Extend compiler_version.py to work with clang output.

build/compiler_version.py

Index: build/compiler_version.py
diff --git a/build/compiler_version.py b/build/compiler_version.py
index b06712d25b2d3c25990a97f99a630a66c703ce0b..aa6df62f7542d3d7231e0f9923b3f71ef183d843 100755
--- a/build/compiler_version.py
+++ b/build/compiler_version.py
@@ -2,61 +2,125 @@
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+# vim: set ts=2 sw=2 et sts=2 ai:
 
-"""Compiler version checking tool for gcc
 
-Print gcc version as XY if you are running gcc X.Y.*.
-This is used to tweak build flags for gcc 4.4.
+"""Compiler version checking tool.
+
+Currently supports gcc and clang on Linux.
+
+Allows getting the compiler, assembler and linker versions.
 """
 
 import os
 import re
 import subprocess
+import signal
+import threading
 import sys
 
 
-def GetVersion(compiler, tool):
-  tool_output = tool_error = None
+def call(cmdline):
   try:
-    # Note that compiler could be something tricky like "distcc g++".
-    if tool == "compiler":
-      compiler = compiler + " -dumpversion"
-      # 4.6
-      version_re = re.compile(r"(\d+)\.(\d+)")
-    elif tool == "assembler":
-      compiler = compiler + " -Xassembler --version -x assembler -c /dev/null"
-      # Unmodified: GNU assembler (GNU Binutils) 2.24
-      # Ubuntu: GNU assembler (GNU Binutils for Ubuntu) 2.22
-      # Fedora: GNU assembler version 2.23.2
-      version_re = re.compile(r"^GNU [^ ]+ .* (\d+).(\d+).*?$", re.M)
-    elif tool == "linker":
-      compiler = compiler + " -Xlinker --version"
-      # Using BFD linker
-      # Unmodified: GNU ld (GNU Binutils) 2.24
-      # Ubuntu: GNU ld (GNU Binutils for Ubuntu) 2.22
-      # Fedora: GNU ld version 2.23.2
-      # Using Gold linker
-      # Unmodified: GNU gold (GNU Binutils 2.24) 1.11
-      # Ubuntu: GNU gold (GNU Binutils for Ubuntu 2.22) 1.11
-      # Fedora: GNU gold (version 2.23.2) 1.11
-      version_re = re.compile(r"^GNU [^ ]+ .* (\d+).(\d+).*?$", re.M)
-    else:
-      raise Exception("Unknown tool %s" % tool)
-
-    pipe = subprocess.Popen(compiler, shell=True,
-                            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    pipe = subprocess.Popen(
+        cmdline, shell=True,
+        stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+
+    t = threading.Timer(0.25, pipe.terminate)
+    t.start()
     tool_output, tool_error = pipe.communicate()
-    if pipe.returncode:
-      raise subprocess.CalledProcessError(pipe.returncode, compiler)
+    t.cancel()
+    return pipe.returncode, tool_output, tool_error
+  except subprocess.CalledProcessError, e:
+    return e.returncode, e.output[0], e.output[1]
+
+
+class GetVersionError(Exception):
+  pass
+
+
+def GetVersion(compiler, tool, call=call):
+  # Note that "compiler" is the string to launch the compiler which could
+  # contains all types of weirdness like "distcc g++".
+
+  if tool == "compiler":
+    totry = [" --version"]
+    version_re = re.compile(r"(?P<major>\d+)\.(?P<minor>\d+)")
+    output_fmt = "%i%i"
+  elif tool == "assembler":
+    totry = [
+        "-Xassembler -version -x assembler -c /dev/null",
+        # Mac's need just -v
+        "-Xassembler -v -x assembler -c /dev/null",
+        ]
+
+    # With clang we have to pass -no-integrated-as or -fno-integrated-as for
+    # the system assembler.
+    for args in list(totry):
+      totry.append("-no-integrated-as " + args)
+      totry.append("-fno-integrated-as " + args)
+
+    version_re = re.compile(
+        r"^.* assembler[ )].* (?P<major>\d+).(?P<minor>\d+).*?$",
+        re.M)
+    output_fmt = "%i%02i"
+  elif tool == "linker":
+    totry = ["-Xlinker -version"]
+    version_re = re.compile(
+        r"^.*[ :(-](ld|gold)[ )].* (?P<major>\d+).(?P<minor>\d+)(\.\d+)?$",
+        re.M)
+    output_fmt = "%i%02i"
+  else:
+    raise ValueError("Unknown tool %s" % tool)
+
+  errors = []
+  for arguments in totry:
+    cmdline = "%s %s" % (compiler, arguments)
+
+    retcode, tool_output, tool_error = call(cmdline)
 
-    result = version_re.match(tool_output)
-    return result.group(1) + result.group(2)
-  except Exception, e:
-    if tool_error:
-      sys.stderr.write(tool_error)
-    print >> sys.stderr, "compiler_version.py failed to execute:", compiler
-    print >> sys.stderr, e
-    return ""
+    result = version_re.search(tool_output)
+    if not result:
+      errors.append((retcode, cmdline, tool_output, tool_error))
+      continue
+
+    return output_fmt % (
+        int(result.group('major')), int(result.group('minor')))
+
+  error_output = """\
+compiler_version.py was unable to execute requested tool. Error output follows
+
+"""
+  for retcode, cmdline, stdout, stderr in errors:
+    error_output += """\
+compiler_version.py tried to execute: %s
+Command returned %s
+
+stdout output was
+--------------------------------------------------------------------------
+%s
+--------------------------------------------------------------------------
+stderr output was
+--------------------------------------------------------------------------
+%s
+==========================================================================
+""" % (cmdline, retcode, stdout, stderr)
+  raise GetVersionError(error_output)
+
+
+def FindCompiler(env):
+  cxx = env.get("CXX", None)
+  flags = env.get("CXXFLAGS", None)
+
+  if not cxx:
+    cxx = "c++"
+
+  if flags:
+    flags = " "+flags
+  else:
+    flags = ""
+
+  return cxx+flags
 
 
 def main(args):
@@ -66,22 +130,9 @@ def main(args):
   elif len(args) > 1:
     print "Unknown arguments!"
 
-  # Check if CXX environment variable exists and
-  # if it does use that compiler.
-  cxx = os.getenv("CXX", None)
-  if cxx:
-    cxxversion = GetVersion(cxx, tool)
-    if cxxversion != "":
-      print cxxversion
-      return 0
-  else:
-    # Otherwise we check the g++ version.
-    gccversion = GetVersion("g++", tool)
-    if gccversion != "":
-      print gccversion
-      return 0
-
-  return 1
+  cxxversion = GetVersion(FindCompiler(os.environ), tool)
+  print cxxversion
+  return 0
 
 
 if __name__ == "__main__":