This patch fixes the following bugs:

[#413582] g++ must be called for c++ extensions
[#454030] distutils cannot link C++ code with GCC

topdir = "Lib/distutils"

* bcppcompiler.py
  (BCPPCompiler.create_static_lib): Fixed prototype, removing extra_preargs
  and extra_postargs parameters. Included target_lang parameter.
  (BCPPCompiler.link): Included target_lang parameter.

* msvccompiler.py
  (MSVCCompiler.create_static_lib): Fixed prototype, removing extra_preargs
  and extra_postargs parameters. Included target_lang parameter.
  (MSVCCompiler.link): Included target_lang parameter.

* ccompiler.py
  (CCompiler): New language_map and language_order attributes, used by
  CCompiler.detect_language().

  (CCompiler.detect_language): New method, will return the language of
  a given source, or list of sources. Individual source language is
  detected using the language_map dict. When mixed sources are used,
  language_order will stablish the language precedence.

  (CCompiler.create_static_lib, CCompiler.link, CCompiler.link_executable,
   CCompiler.link_shared_object, CCompiler.link_shared_lib):
  Inlcuded target_lang parameter.

* cygwinccompiler.py
  (CygwinCCompiler.link): Included target_lang parameter.

* emxccompiler.py
  (EMXCCompiler.link): Included target_lang parameter.

* mwerkscompiler.py
  (MWerksCompiler.link): Included target_lang parameter.

* extension.py
  (Extension.__init__): New 'language' parameter/attribute, initialized
  to None by default. If provided will overlap the automatic detection
  made by CCompiler.detect_language(), in build_ext command.

* sysconfig.py
  (customize_compiler): Check Makefile for CXX option, and also the
  environment variable CXX. Use the resulting value in the 'compiler_cxx'
  parameter of compiler.set_executables().

* unixccompiler.py
  (UnixCCompiler): Included 'compiler_cxx' in executables dict, defaulting
  to 'cc'.
  (UnixCCompiler.create_static_lib): Included target_lang parameter.
  (UnixCCompiler.link): Included target_lang parameter, and made
  linker command use compiler_cxx, if target_lang is 'c++'.

* command/build_ext.py
  (build_ext.build_extension): Pass new ext.language attribute
  to compiler.link_shared_object()'s target_lang parameter. If
  ext.language is not provided, detect language using
  compiler.detect_language(sources) instead.

* command/config.py
  (config._link): Pass already available lang parameter as target_lang
  parameter of compiler.link_executable().

1 files changed, 55 insertions, 8 deletions

diff --git a/Lib/distutils/ccompiler.py b/Lib/distutils/ccompiler.py
index 60d1cae..317e21e 100644
--- a/Lib/distutils/ccompiler.py
+++ b/Lib/distutils/ccompiler.py
@@ -74,6 +74,19 @@ class CCompiler:
     shared_lib_format = None            # prob. same as static_lib_format
     exe_extension = None                # string
 
+    # Default language settings. language_map is used to detect a source
+    # file or Extension target language, checking source filenames.
+    # language_order is used to detect the language precedence, when deciding
+    # what language to use when mixing source types. For example, if some
+    # extension has two files with ".c" extension, and one with ".cpp", it
+    # is still linked as c++.
+    language_map = {".c"   : "c",
+                    ".cc"  : "c++",
+                    ".cpp" : "c++",
+                    ".cxx" : "c++",
+                    ".m"   : "objc",
+                   }
+    language_order = ["c++", "objc", "c"]
 
     def __init__ (self,
                   verbose=0,
@@ -572,6 +585,27 @@ class CCompiler:
 
     # _need_link ()
 
+    def detect_language (self, sources):
+        """Detect the language of a given file, or list of files. Uses
+        language_map, and language_order to do the job.
+        """
+	if type(sources) is not ListType:
+            sources = [sources]
+        lang = None
+        index = len(self.language_order)
+        for source in sources:
+            base, ext = os.path.splitext(source)
+            extlang = self.language_map.get(ext)
+            try:
+                extindex = self.language_order.index(extlang)
+                if extindex < index:
+                    lang = extlang
+                    index = extindex
+            except ValueError:
+                pass
+        return lang
+
+    # detect_language ()
 
     # -- Worker methods ------------------------------------------------
     # (must be implemented by subclasses)
@@ -671,7 +705,8 @@ class CCompiler:
                            objects,
                            output_libname,
                            output_dir=None,
-                           debug=0):
+                           debug=0,
+                           target_lang=None):
         """Link a bunch of stuff together to create a static library file.
         The "bunch of stuff" consists of the list of object files supplied
         as 'objects', the extra object files supplied to
@@ -688,6 +723,10 @@ class CCompiler:
         compile step where this matters: the 'debug' flag is included here
         just for consistency).
 
+        'target_lang' is the target language for which the given objects
+        are being compiled. This allows specific linkage time treatment of
+        certain languages.
+
         Raises LibError on failure.
         """
         pass
@@ -710,7 +749,8 @@ class CCompiler:
               debug=0,
               extra_preargs=None,
               extra_postargs=None,
-              build_temp=None):
+              build_temp=None,
+              target_lang=None):
         """Link a bunch of stuff together to create an executable or
         shared library file.
 
@@ -748,6 +788,10 @@ class CCompiler:
         of course that they supply command-line arguments for the
         particular linker being used).
 
+        'target_lang' is the target language for which the given objects
+        are being compiled. This allows specific linkage time treatment of
+        certain languages.
+
         Raises LinkError on failure.
         """
         raise NotImplementedError
@@ -766,13 +810,14 @@ class CCompiler:
                          debug=0,
                          extra_preargs=None,
                          extra_postargs=None,
-                         build_temp=None):
+                         build_temp=None,
+                         target_lang=None):
         self.link(CCompiler.SHARED_LIBRARY, objects,
                   self.library_filename(output_libname, lib_type='shared'),
                   output_dir,
                   libraries, library_dirs, runtime_library_dirs,
                   export_symbols, debug,
-                  extra_preargs, extra_postargs, build_temp)
+                  extra_preargs, extra_postargs, build_temp, target_lang)
 
 
     def link_shared_object (self,
@@ -786,12 +831,13 @@ class CCompiler:
                             debug=0,
                             extra_preargs=None,
                             extra_postargs=None,
-                            build_temp=None):
+                            build_temp=None,
+                            target_lang=None):
         self.link(CCompiler.SHARED_OBJECT, objects,
                   output_filename, output_dir,
                   libraries, library_dirs, runtime_library_dirs,
                   export_symbols, debug,
-                  extra_preargs, extra_postargs, build_temp)
+                  extra_preargs, extra_postargs, build_temp, target_lang)
 
 
     def link_executable (self,
@@ -803,11 +849,12 @@ class CCompiler:
                          runtime_library_dirs=None,
                          debug=0,
                          extra_preargs=None,
-                         extra_postargs=None):
+                         extra_postargs=None,
+                         target_lang=None):
         self.link(CCompiler.EXECUTABLE, objects,
                   self.executable_filename(output_progname), output_dir,
                   libraries, library_dirs, runtime_library_dirs, None,
-                  debug, extra_preargs, extra_postargs, None)
+                  debug, extra_preargs, extra_postargs, None, target_lang)
 
 
     # -- Miscellaneous methods -----------------------------------------