re PR c/25682 (ICE when using old sytle offsetof (with non zero start) as array size)

	PR c/25682
	* c-typeck.c (build_unary_op): Fold offsetof-like expressions
	even when the pointer is not NULL.
cp/
	* decl.c (compute_array_index_type): After issuing not an integral
	constant-expression error, set size to 1 to avoid ICEs later on.
testsuite/
	* gcc.dg/pr25682.c: New test.
	* g++.dg/parse/array-size2.C: New test.

From-SVN: r109812

1 files changed, 27 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/pr25682.c b/gcc/testsuite/gcc.dg/pr25682.c
new file mode 100644
index 0000000..3a1d7c2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr25682.c
@@ -0,0 +1,27 @@
+/* PR c/25682 */
+/* { dg-do compile } */
+/* Test whether we don't ICE on questionable constructs where offsetof
+   should have been used instead.  */
+
+struct S
+{
+  char a[4];
+  int b;
+};
+
+char c[(char *) &((struct S *) 0)->b - (char *) 0];
+char d[(__SIZE_TYPE__) &((struct S *) 8)->b];
+char e[sizeof (c) == __builtin_offsetof (struct S, b) ? 1 : -1];
+char f[sizeof (d) == __builtin_offsetof (struct S, b) + 8 ? 1 : -1];
+
+extern void bar (char *, char *);
+
+void
+foo (void)
+{
+  char g[(char *) &((struct S *) 0)->b - (char *) 0];
+  char h[(__SIZE_TYPE__) &((struct S *) 8)->b];
+  char i[sizeof (g) == __builtin_offsetof (struct S, b) ? 1 : -1];
+  char j[sizeof (h) == __builtin_offsetof (struct S, b) + 8 ? 1 : -1];
+  bar (g, h);
+}