Fix Trac #3155: better error message when -XRankNTypes is omitted

[ghc-hetmet.git] / compiler / parser / Parser.y.pp

diff --git a/compiler/parser/Parser.y.pp b/compiler/parser/Parser.y.pp
index b73deb5..f0fc523 100644 (file)
--- a/compiler/parser/Parser.y.pp
+++ b/compiler/parser/Parser.y.pp
@@ -1829,6 +1829,11 @@ tyvar   : tyvarid                { $1 }
 tyvarop :: { Located RdrName }
 tyvarop : '`' tyvarid '`'      { LL (unLoc $2) }
        | tyvarsym              { $1 }
+       | '.'                   {% parseErrorSDoc (getLoc $1) 
+                                     (vcat [ptext (sLit "Illegal symbol '.' in type"), 
+                                            ptext (sLit "Perhaps you intended -XRankNTypes or similar flag"),
+                                            ptext (sLit "to enable explicit-forall syntax: forall <tvs>. <type>")])
+                               }
 
 tyvarid        :: { Located RdrName }
        : VARID                 { L1 $! mkUnqual tvName (getVARID $1) }