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34fc50c1
by Ben Gamari at 2025-08-11T13:36:25-04:00
Kill IOPort#
This type is unnecessary, having been superceded by `MVar` and a rework
of WinIO's blocking logic.
See #20947.
See https://github.com/haskell/core-libraries-committee/issues/213.
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56b32c5a
by sheaf at 2025-08-12T10:00:19-04:00
Improve deep subsumption
This commit improves the DeepSubsumption sub-typing implementation
in GHC.Tc.Utils.Unify.tc_sub_type_deep by being less eager to fall back
to unification.
For example, we now are properly able to prove the subtyping relationship
((∀ a. a->a) -> Int) -> Bool <= β[tau] Bool
for an unfilled metavariable β. In this case (with an AppTy on the right),
we used to fall back to unification. No longer: now, given that the LHS
is a FunTy and that the RHS is a deep rho type (does not need any instantiation),
we try to make the RHS into a FunTy, viz.
β := (->) γ
We can then continue using covariance & contravariance of the function
arrow, which allows us to prove the subtyping relationship, instead of
trying to unify which would cause us to error out with:
Couldn't match expected type ‘β’ with actual type ‘(->) ((∀ a. a -> a) -> Int)
See Note [FunTy vs non-FunTy case in tc_sub_type_deep] in GHC.Tc.Utils.Unify.
The other main improvement in this patch concerns type inference.
The main subsumption logic happens (before & after this patch) in
GHC.Tc.Gen.App.checkResultTy. However, before this patch, all of the
DeepSubsumption logic only kicked in in 'check' mode, not in 'infer' mode.
This patch adds deep instantiation in the 'infer' mode of checkResultTy
when we are doing deep subsumption, which allows us to accept programs
such as:
f :: Int -> (forall a. a->a)
g :: Int -> Bool -> Bool
test1 b =
case b of
True -> f
False -> g
test2 b =
case b of
True -> g
False -> f
See Note [Deeply instantiate in checkResultTy when inferring].
Finally, we add representation-polymorphism checks to ensure that the
lambda abstractions we introduce when doing subsumption obey the
representation polymorphism invariants of Note [Representation polymorphism invariants]
in GHC.Core. See Note [FunTy vs FunTy case in tc_sub_type_deep].
This is accompanied by a courtesy change to `(<.>) :: HsWrapper -> HsWrapper -> HsWrapper`,
adding the equation:
WpCast c1 <.> WpCast c2 = WpCast (c1 `mkTransCo` c2)
This is useful because mkWpFun does not introduce an eta-expansion when
both of the argument & result wrappers are casts; so this change allows
us to avoid introducing lambda abstractions when casts suffice.
Fixes #26225
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d175aff8
by Sylvain Henry at 2025-08-12T10:01:31-04:00
Add regression test for #18619
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a3983a26
by Sylvain Henry at 2025-08-12T10:02:20-04:00
RTS: remove some TSAN annotations (#20464)
Use RELAXED_LOAD_ALWAYS macro instead.
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0434af81
by Ben Gamari at 2025-08-12T10:03:02-04:00
Bump time submodule to 1.15
Also required bumps of Cabal, directory, and hpc.
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e3a67b04
by Recursion Ninja at 2025-08-12T15:41:40-04:00
Resolving issues #20645 and #26109
Correctly sign extending and casting smaller bit width types for LLVM operations:
- bitReverse8#
- bitReverse16#
- bitReverse32#
- byteSwap16#
- byteSwap32#
- pdep8#
- pdep16#
- pext8#
- pext16#