Added 'preprocess()' method to CCompiler interface, and implemented

it in UnixCCompiler.  Still needs to be implemented in MSVCCompiler (and
whatever other compiler classes are lurking out there, waiting to be
checked in).

Lib/distutils/ccompiler.py

@@ -414,6 +414,22 @@ class CCompiler:
     # -- Worker methods ------------------------------------------------
     # (must be implemented by subclasses)
 
+    def preprocess (self,
+                    source,
+                    output_file=None,
+                    macros=None,
+                    include_dirs=None,
+                    extra_preargs=None,
+                    extra_postargs=None):
+        """Preprocess a single C/C++ source file, named in 'source'.
+        Output will be written to file named 'output_file', or stdout if
+        'output_file' not supplied.  'macros' is a list of macro
+        definitions as for 'compile()', which will augment the macros set
+        with 'define_macro()' and 'undefine_macro()'.  'include_dirs' is a
+        list of directory names that will be added to the default list.
+        """
+        pass
+
     def compile (self,
                  sources,
                  output_dir=None,

Lib/distutils/unixccompiler.py

@@ -21,6 +21,7 @@ import string, re, os
 from types import *
 from copy import copy
 from distutils import sysconfig
+from distutils.dep_util import newer
 from distutils.ccompiler import \
      CCompiler, gen_preprocess_options, gen_lib_options
 from distutils.errors import \
@@ -104,6 +105,37 @@ class UnixCCompiler (CCompiler):
     # __init__ ()
 
 
+    def preprocess (self,
+                    source,
+                    output_file=None,
+                    macros=None,
+                    include_dirs=None,
+                    extra_preargs=None,
+                    extra_postargs=None):
+
+        (_, macros, include_dirs) = \
+            self._fix_compile_args (None, macros, include_dirs)
+        pp_opts = gen_preprocess_options (macros, include_dirs)
+        cc_args = ['-E'] + pp_opts
+        if output_file:
+            cc_args.extend(['-o', output_file])
+        if extra_preargs:
+            cc_args[:0] = extra_preargs
+        if extra_postargs:
+            extra_postargs.extend(extra_postargs)
+
+        # We need to preprocess: either we're being forced to, or the
+        # source file is newer than the target (or the target doesn't
+        # exist).
+        if self.force or (output_file and newer(source, output_file)):
+            if output_file:
+                self.mkpath(os.path.dirname(output_file))
+            try:
+                self.spawn ([self.cc] + cc_args)
+            except DistutilsExecError, msg:
+                raise CompileError, msg
+
+
     def compile (self,
                  sources,
                  output_dir=None,