-
fbc0b92a
by Vladislav Zavialov at 2025-06-22T04:25:16+03:00
Visible forall in GADTs (#25127)
Add support for visible dependent quantification `forall a -> t` in
types of data constructors, e.g.
data KindVal a where
K :: forall k.
forall (a::k) -> -- now allowed!
k ->
KindVal a
For details, see docs/users_guide/exts/required_type_arguments.rst,
which has gained a new subsection.
DataCon in compiler/GHC/Core/DataCon.hs
---------------------------------------
The main change in this patch is that DataCon, the Core representation
of a data constructor, now uses a different type to store user-written
type variable binders:
- dcUserTyVarBinders :: [InvisTVBinder]
+ dcUserTyVarBinders :: [TyVarBinder]
where
type TyVarBinder = VarBndr TyVar ForAllTyFlag
type InvisTVBinder = VarBndr TyVar Specificity
and
data Specificity = InferredSpec | SpecifiedSpec
data ForAllTyFlag = Invisible Specificity | Required
This change necessitates some boring, mechanical changes scattered
throughout the diff:
... is now used in place of ...
-----------------+---------------
TyVarBinder | InvisTVBinder
IfaceForAllBndr | IfaceForAllSpecBndr
Specified | SpecifiedSpec
Inferred | InferredSpec
mkForAllTys | mkInvisForAllTys
additionally,
tyVarSpecToBinders -- added or removed calls
ifaceForAllSpecToBndrs -- removed calls
Visibility casts in mkDataConRep
--------------------------------
Type abstractions in Core (/\a. e) always have type (forall a. t)
because coreTyLamForAllTyFlag = Specified. This is also true of data
constructor workers. So we may be faced with the following:
data con worker: (forall a. blah)
data con wrapper: (forall a -> blah)
In this case the wrapper must use a visibility cast (e |> ForAllCo ...)
with appropriately set fco_vis{L,R}. Relevant functions:
mkDataConRep in compiler/GHC/Types/Id/Make.hs
dataConUserTyVarBindersNeedWrapper in compiler/GHC/Core/DataCon.hs
mkForAllVisCos in compiler/GHC/Core/Coercion.hs
mkCoreTyLams in compiler/GHC/Core/Make.hs
mkWpForAllCast in compiler/GHC/Tc/Types/Evidence.hs
More specifically:
- dataConUserTyVarBindersNeedWrapper has been updated to answer "yes"
if there are visible foralls in the type of the data constructor.
- mkDataConRep now uses mkCoreTyLams to generate the big lambda
abstractions (/\a b c. e) in the data con wrapper.
- mkCoreTyLams is a variant of mkCoreLams that applies visibility casts
as needed. It similar in purpose to the pre-existing mkWpForAllCast,
so the common bits have been factored out into mkForAllVisCos.
ConDecl in compiler/Language/Haskell/Syntax/Decls.hs
----------------------------------------------------
The surface syntax representation of a data constructor declaration is
ConDecl. In accordance with the proposal, only GADT syntax is extended
with support for visible forall, so we are interested in ConDeclGADT.
ConDeclGADT's field con_bndrs has been renamed to con_outer_bndrs
and is now accompanied by con_inner_bndrs:
con_outer_bndrs :: XRec pass (HsOuterSigTyVarBndrs pass)
con_inner_bndrs :: [HsForAllTelescope pass]
Visible foralls always end up in con_inner_bndrs. The outer binders are
stored and processed separately to support implicit quantification and
the forall-or-nothing rule, a design established by HsSigType.
A side effect of this change is that even in absence of visible foralls,
GHC now permits multiple invisible foralls, e.g.
data T a where { MkT :: forall a b. forall c d. ... -> T a }
But of course, this is done in service of making at least some of these
foralls visible. The entire compiler front-end has been updated to deal
with con_inner_bndrs. See the following modified or added functions:
Parser:
mkGadtDecl in compiler/GHC/Parser/PostProcess.hs
splitLHsGadtTy in compiler/GHC/Hs/Type.hs
Pretty-printer:
pprConDecl in compiler/GHC/Hs/Decls.hs
pprHsForAllTelescope in compiler/GHC/Hs/Type.hs
Renamer:
rnConDecl in compiler/GHC/Rename/Module.hs
bindHsForAllTelescopes in compiler/GHC/Rename/HsType.hs
extractHsForAllTelescopes in compiler/GHC/Rename/HsType.hs
Type checker:
tcConDecl in compiler/GHC/Tc/TyCl.hs
tcGadtConTyVarBndrs in compiler/GHC/Tc/Gen/HsType.hs
Template Haskell
----------------
The TH AST is left unchanged for the moment to avoid breakage. An
attempt to quote or reify a data constructor declaration with visible
forall in its type will result an error:
data ThRejectionReason -- in GHC/HsToCore/Errors/Types.hs
= ...
| ThDataConVisibleForall -- new error constructor
However, as noted in the previous section, GHC now permits multiple
invisible foralls, and TH was updated accordingly. Updated code:
repC in compiler/GHC/HsToCore/Quote.hs
reifyDataCon in compiler/GHC/Tc/Gen/Splice.hs
ppr @Con in libraries/ghc-boot-th/GHC/Boot/TH/Ppr.hs
Pattern matching
----------------
Everything described above concerns data constructor declarations, but
what about their use sites? Now it is trickier to type check a pattern
match fn(Con a b c)=... because we can no longer assume that a,b,c are
all value arguments. Indeed, some or all of them may very well turn out
to be required type arguments.
To that end, see the changes to:
tcDataConPat in compiler/GHC/Tc/Gen/Pat.hs
splitConTyArgs in compiler/GHC/Tc/Gen/Pat.hs
and the new helpers split_con_ty_args, zip_pats_bndrs.
This is also the reason the TcRnTooManyTyArgsInConPattern error
constructor has been removed. The new code emits TcRnArityMismatch
or TcRnIllegalInvisibleTypePattern.
Summary
-------
DataCon, ConDecl, as well as all related functions have been updated to
support required type arguments in data constructors.
Test cases:
HieGadtConSigs GadtConSigs_th_dump1 GadtConSigs_th_pprint1
T25127_data T25127_data_inst T25127_infix
T25127_newtype T25127_fail_th_quote T25127_fail_arity
TyAppPat_Tricky
Co-authored-by: mniip <mniip@mniip.com>
-
ae003a3a
by Teo Camarasu at 2025-06-23T05:21:48-04:00
linters: lint-whitespace: bump upper-bound for containers
The version of containers was bumped in https://gitlab.haskell.org/ghc/ghc/-/merge_requests/13989
-
0fb37893
by Matthew Pickering at 2025-06-23T13:55:10-04:00
Move ModuleGraph into UnitEnv
The ModuleGraph is a piece of information associated with the
ExternalPackageState and HomeUnitGraph. Therefore we should store it
inside the HomeUnitEnv.
-
3bf6720e
by soulomoon at 2025-06-23T13:55:52-04:00
Remove hptAllFamInstances usage during upsweep
Fixes #26118
This change eliminates the use of hptAllFamInstances during the upsweep phase,
as it could access non-below modules from the home package table.
The following updates were made:
* Updated checkFamInstConsistency to accept an explicit ModuleEnv FamInstEnv
parameter and removed the call to hptAllFamInstances.
* Adjusted hugInstancesBelow so we can construct ModuleEnv FamInstEnv
from its result,
* hptAllFamInstances and allFamInstances functions are removed.
-
83ee7b78
by Ben Gamari at 2025-06-24T05:02:07-04:00
configure: Don't force value of OTOOL, etc. if not present
Previously if `otool` and `install_name_tool` were not present they
would be overridden by `fp_settings.m4`. This logic was introduced in
4ff93292243888545da452ea4d4c1987f2343591 without explanation.
-
9329c9e1
by Ben Gamari at 2025-06-24T05:02:07-04:00
ghc-toolchain: Add support for otool, install_name_tool
Fixes part of ghc#23675.
-
25f5c998
by Ben Gamari at 2025-06-24T05:02:08-04:00
ghc-toolchain: Add support for llc, opt, llvm-as
Fixes #23675.
-
51d150dd
by Rodrigo Mesquita at 2025-06-24T05:02:08-04:00
hadrian: Use settings-use-distro-mingw directly
The type `ToolchainSetting` only made sense when we had more settings to
fetch from the system config file. Even then "settings-use-distro-mingw"
is arguably not a toolchain setting.
With the fix for #23675, all toolchain tools were moved to the
`ghc-toolchain` `Toolchain` format. Therefore, we can inline
`settings-use-distro-mingw` accesses and delete `ToolchainSetting`.
-
dcf68a83
by Rodrigo Mesquita at 2025-06-24T05:02:08-04:00
configure: Check LlvmTarget exists for LlvmAsFlags
If LlvmTarget was empty, LlvmAsFlags would be just "--target=".
If it is empty now, simply keep LlvmAsFlags empty.
ghc-toolchain already does this right. This fix makes the two
configurations match up.
-
580a3353
by Ben Gamari at 2025-06-24T05:02:51-04:00
rts/linker/LoadArchive: Use bool
Improve type precision by using `bool` instead of `int` and `StgBool`.
-
76d1041d
by Ben Gamari at 2025-06-24T05:02:51-04:00
rts/linker/LoadArchive: Don't rely on file extensions for identification
Previously archive members would be identified via their file extension,
as described in #13103. We now instead use a more principled approach,
relying on the magic number in the member's header.
As well, we refactor treatment of archive format detection to improve
code clarity and error handling.
Closes #13103.
-
878c3888
by Teo Camarasu at 2025-06-24T13:46:32+00:00
cabal.project-reinstall: allow newer ghc-paths:Cabal
This upper bound will be wrong whenever we are using a development version of Cabal in-tree, so let's just add an allow-newer here