[glib/wip/smcv/address-sanitizer: 25/28] gtestutils: Default to -m no-undefined under AddressSanitizer

[Simon McVittie <smcv src gnome org>]

commit 9fef98cf84216b33b6a2a488b544cd4056232ac1
Author: Simon McVittie <smcv collabora com>
Date:   Fri Jan 29 18:58:48 2021 +0000

    gtestutils: Default to -m no-undefined under AddressSanitizer
    
    AddressSanitizer detects memory leaks, NULL parameters where only a
    non-NULL parameter is expected, and other suspicious behaviour, so if
    we try to test that sort of thing we can expect it to fail.
    
    Signed-off-by: Simon McVittie <smcv collabora com>

 glib/gtestutils.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/glib/gtestutils.c b/glib/gtestutils.c
index 473e1b677..5660fc8be 100644
--- a/glib/gtestutils.c
+++ b/glib/gtestutils.c
@@ -309,8 +309,12 @@
  * behaviour, to verify that appropriate warnings are given. It might, in some
  * cases, be useful to turn this off with if running tests under valgrind;
  * in tests that use g_test_init(), the option `-m no-undefined` disables
- * those tests, while `-m undefined` explicitly enables them (the default
- * behaviour).
+ * those tests, while `-m undefined` explicitly enables them (normally
+ * the default behaviour).
+ *
+ * Since GLib 2.68, if GLib was compiled with gcc or clang and
+ * [AddressSanitizer](https://github.com/google/sanitizers/wiki/AddressSanitizer)
+ * is enabled, the default changes to not exercising undefined behaviour.
  *
  * Returns: %TRUE if tests may provoke programming errors
  */
@@ -1573,6 +1577,10 @@ void
   g_return_if_fail (g_test_config_vars->test_initialized == FALSE);
   mutable_test_config_vars.test_initialized = TRUE;
 
+#ifdef _GLIB_ADDRESS_SANITIZER
+  mutable_test_config_vars.test_undefined = FALSE;
+#endif
+
   va_start (args, argv);
   while ((option = va_arg (args, char *)))
     {