[Bug c++/78313] [7 Regression] Misleading spelling suggestion

["dmalcolm at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78313

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #0)
> +++ This bug was initially created as a clone of Bug #72774 +++
> 
> // PR c++/72774
> // { dg-do compile }
> 
> void baz ();
> namespace A { void foo (); }
> void bar ()
> {
>   using A::foo;
>   0 ? static_cast<foo> (0) : baz;	// { dg-error "does not name a type" }
> }
> 
> Actually, the suggestion looks wrong:
> 
> pr72774.C:9:19: error: ‘foo’ does not name a type; did you mean ‘foo’?
> 
> We call lookup_name_fuzzy with kind that we want a typename, but we actually
> except for members consider even FUNCTION_DECLs/VAR_DECLs.  That doesn't
> look right.

I tried fixing this with:

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 84e064d..f0205a6 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -4723,11 +4723,12 @@ consider_binding_level (tree name, best_match <tree,
tree> &bm,
                        cp_binding_level *lvl, bool look_within_fields,
                        enum lookup_name_fuzzy_kind kind)
 {
+  bool want_type_p = (kind == FUZZY_LOOKUP_TYPENAME);
+
   if (look_within_fields)
     if (lvl->this_entity && TREE_CODE (lvl->this_entity) == RECORD_TYPE)
       {
        tree type = lvl->this_entity;
-       bool want_type_p = (kind == FUZZY_LOOKUP_TYPENAME);
        tree best_matching_field
          = lookup_member_fuzzy (type, name, want_type_p);
        if (best_matching_field)
@@ -4757,6 +4758,11 @@ consider_binding_level (tree name, best_match <tree,
tree> &bm,
          && DECL_ANTICIPATED (d))
        continue;

+      /* Function decls are not types.  */
+      if (TREE_CODE (d) == FUNCTION_DECL
+         && want_type_p)
+       continue;
+
       if (DECL_NAME (d))
        bm.consider (DECL_NAME (d));
     }

but then I get this:

  error: 'foo' does not name a type; did you mean 'bool'?

It seems better to simply not offer a suggestion for this case (I have a patch
to do this, by detecting suggestion==goal, and suppressing such a suggestion)