ApiAnnotations : Nested forall loses forall annotation

When parsing

{-# LANGUAGE ScopedTypeVariables #-}

extremumNewton :: forall tag. forall tag1.
                   tag -> tag1 -> Int
extremumNewton = undefined

The parser attaches an AnnForall to the second forall, which appears as a nested HsForAllTy.

Somewhere this nesting is flattened, and the tyvarbndrs are collapsed into a single HsForAllTy. In this process the second AnnForAll loses its anchor in the AST.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Parser)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	mpickering
Operating system
Architecture