Make win_as.py notice and report errors better

tools/win_as.py

 #!/usr/bin/python
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import getopt
 import sys
 import subprocess
 import re
 import os
@@ skipping 39 matching lines @@
     # endif
 
     for filename in args:
       # normalize the filename to avoid any DOS-type funkiness
       filename = os.path.abspath(filename)
       filename = filename.replace('\\', '/')
 
       #
       # Run the C compiler as a preprocessor and pipe the output into a string
       #
-      p = subprocess.Popen(['cl.exe',
-                            '/nologo',
-                            '/D__ASSEMBLER__',
-                            '/DNACL_BUILD_ARCH=' + nacl_build_arch,
-                            '/DNACL_BUILD_SUBARCH=' + str(nacl_build_subarch),
-                            '/DNACL_WINDOWS=1',
-                            '/TP',
-                            '/E',
-                            '/I' + nacl_path,
-                            filename],
+      cl_command = ['cl.exe',
+                    '/nologo',
+                    '/D__ASSEMBLER__',
+                    '/DNACL_BUILD_ARCH=' + nacl_build_arch,
+                    '/DNACL_BUILD_SUBARCH=' + str(nacl_build_subarch),
+                    '/DNACL_WINDOWS=1',
+                    '/TP',
+                    '/E',
+                    '/I' + nacl_path,
+                    filename]
+      p = subprocess.Popen(cl_command,
                            shell=True,
                            stdout=subprocess.PIPE,
-                           stderr=open(os.devnull, 'w'))
-      cl_output = p.communicate()[0]
+                           stderr=subprocess.PIPE)
+      cl_results = p.communicate()
+      cl_status = p.wait()

[scottmg, 2015/11/04 23:08:40]

It's weird to communicate() and then wait() as they both wait for termination.
This should just be cl_status = p.returncode.

[Roland McGrath, 2015/11/04 23:15:33]

Done.

+      cl_output = cl_results[0]
+      cl_errors = cl_results[1]
+
+      if cl_status != 0:
+        print >>sys.stderr, 'FAILED: %s\n%s\n' % (' '.join(cl_command),
+                                                  cl_errors)
+        return cl_status
 
       #
       # Uncomment this if you need to see exactly what the MSVC preprocessor
       # has done to your input file.
       #print >>sys.stderr, '-------------------------------------'
       #print >>sys.stderr, '# PREPROCESSOR OUTPUT BEGINS        #'
       #print >>sys.stderr, '-------------------------------------'
       #print >>sys.stderr, cl_output
       #print >>sys.stderr, '-------------------------------------'
       #print >>sys.stderr, '# PREPROCESSOR OUTPUT ENDS          #'
       #print >>sys.stderr, '-------------------------------------'
 
       # GNU uses '#<linenum> for line number directives; MSVC uses
       # '#line <linenum>.'
       foo = re.compile(r'^#line ', re.MULTILINE)
       cl_output = foo.sub(r'#', cl_output)
 
-      if p.wait() == 0: # success

[scottmg, 2015/11/04 23:08:40]

Although I see it was already like this. Well.

-        #
-        # Pipe the preprocessor output into the assembler
-        #
-        p = subprocess.Popen([nacl_path + as_exe,
-                              '-defsym','@feat.00=1',
-                              '--' + str(nacl_build_subarch),
-                              '-o', output_filename ],
-                             stdin=subprocess.PIPE,
-                             stderr=subprocess.PIPE)
-        as_output, as_error = p.communicate(cl_output)
+      #
+      # Pipe the preprocessor output into the assembler
+      #
+      as_command = [nacl_path + as_exe,
+                    '-defsym','@feat.00=1',
+                    '--' + str(nacl_build_subarch),
+                    '-o', output_filename]
+      p = subprocess.Popen(as_command,
+                           stdin=subprocess.PIPE,
+                           stderr=subprocess.PIPE)
+      as_output, as_error = p.communicate(cl_output)
+      as_status = p.wait()

[scottmg, 2015/11/04 23:08:40]

Same.

[Roland McGrath, 2015/11/04 23:15:33]

Done.

 
-        #
-        # massage the assembler stderr into a format that Visual Studio likes
-        #
-        as_error = re.sub(r'\{standard input\}', filename, as_error)
-        as_error = re.sub(r':([0-9]+):', r'(\1) :', as_error)
-        as_error = re.sub(r'Error', 'error', as_error)
-        as_error = re.sub(r'Warning', 'warning', as_error)
+      #
+      # massage the assembler stderr into a format that Visual Studio likes
+      #
+      as_error = re.sub(r'\{standard input\}', filename, as_error)
+      as_error = re.sub(r':([0-9]+):', r'(\1) :', as_error)
+      as_error = re.sub(r'Error', 'error', as_error)
+      as_error = re.sub(r'Warning', 'warning', as_error)
 
-        if as_error:
-          print >>sys.stderr, as_error
+      if as_error:
+        print >>sys.stderr, as_error
 
-      # endif
+      if as_status != 0:
+        print >>sys.stderr, 'FAILED: %s\n' % ' '.join(as_command)
+        return as_status
+
     # endfor
 
   except getopt.error, e:
     print >>sys.stderr, str(e)
     print >>sys.stderr, ['Usage: ',
       argv[0],
       '-a {Win32|x64} -o output_file [-p native_client_path] input_file']
   # endtry
 
 # enddef
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))
 # endif