[committed] ubsan: Add another testcase for [0] array in the middle of struct [PR108894]

[Jakub Jelinek <jakub@redhat.com>]

Hi!

On Tue, Feb 28, 2023 at 10:59:03PM +0100, Jakub Jelinek via Gcc-patches wrote:
> On Tue, Feb 28, 2023 at 07:19:40PM +0000, Qing Zhao wrote:
> > Understood.  
> > So, your patch fixed this bug, and then [0] arrays are instrumented by default with this patch.
> > 
> > > Well, it would complain about
> > > struct S { int a; int b[0]; int c; } s;
> > > ... &s.b[1] ...
> > > for C++, but not for C.
> > 
> > A little confused here: [0] arrays were instrumented by default for C++ if it’s not a trailing array, but not for C?
> 
> Given say
> struct S { int a; int b[0]; int c; } s;
> 
> int
> main ()
> {
>   int *volatile p = &s.b[0];
>   p = &s.b[1];
>   int volatile q = s.b[0];
> }

And, when I wrote such a testcase, I thought it would be worth it to have it
in the testsuite too.
Tested on x86_64-linux -m32/-m64, committed to trunk as obvious:

2023-03-01  Jakub Jelinek  <jakub@redhat.com>

	PR sanitizer/108894
	* c-c++-common/ubsan/bounds-16.c: New test.

--- gcc/testsuite/c-c++-common/ubsan/bounds-16.c.jj	2023-03-01 10:35:29.751959193 +0100
+++ gcc/testsuite/c-c++-common/ubsan/bounds-16.c	2023-03-01 10:38:09.087645556 +0100
@@ -0,0 +1,15 @@
+/* PR sanitizer/108894 */
+/* { dg-do run } */
+/* { dg-options "-fsanitize=bounds -fsanitize-recover=bounds" } */
+/* { dg-output "index 1 out of bounds for type 'int \\\[\[*0-9x]*\\\]'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*index 0 out of bounds for type 'int \\\[\[*0-9x]*\\\]'" } */
+
+struct S { int a; int b[0]; int c; } s;
+
+int
+main ()
+{
+  int *volatile p = &s.b[0];
+  p = &s.b[1];
+  int volatile q = s.b[0];
+}


	Jakub