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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Marge Bot pushed to branch master at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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Commits:
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<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2afbddb0f24df20cfc42279bb8695f91bbd3c1e0">2afbddb0</a></strong>
<div>
<span> by Andrei Borzenkov </span> <i> at 2023-07-16T10:21:24+04:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: "GitLab Mono", "JetBrains Mono", "Menlo", "DejaVu Sans Mono", "Liberation Mono", "Consolas", "Ubuntu Mono", "Courier New", "andale mono", "lucida console", monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Type patterns (#22478, #18986)
Improved name resolution and type checking of type patterns in constructors:
1. HsTyPat: a new dedicated data type that represents type patterns in
HsConPatDetails instead of reusing HsPatSigType
2. rnHsTyPat: a new function that renames a type
pattern and collects its binders into three groups:
- explicitly bound type variables, excluding locally bound
variables
- implicitly bound type variables from kind signatures
(only if ScopedTypeVariables are enabled)
- named wildcards (only from kind signatures)
2a. rnHsPatSigTypeBindingVars: removed in favour of rnHsTyPat
2b. rnImplcitTvBndrs: removed because no longer needed
3. collect_pat: updated to collect type variable binders from type patterns
(this means that types and terms use the same infrastructure to detect
conflicting bindings, unused variables and name shadowing)
3a. CollVarTyVarBinders: a new CollectFlag constructor that enables
collection of type variables
4. tcHsTyPat: a new function that typechecks type patterns, capable of
handling polymorphic kinds.
See Note [Type patterns: binders and unifiers]
Examples of code that is now accepted:
f = \(P @a) -> \(P @a) -> ... -- triggers -Wname-shadowing
g :: forall a. Proxy a -> ...
g (P @a) = ... -- also triggers -Wname-shadowing
h (P @($(TH.varT (TH.mkName "t")))) = ...
-- t is bound at splice time
j (P @(a :: (x,x))) = ... -- (x,x) is no longer rejected
data T where
MkT :: forall (f :: forall k. k -> Type).
f Int -> f Maybe -> T
k :: T -> ()
k (MkT @f (x :: f Int) (y :: f Maybe)) = ()
-- f :: forall k. k -> Type
Examples of code that is rejected with better error messages:
f (Left @a @a _) = ...
-- new message:
-- • Conflicting definitions for ‘a’
-- Bound at: Test.hs:1:11
-- Test.hs:1:14
Examples of code that is now rejected:
{-# OPTIONS_GHC -Werror=unused-matches #-}
f (P @a) = ()
-- Defined but not used: type variable ‘a’
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30 changed files:
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<a href="#75bfcd03f3ba9315d33104fcb0424c6bfeb4e334">
compiler/GHC/Hs/Decls.hs
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<li class="file-stats">
<a href="#9f00edfedb0f969865b049a78de3866545b4a60b">
compiler/GHC/Hs/Instances.hs
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<li class="file-stats">
<a href="#0bae7e7e67b5f9b6ba2a371f8917cf74423a0c6f">
compiler/GHC/Hs/Pat.hs
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<li class="file-stats">
<a href="#018be522bc4813b147a1525e4f96a7a493207d96">
compiler/GHC/Hs/Type.hs
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<a href="#7a1af22e4c32b9aa6ec708d9d3788e1c4db5da9a">
compiler/GHC/Hs/Utils.hs
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<a href="#3c19c0be465f9a28d7b69f89c55648080fcc37eb">
compiler/GHC/HsToCore/Quote.hs
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<a href="#649144a78135a23cabfc90dd83c4aabf448eb6ab">
compiler/GHC/Iface/Ext/Ast.hs
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<a href="#446cb12ca6cefaf1c6eb79b7db643632744263c7">
compiler/GHC/Parser/PostProcess.hs
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<a href="#211a448f1df996899df14cfbd91d498ffa77b8bd">
compiler/GHC/Parser/Types.hs
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<a href="#892acbb198a9095c917740d3c1297b56df4e3b7e">
compiler/GHC/Rename/HsType.hs
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<a href="#cfa41b5649933e5b12f7796e9d49b9dd6a0bc59f">
compiler/GHC/Rename/Pat.hs
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<a href="#16b273b96a1c03d4261e2ac6de4cc456ba2dd014">
compiler/GHC/Rename/Splice.hs
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<a href="#c825eeae0b690f96795a0930caa038a4829d5fc6">
compiler/GHC/Rename/Splice.hs-boot
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<a href="#939d24c1002dc322659c1f67c9f3d2db2ae31dd4">
compiler/GHC/Rename/Utils.hs
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<a href="#1dd9c7a6bbc222c976a6ec1c4b772232ae60f7e5">
compiler/GHC/Tc/Errors/Ppr.hs
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<a href="#cdba811872892f235fe7059df1a6c538fba60816">
compiler/GHC/Tc/Errors/Types.hs
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<a href="#9355bef855426caf5f526925edf351b20f9a86c4">
compiler/GHC/Tc/Gen/HsType.hs
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<a href="#3ee8be814b6c6727880deab3772e6af922524bf0">
compiler/GHC/Tc/Gen/Pat.hs
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<a href="#83d23a46bb6cdc8b1edc16f1fd2c8f5c53e2c9ca">
compiler/GHC/Tc/TyCl.hs
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<li class="file-stats">
<a href="#e63425e031ffe9350ee6b1687e506aaea75d11e1">
compiler/GHC/Tc/TyCl/Instance.hs
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<a href="#94c96afe1bb3b771ffbcfeeca34ce43ebbe76ccb">
compiler/GHC/Tc/Utils/TcMType.hs
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<a href="#2eac51f9871ca0c0698aa1fc7f79c05ef8fc4a49">
compiler/GHC/ThToHs.hs
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<a href="#e2c828ee9e003df518a07b05beaa6971e5c62eb0">
compiler/GHC/Types/Error/Codes.hs
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<a href="#03e77c5a7f093768fb8c3be51f8c4ece06b78463">
compiler/GHC/Types/Name/Reader.hs
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<a href="#997b81d43f8807b1b83ca6cc7c52b367982f2bf7">
compiler/Language/Haskell/Syntax/Decls.hs
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<a href="#55fd4da29695073f23c02f21476e753eb7c467b4">
compiler/Language/Haskell/Syntax/Extension.hs
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<li class="file-stats">
<a href="#f92237bbf761245188d3b0de16bb685b3eaa2b60">
compiler/Language/Haskell/Syntax/Pat.hs
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<li class="file-stats">
<a href="#ef5ad6f4dfc8fa107eace213eecba4bc1014ca57">
compiler/Language/Haskell/Syntax/Type.hs
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<li class="file-stats">
<a href="#6adce33441521c9a45a2444bb43e44da8e212513">
testsuite/tests/gadt/T18191.stderr
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<a href="#89908b49c35333d3ad5be6d9b93c4f963dde3215">
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testsuite/tests/rename/should_compile/T22478a.hs
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The diff was not included because it is too large.
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