Merge branch 'free-sized-macro' into 'main'

gmem: Add an inline definition of g_free() to automatically use g_free_sized()

See merge request GNOME/glib!3252

glib/glibconfig.h.in

@@ -212,6 +212,8 @@ typedef @g_pid_type@ GPid;
 #define G_SEARCHPATH_SEPARATOR '@g_searchpath_separator@'
 #define G_SEARCHPATH_SEPARATOR_S "@g_searchpath_separator@"
 
+#mesondefine G_HAVE_FREE_SIZED
+
 G_END_DECLS
 
 #endif /* __GLIBCONFIG_H__ */

glib/gmem.c

@@ -223,11 +223,17 @@ g_realloc (gpointer mem,
  * If you know the allocated size of @mem, calling g_free_sized() may be faster,
  * depending on the libc implementation in use.
  *
+ * Starting from GLib 2.78, this may happen automatically in case a GCC
+ * compatible compiler is used with some optimization level and the allocated
+ * size is known at compile time (see [documentation of
+ * `__builtin_object_size()`](https://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html)
+ * to understand its caveats).
+ *
  * If @mem is %NULL it simply returns, so there is no need to check @mem
  * against %NULL before calling this function.
  */
 void
-g_free (gpointer mem)
+(g_free) (gpointer mem)
 {
   free (mem);
   TRACE(GLIB_MEM_FREE((void*) mem));
@@ -246,6 +252,10 @@ g_free (gpointer mem)
  * allocated. @size is passed to this function to allow optimizations in the
  * allocator. If you don’t know the allocation size, use g_free() instead.
  *
+ * In case a GCC compatible compiler is used, this function may be used
+ * automatically via g_free() if the allocated size is known at compile time,
+ * since GLib 2.78.
+ *
  * Since: 2.76
  */
 void

glib/gmem.h

@@ -71,7 +71,7 @@ typedef struct _GMemVTable GMemVTable;
  */
 
 GLIB_AVAILABLE_IN_ALL
-void	 g_free	          (gpointer	 mem);
+void     (g_free)         (gpointer	     mem);
 GLIB_AVAILABLE_IN_2_76
 void     g_free_sized     (gpointer      mem,
                            size_t        size);
@@ -165,6 +165,15 @@ void     g_aligned_free_sized (gpointer  mem,
   GLIB_AVAILABLE_MACRO_IN_2_34
 #endif /* __GNUC__ */
 
+
+#if G_GNUC_CHECK_VERSION (4, 1) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_78 && defined(G_HAVE_FREE_SIZED)
+
+#define g_free(mem)                                                            \
+  (__builtin_object_size ((mem), 0) != ((size_t) - 1)) ?                       \
+    g_free_sized (mem, __builtin_object_size ((mem), 0)) : (g_free) (mem)
+
+#endif /* G_GNUC_CHECK_VERSION (4, 1) && && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_78 && defined(G_HAVE_FREE_SIZED) */
+
 /**
  * g_steal_pointer:
  * @pp: (not nullable): a pointer to a pointer

meson.build

@@ -729,6 +729,10 @@ foreach f : functions
   endif
 endforeach
 
+# Export the information about free_sized() so we can correctly define a macro
+# wrapper around g_free()/g_free_sized() depending on whether it’s available
+glibconfig_conf.set('G_HAVE_FREE_SIZED', have_func_free_sized)
+
 # Check that stpcpy() is usable; must use header.
 # See:
 # https://github.com/mesonbuild/meson/issues/5628.