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Files
glib/gobject/gbinding.h
Sam James 016829559e Drop G_GNUC_CONST for *_get_type
g_type_ensure has a large comment saying _get_type shouldn't be
marked with G_GNUC_CONST because it has side-effects on the first
run, but it's OK if you consistently call g_type_ensure first.

Unfortunately, this isn't accurate. GCC trunk (observed at r17-1725-ge259a182e1f100)
now analyses points-to information more effectively and propagates its
findings, so it sees the function modifies some global state, concludes
that can't be possible (because of the const attribute), and deletes
the stores.

pure unfortunately is unsuitable for *_get_type too as it has a side-effect
(writes to global memory).

Mesa had a similar issue which I fixed recently [0]. glib and glibmm likely
want the (not-yet-implemented) 'idempotent' attribute instead [1]. In fact,
this exact problem is what motivated that request! :)

ebassi mentions an alternative to the current setup as well, using
atomics [2].

This problem has gone back many years but the compiler has finally
fully outsmarted us here, so give in.

[0] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/42361
[1] https://gcc.gnu.org/PR32911
[2] https://gitlab.gnome.org/GNOME/glib/-/merge_requests/4249#note_2583110

Fixes: https://gitlab.gnome.org/GNOME/glib/-/work_items/3984
Signed-off-by: Sam James <sam@gentoo.org>
2026-06-25 17:23:46 +01:00

149 lines
6.4 KiB
C

/* gbinding.h: Binding for object properties
*
* Copyright (C) 2010 Intel Corp.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: Emmanuele Bassi <ebassi@linux.intel.com>
*/
#ifndef __G_BINDING_H__
#define __G_BINDING_H__
#if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
#error "Only <glib-object.h> can be included directly."
#endif
#include <glib.h>
#include <gobject/gobject.h>
G_BEGIN_DECLS
#define G_TYPE_BINDING_FLAGS (g_binding_flags_get_type ())
#define G_TYPE_BINDING (g_binding_get_type ())
#define G_BINDING(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), G_TYPE_BINDING, GBinding))
#define G_IS_BINDING(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), G_TYPE_BINDING))
typedef struct _GBinding GBinding;
/**
* GBindingTransformFunc:
* @binding: a #GBinding
* @from_value: the #GValue containing the value to transform
* @to_value: the #GValue in which to store the transformed value
* @user_data: data passed to the transform function
*
* A function to be called to transform @from_value to @to_value.
*
* If this is the @transform_to function of a binding, then @from_value
* is the @source_property on the @source object, and @to_value is the
* @target_property on the @target object. If this is the
* @transform_from function of a %G_BINDING_BIDIRECTIONAL binding,
* then those roles are reversed.
*
* Returns: %TRUE if the transformation was successful, and %FALSE
* otherwise
*
* Since: 2.26
*/
typedef gboolean (* GBindingTransformFunc) (GBinding *binding,
const GValue *from_value,
GValue *to_value,
gpointer user_data);
/**
* GBindingFlags:
* @G_BINDING_DEFAULT: The default binding; if the source property
* changes, the target property is updated with its value.
* @G_BINDING_BIDIRECTIONAL: Bidirectional binding; if either the
* property of the source or the property of the target changes,
* the other is updated.
* @G_BINDING_SYNC_CREATE: Synchronize the values of the source and
* target properties when creating the binding; the direction of
* the synchronization is always from the source to the target.
* @G_BINDING_INVERT_BOOLEAN: If the two properties being bound are
* booleans, setting one to %TRUE will result in the other being
* set to %FALSE and vice versa. This flag will only work for
* boolean properties, and cannot be used when passing custom
* transformation functions to g_object_bind_property_full().
*
* Flags to be passed to g_object_bind_property() or
* g_object_bind_property_full().
*
* This enumeration can be extended at later date.
*
* Since: 2.26
*/
typedef enum { /*< prefix=G_BINDING >*/
G_BINDING_DEFAULT = 0,
G_BINDING_BIDIRECTIONAL = 1 << 0,
G_BINDING_SYNC_CREATE = 1 << 1,
G_BINDING_INVERT_BOOLEAN = 1 << 2
} G_GNUC_FLAG_ENUM GBindingFlags;
GOBJECT_AVAILABLE_IN_ALL
GType g_binding_flags_get_type (void);
GOBJECT_AVAILABLE_IN_ALL
GType g_binding_get_type (void);
GOBJECT_AVAILABLE_IN_ALL
GBindingFlags g_binding_get_flags (GBinding *binding);
GOBJECT_DEPRECATED_IN_2_68_FOR(g_binding_dup_source)
GObject * g_binding_get_source (GBinding *binding);
GOBJECT_AVAILABLE_IN_2_68
GObject * g_binding_dup_source (GBinding *binding);
GOBJECT_DEPRECATED_IN_2_68_FOR(g_binding_dup_target)
GObject * g_binding_get_target (GBinding *binding);
GOBJECT_AVAILABLE_IN_2_68
GObject * g_binding_dup_target (GBinding *binding);
GOBJECT_AVAILABLE_IN_ALL
const gchar * g_binding_get_source_property (GBinding *binding);
GOBJECT_AVAILABLE_IN_ALL
const gchar * g_binding_get_target_property (GBinding *binding);
GOBJECT_AVAILABLE_IN_2_38
void g_binding_unbind (GBinding *binding);
GOBJECT_AVAILABLE_IN_ALL
GBinding *g_object_bind_property (gpointer source,
const gchar *source_property,
gpointer target,
const gchar *target_property,
GBindingFlags flags);
GOBJECT_AVAILABLE_IN_ALL
GBinding *g_object_bind_property_full (gpointer source,
const gchar *source_property,
gpointer target,
const gchar *target_property,
GBindingFlags flags,
GBindingTransformFunc transform_to,
GBindingTransformFunc transform_from,
gpointer user_data,
GDestroyNotify notify);
GOBJECT_AVAILABLE_IN_ALL
GBinding *g_object_bind_property_with_closures (gpointer source,
const gchar *source_property,
gpointer target,
const gchar *target_property,
GBindingFlags flags,
GClosure *transform_to,
GClosure *transform_from);
G_END_DECLS
#endif /* __G_BINDING_H__ */