (#25855)
* Recompilation checking does not take into account COMPLETE pragmas (#25854)
* mi_deps_ field in an interface is confused about whether the
  information is for self-recompilation checking or part of the ABI
  (#25844)

Fixes #25845

-------------------------
Metric Decrease:
    MultiLayerModulesDefsGhciWithCore
-------------------------

c758cb71

by Ben Gamari at 2025-03-15T05:37:17-04:00

configure: Fix incorrect SettingsLlvmAsFlags value

Previously this was set to `LlvmAsCmd` rather than `LlvmAsFlags`,
resulting in #25856.

cfaaca14

by sheaf at 2025-03-18T20:05:03-04:00

Fix buglet in isEmptyWorkList

There was a missing case in GHC.Tc.Solver.InertSet.isEmptyWorkList; it
mistakenly ignored the 'wl_rw_eqs' field. This commit simply fixes that.
No test case.

9f9fe0b3

by sheaf at 2025-03-18T20:05:03-04:00

Add mapMaybeTM method to TrieMap class

This commit adds a new method to the TrieMap class, mapMaybeTM, and
adds implementations to all the instances.

mapMaybeTM is useful when filtering containers that contain other
containers.

393531ff

by Simon Peyton Jones at 2025-03-18T20:05:03-04:00

Specialising expressions -- at last

This MR addresses #24359, which implements the GHC proposal 493 on SPECIALISE pragmas.

* The old code path (using SpecSig and SpecPrag) still exists.
* The new code path (using SpecSigE and SpecPragE) runs alongside it.
* All SPECIALISE pragmas are routed through the new code path, except
  if you give multiple type sigs, when the old code path is still used.
* Main documentation: Note [Handling new-form SPECIALISE pragmas] in
  GHC.Tc.Gen.Sig`

Thanks to @sheaf for helping with this MR.

The Big Thing is to introduce

  {-# SPECIALISE forall x.  f @Int x True #-}

where you can give type arguments and value argument to specialise; and
you can quantify them with forall, just as in Rules.

I thought it was going to be pretty simple, but it was a Long, Long Saga.

Highlights

* Overview Note [Handling new-form SPECIALISE pragmas] in GHC.Tc.Gen.Sig
  - New data constructor `SpecSigE` in data type `L.H.S.Binds.Sig`
  - New data construtor `SpecPragE` in data type `GHC.Hs.Binds.TcSpecPrag`
  - Renamer: uses `checkSpecESigShape` to decide which function to assocate the
             SPECIALISE pragma with
  - Some of the action is in `GHC.Tc.Gen.Sig.tcSpecPrag`
  - The rest is in `GHC.HsToCore.Binds.dsSpec`

* We use a new TcS mode, TcSFullySolve, when simplifying the Wanteds
  that arise from the specialise expression. The mechanism is explained
  in Note [TcSFullySolve] in GHC.Tc.Solver.Monad. The reason why we need
  to do this is explained in Note [Fully solving constraints for specialisation]
  in GHC.Tc.Gen.Sig.

* All of GHC.Tc.Gen.Rule is moved into GHC.Tc.Gen.Sig, because the code is
  very closely related.

* The forall'd binders for SPECIALISE are the same as those for a RULE, so I
  refactored, introducing data type `L.H.S.Binds.RuleBndrs`, with functions
  to rename, zonk, typecheck it.  I refactored this data type a bit; nicer now.

* On the LHS of RULES, or SPECIALISE, we want to disable the tricky mechanims
  described in Note [Desugaring non-canonical evidence] in GHC.HsToCore.Expr.
  Previously it wasn't fully disabled (just set to the empty set), and that
  didn't quite work in the new regime.

* There are knock-on changes to Template Haskell.

* For the LHS of a RULE and a SPECIALISE expression, I wanted to simplify
  it /without/ inlining the let-bindings for evidence variables.  I added
  a flag `so_inline` to the SimpleOpt optimiser to support this.  The
  entry point is `GHC.Core.SimpleOpt.simpleOptExprNoInline`

* Since forever we have had a hack for type variables on the LHS of
  RULES. I took the opportunity to tidy this up.  The main action is
  in the zonker.  See GHC.Tc.Zonk.Type Note [Free tyvars on rule LHS],
  and especially data construtor `SkolemiseFlexi`
  in data type `GHC.Tc.Zonk.Env.ZonkFlexi`

* Move `scopedSort` from GHC.Core.TyCo.FVs to GHC.Core.Predicate
  Reason: it now works for Ids as well, and I wanted to use isEvVar,
          which is defined in GHC.Core.Predicate
  Avoiding module loops meant that instead of exporting GHC.Core.TyCo.Tidy
  from GHC.Core.Type, modules now import the former directly.

  I also took the opportunity to remove unused exports
  from GHC.Core.Type.hs-boot

* Flag stuff:
  - Add flag `-Wdeprecated-pragmas` and use it to control the warning when
    using old-style SPECIALISE pragmas with multiple type ascriptions,

  - Add flag `-Wuseless-specialisations` and use it to control the warning emitted
    when GHC determines that a SPECIALISE pragma would have no effect. Don't
    want if the SPECIALISE is SPECIALISE INLINE (#4444)

    In response to #25389, we continue to generate these seemingly code for these
    seemingly useless SPECIALISE pragmas

  - Adds deprecations to Template Haskell `pragSpecD` and `pracSpecInlD`,

* Split up old-style SPECIALISE pragmas in GHC.Internal.Float,
  GHC.Internal.Numeric, GHC.Internal.Real

* Remove useless SPECIALISE pragmas in Data.Array (updating the array submodule)

Smaller things:

- Update the Users Guide

- Add mention of the changes to the 9.14 release notes as well as
  the Template Haskell changelog,

1884dd1a

by Simon Peyton Jones at 2025-03-18T20:05:03-04:00

Add -Wrule-lhs-equalities warning

This commit adds a new warning, controlled by the warning flag,
-Wrule-lhs-equalities, which is emitted when the LHS of a RULE gives
rise to equality constraints that previous GHC versions would have
quantified over.

GHC instead discards such RULES, as GHC was never able to generate
a rule template that would ever fire; it's better to be explicit about
the fact that the RULE doesn't work.

b00b3ef0

by Ben Gamari at 2025-03-18T20:05:41-04:00

compiler: Add export list to GHC.SysTools.Process

This also revealed that `readProcessEnvWithExitCode` and its local
helpers were dead code.

25850b22

by ARATA Mizuki at 2025-03-18T20:06:25-04:00

Fix code generation for SSE vector operations

The new implementation generates correct code
even if the registers overlap.

Closes #25859

e576468c

by Andreas Klebinger at 2025-03-18T20:07:02-04:00

Bump nofib submodule.

Fixes #25867. (Ben-raytrace being broken by library changes)

443fc8b1

by Sjoerd Visscher at 2025-03-19T12:01:04-04:00

Multiplicity annotation on records

Needing to store multiplicity annotations on records triggered a refactoring of AST of data declarations:

Moved HsBangTy and HsRecTy from HsType to HsTypeGhcPsExt, the extension of HsType during parsing, since they are only needed during parsing.

New HsConDeclField that stores all source data shared by all constructor declaration fields: unpackedness, strictness, multiplicity, documentation and the type of the field.

Merged HsMultAnn and HsArrowOf, so all multiplicity annotations share the same data type.

HsBang was no longer needed as a separate type, and was inlined into HsSrcBang.

313cf271

by Ben Gamari at 2025-03-19T12:01:43-04:00

gitlab-ci: Drop CentOS 7 binary distributions

CentOS 7 is EoL and moreover we cannot even build images for it.

See #25061.

5b94f99f

by Ben Gamari at 2025-03-19T12:02:21-04:00

rts: Ensure that WinIO flag is set when --io-manager=auto

As noted in #25838, previously `selectIOManager` failed to set
`rts_IOManagerIsWin32Native` in its `IO_MNGR_FLAG_AUTO`. This meant
that the MIO path was taken when WinIO was supposedly selected,
resulting in chaos.

Fixes #25838.

1a3f1131

by Peng Fan at 2025-03-19T12:03:10-04:00

Pass the mcmodel=medium parameter to CC via GHC

Ensure that GHC-driver builds default to mcmodel=medium, so that GHC
passes this default parameter to CC without having to add it to the
compiled project.

Commit e70d41406b5d5638b42c4d8222cd03e76bbfeb86 does not ensure that all
GHC-built object files have a default model of medium, and will raise an
R_LARCH_B26 overflow error.

27cf7361

by Matthew Craven at 2025-03-19T12:03:48-04:00

Add interface-stability test for ghc-bignum

As with ghc-prim, it makes sense to have some protection against
accidental interface changes to this package caused by changes
in ghc-internal.

25d46547

by Matthew Craven at 2025-03-19T12:03:48-04:00

Add README reference for the interface-stability tests

5d65393e

by Simon Peyton Jones at 2025-03-20T05:41:24-04:00

Remove the Core flattener

This big MR entirely removes the "flattener" that took a type and
replaced each type-family application with a fresh type variable.
The flattener had its origin in the paper
     Injective type families for Haskell

But (a) #25657 showed that flattening doesn't really work.
    (b) since we wrote the paper we have introduced the so-called
        "fine-grained" unifier GHC.Core.Unify, which can return
                 * SurelyApart
                 * Unifiable subst
                 * MaybeApart subst
        where the MaybeApart says that the two types are not unifiable by a
        substitution, but could (perhaps) be unified "later" after some type
        family reductions.  This turns out to subsume flattening.

This MR does a major refactor of GHC.Core.Unify to make it capable of
subsuming flattening.   The main payload is described in
       Note [Apartness and type families]
and its many wrinkles.

The key (non-refactoring) implementation change is to add `um_fam_env`
to the `UMState` in the unification monad.

Careful review with Richard revealed various bugs in the treament of
`kco`, the kind coercion carried around by the unifier, so that is
substantially fixed too: see Note [Kind coercions in Unify].

Compile-time performance is improved by 0.1% with a few improvements over
1% and one worsening by 1.3% namely T9872a.  (I have not investigated the
latter.)

Metric Decrease:
    T9872b
    T9872c
    TcPlugin_RewritePerf
Metric Increase:
    T9872a

9003ef0a

by sheaf at 2025-03-20T05:42:08-04:00

Remove SDoc from UnknownSubordinate/MissingBinding

This commit replaces unstructured SDoc arguments in error message constructors
with uses of the following two datatypes:

  - SigLike: for different kinds of signatures (e.g. standalone kind signatures,
    fixity signatures, COMPLETE pragmas, etc)
  - Subordinate: for class methods, associated types, and record fields

The following error message constructors now no longer have any SDocs in them:

  - TcRnIllegalBuiltinSyntax: SDoc -> SigLike
  - MissingBinding: SDoc -> SigLike
  - UnknownSubordinate: SDoc -> (Name, Subordinate)
  - SuggestMoveToDeclarationSite: SDoc -> SigLike

4329f3b6

by sheaf at 2025-03-20T05:42:08-04:00

Remove SDocs from HsDocContext

This commit removes the remaining SDocs from the HsDocContext data type.
It adds the following constructors:

  ClassInstanceCtx  -- Class instances
  ClassMethodSigCtx -- Class method signatures
  SpecialiseSigCtx  -- SPECIALISE pragmas
  PatSynSigCtx      -- Pattern synonym signatures

We now report a bit more information for errors while renaming class instances,
which slightly improves renamer-emitted error messages.

75c29aa1

by sheaf at 2025-03-20T05:42:08-04:00

Reject instance with non-class head in renamer

This commit modifies rnClsInstDecl so that, when renaming, we reject a class
instance declaration in which the head is not a class. Before this change, it
would get rejected in the type-checker, but that meant that the renamer could
emit unhelpful error messages, e.g.:

  data Foo m a
  instance Foo m where
    fmap _ x = case x of

would rather unhelpfully say:

    ‘fmap’ is not a (visible) method of class ‘Foo’

when of course 'Foo' is not even a class. We now reject the above program
with the following error message:

    Illegal instance for data type ‘Foo’.
    Instance heads must be of the form
      C ty_1 ... ty_n
    where ‘C’ is a class.

Fixes #22688

a8f543a9

by Cheng Shao at 2025-03-20T18:47:19-04:00

testsuite: mark T7919 as fragile on i386 as well

T7919 may also fail i386 CI jobs with test timeout.

256ac29c

by sheaf at 2025-03-20T18:48:07-04:00

Don't cache solved [W] HasCallStack constraints

This commit ensures we do not add solved Wanted constraints that mention
HasCallStack or HasExceptionContext constraints to the set of solved
Wanted dictionary constraints: caching them is invalid, because re-using
such cached dictionaries means using an old call-stack instead of
constructing a new one, as was reported in #25529.

Fixes #25529.

47646ce2

by Andrew Lelechenko at 2025-03-20T18:48:43-04:00

Improve haddock-visible documentation for GHC.Driver.Flags

2e4e15ed
by Sylvain Henry at 2025-03-21T17:49:36-04:00
```
Document -fnum-constant-folding (#25862)
```

044a6e08

by sheaf at 2025-03-21T17:50:24-04:00

LLVM: fix typo in padLiveArgs

This commit fixes a serious bug in the padLiveArgs function, which
was incorrectly computing too many padding registers. This caused
segfaults, e.g. in the UnboxedTuples test.

Fixes #25770
Fixes #25773

1745c749

by Teo Camarasu at 2025-03-22T18:42:37-04:00

template-haskell: remove Language.Haskell.TH.Lib.Internal

This module is purely used for the implementation of TH quote
desugarring.

Historically this needed to be exposed from `template-haskell`, since
that's the package that the desugarred expressions referenced but since
https://gitlab.haskell.org/ghc/ghc/-/merge_requests/12479, this is no
longer the case.

Now these identifiers are in `ghc-internal`.

Note that this module has carried the following warning for a long time:

> This is not a part of the public API, and as such, there are no API guarantees for this
module from version to version.

Resolves #24766

3bc507db

by Alan Zimmerman at 2025-03-22T18:43:13-04:00

EPA: Fix exact printing of SPECIALISE pragma

This commit fixes two minor issues with exactprinting of the
SPECIALISE pragma after !12319 landed

- The span for the RHS did not include the optional signature type
- The `::` was printed twice when the legacy path was used

Closes #25885

bdf93da8

by sheaf at 2025-03-24T11:25:12+01:00

Renamer: improve handling of export children

This commit refactors the 'childGREPriority' function which is used when
renaming subordinate items in export lists and class declarations.

Instead of having a complicated LookupChild parameter, we now simply pass the
GREInfo of the parent, which allows us to decide what is a valid child:

  - classes can have children that are in the type constructor namespace,
  - promoted data constructors should be treated the same as normal data
    constructors.

Fixes #24027

1dbc7846

by Matthew Pickering at 2025-03-24T15:35:17-04:00

Revert "mk-ghcup-metadata: Clean up and add type annotations"

This reverts commit 64ea68d9a206ec4db5020b0a3fc563199ab18be3.

See #25889

6941c825

by doyougnu at 2025-03-25T10:05:58-04:00

base: construct compat RTSFlags

-- see CLC #289

730e6f77

by doyougnu at 2025-03-25T10:06:02-04:00

base: construct compat GHC.Stats

-- see CLC #289

cd9e6605

by Ben Gamari at 2025-03-25T17:59:52-04:00

rel_eng/upload: Clarify usage directions

Previously it was not made clear that the directory name is significant.

7d18c19b

by Cheng Shao at 2025-03-25T22:00:56+00:00

ghci: make the Pipe type opaque

This commit makes the Pipe type in ghci opaque, and introduce the
mkPipeFromHandles constructor for creating a Pipe from a pair of
Handles. Pipe is now just a pair of receiver/sender continuations
under the hood. This allows a Pipe to be potentially backed by other
IPC mechanisms (e.g. WebSockets) which is essential for wasm ghci
browser mode.

a2103fd2

by Cheng Shao at 2025-03-25T22:00:56+00:00

ghci: use improved Pipe logic for wasm iserv

This commit makes wasm iserv take advantage of the Pipe refactoring by
passing binary receiver/sender js callbacks from the dyld script. This
paves the way for piping the binary messages through WebSockets in
order to run wasm iserv in the browser, but more importantly, it
allows us to get rid of a horrible hack in the dyld script: we no
longer have to fake magical wasi file descriptors that are backed by
nodejs blocking I/O! The legacy hack was due to these facts:

- iserv only supported exchanging binary messages via handles backed
  by file descriptors
- In wasi you can't access host file descriptors passed by host ghc
- The nodejs wasi implementation only allows mapping host directories
  into the wasi vfs, not host file descriptors
- Named pipes with file paths (mkfifo) doesn't work well with nodejs
  wasi implementation, causes spurious testsuite failures on macos

But starting from this point, we can fully take advantage of
non-blocking I/O on the js side.

fa2fbd2b

by Cheng Shao at 2025-03-25T22:00:56+00:00

ghci: fix ^C handling for wasm iserv

This commit fixes ^C handling for wasm iserv. Previously we didn't
handle it at all, so ^C would kill the node process and host ghc would
then crash as well. But native ghc with external interpreter can
handle ^C just fine and wasm should be no different. Hence the fix:
wasm iserv exports its signal handler as a js callback to be handled
by the dyld script. Also see added note for details.

efcebed6

by Cheng Shao at 2025-03-25T22:00:56+00:00

wasm: fix post-link.mjs for browser

The wasm ghci browser mode needs to run dyld.mjs in the browser which
imports post-link.mjs. This script makes post-link.mjs runnable in the
browser by deferring node-specific module imports to their actual use
sites.

27bb73c6

by Cheng Shao at 2025-03-25T22:00:56+00:00

wasm: use console.assert in dyld script

This commit uses console.assert() instead of node-specific strict
assert in the dyld script, in order to make it runnable in the
browser. console.assert() only warns and doesn't crash upon assertion
failure, but this is fine; we can always trivially define a strict
assert function shall it be necessary when debugging, and there hasn't
been such an assertion failure seen in the wild for long enough.

929df0ba

by Cheng Shao at 2025-03-25T22:00:56+00:00

wasm: asyncify the dylink.0 custom section parser

This commit refactors the simple binary parser in the dyld script in
charge of parsing the dylink.0 custom section. Previously the parser
was synchronous and operated on the entire input buffer; this was
simple and easy and worked well enough when the input wasm modules are
instantly read from local filesystem.

However, when running dyld in the browser, the wasm modules are
transferred via fetch() requests. The host ghc and the browser might
not be on the same machine, so slow network uplink does need to be
considered. We only need to parse dylink.0 custom section to extract
dependency info, and dylink.0 is the very first custom section in the
wasm shared library binary payload, so the parsing process should not
require fetch() to complete and should return the parsing result asap.

Hence the refactorings in this commit: asyncify the parser, make it
only consume as many bytes as needed by invoking an async consumer
callback. The input is a readable stream from the fetch() response;
once the response is available, the async wasm compilation can start
in the background, and dylink.0 parsing shall end asap which results
in more wasm shared libraries to be loaded earlier. Profit.

9a697181

by Cheng Shao at 2025-03-25T22:00:56+00:00

wasm: fix dyld setImmediate usage in browser

The wasm dyld script used to only run in node and directly uses
setImmediate in globalThis. In case of browsers, it needs to import
setImmediate from the prelude, hence this commit.

d9b71e82