Merge branch 'atomic-typeof' into 'master'

Define glib_typeof with C++11 decltype()

Closes #2226

See merge request GNOME/glib!1715

docs/reference/glib/glib-sections.txt

@@ -735,6 +735,7 @@ G_ANALYZER_ANALYZING
 G_ANALYZER_NORETURN
 g_autoptr_cleanup_generic_gfree
 glib_typeof
+glib_typeof_2_68
 g_macro__has_attribute
 g_macro__has_builtin
 g_macro__has_feature

glib/gatomic.h

@@ -182,17 +182,6 @@ G_END_DECLS
     (void) (0 ? *(atomic) ^ (val) : 1);                                      \
     (guint) __atomic_fetch_xor ((atomic), (val), __ATOMIC_SEQ_CST);          \
   }))
-
-#if defined(glib_typeof)
-#define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
-  (G_GNUC_EXTENSION ({                                                       \
-    G_STATIC_ASSERT (sizeof (oldval) == sizeof (gpointer));                  \
-    glib_typeof ((oldval)) gapcae_oldval = (oldval);                         \
-    G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer));                 \
-    (void) (0 ? (gpointer) *(atomic) : NULL);                                \
-    __atomic_compare_exchange_n ((atomic), &gapcae_oldval, (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \
-  }))
-#else /* if !defined(glib_typeof) */
 #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
   (G_GNUC_EXTENSION ({                                                       \
     G_STATIC_ASSERT (sizeof (oldval) == sizeof (gpointer));                  \
@@ -201,7 +190,6 @@ G_END_DECLS
     (void) (0 ? (gpointer) *(atomic) : NULL);                                \
     __atomic_compare_exchange_n ((atomic), &gapcae_oldval, (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \
   }))
-#endif /* defined(glib_typeof) */
 #define g_atomic_pointer_add(atomic, val) \
   (G_GNUC_EXTENSION ({                                                       \
     G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer));                 \

glib/gmacros.h

@@ -236,6 +236,11 @@
      ((defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8))) || \
       defined(__clang__))
 #define glib_typeof(t) __typeof__ (t)
+#elif defined(__cplusplus) && __cplusplus >= 201103L
+/* C++11 decltype() is close enough for our usage */
+#include <type_traits>
+#define glib_typeof(t) typename std::remove_reference<decltype (t)>::type
+#define glib_typeof_2_68
 #endif
 
 /*

glib/gmem.h

@@ -110,7 +110,7 @@ gpointer g_try_realloc_n  (gpointer	 mem,
 			   gsize	 n_blocks,
 			   gsize	 n_block_bytes) G_GNUC_WARN_UNUSED_RESULT;
 
-#if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58
+#if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58 && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)
 #define g_clear_pointer(pp, destroy)                     \
   G_STMT_START                                           \
   {                                                      \
@@ -213,7 +213,7 @@ g_steal_pointer (gpointer pp)
 }
 
 /* type safety */
-#if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58
+#if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58 && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)
 #define g_steal_pointer(pp) ((glib_typeof (*pp)) (g_steal_pointer) (pp))
 #else  /* __GNUC__ */
 /* This version does not depend on gcc extensions, but gcc does not warn

glib/grcbox.h

@@ -71,7 +71,7 @@ gsize           g_atomic_rc_box_get_size        (gpointer        mem_block);
 #define g_atomic_rc_box_new0(type) \
   ((type *) g_atomic_rc_box_alloc0 (sizeof (type)))
 
-#ifdef glib_typeof
+#if defined(glib_typeof) && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)
 /* Type check to avoid assigning references to different types */
 #define g_rc_box_acquire(mem_block) \
   ((glib_typeof (mem_block)) (g_rc_box_acquire) (mem_block))

glib/tests/cxx.cpp

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2020 Xavier Claessens
+ *
+ * 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/>.
+ */
+
+#include <glib.h>
+
+typedef struct
+{
+  int dummy;
+} MyObject;
+
+static void
+test_typeof (void)
+{
+#if __cplusplus >= 201103L
+  // Test that with C++11 we don't get those kind of errors:
+  // error: invalid conversion from ‘gpointer’ {aka ‘void*’} to ‘MyObject*’ [-fpermissive]
+  MyObject *obj = g_rc_box_new0 (MyObject);
+  MyObject *obj2 = g_rc_box_acquire (obj);
+  g_assert_true (obj2 == obj);
+
+  MyObject *obj3 = g_atomic_pointer_get (&obj2);
+  g_assert_true (obj3 == obj);
+
+  MyObject *obj4 = nullptr;
+  g_atomic_pointer_set (&obj4, obj3);
+  g_assert_true (obj4 == obj);
+
+  MyObject *obj5 = nullptr;
+  g_atomic_pointer_compare_and_exchange (&obj5, nullptr, obj4);
+  g_assert_true (obj5 == obj);
+
+  MyObject *obj6 = g_steal_pointer (&obj5);
+  g_assert_true (obj6 == obj);
+
+  g_clear_pointer (&obj6, g_rc_box_release);
+  g_rc_box_release (obj);
+#else
+  g_test_skip ("This test requires C++11 compiler");
+#endif
+}
+
+int
+main (int argc, char *argv[])
+{
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/C++/typeof", test_typeof);
+
+  return g_test_run ();
+}

glib/tests/meson.build

@@ -14,6 +14,9 @@ glib_tests = {
   'collate' : {},
   'cond' : {},
   'convert' : {},
+  'cxx' : {
+    'source' : ['cxx.cpp'],
+  },
   'dataset' : {},
   'date' : {},
   'dir' : {},

gobject/gobject.h

@@ -513,7 +513,7 @@ GLIB_AVAILABLE_IN_ALL
 void        g_object_remove_weak_pointer      (GObject        *object, 
                                                gpointer       *weak_pointer_location);
 
-#if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_56
+#if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_56 && (!defined(glib_typeof_2_68) || GLIB_VERSION_MIN_REQUIRED >= GLIB_VERSION_2_68)
 /* Make reference APIs type safe with macros */
 #define g_object_ref(Obj) ((glib_typeof (Obj)) (g_object_ref) (Obj))
 #define g_object_ref_sink(Obj) ((glib_typeof (Obj)) (g_object_ref_sink) (Obj))