Add support for building the Dart VM for Android OS.

utils/apidoc/apidoc.gyp

 # 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.
 
 {
   'variables' : {
     'script_suffix%': '',
   },
   'conditions' : [
     ['OS=="win"', {
@@ skipping 29 matching lines @@
           ],
           'action': [
             '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)dart<(EXECUTABLE_SUFFIX)',
             'apidoc.dart',
             '--out=<(PRODUCT_DIR)/api_docs',
             '--mode=static',
           ],
           'message': 'Running apidoc: <(_action)',
         },
       ],
+      'conditions': [

[Emily Fortuna, 2012/08/08 01:28:37]

You're almost certainly much more of a gyp expert than I am after having made
all these changes, but I thought variables defined at the top level gyp file
were passed on to the sub-gyp files (?). So you wouldn't have to add this
'conditions': host/target in every gyp file. Am I mistaken?

[jackpal, 2012/08/08 23:06:45]

It's complicated. Here's my understanding of this under-documented feature:

Gyp supports a build that is composed of multiple toolsets. Each toolset has its
own set tools (compilers, linkers, etc.) and its own output directory (so that
you don't try to mix artifacts between toolsets.)

For a normal build we use just one toolset, called the "target" toolset. For an
Android build we use two toolsets: a "host" toolset for build artifacts that
need to run on the host (e.g. the build machine) and a "target" toolset for
build artifacts that need to run on the "target" (e.g. the Android device.) It
is even possible for an artifact to be built twice, once for the host and once
for the target.

The reason you see the 'conditions' statement all over the place is that it's
necessary for any artifact that needs to be built on the "host". There's no way
to inherit this, as it needs to be indicated on a target-by-target basis.

This particular target is the "apidoc" target, and it needs to be built to run
on the host.

I made this change when I was trying to make the cross platform Android build
build "all" targets correctly.

More recently I've scaled back my ambitions to just trying to get the dart
target (and other similar targets related to the Dart VM) to build on Android.

So this particular change isn't needed any more, and I'm going to remove it.

+            ['dart_want_separate_host_toolset==1', {
+              'toolsets': ['host'],
+            }, {
+              'toolsets': ['target'],
+            }]
+      ],
     }
   ],
 }