re PR c/39582 (bad errors for some uses of [*] arrays)

	PR c/39582
	* c-typeck.c (c_expr_sizeof_type): Create a C_MAYBE_CONST_EXPR
	with non-null C_MAYBE_CONST_EXPR_PRE if size of a variable-length
	type is an integer constant.

testsuite:
	* gcc.dg/vla-20.c: New test.

From-SVN: r146787

gcc/ChangeLog

+2009-04-25  Joseph Myers  <joseph@codesourcery.com>
+
+	PR c/39582
+	* c-typeck.c (c_expr_sizeof_type): Create a C_MAYBE_CONST_EXPR
+	with non-null C_MAYBE_CONST_EXPR_PRE if size of a variable-length
+	type is an integer constant.
+
 2009-04-25  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/39897

gcc/c-typeck.c

@@ -2391,8 +2391,18 @@ c_expr_sizeof_type (struct c_type_name *t)
   ret.value = c_sizeof (type);
   ret.original_code = ERROR_MARK;
   ret.original_type = NULL;
-  if (type_expr && c_vla_type_p (type))
-    {
+  if ((type_expr || TREE_CODE (ret.value) == INTEGER_CST)
+      && c_vla_type_p (type))
+    {
+      /* If the type is a [*] array, it is a VLA but is represented as
+	 having a size of zero.  In such a case we must ensure that
+	 the result of sizeof does not get folded to a constant by
+	 c_fully_fold, because if the size is evaluated the result is
+	 not constant and so constraints on zero or negative size
+	 arrays must not be applied when this sizeof call is inside
+	 another array declarator.  */
+      if (!type_expr)
+	type_expr = integer_zero_node;
       ret.value = build2 (C_MAYBE_CONST_EXPR, TREE_TYPE (ret.value),
 			  type_expr, ret.value);
       C_MAYBE_CONST_EXPR_NON_CONST (ret.value) = !type_expr_const;

gcc/testsuite/ChangeLog

 2009-04-25  Joseph Myers  <joseph@codesourcery.com>
 
+	PR c/39582
+	* gcc.dg/vla-20.c: New test.
+
+2009-04-25  Joseph Myers  <joseph@codesourcery.com>
+
 	PR c/39564
 	* gcc.dg/vla-19.c: New test.
 

gcc/testsuite/gcc.dg/vla-20.c

+/* Test use of sizeof with [*] in type name: should not refer to
+   zero-size array.  PR 39582.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c99 -pedantic-errors" } */
+
+void foo11d(int x[sizeof(int *[*])]); /* { dg-warning "not in a declaration" } */
+
+/* Although the size is not constant, it may nevertheless appear in a
+   constant expression if not evaluated.  */
+
+void foo11e(int x[1 ? 0 : sizeof(int *[*])]); /* { dg-warning "not in a declaration" } */
+/* { dg-error "zero-size array" "correct zero size" { target *-*-* } 11 } */