diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0d4284cca78..88c990397be 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+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
diff --git a/gcc/c-typeck.c b/gcc/c-typeck.c
index 2296cbe2f93..681c0e42df9 100644
--- a/gcc/c-typeck.c
+++ b/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);
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fe70fb42424..642f08525ba 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 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.
 
diff --git a/gcc/testsuite/gcc.dg/Wunused-var-7.c b/gcc/testsuite/gcc.dg/Wunused-var-7.c
new file mode 100644
index 00000000000..e82e708deae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wunused-var-7.c
@@ -0,0 +1,29 @@
+/* { 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;
+}