Merge branch 'std-deprecated-attr'

Add wxDEPRECATED_ATTR expanding to the standard C++14 [[deprecated]]
attribute.

docs/doxygen/mainpages/const_cpp.h

@@ -171,6 +171,8 @@ Currently the following symbols exist:
     wxBitmapToggleButton class is available in addition to wxToggleButton.}
 @itemdef{wxHAS_CONFIG_TEMPLATE_RW, Defined if the currently used compiler
     supports template Read() and Write() methods in wxConfig.}
+@itemdef{wxHAS_DEPRECATED_ATTR, Defined if C++14 @c [[deprecated]] attribute is
+    supported (this symbol only exists in wxWidgets 3.1.6 or later).}
 @itemdef{wxHAS_MEMBER_DEFAULT, Defined if the currently used compiler supports
     C++11 @c =default.}
 @itemdef{wxHAS_LARGE_FILES, Defined if wxFile supports files more than 4GB in

include/wx/defs.h

@@ -573,14 +573,29 @@ typedef short int WXTYPE;
 /*
     Macros for marking functions as being deprecated.
 
-    The preferred macro in the new code is wxDEPRECATED_MSG() which allows to
-    explain why is the function deprecated. Almost all the existing code uses
-    the older wxDEPRECATED() or its variants currently, but this will hopefully
-    change in the future.
+    The preferred macro in the new code is wxDEPRECATED_ATTR() which expands to
+    the standard [[deprecated]] attribute if supported and allows to explain
+    why is the function deprecated. If supporting older compilers is important,
+    wxDEPRECATED_MSG() can be used as it's almost universally available and
+    still allows to explain the reason for the deprecation.
+
+    However almost all the existing code uses the older wxDEPRECATED() or its
+    variants currently, but this will hopefully change in the future.
  */
 
+#if defined(__has_cpp_attribute)
+    #if __has_cpp_attribute(deprecated)
+        /* gcc 5 claims to support this attribute, but actually doesn't */
+        #if !defined(__GNUC__) || wxCHECK_GCC_VERSION(6, 0)
+            #define wxHAS_DEPRECATED_ATTR
+        #endif
+    #endif
+#endif
+
 /* The basic compiler-specific construct to generate a deprecation warning. */
-#ifdef __clang__
+#ifdef wxHAS_DEPRECATED_ATTR
+    #define wxDEPRECATED_DECL [[deprecated]]
+#elif defined(__clang__)
     #define wxDEPRECATED_DECL __attribute__((deprecated))
 #elif defined(__GNUC__)
     #define wxDEPRECATED_DECL __attribute__((deprecated))
@@ -590,13 +605,28 @@ typedef short int WXTYPE;
     #define wxDEPRECATED_DECL
 #endif
 
+#ifdef wxHAS_DEPRECATED_ATTR
+    #define wxDEPRECATED_ATTR(msg) [[deprecated(msg)]]
+#else
+    /*
+        Note that we can't fall back on wxDEPRECATED_DECL here, as the standard
+        attribute works in places where the compiler-specific one don't,
+        notably it can be used after enumerator declaration with MSVC, while
+        __declspec(deprecated) can't occur there as it can only be used before
+        the declaration.
+     */
+    #define wxDEPRECATED_ATTR(msg)
+#endif
+
 /*
     Macro taking the deprecation message. It applies to the next declaration.
 
     If the compiler doesn't support showing the message, this degrades to a
     simple wxDEPRECATED(), i.e. at least gives a warning, if possible.
  */
-#if defined(__clang__) && defined(__has_extension)
+#ifdef wxHAS_DEPRECATED_ATTR
+    #define wxDEPRECATED_MSG(msg) [[deprecated(msg)]]
+#elif defined(__clang__) && defined(__has_extension)
     #if __has_extension(attribute_deprecated_with_message)
         #define wxDEPRECATED_MSG(msg) __attribute__((deprecated(msg)))
     #else

interface/wx/defs.h

@@ -1600,6 +1600,17 @@ template <typename T> void wxDELETE(T*& ptr);
 */
 template <typename T> void wxDELETEA(T*& array);
 
+/**
+    Expands to the standard C++14 [[deprecated]] attribute if supported.
+
+    If not supported by the compiler, expands to nothing. If support for such
+    compilers is important, use wxDEPRECATED_MSG() which is almost universally
+    available.
+
+    @since 3.1.6
+ */
+#define wxDEPRECATED_ATTR(msg) [[deprecated(msg)]]
+
 /**
     Generate deprecation warning with the given message when a function is
     used.