re PR c++/12266 (incorrect instantiation of unneeded template during overload resolution)

PR c++/12266
	* cp-tree.h (tsubst_flags_t): Add tf_conv.
	* class.c (standard_conversion): Pass tf_conv to
	instantiate_type.
	(resolve_address_of_overloaded_function): Do not call mark_used
	when just checking conversions.

	PR c++/12266
	* g++.dg/overload/template1.C: New test.

From-SVN: r71483

gcc/cp/ChangeLog

@@ -1,5 +1,12 @@
 2003-09-17  Mark Mitchell  <mark@codesourcery.com>
 
+	PR c++/12266
+	* cp-tree.h (tsubst_flags_t): Add tf_conv.
+	* class.c (standard_conversion): Pass tf_conv to
+	instantiate_type.
+	(resolve_address_of_overloaded_function): Do not call mark_used
+	when just checking conversions.
+
 	PR debug/12066
 	* cp-lang.c (LANG_HOOKS_BUILTIN_TYPE_DECLS): Define.
 	* cp-tree.h (cxx_builtin_type_decls): Declare.

gcc/cp/call.c

@@ -593,7 +593,7 @@ standard_conversion (tree to, tree from, tree expr)
   if ((TYPE_PTRFN_P (to) || TYPE_PTRMEMFUNC_P (to))
       && expr && type_unknown_p (expr))
     {
-      expr = instantiate_type (to, expr, tf_none);
+      expr = instantiate_type (to, expr, tf_conv);
       if (expr == error_mark_node)
 	return NULL_TREE;
       from = TREE_TYPE (expr);

gcc/cp/class.c

@@ -5937,7 +5937,13 @@ cannot resolve overloaded function `%D' based on conversion to type `%T'",
           explained = 1;
         }
     }
-  mark_used (fn);
+
+  /* If we're doing overload resolution purely for the purpose of
+     determining conversion sequences, we should not consider the
+     function used.  If this conversion sequence is selected, the
+     function will be marked as used at this point.  */
+  if (!(flags & tf_conv))
+    mark_used (fn);
 
   if (TYPE_PTRFN_P (target_type) || TYPE_PTRMEMFUNC_P (target_type))
     return build_unary_op (ADDR_EXPR, fn, 0);

gcc/cp/cp-tree.h

@@ -3034,9 +3034,13 @@ typedef enum tsubst_flags_t {
 				   (lookup_template_class use) */
   tf_stmt_expr_cmpd = 1 << 6,   /* tsubsting the compound statement of
 				   a statement expr.  */
-  tf_stmt_expr_body = 1 << 7    /* tsubsting the statements in the
+  tf_stmt_expr_body = 1 << 7,   /* tsubsting the statements in the
 			       	   body of the compound statement of a
 			       	   statement expr.  */
+  tf_conv = 1 << 8              /* We are determining what kind of
+				   conversion might be permissible,
+				   not actually performing the
+				   conversion.  */
 } tsubst_flags_t;
 
 /* The kind of checking we can do looking in a class hierarchy.  */

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2003-09-17  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/12266
+	* g++.dg/overload/template1.C: New test.
+
 2003-09-17  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	* g++.dg/opt/cfg3.C: New test.

gcc/testsuite/g++.dg/overload/template1.C

@@ -0,0 +1,12 @@
+template<typename T> T Foo (int) {T d;}
+
+void Baz (void (*)(int), int);
+
+int Foo ();
+int Baz (int (*)(), float);
+
+void Bar ()
+{
+  Baz (Foo, 1.0f);
+  
+}