Add ninja generator flag for writing library deps.

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 b7dbd521c37ad7c77c8b059132d2f33a6c3eabd0..5b89dad43a179c6ab88c4e518e2791d4ed14dd1e 100644
--- a/pylib/gyp/generator/ninja.py
+++ b/pylib/gyp/generator/ninja.py
@@ -210,7 +210,7 @@ class Target:
 class NinjaWriter:
   def __init__(self, qualified_target, target_outputs, base_dir, build_dir,
                output_file, toplevel_build, output_file_name, flavor,
-               toplevel_dir=None):
+               generator_flags, toplevel_dir=None):

[Nico, 2013/09/09 23:27:27]

It's nicer to not pass in the whole flags object, just the bits you need
(deps_file_name=None) and do the flags parsing where the NinjaWriters are
instantiated.

[brettw, 2013/09/10 21:12:13]

Done.

     """
     base_dir: path from source root to directory containing this gyp file,
               by gyp semantics, all input paths are relative to this
@@ -245,6 +245,15 @@ class NinjaWriter:
     base_to_top = gyp.common.InvertRelativePath(base_dir, toplevel_dir)
     self.base_to_build = os.path.join(base_to_top, build_dir)
 
+    # The self.link_deps_file will either be a file object if the file is
+    # requested, or it will be false if not. This file should contain a
+    # mapping from target to the list of library dependencies it has.
+    LINK_DEPS_FILE = 'link_deps_file'
+    if LINK_DEPS_FILE in generator_flags:
+      self.link_deps_file = open(generator_flags.get(LINK_DEPS_FILE), 'ab')

[Nico, 2013/09/09 23:27:27]

Do you want to empty the file before creating the first NinjaWriter? Else this
file will grow and grow every time gyp runs.

[brettw, 2013/09/10 21:12:13]

I currently delete it from GN before doing the spawning. I guess I can add the
delete logic to GYP also, but that would be in a different file and it seemed
messy (since these are generator flags).

[Nico, 2013/09/10 21:56:55]

Huh? Couldn't you create the file in GenerateOutputForConfig() at the bottom, i
guess even just once in 'wb' mode, and then pass in the file object to every
NinjaWriter?

+    else:
+      self.link_deps_file = False

[Evan Martin, 2013/09/09 23:49:34]

Why not "None" (also above in the comment), since it's still falsey and it makes
link_deps_file well-typed.

[brettw, 2013/09/10 21:12:13]

Good idea, done.

+
   def ExpandSpecial(self, path, product_dir=None):
     """Expand specials like $!PRODUCT_DIR in |path|.
 
@@ -975,6 +984,13 @@ class NinjaWriter:
           continue
         linkable = target.Linkable()
         if linkable:
+          if self.link_deps_file:
+            # Save the mapping of link deps.
+            self.link_deps_file.write(self.qualified_target)
+            self.link_deps_file.write(' ')
+            self.link_deps_file.write(target.binary)

[Nico, 2013/09/09 23:27:27]

This isn't correct on windows if you want to use incremental linking. Not sure
if you care.

Note that target.binary can contain spaces. self.qualified_target won't so this
encoding is fine (but maybe surprising)

[brettw, 2013/09/10 21:12:13]

I'll worry about this later, I don't understand how it works now.
 
Okay, I think my parser handles this currently so we should be OK.

+            self.link_deps_file.write('\n')
+
           if (self.flavor == 'win' and
               target.component_objs and
               self.msvs_settings.IsUseLibraryDependencyInputs(config_name)):
@@ -2022,7 +2038,8 @@ def GenerateOutputForConfig(target_list, target_dicts, data, params,
     writer = NinjaWriter(qualified_target, target_outputs, base_path, build_dir,
                          OpenOutput(os.path.join(toplevel_build, output_file)),
                          toplevel_build, output_file,
-                         flavor, toplevel_dir=options.toplevel_dir)
+                         flavor, generator_flags,
+                         toplevel_dir=options.toplevel_dir)
     master_ninja.subninja(output_file)
 
     target = writer.WriteSpec(spec, config_name, generator_flags)