Fixes for determining "GCC" version when compiler is clang.
https://sourceforge.net/p/ggt/bugs/28/
--- SConstruct.orig	2009-11-21 15:31:52.000000000 -0600
+++ SConstruct	2023-03-08 18:28:02.000000000 -0600
@@ -3,6 +3,7 @@
 EnsureSConsVersion(0,96)
 SConsignFile()
 
+from subprocess import Popen, PIPE
 import os, string, sys
 import re
 import distutils.sysconfig
@@ -129,26 +126,28 @@
    framework_opt = '-F' + m.group(1)
 
    CXX = os.environ.get("CXX", WhereIs('g++'))
-
-   ver_re = re.compile(r'gcc version ((\d+)\.(\d+)\.(\d+))')
-   (gv_stdout, gv_stdin, gv_stderr) = os.popen3(CXX + ' -v')
-   ver_str = gv_stderr.read()
-
-   match_obj = ver_re.search(ver_str)
-
    LINK = CXX
    CXXFLAGS = ['-ftemplate-depth-256', '-DBOOST_PYTHON_DYNAMIC_LIB',
                '-Wall', framework_opt, '-pipe']
 
-   compiler_ver       = match_obj.group(1)
-   compiler_major_ver = int(match_obj.group(2))
-   compiler_minor_ver = int(match_obj.group(3))
+   p = Popen([CXX, '-dM', '-E', '-x', 'c++', '-'], stdout=PIPE)
+   preprocessor_macros = p.stdout.read().decode('utf-8')
+
+   ver_re = re.compile(r'#define __GNUC__ (\d+)')
+   match_obj = ver_re.search(preprocessor_macros)
+   compiler_major_ver = int(match_obj.group(1))
+
+   ver_re = re.compile(r'#define __GNUC_MINOR__ (\d+)')
+   match_obj = ver_re.search(preprocessor_macros)
+   compiler_minor_ver = int(match_obj.group(1))
+
+   compiler_ver = f'{compiler_major_ver}.{compiler_minor_ver}'
 
    # GCC 4.0 in Mac OS X 10.4 and newer does not have -fcoalesce-templates.
    if compiler_major_ver < 4:
       CXXFLAGS.append('-fcoalesce-templates')
    else:
-      if compiler_minor_ver < 2:
+      if compiler_major_ver == 4 and compiler_minor_ver < 2:
          CXXFLAGS += ['-Wno-long-double', '-no-cpp-precomp']
 
    SHLIBSUFFIX = distutils.sysconfig.get_config_var('SO')