[glib/wip/smcv/none-flags: 1/8] gtype: Add G_TYPE_FLAG_NONE

[Simon McVittie <smcv src gnome org>]

commit 5e164c661537f6b6ef5adcf0fac949959ef9ffd5
Author: Simon McVittie <smcv collabora com>
Date:   Thu Mar 31 13:58:36 2022 +0100

    gtype: Add G_TYPE_FLAG_NONE
    
    This makes code that sets no flags a bit more self-documenting:
    using G_TYPE_FLAG_NONE makes it clearer that no special behaviour is
    required than literal 0, and clearer that there is no weird casting
    between types than (GTypeFlags) 0.
    
    GTypeFlags and GTypeFundamentalFlags occupy the same namespace and the
    same bitfield, so I intentionally haven't added
    G_TYPE_FUNDAMENTAL_FLAGS_NONE.
    
    Signed-off-by: Simon McVittie <smcv collabora com>

 gobject/gtype.h | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gobject/gtype.h b/gobject/gtype.h
index 66cac1fc58..73d665626b 100644
--- a/gobject/gtype.h
+++ b/gobject/gtype.h
@@ -1030,6 +1030,8 @@ typedef void     (*GTypeInterfaceCheckFunc)  (gpointer           check_data,
  */
 typedef enum    /*< skip >*/
 {
+  /* There is no G_TYPE_FUNDAMENTAL_FLAGS_NONE: this is implemented to use
+   * the same bits as GTypeFlags */
   G_TYPE_FLAG_CLASSED           = (1 << 0),
   G_TYPE_FLAG_INSTANTIATABLE    = (1 << 1),
   G_TYPE_FLAG_DERIVABLE         = (1 << 2),
@@ -1037,6 +1039,7 @@ typedef enum    /*< skip >*/
 } GTypeFundamentalFlags;
 /**
  * GTypeFlags:
+ * @G_TYPE_FLAG_NONE: No special flags. Since: 2.74
  * @G_TYPE_FLAG_ABSTRACT: Indicates an abstract type. No instances can be
  *  created for an abstract type
  * @G_TYPE_FLAG_VALUE_ABSTRACT: Indicates an abstract value type, i.e. a type
@@ -1049,6 +1052,7 @@ typedef enum    /*< skip >*/
  */
 typedef enum    /*< skip >*/
 {
+  G_TYPE_FLAG_NONE GLIB_AVAILABLE_ENUMERATOR_IN_2_74 = 0,
   G_TYPE_FLAG_ABSTRACT = (1 << 4),
   G_TYPE_FLAG_VALUE_ABSTRACT = (1 << 5),
   G_TYPE_FLAG_FINAL GLIB_AVAILABLE_ENUMERATOR_IN_2_70 = (1 << 6)
@@ -2180,6 +2184,8 @@ type_name##_get_type_once (void) \
   _G_DEFINE_TYPE_EXTENDED_BEGIN_PRE(TypeName, type_name, TYPE_PARENT) \
   _G_DEFINE_TYPE_EXTENDED_BEGIN_REGISTER(TypeName, type_name, TYPE_PARENT, flags) \
 
+/* Intentionally using (GTypeFlags) 0 instead of G_TYPE_FLAG_NONE here,
+ * to avoid deprecation warnings with older GLIB_VERSION_MAX_ALLOWED */
 #define _G_DEFINE_INTERFACE_EXTENDED_BEGIN(TypeName, type_name, TYPE_PREREQ) \
 \
 static void     type_name##_default_init        (TypeName##Interface *klass); \