[gtkmm/use-dllexport: 7/12] class_gtkobject.m4: Add ability to decorate generated classes

[Chun-wei Fan <fanchunwei src gnome org>]

commit 8358d3997c749d6435be9ba6134c74be346aa1fe
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Jun 5 16:27:10 2020 +0800

    class_gtkobject.m4: Add ability to decorate generated classes
    
    Add an optional `__FUNC_DECORATION__` (eighth) parameter to _CLASS_GTKOBJECT so
    that we can use it to decorate the classes, functions and methods with
    __FUNC_DECORATION__ if it is needed, so that we can use that to export the
    symbols without using additional tools if the compiler does not support
    automatic all-symbol exporting or export by regex, or when we want to have a
    more fine-grained approach to how we want to export the symbols, as in the
    case of Visual Studio builds.

 tools/m4/class_gtkobject.m4 | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/tools/m4/class_gtkobject.m4 b/tools/m4/class_gtkobject.m4
index 1cf15669..dd3ce146 100644
--- a/tools/m4/class_gtkobject.m4
+++ b/tools/m4/class_gtkobject.m4
@@ -17,6 +17,7 @@ dnl rather than the real instance type.  That is really ugly, yes.  We get aroun
 dnl the problem by supporting optional __REAL_* arguments to this macro.
 define(`__REAL_CNAME__',ifelse(`$6',,__CNAME__,`$6'))
 define(`__REAL_CPARENT__',ifelse(`$7',,__CPARENT__,`$7'))
+define(`__FUNC_DECORATION__',`$8')
 
 
 dnl
@@ -111,7 +112,7 @@ dnl _STRUCT_PROTOTYPE() can be disabled with _STRUCT_NOT_HIDDEN.
 _STRUCT_PROTOTYPE()
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
-__NAMESPACE_BEGIN__ class __CPPNAME__`'_Class; __NAMESPACE_END__
+__NAMESPACE_BEGIN__ class __FUNC_DECORATION__ __CPPNAME__`'_Class; __NAMESPACE_END__
 #endif //DOXYGEN_SHOULD_SKIP_THIS
 
 _SECTION(SECTION_HEADER3)
@@ -128,6 +129,7 @@ namespace Glib
    *
    * @relates __NAMESPACE__::__CPPNAME__
    */
+  __FUNC_DECORATION__
   __NAMESPACE__::__CPPNAME__`'* wrap(__CNAME__`'* object, bool take_copy = false);
 } //namespace Glib
 ')dnl endif __BOOL_NO_WRAP_FUNCTION__
@@ -262,7 +264,7 @@ m4_ifdef(`__BOOL_PROTECTED_GCLASS__',
 `protected:',`dnl else
 private:')dnl endif
 
-  friend class __CPPNAME__`'_Class;
+  friend __FUNC_DECORATION__ class __CPPNAME__`'_Class;
   static CppClassType `'__BASE__`'_class_;
 
 protected: