Ninja generator: support using clang-cl for Windows

pylib/gyp/generator/ninja.py

Index: pylib/gyp/generator/ninja.py
diff --git a/pylib/gyp/generator/ninja.py b/pylib/gyp/generator/ninja.py
index 4c2a55e40fa247b4f5fcaec9f9e80568864da618..2cbc5fef3da5efd26a5c1b0c9c4062ad39180c0a 100644
--- a/pylib/gyp/generator/ninja.py
+++ b/pylib/gyp/generator/ninja.py
@@ -1682,6 +1682,7 @@ def GenerateOutputForConfig(target_list, target_dicts, data, params,
   cxx_host = None
   cc_host_global_setting = None
   cxx_host_global_setting = None
+  clang_cl = None
 
   build_file, _, _ = gyp.common.ParseQualifiedTarget(target_list[0])
   make_global_settings = data[build_file].get('make_global_settings', [])
@@ -1701,6 +1702,8 @@ def GenerateOutputForConfig(target_list, target_dicts, data, params,
       cxx_host_global_setting = value
     if key.endswith('_wrapper'):
       wrappers[key[:-len('_wrapper')]] = os.path.join(build_to_root, value)
+    if key == 'clang-cl':
+      clang_cl = os.path.join(build_to_root, value)
 
   # Support wrappers from environment variables too.
   for key, value in os.environ.iteritems():
@@ -1713,9 +1716,15 @@ def GenerateOutputForConfig(target_list, target_dicts, data, params,
     cl_paths = gyp.msvs_emulation.GenerateEnvironmentFiles(
         toplevel_build, generator_flags, OpenOutput)
     for arch, path in cl_paths.iteritems():
-      master_ninja.variable(
-          'cl_' + arch, CommandWithWrapper('CC', wrappers,
-                                           QuoteShellArgument(path, flavor)))
+      if clang_cl:
+        # If we have clang-cl, use that instead.
+        path = clang_cl

[Nico, 2014/01/28 17:48:20]

Can't you use one of the existing keys (CC or CXX, and maybe warn if both are
set to different values) instead?

[scottmg, 2014/01/28 17:59:02]

That sounds better to me.

+      command = CommandWithWrapper('CC', wrappers,
+          QuoteShellArgument(path, 'win'))
+      if clang_cl:
+        # Use clang-cl to cross-compile for x86 or x86_64.
+        command += (' -m32' if arch == 'x86' else ' -m64')

[scottmg, 2014/01/28 17:59:02]

Slightly concerned about this as it's expecting a binary for CreateProcess, but
I think it'll work ok because of the ninja -t wrapper. Is there somewhere to get
it into cflags instead?

(It'll be nice to get rid of the ridiculous path manipulation we have to do for
cl, some day.)

+      master_ninja.variable('cl_' + arch, command)
 
   cc = GetEnvironFallback(['CC_target', 'CC'], cc)
   master_ninja.variable('cc', CommandWithWrapper('CC', wrappers, cc))