re PR c++/34691 (Default argument checking not performed after overload resolution with C linkage)

PR c++/34691
        * name-lookup.c (merge_functions): Keep multiple extern C functions.
        * call.c (joust): Complain about mismatched default arguments
        in extern C functions.
        * class.c (resolve_address_of_overloaded_function): Handle multiple
        extern C functions.
        * pt.c (resolve_overloaded_unification): Likewise.

From-SVN: r145710

gcc/cp/ChangeLog

@@ -1,5 +1,13 @@
 2009-04-07  Jason Merrill  <jason@redhat.com>
 
+	PR c++/34691
+	* name-lookup.c	(merge_functions): Keep multiple extern "C" functions.
+	* call.c (joust): Complain about mismatched default arguments
+	in extern "C" functions.
+	* class.c (resolve_address_of_overloaded_function): Handle multiple
+	extern "C" functions.
+	* pt.c (resolve_overloaded_unification): Likewise.
+
 	* decl.c (grokdeclarator): Reject pointer to qualified function
 	type.
 

gcc/cp/call.c

@@ -6787,11 +6787,53 @@ joust (struct z_candidate *cand1, struct z_candidate *cand2, bool warn)
 	}
     }
 
-  /* If the two functions are the same (this can happen with declarations
-     in multiple scopes and arg-dependent lookup), arbitrarily choose one.  */
+  /* If the two function declarations represent the same function (this can
+     happen with declarations in multiple scopes and arg-dependent lookup),
+     arbitrarily choose one.  But first make sure the default args we're
+     using match.  */
   if (DECL_P (cand1->fn) && DECL_P (cand2->fn)
       && equal_functions (cand1->fn, cand2->fn))
-    return 1;
+    {
+      tree parms1 = TYPE_ARG_TYPES (TREE_TYPE (cand1->fn));
+      tree parms2 = TYPE_ARG_TYPES (TREE_TYPE (cand2->fn));
+
+      gcc_assert (!DECL_CONSTRUCTOR_P (cand1->fn));
+
+      for (i = 0; i < len; ++i)
+	{
+	  parms1 = TREE_CHAIN (parms1);
+	  parms2 = TREE_CHAIN (parms2);
+	}
+
+      if (off1)
+	parms1 = TREE_CHAIN (parms1);
+      else if (off2)
+	parms2 = TREE_CHAIN (parms2);
+
+      for (; parms1; ++i)
+	{
+	  if (!cp_tree_equal (TREE_PURPOSE (parms1),
+			      TREE_PURPOSE (parms2)))
+	    {
+	      if (warn)
+		{
+		  permerror (input_location, "default argument mismatch in "
+			     "overload resolution");
+		  inform (input_location,
+			  " candidate 1: %q+#F", cand1->fn);
+		  inform (input_location,
+			  " candidate 2: %q+#F", cand2->fn);
+		}
+	      else
+		add_warning (cand1, cand2);
+	      break;
+	    }
+	  parms1 = TREE_CHAIN (parms1);
+	  parms2 = TREE_CHAIN (parms2);
+	}
+
+      return 1;
+    }
 
 tweak:
 

gcc/cp/class.c

@@ -6152,25 +6152,33 @@ resolve_address_of_overloaded_function (tree target_type,
     }
   else if (TREE_CHAIN (matches))
     {
-      /* There were too many matches.  */
+      /* There were too many matches.  First check if they're all
+	 the same function.  */
+      tree match;
 
-      if (flags & tf_error)
+      fn = TREE_PURPOSE (matches);
+      for (match = TREE_CHAIN (matches); match; match = TREE_CHAIN (match))
+	if (!decls_match (fn, TREE_PURPOSE (matches)))
+	  break;
+
+      if (match)
 	{
-	  tree match;
+	  if (flags & tf_error)
+	    {
+	      error ("converting overloaded function %qD to type %q#T is ambiguous",
+		     DECL_NAME (OVL_FUNCTION (overload)),
+		     target_type);
 
-	  error ("converting overloaded function %qD to type %q#T is ambiguous",
-		    DECL_NAME (OVL_FUNCTION (overload)),
-		    target_type);
+	      /* Since print_candidates expects the functions in the
+		 TREE_VALUE slot, we flip them here.  */
+	      for (match = matches; match; match = TREE_CHAIN (match))
+		TREE_VALUE (match) = TREE_PURPOSE (match);
 
-	  /* Since print_candidates expects the functions in the
-	     TREE_VALUE slot, we flip them here.  */
-	  for (match = matches; match; match = TREE_CHAIN (match))
-	    TREE_VALUE (match) = TREE_PURPOSE (match);
+	      print_candidates (matches);
+	    }
 
-	  print_candidates (matches);
+	  return error_mark_node;
 	}
-
-      return error_mark_node;
     }
 
   /* Good, exactly one match.  Now, convert it to the correct type.  */

gcc/cp/name-lookup.c

@@ -3601,10 +3601,9 @@ merge_functions (tree s1, tree s2)
 	  /* If the function from S2 is already in S1, there is no
 	     need to add it again.  For `extern "C"' functions, we
 	     might have two FUNCTION_DECLs for the same function, in
-	     different namespaces; again, we only need one of them.  */
-	  if (fn1 == fn2
-	      || (DECL_EXTERN_C_P (fn1) && DECL_EXTERN_C_P (fn2)
-		  && DECL_NAME (fn1) == DECL_NAME (fn2)))
+	     different namespaces, but let's leave them in in case
+	     they have different default arguments.  */
+	  if (fn1 == fn2)
 	    break;
 	}
 

gcc/cp/pt.c

@@ -12635,6 +12635,7 @@ resolve_overloaded_unification (tree tparms,
 {
   tree tempargs = copy_node (targs);
   int good = 0;
+  tree goodfn = NULL_TREE;
   bool addr_p;
 
   if (TREE_CODE (arg) == ADDR_EXPR)
@@ -12680,8 +12681,13 @@ resolve_overloaded_unification (tree tparms,
 	  if (subargs)
 	    {
 	      elem = tsubst (TREE_TYPE (fn), subargs, tf_none, NULL_TREE);
-	      good += try_one_overload (tparms, targs, tempargs, parm,
-					elem, strict, sub_strict, addr_p);
+	      if (try_one_overload (tparms, targs, tempargs, parm,
+				    elem, strict, sub_strict, addr_p)
+		  && (!goodfn || !decls_match (goodfn, elem)))
+		{
+		  goodfn = elem;
+		  ++good;
+		}
 	    }
 	  --processing_template_decl;
 	}
@@ -12694,9 +12700,14 @@ resolve_overloaded_unification (tree tparms,
     return false;
   else
     for (; arg; arg = OVL_NEXT (arg))
-      good += try_one_overload (tparms, targs, tempargs, parm,
-				TREE_TYPE (OVL_CURRENT (arg)),
-				strict, sub_strict, addr_p);
+      if (try_one_overload (tparms, targs, tempargs, parm,
+			    TREE_TYPE (OVL_CURRENT (arg)),
+			    strict, sub_strict, addr_p)
+	  && (!goodfn || !decls_match (goodfn, OVL_CURRENT (arg))))
+	{
+	  goodfn = OVL_CURRENT (arg);
+	  ++good;
+	}
 
   /* [temp.deduct.type] A template-argument can be deduced from a pointer
      to function or pointer to member function argument if the set of

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2009-04-07  Jason Merrill  <jason@redhat.com>
+
+	PR c++/34691
+	* g++.dg/overload/extern-C-1.C: New.
+
 2009-04-07  Dominique d'Humieres  <dominiq@lps.ens.fr>
 
 	PR testsuite/39325

gcc/testsuite/g++.dg/overload/extern-C-1.C

@@ -0,0 +1,17 @@
+// PR c++/34691
+
+namespace A {
+  extern "C" void f(int = 5);	// { dg-message "= 5" }
+}
+namespace B {
+  extern "C" void f(int = 4);	// { dg-message "= 4" }
+}
+
+using A::f;
+using B::f;
+int main() {
+  void (*fp)(int) = f;		// OK
+  f(3);				// OK
+  f();				// { dg-error "default argument mismatch" }
+}
+