glib2.0/docs/macros.txt

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GLib's configure options and corresponding macros
=================================================
--buildtype={plain,release,minsize,custom}
none
--buildtype={debug,debugoptimized} [debugoptimized is the default]
-DG_ENABLE_DEBUG -g
-Dglib_debug=disabled
Omits G_ENABLE_DEBUG when implied by --buildtype/-Ddebug
-Dglib_debug=enabled
Defines G_ENABLE_DEBUG regardless of --buildtype/-Ddebug
-Dglib_asserts=false
-DG_DISABLE_ASSERT
-Dglib_checks=false
-DG_DISABLE_CHECKS
Besides these, there are some local feature specific options, but my main
focus here is to concentrate on macros that affect overall GLib behaviour
and/or third party code.
Notes on GLib's internal and global macros
==========================================
G_DISABLE_ASSERT
The g_assert() and g_assert_not_reached() become non-functional
with this define. The motivation is to speed up end-user apps by
avoiding expensive checks.
This macro can affect third-party code. Defining it when building GLib
will only disable the assertion macros for GLib itself, but third-party code
that passes -DG_DISABLE_ASSERT to the compiler upon its own build
will end up with the non-functional variants after including glib.h
as well.
NOTE: Code inside the assertion macros should not have side effects
that affect the operation of the program.
G_DISABLE_CHECKS
This macro is similar to G_DISABLE_ASSERT, it affects third-party
code as mentioned above and the NOTE about G_DISABLE_ASSERT applies
too. The macros that become non-functional here are
g_return_if_fail(), g_return_val_if_fail(), g_return_if_reached() and
g_return_val_if_reached().
Additionally the glib_mem_profiler_table and g_mem_profile() from
gmem.h become non-functional if this macro is supplied.
This macro also switches off certain checks in the GSignal code.
G_ENABLE_DEBUG
Quite a bit of additional debugging code is compiled into GLib for this
macro, and since it is a globally visible define, third-party code may
be affected by it similar to G_DISABLE_ASSERT.
The additional code executed/compiled for this macro currently involve:
- extra validity checks for GDate
- memory profiling traps in gmem.c (consult debugging.txt for details)
- BREAKPOINT abortion for fatal log levels in gmessage.c instead of
plain abort() to allow debuggers trapping and overriding them
- added verbosity of gscanner.c to catch deprecated code paths
- added verbosity of gutils.c to catch deprecated code paths
- object ref/unref traps (consult debugging.txt) and object bookkeeping
in gobject.c
- extra validity checks in gsignal.c