Enable crash dump collection on builders

win_toolchain/get_toolchain_if_necessary.py

Index: win_toolchain/get_toolchain_if_necessary.py
diff --git a/win_toolchain/get_toolchain_if_necessary.py b/win_toolchain/get_toolchain_if_necessary.py
index dbfb0eb0e29857da8eb3f9ef4bedb797f64b42f4..d176665bef79a5c63b834f60609280dd245e73ed 100755
--- a/win_toolchain/get_toolchain_if_necessary.py
+++ b/win_toolchain/get_toolchain_if_necessary.py
@@ -357,6 +357,25 @@ def InstallUniversalCRTIfNeeded(abs_target_dir):
   return
 
 
+def EnableCrashDumpCollection():
+  """Tell Windows Error Reporting to record crash dumps so that we can diagnose
+  linker crashes and other toolchain failures. Documented at:
+  https://msdn.microsoft.com/en-us/library/windows/desktop/bb787181(v=vs.85).aspx

[scottmg, 2016/03/22 19:27:44]

Remove "(v=vs.85)" to make it fix in 80 col

[brucedawson, 2016/03/22 20:39:18]

Done.

+  """
+  key_name = r'SOFTWARE\Microsoft\Windows\Windows Error Reporting\LocalDumps'

[scottmg, 2016/03/22 19:27:44]

if not sys.platform.startswith('win'):
  return

before this line for --force on Linux.

[brucedawson, 2016/03/22 20:39:18]

sys.platform == 'win32' seems to be standard in this file, so using that.

+  try:
+    key = winreg.CreateKey(winreg.HKEY_LOCAL_MACHINE, key_name)
+    # None of the settings are touched because that could over-ride user
+    # specific settings. Merely creating LocalDumps is sufficient to enable the
+    # defaults.
+    key.Close()
+  # Trap OSError instead of WindowsError so pylint will succeed on Linux.
+  # Catching errors is important because some build machines and most user
+  # machines are not elevated and writing to HKLM requires elevation.
+  except OSError:
+    return

[scottmg, 2016/03/22 19:27:44]

Normally just "pass" instead of "return" to indicate it's being ignored.

[brucedawson, 2016/03/22 20:39:18]

Yep. I previously had the except elsewhere where 'return' was needed, but now it
isn't.

Done.

+
+
 def main():
   parser = optparse.OptionParser(description=sys.modules[__name__].__doc__)
   parser.add_option('--output-json', metavar='FILE',
@@ -471,6 +490,8 @@ def main():
     shutil.copyfile(os.path.join(target_dir, '..', 'data.json'),
                     options.output_json)
 
+  EnableCrashDumpCollection()
+
   if os.environ.get('GYP_MSVS_VERSION') == '2015':
     InstallUniversalCRTIfNeeded(abs_toolchain_target_dir)