ApiAnnotations : preserve parens in GADTs

A cleanup in 7f418acf61e accidentally discarded some parens in
ConDeclGADT.

Make sure these stay in the AST in a usable format.

Also ensure the AnnLolly does not get lost in a GADT.

1 files changed, 39 insertions, 0 deletions

diff --git a/compiler/GHC/Parser/Annotation.hs b/compiler/GHC/Parser/Annotation.hs
index 6560d5e735..0cbf44296f 100644
--- a/compiler/GHC/Parser/Annotation.hs
+++ b/compiler/GHC/Parser/Annotation.hs
@@ -6,6 +6,7 @@ module GHC.Parser.Annotation (
   ApiAnns(..),
   ApiAnnKey,
   AnnKeywordId(..),
+  AddAnn(..),mkParensApiAnn,
   AnnotationComment(..),
   IsUnicodeSyntax(..),
   unicodeAnn,
@@ -148,6 +149,44 @@ data ApiAnns =
 type ApiAnnKey = (RealSrcSpan,AnnKeywordId)
 
 
+-- ---------------------------------------------------------------------
+
+-- | Encapsulated call to addAnnotation, requiring only the SrcSpan of
+--   the AST construct the annotation belongs to; together with the
+--   AnnKeywordId, this is the key of the annotation map.
+--
+--   This type is useful for places in the parser where it is not yet
+--   known what SrcSpan an annotation should be added to.  The most
+--   common situation is when we are parsing a list: the annotations
+--   need to be associated with the AST element that *contains* the
+--   list, not the list itself.  'AddAnn' lets us defer adding the
+--   annotations until we finish parsing the list and are now parsing
+--   the enclosing element; we then apply the 'AddAnn' to associate
+--   the annotations.  Another common situation is where a common fragment of
+--   the AST has been factored out but there is no separate AST node for
+--   this fragment (this occurs in class and data declarations). In this
+--   case, the annotation belongs to the parent data declaration.
+--
+--   The usual way an 'AddAnn' is created is using the 'mj' ("make jump")
+--   function, and then it can be discharged using the 'ams' function.
+data AddAnn = AddAnn AnnKeywordId SrcSpan
+
+-- |Given a 'SrcSpan' that surrounds a 'HsPar' or 'HsParTy', generate
+-- 'AddAnn' values for the opening and closing bordering on the start
+-- and end of the span
+mkParensApiAnn :: SrcSpan -> [AddAnn]
+mkParensApiAnn (UnhelpfulSpan _)  = []
+mkParensApiAnn (RealSrcSpan ss _) = [AddAnn AnnOpenP lo,AddAnn AnnCloseP lc]
+  where
+    f = srcSpanFile ss
+    sl = srcSpanStartLine ss
+    sc = srcSpanStartCol ss
+    el = srcSpanEndLine ss
+    ec = srcSpanEndCol ss
+    lo = RealSrcSpan (mkRealSrcSpan (realSrcSpanStart ss)        (mkRealSrcLoc f sl (sc+1))) Nothing
+    lc = RealSrcSpan (mkRealSrcSpan (mkRealSrcLoc f el (ec - 1)) (realSrcSpanEnd ss))        Nothing
+
+-- ---------------------------------------------------------------------
 -- | Retrieve a list of annotation 'SrcSpan's based on the 'SrcSpan'
 -- of the annotated AST element, and the known type of the annotation.
 getAnnotation :: ApiAnns -> RealSrcSpan -> AnnKeywordId -> [RealSrcSpan]