An unwritten kind variable is "specified", when it shouldn't be.

This fails:

{-# LANGUAGE PolyKinds, TypeApplications, ScopedTypeVariables #-}

module Bug where

import Data.Proxy

class C a where
  foo :: Proxy a

bar :: forall a. C a => Proxy a
bar = foo @a

But it really should work, because the invisible kind variable to class C should not be available for type application. On the last line, foo @_ @a works, when you explicitly instantiate the kind variable. Also, saying :t foo in GHCi shows the specified kind variable.

Will fix. At some point.

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
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Operating system
Architecture

changed weight to 5

added Tbug Trac import TypeApplications labels

mentioned in commit f4f315a3

Trac metadata

Trac field	Value
Test case	- → typecheck/should_compile/T11512

added 1 deleted label

changed milestone to %8.0.1

Merged as 4c64da07.

mentioned in commit 35e93797

closed

Merged as fefaba91.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

removed 1 deleted label

added Pnormal label