re PR c/23075 (Redundant / bogus warning)

	PR c/23075
	* c-typeck.c (c_finish_return): Set TREE_NO_WARNING on RETURN_EXPR
	if "return with no value, in function returning non-void" warning
	has been issued.
  	* tree-cfg.c (execute_warn_function_return): Don't look at
	RETURN_EXPRs with TREE_NO_WARNING set.

	* typeck.c (check_return_expr): Add no_warning argument.  Set
	*no_warning to true if "return-statement with no value, in function
	returning" warning has been issued.
	* cp-tree.h (check_return_expr): Adjust prototype.
	* semantics.c (finish_return_stmt): Set TREE_NO_WARNING if
	check_return_expr set *no_warning to true.

	* gcc.dg/pr23075.c: New test.
	* g++.dg/warn/pr23075.C: New test.

From-SVN: r103967

gcc/ChangeLog

 2005-09-06  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c/23075
+	* c-typeck.c (c_finish_return): Set TREE_NO_WARNING on RETURN_EXPR
+	if "return with no value, in function returning non-void" warning
+	has been issued.
+  	* tree-cfg.c (execute_warn_function_return): Don't look at
+	RETURN_EXPRs with TREE_NO_WARNING set.
+
 	PR target/22362
 	* config/i386/i386.c (ix86_function_regparm): Make sure automatic regparm
 	for internal functions doesn't use registers used by global registers

gcc/c-typeck.c

@@ -6702,7 +6702,8 @@ c_finish_goto_ptr (tree expr)
 tree
 c_finish_return (tree retval)
 {
-  tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl));
+  tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl)), ret_stmt;
+  bool no_warning = false;
 
   if (TREE_THIS_VOLATILE (current_function_decl))
     warning (0, "function declared %<noreturn%> has a %<return%> statement");
@@ -6712,8 +6713,11 @@ c_finish_return (tree retval)
       current_function_returns_null = 1;
       if ((warn_return_type || flag_isoc99)
 	  && valtype != 0 && TREE_CODE (valtype) != VOID_TYPE)
+	{
 	  pedwarn_c99 ("%<return%> with no value, in "
 		       "function returning non-void");
+	  no_warning = true;
+	}
     }
   else if (valtype == 0 || TREE_CODE (valtype) == VOID_TYPE)
     {
@@ -6789,7 +6793,9 @@ c_finish_return (tree retval)
       retval = build2 (MODIFY_EXPR, TREE_TYPE (res), res, t);
     }
 
-  return add_stmt (build_stmt (RETURN_EXPR, retval));
+  ret_stmt = build_stmt (RETURN_EXPR, retval);
+  TREE_NO_WARNING (ret_stmt) |= no_warning;
+  return add_stmt (ret_stmt);
 }
 
 struct c_switch {

gcc/cp/ChangeLog

+2005-09-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/23075
+	* typeck.c (check_return_expr): Add no_warning argument.  Set
+	*no_warning to true if "return-statement with no value, in function
+	returning" warning has been issued.
+	* cp-tree.h (check_return_expr): Adjust prototype.
+	* semantics.c (finish_return_stmt): Set TREE_NO_WARNING if
+	check_return_expr set *no_warning to true.
+
 2005-09-06  Mark Mitchell  <mark@codesourcery.com>
 
 	* cp-tree.h (rvalue): New function.

gcc/cp/cp-tree.h

@@ -4322,7 +4322,7 @@ extern tree type_after_usual_arithmetic_conversions (tree, tree);
 extern tree composite_pointer_type		(tree, tree, tree, tree,
 						 const char*);
 extern tree merge_types				(tree, tree);
-extern tree check_return_expr			(tree);
+extern tree check_return_expr			(tree, bool *);
 #define cp_build_binary_op(code, arg1, arg2) \
   build_binary_op(code, arg1, arg2, 1)
 #define cxx_sizeof(T)  cxx_sizeof_or_alignof_type (T, SIZEOF_EXPR, true)

gcc/cp/semantics.c

@@ -743,8 +743,9 @@ tree
 finish_return_stmt (tree expr)
 {
   tree r;
+  bool no_warning;
 
-  expr = check_return_expr (expr);
+  expr = check_return_expr (expr, &no_warning);
   if (!processing_template_decl)
     {
       if (DECL_DESTRUCTOR_P (current_function_decl)
@@ -760,6 +761,7 @@ finish_return_stmt (tree expr)
     }
 
   r = build_stmt (RETURN_EXPR, expr);
+  TREE_NO_WARNING (r) |= no_warning;
   r = maybe_cleanup_point_expr_void (r);
   r = add_stmt (r);
   finish_stmt ();

gcc/cp/typeck.c

@@ -6134,10 +6134,12 @@ maybe_warn_about_returning_address_of_local (tree retval)
 /* Check that returning RETVAL from the current function is valid.
    Return an expression explicitly showing all conversions required to
    change RETVAL into the function return type, and to assign it to
-   the DECL_RESULT for the function.  */
+   the DECL_RESULT for the function.  Set *NO_WARNING to true if
+   code reaches end of non-void function warning shouldn't be issued
+   on this RETURN_EXPR.  */
 
 tree
-check_return_expr (tree retval)
+check_return_expr (tree retval, bool *no_warning)
 {
   tree result;
   /* The type actually returned by the function, after any
@@ -6145,6 +6147,8 @@ check_return_expr (tree retval)
   tree valtype;
   int fn_returns_value_p;
 
+  *no_warning = false;
+
   /* A `volatile' function is one that isn't supposed to return, ever.
      (This is a G++ extension, used to get better code for functions
      that call the `volatile' function.)  */
@@ -6195,6 +6199,10 @@ check_return_expr (tree retval)
 	 end of a non-void function (which we don't, we gave a
 	 return!).  */
       current_function_returns_null = 0;
+      /* And signal caller that TREE_NO_WARNING should be set on the
+         RETURN_EXPR to avoid control reaches end of non-void function
+         warnings in tree-cfg.c.  */
+      *no_warning = true;
     }
   /* Check for a return statement with a value in a function that
      isn't supposed to return a value.  */

gcc/testsuite/ChangeLog

 2005-09-06  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c/23075
+	* gcc.dg/pr23075.c: New test.
+	* g++.dg/warn/pr23075.C: New test.
+
 	PR target/22362
 	* gcc.target/i386/pr22362.c: New test.
 

gcc/testsuite/g++.dg/warn/pr23075.C

+// PR c/23075
+// { dg-do compile }
+// { dg-options "-O2 -Wreturn-type" }
+
+int
+foo (void)
+{
+  return;	// { dg-error "with no value" }
+}		// { dg-bogus "control reaches end" }
+
+int
+bar (void)
+{
+}		// { dg-warning "control reaches end" }

gcc/testsuite/gcc.dg/pr23075.c

+/* PR c/23075 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wreturn-type" } */
+
+int
+foo (void)
+{
+  return;	/* { dg-warning "with no value" } */
+}		/* { dg-bogus "control reaches end" } */
+
+int
+bar (void)
+{
+}		/* { dg-warning "control reaches end" } */

gcc/tree-cfg.c

@@ -5125,7 +5125,8 @@ execute_warn_function_return (void)
 	{
 	  tree last = last_stmt (e->src);
 	  if (TREE_CODE (last) == RETURN_EXPR
-	      && TREE_OPERAND (last, 0) == NULL)
+	      && TREE_OPERAND (last, 0) == NULL
+	      && !TREE_NO_WARNING (last))
 	    {
 #ifdef USE_MAPPED_LOCATION
 	      location = EXPR_LOCATION (last);