re PR bootstrap/43699 ("variable set but not used" error during bootstrap)

	PR bootstrap/43699
	* c-typeck.c (c_process_expr_stmt): Call mark_exp_read even
	for exprs satisfying handled_component_p.

	* gcc.dg/Wunused-var-7.c: New test.

From-SVN: r158224

gcc/ChangeLog

+2010-04-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR bootstrap/43699
+	* c-typeck.c (c_process_expr_stmt): Call mark_exp_read even
+	for exprs satisfying handled_component_p.
+
 2010-04-12  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* expr.c (categorize_ctor_elements_1): Properly count sub-elements of

gcc/c-typeck.c

@@ -8826,11 +8826,13 @@ c_process_expr_stmt (location_t loc, tree expr)
       && warn_unused_value)
     emit_side_effect_warnings (loc, expr);
 
+  if (DECL_P (expr) || handled_component_p (expr))
+    mark_exp_read (expr);
+
   /* If the expression is not of a type to which we cannot assign a line
      number, wrap the thing in a no-op NOP_EXPR.  */
   if (DECL_P (expr) || CONSTANT_CLASS_P (expr))
     {
-      mark_exp_read (expr);
       expr = build1 (NOP_EXPR, TREE_TYPE (expr), expr);
       SET_EXPR_LOCATION (expr, loc);
     }

gcc/testsuite/ChangeLog

 2010-04-12  Jakub Jelinek  <jakub@redhat.com>
 
+	PR bootstrap/43699
+	* gcc.dg/Wunused-var-7.c: New test.
+
 	PR tree-optimization/43560
 	* gcc.c-torture/execute/pr43560.c: New test.
 

gcc/testsuite/gcc.dg/Wunused-var-7.c

+/* { dg-do compile } */
+/* { dg-options "-Wunused -W" } */
+
+int
+f1 (unsigned int x)
+{
+  int c = ({ union { unsigned int a; int b; } u; u.a = x; u.b; });
+  return c;
+}
+
+void
+f2 (void)
+{
+  struct S { int i; } a;
+  int b[1];
+  a.i = 1;
+  a.i;				/* { dg-warning "with no effect" } */
+  b[0] = 1;
+  b[0];				/* { dg-warning "with no effect" } */
+}
+
+void
+f3 (void)
+{
+  struct S { int i; } a;	/* { dg-warning "set but not used" } */
+  int b[1];			/* { dg-warning "set but not used" } */
+  a.i = 1;
+  b[0] = 1;
+}