GHCi :complete command for operators: Fix spaceless cases of #10576.

When separating operators from identifiers in a `:complete` command
take advantage from the different character sets of the two items:
* operators contain only specialSymbol characters.
* Identifiers don't contain specialSymbol characters, with the exception of dots.

1 files changed, 11 insertions, 2 deletions

diff --git a/ghc/GHCi/UI.hs b/ghc/GHCi/UI.hs
index 7dc253b894..97b5f57447 100644
--- a/ghc/GHCi/UI.hs
+++ b/ghc/GHCi/UI.hs
@@ -3466,9 +3466,18 @@ completeMacro = wrapIdentCompleter $ \w -> do
 completeIdentifier line@(left, _) =
   -- Note: `left` is a reversed input
   case left of
-    (x:_) | isSymbolChar x -> wrapCompleter (specials ++ spaces) complete line
-    _                      -> wrapIdentCompleter complete line
+    ('.':_)  -> wrapCompleter (specials ++ spaces) complete line
+               -- operator or qualification
+    (x:_) | isSymbolChar x -> wrapCompleter (specials ++ spaces)
+                                 complete (takeOpChars line)         -- operator
+    _                      -> wrapIdentCompleter complete (takeIdentChars line)
   where
+    takeOpChars (l, r) = (takeWhile isSymbolChar l, r)               -- #10576
+       -- An operator contains only symbol characters
+    takeIdentChars (l, r) = (takeWhile notOpChar l, r)
+       -- An identifier doesn't contain symbol characters with the
+       -- exception of a dot
+    notOpChar c = (not .isSymbol ) c || c == '.'
     complete w = do
       rdrs <- GHC.getRdrNamesInScope
       dflags <- GHC.getSessionDynFlags