re PR c/42708 (ICE in gimplify_expr, at gimplify.c:6993)

	PR c/42708
	* c-typeck.c (build_c_cast): Fold value cast to union type before
	wrapping it in a CONSTRUCTOR.

testsuite:
	* gcc.c-torture/compile/pr42708-1.c: New test.

From-SVN: r155846

gcc/ChangeLog

+2010-01-12  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/42708
+	* c-typeck.c (build_c_cast): Fold value cast to union type before
+	wrapping it in a CONSTRUCTOR.
+
 2010-01-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/42699

gcc/c-typeck.c

@@ -4429,10 +4429,14 @@ build_c_cast (location_t loc, tree type, tree expr)
       if (field)
 	{
 	  tree t;
+	  bool maybe_const = true;
 
 	  pedwarn (loc, OPT_pedantic, "ISO C forbids casts to union type");
-	  t = digest_init (loc, type,
-			   build_constructor_single (type, field, value),
+	  t = c_fully_fold (value, false, &maybe_const);
+	  t = build_constructor_single (type, field, t);
+	  if (!maybe_const)
+	    t = c_wrap_maybe_const (t, true);
+	  t = digest_init (loc, type, t,
 			   NULL_TREE, false, true, 0);
 	  TREE_CONSTANT (t) = TREE_CONSTANT (value);
 	  return t;

gcc/testsuite/ChangeLog

+2010-01-12  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/42708
+	* gcc.c-torture/compile/pr42708-1.c: New test.
+
 2010-01-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/42662

gcc/testsuite/gcc.c-torture/compile/pr42708-1.c

+typedef __SIZE_TYPE__ size_t;
+void *malloc(size_t);
+typedef union YYSTYPE {
+    char *id;
+}  YYSTYPE;
+extern YYSTYPE yylval;
+void yylex (int b)
+{
+  yylval = (YYSTYPE) (b ? 0 : (char *) malloc (4));
+}