DisambiguateRecordFields fails for PatternSynonyms

Consider:

{-# LANGUAGE PatternSynonyms #-}

module A where

pattern S{x} = [x]

{-# LANGUAGE PatternSynonyms, DisambiguateRecordFields #-}

module B where

import A

pattern T{x} = [x]

e = S { x = 42 }

Compiling module B fails with Ambiguous occurrence ‘x’ in the definition of e. In principle, DisambiguateRecordFields should select the field belonging to the S "data constructor". However, the current implementation of this works by identifying the parent type constructor, which doesn't exist for a pattern synonym.

This continues to fail if T is replaced by a data type with a field x. If S is replaced by a data type, however, it starts working.

Trac metadata

Trac field	Value
Version	8.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related	#11283 (closed)
Blocking
CC	mpickering
Operating system
Architecture