Type aliases for TypeError constrains fire during compilation time

Hello!

The following code should compile fine:

module Main where 

import GHC.TypeLits (ErrorMessage(Text, ShowType, (:<>:)), TypeError)

type MyError a b = TypeError (ShowType a :<>: ShowType b)

main :: IO ()
main = return ()

but it raises an error during compilation:

Main.hs:5:1: error:
    • ab
    • In the type synonym declaration for ‘MyError’

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture