Make gn wrapper use the one in buildtools rather than tools/gn/bin.

gclient_utils.py

Index: gclient_utils.py
===================================================================
--- gclient_utils.py	(revision 277924)
+++ gclient_utils.py	(working copy)
@@ -650,6 +650,37 @@
   raise Error('Unknown platform: ' + sys.platform)
 
 
+def GetBuildtoolsPath():

[M-A Ruel, 2014/06/18 00:55:36]

Why put these functions here and not put it in gn.py?

[brettw, 2014/06/18 05:41:18]

I think some more stuff will be added to buildtools that will need this kind of
thing.

+  """Returns the full path to the buildtools directory.
+  This is based on the root of the checkout containing the current directory."""
+  gclient_root = FindGclientRoot(os.getcwd())
+  if not gclient_root:
+    return None
+  return os.path.join(gclient_root, 'src', 'buildtools')
+
+
+def GetBuildtoolsPlatformBinaryPath():
+  """Returns the full path to the binary directory for the current platform."""
+  # Mac and Windows just have one directory, Linux has two according to whether
+  # it's 32 or 64 bits.
+  buildtools_path = GetBuildtoolsPath()
+  if not buildtools_path:
+    return None;
+
+  if sys.platform.startswith(('cygwin', 'win')):
+    subdir = 'win'
+  elif sys.platform == 'darwin':
+    subdir = 'mac'

[iannucci, 2014/06/20 22:24:22]

Can we keep the naming scheme uniform across all platforms? Even if we only have
one binary, I think that uniformity will help in the long run (fewer special
cases, etc.).

[brettw, 2014/06/20 23:43:37]

That doesn't really make sense. The idea here is that there is one directory for
all the binaries for your platform. I would like to change the download script
to just download all binaries from the appropriate directory (this involves
encoding the bucket in the .sha1 file somehow).

The Windows and Mac tools in the checkout are 32-bit, even though basically all
development platforms are 64-bit. I might change to 64-bit builds sometime in
the future for GN, but I am certainly not going to make both 32-bit and 64-bit
builds.

Linux is different here because there is typically no capability for running
32-bit binaries on 64-bit systems. We need a 32-bit GN because some of the
Android builds happen on some kind of Google AppEngine thing that's 32-bit.

I'm thinking about it that tools we want regardless of bit-tedness would go into
win/mac/linux, and the bit-specific ones would go into
win32/win64/mac32/mac64/linux32/linux64. We just don't currently have all of
those combinations.

+  elif sys.platform.startswith('linux'):
+    if sys.maxsize > 2**32:
+      subdir = 'linux64'
+    else:
+      subdir = 'linux32'
+  else:
+    raise Error('Unknown platform: ' + sys.platform)
+  return os.path.join(buildtools_path, subdir)
+
+
 def GetExeSuffix():
   """Returns '' or '.exe' depending on how executables work on this platform."""
   if sys.platform.startswith(('cygwin', 'win')):