[Git][ghc/ghc][master] Add a test for #21765

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
dd39bdc0 by sheaf at 2023-08-31T00:05:27-04:00
Add a test for #21765

This issue (of reporting a constraint as being redundant even though
removing it causes typechecking to fail) was fixed in aed1974e.
This commit simply adds a regression test.

Fixes #21765

- - - - -


2 changed files:

- + testsuite/tests/typecheck/should_compile/T21765.hs
- testsuite/tests/typecheck/should_compile/all.T


Changes:

=====================================
testsuite/tests/typecheck/should_compile/T21765.hs
=====================================
@@ -0,0 +1,9 @@
+{-# LANGUAGE UndecidableInstances, FlexibleInstances #-}
+
+{-# OPTIONS_GHC -Wredundant-constraints #-}
+
+module T21765 where
+
+class Functor f => C f where c :: f Int
+
+instance (Functor f, Applicative f) => C f where c = pure 42


=====================================
testsuite/tests/typecheck/should_compile/all.T
=====================================
@@ -847,6 +847,7 @@ test('DeepSubsumption06', normal, compile, ['-XHaskell98'])
 test('DeepSubsumption07', normal, compile, ['-XHaskell2010'])
 test('DeepSubsumption08', normal, compile, [''])
 test('DeepSubsumption09', normal, compile, [''])
+test('T21765', normal, compile, [''])
 test('T21951a', normal, compile, ['-Wredundant-strictness-flags'])
 test('T21951b', normal, compile, ['-Wredundant-strictness-flags'])
 test('T21550', normal, compile, [''])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/dd39bdc0f2daef27b42081b7b4a81bdd476eb0b6

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/dd39bdc0f2daef27b42081b7b4a81bdd476eb0b6
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