Try to better guess Visual Studio path when building Dart on Windows.

tools/utils.py

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # This file contains a set of utilities functions used by other Python-based
 # scripts.
 
 import commands
 import os
 import platform
@@ skipping 43 matching lines @@
   if os.path.exists("/proc/cpuinfo"):
     return int(commands.getoutput("grep -E '^processor' /proc/cpuinfo | wc -l"))
   if os.path.exists("/usr/bin/hostinfo"):
     return int(commands.getoutput('/usr/bin/hostinfo | grep "processors are logically available." | awk "{ print \$1 }"'))
   win_cpu_count = os.getenv("NUMBER_OF_PROCESSORS")
   if win_cpu_count:
     return int(win_cpu_count)
   return int(os.getenv("DART_NUMBER_OF_CORES", 2))
 
 
+# Try to guess Visual Studio location when buiding on Windows.
+def GuessVisualStudioPath():

[kustermann, 2013/02/18 21:17:52]

I have one major concern with this function:
- In the previous version we've always used Visual Studio 10.
- GuessVisualStudioPath picks the first best Visual Studio version it finds in
the registry (not necessarily the newest version), falling back to 10 if it
can't find any version.
- We have currently up to 3 different versions of Visual Studio installed on the
BuildBots (AFAIK).

Now this can result in a situation where we pick different versions of VS on
different bots. This, in return, can result in hard-to-find building issues,
flakiness, ... on the bots (we had already issues with gyp and different VS
versions).

Here's what I would prefer: If VS 10 is installed, just take it (so we don't
change the default behavior of build.py). If VS 10 is not installed, do the
registry lookup and take any version:

def GuessVisualStudioPath():
  defaultPath = r'C:\Program Files ...'
  if os.path.exists(defaultPath):
    return defaultPath
  else:
    import win32process
    ....

[aam-me, 2013/02/19 04:06:31]

Done.

This script can also retrieve Visual Studio version it should use from some
environment variable(BUILD_DART_MSVS_VERSION, for example, similar to
GYP_MSVS_VERSION) that would override whatever guessing logic is in the script.
That might help with flakiness caused by different builder setup.

+  defaultPath = 'C:\\Program Files (x86)\\Microsoft Visual Studio 10.0\\Common7'
+  '\\IDE'

[kustermann, 2013/02/18 21:17:52]

In general I usually prefer raw strings for windows path names (to eliminate
double backslashes).

[aam-me, 2013/02/19 04:06:31]

Done.

+  if not IsWindows():
+    return defaultPath
+
+  import win32process
+  # Check if python process is 64-bit or if it's 32-bit running in 64-bit OS.
+  # We need to know whether host is 64-bit so that we are looking in right
+  # registry for Visual Studio path.
+  if sys.maxsize > 2**32 or win32process.IsWow64Process():
+    wow6432Node = "Wow6432Node\\"
+  else:
+    wow6432Node = ""
+
+  import _winreg
+  try:
+    key = _winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE,
+                          "SOFTWARE\\%sMicrosoft\\VisualStudio" % wow6432Node)
+  except WindowsError:
+    # Can't find traces of Visual Studio. Giving up, then.
+    return defaultPath
+
+  try:
+    subkeyCounter = 0
+    while True:
+      try:
+        subkeyName = _winreg.EnumKey(key, subkeyCounter)
+      except WindowsError:
+        # Reached end of enumeration.
+        return defaultPath
+      match = re.match('^(\\d+\\.\\d+)$', subkeyName)

[kustermann, 2013/02/18 21:17:52]

Consider using a raw string.

[aam-me, 2013/02/19 04:06:31]

Done.

+      if match:
+        with _winreg.OpenKey(key, subkeyName) as subkey:
+          try:
+            (path, registrytype) = _winreg.QueryValueEx(subkey, 'InstallDir')
+            return path
+          except WindowsError:
+            # Can't find value under the key - continue to the next key.
+            pass
+      subkeyCounter = subkeyCounter + 1
+  finally:
+    _winreg.CloseKey(key)
+
 # Returns true if we're running under Windows.
 def IsWindows():
   return GuessOS() == 'win32'
 
 
 # Reads a text file into an array of strings - one for each
 # line. Strips comments in the process.
 def ReadLinesFrom(name):
   result = []
   for line in open(name):
@@ skipping 190 matching lines @@
     os.unlink(name)
   except OSError, e:
     PrintError("os.unlink() " + str(e))
 
 
 def Main(argv):
   print "GuessOS() -> ", GuessOS()
   print "GuessArchitecture() -> ", GuessArchitecture()
   print "GuessCpus() -> ", GuessCpus()
   print "IsWindows() -> ", IsWindows()
+  print "GuessVisualStudioPath() -> ", GuessVisualStudioPath()
 
 
 class Error(Exception):
   pass
 
 
 class ToolError(Exception):
   """Deprecated exception, use Error instead."""
 
   def __init__(self, value):
@@ skipping 37 matching lines @@
 
 def DartSdkBinary():
   tools_dir = os.path.dirname(os.path.realpath(__file__))
   dart_binary_prefix = os.path.join(tools_dir, '..', 'sdk' , 'bin')
   return os.path.join(dart_binary_prefix, 'dart')
 
 
 if __name__ == "__main__":
   import sys
   Main(sys.argv)