Add test for whether the compiler allows referencing to member functions

2005-06-12  Paul Pogonyshev  <pogonyshev@gmx.net>

        * configure.ac:
        * scripts/cxx.m4:
        * sigc++config.h.in: Add test for whether the compiler allows
        referencing to member functions of the class/structure being
        declared from a definition of a static member variable.
        Supposedly a generic solution for GCC 3.2 compilation problems.

        * sigc++/type_traits.h: Define SIGC_WRAP_IS_BASE_CLASS_ based on
        results of the above test.
        (struct is_base_and_derived): Wrap up is_base_class_() functions
        in an internal class if SIGC_WRAP_IS_BASE_CLASS_ is defined.

5 files changed, 70 insertions, 12 deletions

diff --git a/ChangeLog b/ChangeLog
index e2dc912..8c8f8d5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2005-06-12  Paul Pogonyshev  <pogonyshev@gmx.net>
+
+	* configure.ac: 
+	* scripts/cxx.m4: 
+	* sigc++config.h.in: Add test for whether the compiler allows
+	referencing to member functions of the class/structure being
+	declared from a definition of a static member variable.
+	Supposedly a generic solution for GCC 3.2 compilation problems.
+
+	* sigc++/type_traits.h: Define SIGC_WRAP_IS_BASE_CLASS_ based on
+	results of the above test.
+	(struct is_base_and_derived): Wrap up is_base_class_() functions
+	in an internal class if SIGC_WRAP_IS_BASE_CLASS_ is defined.
+
 2005-06-10  Murray Cumming  <murrayc@murrayc.com>
 
 	* sigc++/adaptors/macros/bind.h.m4:
diff --git a/configure.ac b/configure.ac
index 6359f5c..e0fcfaf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -101,6 +101,7 @@ AC_LANG_CPLUSPLUS
 
 SIGC_CXX_GCC_TEMPLATE_SPECIALIZATION_OPERATOR_OVERLOAD()
 SIGC_CXX_MSVC_TEMPLATE_SPECIALIZATION_OPERATOR_OVERLOAD()
+SIGC_CXX_SELF_REFERENCE_IN_MEMBER_INITIALIZATION()
 SIGC_CXX_HAS_NAMESPACE_STD()
 SIGC_CXX_HAS_SUN_REVERSE_ITERATOR()
 
diff --git a/scripts/cxx.m4 b/scripts/cxx.m4
index 0002a4c..11f1969 100644
--- a/scripts/cxx.m4
+++ b/scripts/cxx.m4
@@ -93,3 +93,30 @@ AC_TRY_COMPILE(
   AC_MSG_RESULT([$sigcm_cxx_msvc_template_specialization_operator_overload])
 ])
 ])
+
+
+AC_DEFUN([SIGC_CXX_SELF_REFERENCE_IN_MEMBER_INITIALIZATION], [
+AC_MSG_CHECKING([if C++ compiler allows usage of member function in initialization of static member field.])
+AC_TRY_COMPILE(
+[
+  struct test
+  {
+    static char  test_function();
+
+    // Doesn't work with e.g. GCC 3.2.  However, if test_function()
+    // is wrapped in a nested structure, it works just fine.
+    static const bool  test_value
+      = (sizeof(test_function()) == sizeof(char));
+  };
+],
+[],
+[
+  sigcm_cxx_self_reference_in_member_initialization=yes
+  AC_DEFINE([SIGC_SELF_REFERENCE_IN_MEMBER_INITIALIZATION],[1],
+            [does c++ compiler allows usage of member function in initialization of static member field.])
+  AC_MSG_RESULT([$sigcm_cxx_self_reference_in_member_initialization])
+],[
+  sigcm_cxx_self_reference_in_member_initialization=no
+  AC_MSG_RESULT([$sigcm_cxx_self_reference_in_member_initialization])
+])
+])
diff --git a/sigc++/type_traits.h b/sigc++/type_traits.h
index dee53ca..56b27a9 100644
--- a/sigc++/type_traits.h
+++ b/sigc++/type_traits.h
@@ -19,6 +19,9 @@
 #ifndef _SIGC_TYPE_TRAIT_H_
 #define _SIGC_TYPE_TRAIT_H_
 
+#include <sigc++config.h> //To get SIGC_SELF_REFERENCE_IN_MEMBER_INITIALIZATION
+
+
 namespace sigc {
 
 template <class T_type>
@@ -97,27 +100,39 @@ private:
     char memory[64];
   };
 
-  //Allow the test inner class to access the other (big) inner class.
-  //The Tru64 compiler needs this. murrayc.
-  //struct test;
-  //friend struct test;
+#ifndef SIGC_SELF_REFERENCE_IN_MEMBER_INITIALIZATION
 
-  //The AIX xlC compiler does not like these 2 functions being in the inner class.
-  //It says "The incomplete type "test" must no be used as a qualifier.
-  //It does not seem necessary anyway. murrayc.
+  //Allow the internal inner class to access the other (big) inner
+  //class.  The Tru64 compiler needs this. murrayc.
+  friend struct internal;
 
-  //struct test {
-  //For gcc 3.2, try uncommenting the "struct test" inner class declaration, and also using a test:: prefix below.
-  //If it works then submit a patch. A new configure-time compiler-ability check would be even better. murrayc.
+  //Certain compilers, notably GCC 3.2, require these functions to be inside an inner class.
+  struct internal
+  {
     static big  is_base_class_(...);
     static char is_base_class_(typename type_trait<T_base>::pointer);
-  //};
+  };
+
+public:
+  static const bool value =
+    sizeof(internal::is_base_class_(reinterpret_cast<typename type_trait<T_derived>::pointer>(0))) ==
+    sizeof(char);
+
+#else //SIGC_SELF_REFERENCE_IN_MEMBER_INITIALIZATION
+
+  //The AIX xlC compiler does not like these 2 functions being in the inner class.
+  //It says "The incomplete type "test" must not be used as a qualifier.
+  //It does not seem necessary anyway. murrayc.
+  static big  is_base_class_(...);
+  static char is_base_class_(typename type_trait<T_base>::pointer);
 
 public:
   static const bool value =
     sizeof(is_base_class_(reinterpret_cast<typename type_trait<T_derived>::pointer>(0))) ==
     sizeof(char);
 
+#endif //SIGC_SELF_REFERENCE_IN_MEMBER_INITIALIZATION
+
   void avoid_gcc3_warning_(); //Not implemented. g++ 3.3.5 (but not 3.3.4, and not 3.4) warn that there are no public methods, even though there is a public variable.
 };
 
diff --git a/sigc++config.h.in b/sigc++config.h.in
index a570b5f..1cd8c3e 100644
--- a/sigc++config.h.in
+++ b/sigc++config.h.in
@@ -26,7 +26,8 @@
   // configure checks
   #undef SIGC_GCC_TEMPLATE_SPECIALIZATION_OPERATOR_OVERLOAD
   #undef SIGC_MSVC_TEMPLATE_SPECIALIZATION_OPERATOR_OVERLOAD
-  
+  #undef SIGC_SELF_REFERENCE_IN_MEMBER_INITIALIZATION
+
   #undef SIGC_HAVE_NAMESPACE_STD
   #undef SIGC_HAVE_SUN_REVERSE_ITERATOR
   #undef SIGC_TYPEDEF_REDEFINE_ALLOWED