[Bug c++/57709] -Wshadow is too strict / has false positives

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57709

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic, patch
             Target|x86_64-unknown-linux-gnu    |
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-19
     Ever confirmed|0                           |1

--- Comment #7 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
The following patch compiles and gives the following output:


/home/manuel/t.cc:6:18: warning: declaration of ‘both_var’ shadows a member of
‘C’ [-Wshadow]
   void m() { int both_var, var_and_method; }
                  ^
/home/manuel/t.cc:3:7: note: shadowed declaration is here
   int both_var;
       ^

No other testing besides that. Please feel free to take it from here.


Index: name-lookup.c
===================================================================
--- name-lookup.c       (revision 205004)
+++ name-lookup.c       (working copy)
@@ -1216,13 +1216,25 @@ pushdecl_maybe_friend_1 (tree x, bool is
              else
                member = NULL_TREE;

              if (member && !TREE_STATIC (member))
                {
-                 /* Location of previous decl is not useful in this case.  */
-                 warning (OPT_Wshadow, "declaration of %qD shadows a member of
'this'",
-                          x);
+                 if (BASELINK_P (member))
+                   member = BASELINK_FUNCTIONS (member);
+
+                 /* Do not warn if a variable shadows a function, unless
+                    the variable is a function or a pointer-to-function.  */
+                 if (!(TREE_CODE (member) == METHOD_TYPE
+                      && TREE_CODE (x) != FUNCTION_DECL
+                      && !FUNCTION_POINTER_TYPE_P (TREE_TYPE (x)))) {
+                   if (warning_at (input_location,
+                                   OPT_Wshadow, "declaration of %qD shadows a
member of %qT",
+                                x, current_nonlambda_class_type ())
+                       && DECL_P(member))
+                     inform (DECL_SOURCE_LOCATION (member),
+                             "shadowed declaration is here");
+                 }
                }
              else if (oldglobal != NULL_TREE
                       && (VAR_P (oldglobal)
                            /* If the old decl is a type decl, only warn if the
                               old decl is an explicit typedef or if both the