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| author | Kirill Zaborsky <qrilka@gmail.com> | 2018-06-15 14:12:58 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-06-15 14:13:09 -0400 |
| commit | 42f3b53b5bc4674e41f16de08094821fe1aaec00 (patch) | |
| tree | 2c7d4355a4c1ecb90a2bece332ebac03a3c0fc71 | |
| parent | 7100850eebb1c1aec0aaabca08915bac8b90e188 (diff) | |
| download | haskell-42f3b53b5bc4674e41f16de08094821fe1aaec00.tar.gz | |
Fix #13833: accept type literals with no FlexibleInstances
Test Plan: ./validate
Reviewers: bgamari, simonpj
Reviewed By: bgamari, simonpj
Subscribers: simonpj, rwbarton, thomie, carter
GHC Trac Issues: #13833
Differential Revision: https://phabricator.haskell.org/D4823
| -rw-r--r-- | compiler/typecheck/TcValidity.hs | 5 | ||||
| -rw-r--r-- | docs/users_guide/8.6.1-notes.rst | 5 | ||||
| -rw-r--r-- | testsuite/tests/typecheck/should_compile/T13833.hs | 12 | ||||
| -rw-r--r-- | testsuite/tests/typecheck/should_compile/all.T | 1 |
4 files changed, 21 insertions, 2 deletions
diff --git a/compiler/typecheck/TcValidity.hs b/compiler/typecheck/TcValidity.hs index 84309db598..6d866f795d 100644 --- a/compiler/typecheck/TcValidity.hs +++ b/compiler/typecheck/TcValidity.hs @@ -1121,12 +1121,13 @@ tcInstHeadTyNotSynonym ty tcInstHeadTyAppAllTyVars :: Type -> Bool -- Used in Haskell-98 mode, for the argument types of an instance head --- These must be a constructor applied to type variable arguments. +-- These must be a constructor applied to type variable arguments +-- or a type-level literal. -- But we allow kind instantiations. tcInstHeadTyAppAllTyVars ty | Just (tc, tys) <- tcSplitTyConApp_maybe (dropCasts ty) = ok (filterOutInvisibleTypes tc tys) -- avoid kinds - + | LitTy _ <- ty = True -- accept type literals (Trac #13833) | otherwise = False where diff --git a/docs/users_guide/8.6.1-notes.rst b/docs/users_guide/8.6.1-notes.rst index 147558e139..4bc01c904e 100644 --- a/docs/users_guide/8.6.1-notes.rst +++ b/docs/users_guide/8.6.1-notes.rst @@ -125,6 +125,11 @@ Language This is now an error unless :extension:`PolyKinds` is enabled. +- Type literals now could be used in type class instances without the extension + :extension:`FlexibleInstances`. + + See :ghc-ticket:`13833`. + Compiler ~~~~~~~~ diff --git a/testsuite/tests/typecheck/should_compile/T13833.hs b/testsuite/tests/typecheck/should_compile/T13833.hs new file mode 100644 index 0000000000..266b00bd60 --- /dev/null +++ b/testsuite/tests/typecheck/should_compile/T13833.hs @@ -0,0 +1,12 @@ +{-# LANGUAGE DataKinds, KindSignatures #-} + +import GHC.TypeLits (Nat, Symbol) + +class A (n::Nat) +instance A 0 + +class B (s::Symbol) +instance B "B" + +main :: IO () +main = return () diff --git a/testsuite/tests/typecheck/should_compile/all.T b/testsuite/tests/typecheck/should_compile/all.T index 8a7a7da8ce..beaea5dcd1 100644 --- a/testsuite/tests/typecheck/should_compile/all.T +++ b/testsuite/tests/typecheck/should_compile/all.T @@ -623,3 +623,4 @@ test('T15050', [expect_broken(15050)], compile, ['']) test('T14735', normal, compile, ['']) test('T15180', normal, compile, ['']) test('T15232', normal, compile, ['']) +test('T13833', normal, compile, [''])
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