tree.h (expand_expr_stmt_value): Add maybe_last argument.

	* tree.h (expand_expr_stmt_value): Add maybe_last argument.
	* c-common.h (genrtl_expr_stmt_value): Likewise.
	* stmt.c (expand_expr_stmt): Pass 1 as maybe_last.
	(expand_expr_stmt_value): Add maybe_last argument.
	Don't warn about statement with no effect if it is the last statement
	in expression statement.
	* c-semantics.c (genrtl_expr_stmt): Pass 1 as maybe_last.
	(genrtl_expr_stmt_value): Add maybe_last argument, pass it down to
	expand_expr_stmt_value.
	(expand_stmt) [EXPR_STMT]: Pass 1 as maybe_last to
	genrtl_expr_stmt_value if t is the last EXPR_STMT in its scope.
	* expr.c (expand_expr) [LABELED_BLOCK_EXPR, LOOP_EXPR]: Pass 1
	as maybe_last to expand_expr_stmt_value.

	* gcc.dg/20020104-1.c: New test.

From-SVN: r48541

gcc/ChangeLog

+2002-01-04  Jakub Jelinek  <jakub@redhat.com>
+
+	* tree.h (expand_expr_stmt_value): Add maybe_last argument.
+	* c-common.h (genrtl_expr_stmt_value): Likewise.
+	* stmt.c (expand_expr_stmt): Pass 1 as maybe_last.
+	(expand_expr_stmt_value): Add maybe_last argument.
+	Don't warn about statement with no effect if it is the last statement
+	in expression statement.
+	* c-semantics.c (genrtl_expr_stmt): Pass 1 as maybe_last.
+	(genrtl_expr_stmt_value): Add maybe_last argument, pass it down to
+	expand_expr_stmt_value.
+	(expand_stmt) [EXPR_STMT]: Pass 1 as maybe_last to
+	genrtl_expr_stmt_value if t is the last EXPR_STMT in its scope.
+	* expr.c (expand_expr) [LABELED_BLOCK_EXPR, LOOP_EXPR]: Pass 1
+	as maybe_last to expand_expr_stmt_value.
+
 Fri Jan  4 11:45:05 2002  Jeffrey A Law  (law@redhat.com)
 
         * c-common.c (c_expand_start_cond): Expect the IF_STMT node to

gcc/c-common.h

@@ -721,7 +721,7 @@ extern void add_c_tree_codes		        PARAMS ((void));
 extern void genrtl_do_pushlevel                 PARAMS ((void));
 extern void genrtl_goto_stmt                    PARAMS ((tree));
 extern void genrtl_expr_stmt                    PARAMS ((tree));
-extern void genrtl_expr_stmt_value              PARAMS ((tree, int));
+extern void genrtl_expr_stmt_value              PARAMS ((tree, int, int));
 extern void genrtl_decl_stmt                    PARAMS ((tree));
 extern void genrtl_if_stmt                      PARAMS ((tree));
 extern void genrtl_while_stmt                   PARAMS ((tree));

gcc/c-semantics.c

@@ -313,18 +313,20 @@ void
 genrtl_expr_stmt (expr)
      tree expr;
 {
-  genrtl_expr_stmt_value (expr, -1);
+  genrtl_expr_stmt_value (expr, -1, 1);
 }
 
 /* Generate the RTL for EXPR, which is an EXPR_STMT.  WANT_VALUE tells
    whether to (1) save the value of the expression, (0) discard it or
    (-1) use expr_stmts_for_value to tell.  The use of -1 is
-   deprecated, and retained only for backward compatibility.  */
+   deprecated, and retained only for backward compatibility.
+   MAYBE_LAST is non-zero if this EXPR_STMT might be the last statement
+   in expression statement.  */
 
 void 
-genrtl_expr_stmt_value (expr, want_value)
+genrtl_expr_stmt_value (expr, want_value, maybe_last)
      tree expr;
-     int want_value;
+     int want_value, maybe_last;
 {
   if (expr != NULL_TREE)
     {
@@ -334,7 +336,7 @@ genrtl_expr_stmt_value (expr, want_value)
 	expand_start_target_temps ();
       
       if (expr != error_mark_node)
-	expand_expr_stmt_value (expr, want_value);
+	expand_expr_stmt_value (expr, want_value, maybe_last);
       
       if (stmts_are_full_exprs_p ())
 	expand_end_target_temps ();
@@ -763,7 +765,10 @@ expand_stmt (t)
 	  break;
 
 	case EXPR_STMT:
-	  genrtl_expr_stmt_value (EXPR_STMT_EXPR (t), TREE_ADDRESSABLE (t));
+	  genrtl_expr_stmt_value (EXPR_STMT_EXPR (t), TREE_ADDRESSABLE (t),
+				  TREE_CHAIN (t) == NULL
+				  || (TREE_CODE (TREE_CHAIN (t)) == SCOPE_STMT
+				      && TREE_CHAIN (TREE_CHAIN (t)) == NULL));
 	  break;
 
 	case DECL_STMT:

gcc/expr.c

@@ -6453,7 +6453,7 @@ expand_expr (exp, target, tmode, modifier)
 
     case LABELED_BLOCK_EXPR:
       if (LABELED_BLOCK_BODY (exp))
-	expand_expr_stmt_value (LABELED_BLOCK_BODY (exp), 0);
+	expand_expr_stmt_value (LABELED_BLOCK_BODY (exp), 0, 1);
       /* Should perhaps use expand_label, but this is simpler and safer.  */
       do_pending_stack_adjust ();
       emit_label (label_rtx (LABELED_BLOCK_LABEL (exp)));
@@ -6468,7 +6468,7 @@ expand_expr (exp, target, tmode, modifier)
     case LOOP_EXPR:
       push_temp_slots ();
       expand_start_loop (1);
-      expand_expr_stmt_value (TREE_OPERAND (exp, 0), 0);
+      expand_expr_stmt_value (TREE_OPERAND (exp, 0), 0, 1);
       expand_end_loop ();
       pop_temp_slots ();
 

gcc/stmt.c

@@ -2190,7 +2190,7 @@ void
 expand_expr_stmt (exp)
      tree exp;
 {
-  expand_expr_stmt_value (exp, -1);
+  expand_expr_stmt_value (exp, -1, 1);
 }
 
 /* Generate RTL to evaluate the expression EXP.  WANT_VALUE tells
@@ -2199,9 +2199,9 @@ expand_expr_stmt (exp)
    deprecated, and retained only for backward compatibility.  */
 
 void
-expand_expr_stmt_value (exp, want_value)
+expand_expr_stmt_value (exp, want_value, maybe_last)
      tree exp;
-     int want_value;
+     int want_value, maybe_last;
 {
   rtx value;
   tree type;
@@ -2211,8 +2211,10 @@ expand_expr_stmt_value (exp, want_value)
 
   /* If -W, warn about statements with no side effects,
      except for an explicit cast to void (e.g. for assert()), and
-     except inside a ({...}) where they may be useful.  */
-  if (! want_value && exp != error_mark_node)
+     except for last statement in ({...}) where they may be useful.  */
+  if (! want_value
+      && (expr_stmts_for_value == 0 || ! maybe_last)
+      && exp != error_mark_node)
     {
       if (! TREE_SIDE_EFFECTS (exp))
 	{

gcc/testsuite/ChangeLog

+2002-01-04  Jakub Jelinek  <jakub@redhat.com>
+
+	* gcc.dg/20020104-1.c: New test.
+
 2002-01-04  Hans-Peter Nilsson  <hp@bitrange.com>
 
 	* gcc.dg/20020103-1.c: Fix typo in target selector.

gcc/testsuite/gcc.dg/20020104-1.c

+/* Test whether statement with no effect warnings are not given for last
+   statements inside of statement expression.  */
+/* { dg-do compile } */
+/* { dg-options "-O -Wall" } */
+
+void bar (char *p, char *q);
+
+int main()
+{
+  char foo [32], *p;
+
+  ({
+    void *s = (foo);
+    __builtin_memset (s, '\0', sizeof (foo));
+    s; /* { dg-warning "no effect" "statement with no effect warning" } */
+    s; /* { dg-bogus "no effect" "bogus statement with no effect warning" } */
+  });
+  p = foo;
+  p;   /* { dg-warning "no effect" "statement with no effect warning" } */
+  bar (foo, p);
+  return 0;
+}

gcc/tree.h

@@ -2720,7 +2720,7 @@ extern void expand_fixups			PARAMS ((rtx));
 extern tree expand_start_stmt_expr		PARAMS ((void));
 extern tree expand_end_stmt_expr		PARAMS ((tree));
 extern void expand_expr_stmt			PARAMS ((tree));
-extern void expand_expr_stmt_value		PARAMS ((tree, int));
+extern void expand_expr_stmt_value		PARAMS ((tree, int, int));
 extern int warn_if_unused_value			PARAMS ((tree));
 extern void expand_decl_init			PARAMS ((tree));
 extern void clear_last_expr			PARAMS ((void));