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build: disable type checks in G_TYPE_CHECK_INSTANCE_CAST() macros (bgo#771120)

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Avoid the pointless overhead. Even glib disables them unless you build
with --enable-debug.

https://bugzilla.gnome.org/show_bug.cgi?id=771120
This commit is contained in:
Thomas Haller 2016-09-09 14:31:30 +02:00
parent aae26ebed3
commit eb8da4c282
1 changed files with 57 additions and 4 deletions
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61
shared/nm-default.h
View file

@ -52,15 +52,68 @@
#define NM_VERSION_MAX_ALLOWED NM_VERSION_NEXT_STABLE
#define NM_VERSION_MIN_REQUIRED NM_VERSION_0_9_8
#ifndef NM_MORE_ASSERTS
#define NM_MORE_ASSERTS 0
#endif
#if NM_MORE_ASSERTS == 0
/* The cast macros like NM_TYPE() are implemented via G_TYPE_CHECK_INSTANCE_CAST()
* and _G_TYPE_CIC(). The latter, by default performs runtime checks of the type
* by calling g_type_check_instance_cast().
* This check has a certain overhead without being helpful.
*
* Example 1:
* static void foo (NMType *obj)
* {
* access_obj_without_check (obj);
* }
* foo ((NMType *) obj);
* // There is no runtime check and passing an invalid pointer
* // leads to a crash.
*
* Example 2:
* static void foo (NMType *obj)
* {
* access_obj_without_check (obj);
* }
* foo (NM_TYPE (obj));
* // There is a runtime check which prints a g_warning(), but that doesn't
* // avoid the crash as NM_TYPE() cannot do anything then passing on the
* // invalid pointer.
*
* Example 3:
* static void foo (NMType *obj)
* {
* g_return_if_fail (NM_IS_TYPE (obj));
* access_obj_without_check (obj);
* }
* foo ((NMType *) obj);
* // There is a runtime check which prints a g_critical() which also avoids
* // the crash. That is actually helpful to catch bugs and avoid crashes.
*
* Example 4:
* static void foo (NMType *obj)
* {
* g_return_if_fail (NM_IS_TYPE (obj));
* access_obj_without_check (obj);
* }
* foo (NM_TYPE (obj));
* // The runtime check is performed twice, with printing a g_warning() and
* // a g_critical() and avoiding the crash.
*
* Example 3 is how it should be done. Type checks in NM_TYPE() are pointless.
* Disable them for our production builds.
*/
#ifndef G_DISABLE_CAST_CHECKS
#define G_DISABLE_CAST_CHECKS
#endif
#endif
#include <stdlib.h>
#include <glib.h>
/*****************************************************************************/
#ifndef NM_MORE_ASSERTS
#define NM_MORE_ASSERTS 0
#endif
#if NM_MORE_ASSERTS == 0
/* glib assertions (g_return_*(), g_assert*()) contain a textual representation