re PR middle-end/7651 (Define -Wextra strictly in terms of other warning flags)

2007-02-12  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR middle-end/7651
	* doc/invoke.texi (Wunused-value): Update description.
	(Wextra): Delete item.
	* opts.c (set_Wextra): Don't use the value of Wextra to set the
	value of Wunused-value.
	* c-typeck.c (c_process_expr_stmt): Don't check extra_warnings.
	(c_finish_stmt_expr): Don't check extra_warnings.
	(emit_side_effect_warnings): The caller is responsible to check
	warn_unused_value.
cp/
	* cp-gimplify.c (gimplify_expr_stmt): Don't check extra_warnings.
	Check warn_unused_value just once.

From-SVN: r121843

gcc/ChangeLog

@@ -1,3 +1,15 @@
+2007-02-12  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	PR middle-end/7651
+	* doc/invoke.texi (Wunused-value): Update description.
+	(Wextra): Delete item.
+	* opts.c (set_Wextra): Don't use the value of Wextra to set the
+	value of Wunused-value.
+	* c-typeck.c (c_process_expr_stmt): Don't check extra_warnings.
+	(c_finish_stmt_expr): Don't check extra_warnings.
+	(emit_side_effect_warnings): The caller is responsible to check
+	warn_unused_value.
+	
 2007-02-11  Roger Sayle  <roger@eyesopen.com>
 	    Matt Thomas  <matt@3am-software.com>
 

gcc/c-typeck.c

@@ -7353,10 +7353,10 @@ emit_side_effect_warnings (tree expr)
   else if (!TREE_SIDE_EFFECTS (expr))
     {
       if (!VOID_TYPE_P (TREE_TYPE (expr)) && !TREE_NO_WARNING (expr))
-	warning (0, "%Hstatement with no effect",
+	warning (OPT_Wunused_value, "%Hstatement with no effect",
 		 EXPR_HAS_LOCATION (expr) ? EXPR_LOCUS (expr) : &input_location);
     }
-  else if (warn_unused_value)
+  else
     warn_if_unused_value (expr, input_location);
 }
 
@@ -7381,7 +7381,7 @@ c_process_expr_stmt (tree expr)
      Warnings for statement expressions will be emitted later, once we figure
      out which is the result.  */
   if (!STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
-      && (extra_warnings || warn_unused_value))
+      && warn_unused_value)
     emit_side_effect_warnings (expr);
 
   /* If the expression is not of a type to which we cannot assign a line
@@ -7497,7 +7497,7 @@ c_finish_stmt_expr (tree body)
 
       /* If we're supposed to generate side effects warnings, process
 	 all of the statements except the last.  */
-      if (extra_warnings || warn_unused_value)
+      if (warn_unused_value)
 	{
 	  for (i = tsi_start (last); !tsi_one_before_end_p (i); tsi_next (&i))
 	    emit_side_effect_warnings (tsi_stmt (i));

gcc/cp/ChangeLog

@@ -1,3 +1,9 @@
+2007-02-12  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	PR middle-end/7651
+	* cp-gimplify.c (gimplify_expr_stmt): Don't check extra_warnings.
+	Check warn_unused_value just once.
+
 2007-02-11  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/26988

gcc/cp/cp-gimplify.c

@@ -363,16 +363,16 @@ gimplify_expr_stmt (tree *stmt_p)
      In this case we will not want to emit the gimplified statement.
      However, we may still want to emit a warning, so we do that before
      gimplification.  */
-  if (stmt && (extra_warnings || warn_unused_value))
+  if (stmt && warn_unused_value)
     {
       if (!TREE_SIDE_EFFECTS (stmt))
 	{
 	  if (!IS_EMPTY_STMT (stmt)
 	      && !VOID_TYPE_P (TREE_TYPE (stmt))
 	      && !TREE_NO_WARNING (stmt))
-	    warning (OPT_Wextra, "statement with no effect");
+	    warning (OPT_Wunused_value, "statement with no effect");
 	}
-      else if (warn_unused_value)
+      else
 	warn_if_unused_value (stmt, input_location);
     }
 

gcc/doc/invoke.texi

@@ -2730,10 +2730,14 @@ To suppress this warning use the @samp{unused} attribute
 
 @item -Wunused-value
 @opindex Wunused-value
-Warn whenever a statement computes a result that is explicitly not used.
-This warning is enabled by @option{-Wall}.
+Warn whenever a statement computes a result that is explicitly not
+used. To suppress this warning cast the unused expression to
+@samp{void}. This includes an expression-statement or the left-hand
+side of a comma expression that contains no side effects. For example,
+an expression such as @samp{x[i,j]} will cause a warning, while
+@samp{x[(void)i,j]} will not.
 
-To suppress this warning cast the expression to @samp{void}.
+This warning is enabled by @option{-Wall}.
 
 @item -Wunused
 @opindex Wunused
@@ -2908,13 +2912,6 @@ foo (a)
 @end group
 @end smallexample
 
-@item
-An expression-statement or the left-hand side of a comma expression
-contains no side effects.
-To suppress the warning, cast the unused expression to void.
-For example, an expression such as @samp{x[i,j]} will cause a warning,
-but @samp{x[(void)i,j]} will not.
-
 @item
 An unsigned value is compared against zero with @samp{<} or @samp{>=}.
 

gcc/opts.c

@@ -1042,7 +1042,6 @@ static void
 set_Wextra (int setting)
 {
   extra_warnings = setting;
-  warn_unused_value = setting;
   warn_unused_parameter = (setting && maybe_warn_unused_parameter);
 
   /* We save the value of warn_uninitialized, since if they put