diff options
Diffstat (limited to 'compiler/parser')
| -rw-r--r-- | compiler/parser/Parser.y | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y index 7b40574307..e7618289ee 100644 --- a/compiler/parser/Parser.y +++ b/compiler/parser/Parser.y @@ -1607,12 +1607,28 @@ context :: { LHsContext RdrName } else return () ; ams ctx anns } } +{- Note [GADT decl discards annotations] +~~~~~~~~~~~~~~~~~~~~~ +The type production for + + btype `->` btype + +adds the AnnRarrow annotation twice, in different places. + +This is because if the type is processed as usual, it belongs on the annotations +for the type as a whole. + +But if the type is passed to mkGadtDecl, it discards the top level SrcSpan, and +the top-level annotation will be disconnected. Hence for this specific case it +is connected to the first type too. +-} + -- See Note [Parsing ~] type :: { LHsType RdrName } : btype { splitTilde $1 } | btype qtyconop type { sLL $1 $> $ mkHsOpTy $1 $2 $3 } | btype tyvarop type { sLL $1 $> $ mkHsOpTy $1 $2 $3 } - | btype '->' ctype {% ams $1 [mu AnnRarrow $2] + | btype '->' ctype {% ams $1 [mu AnnRarrow $2] -- See note [GADT decl discards annotations] >> ams (sLL $1 $> $ HsFunTy (splitTilde $1) $3) [mu AnnRarrow $2] } | btype SIMPLEQUOTE qconop type {% ams (sLL $1 $> $ mkHsOpTy $1 $3 $4) |