Improve error message when debuggers not installed

build/vs_toolchain.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 import glob
 import json
 import os
 import pipes
 import platform
@@ skipping 307 matching lines @@
   from the SDK directory avoids using the system copy of dbghelp.dll which then
   ensures compatibility with recent debug information formats, such as VS
   2017 /debug:fastlink PDBs.
   """
   win_sdk_dir = SetEnvironmentAndGetSDKDir()
   if not win_sdk_dir:
     return
 
   debug_file = 'dbghelp.dll'
   full_path = os.path.join(win_sdk_dir, 'Debuggers', target_cpu, debug_file)
+  if not os.path.exists(full_path):
+    raise Exception('dbghelp.dll not found in "%s"\r\nYou must install the '
+                    '"Debugging Tools for Windows" feature from the Windows '
+                    '10 SDK.' % full_path)

[wkorman, 2017/05/01 18:40:19]

Is there a page worth linking to directly? I found four from Google searching,
with varying dead links, these look like the two that I might explore:

https://developer.microsoft.com/en-us/windows/hardware/windows-driver-kit
https://developer.microsoft.com/en-us/windows/hardware/download-windbg

I realize the urls change often so maybe it's not worth including but thought
worth brief discussion. Since I think the way I probably got into trouble is
that one of the above is the right one, but even now I am not sure which.

And maybe VS 2017 even has an in-app checkbox that in theory installs the thing,
separate from above two urls/installers, but I am not sure that worked for me
per previous bug discussion.

   target_path = os.path.join(target_dir, debug_file)
   _CopyRuntimeImpl(target_path, full_path)
 
 
 def _GetDesiredVsToolchainHashes():
   """Load a list of SHA1s corresponding to the toolchains that we want installed
   to build with."""
   env_version = GetVisualStudioVersion()
   if env_version == '2015':
     # Update 3 final with patches with 10.0.14393.0 SDK.
@@ skipping 97 matching lines @@
       'copy_dlls': CopyDlls,
   }
   if len(sys.argv) < 2 or sys.argv[1] not in commands:
     print >>sys.stderr, 'Expected one of: %s' % ', '.join(commands)
     return 1
   return commands[sys.argv[1]](*sys.argv[2:])
 
 
 if __name__ == '__main__':
   sys.exit(main())