Support for source_target_relative expansion in GN

tools/gn/function_process_file_template.cc

Index: tools/gn/function_process_file_template.cc
diff --git a/tools/gn/function_process_file_template.cc b/tools/gn/function_process_file_template.cc
index b7828a6b8aa724c21433923d78f44a5e08b283f3..66bec3fe6baaeb0c54f02fcb58e41a59211f9e12 100644
--- a/tools/gn/function_process_file_template.cc
+++ b/tools/gn/function_process_file_template.cc
@@ -93,7 +93,7 @@ Value RunProcessFileTemplate(Scope* scope,
   }
 

[brettw, 2016/10/05 19:47:50]

Here can you check that subst.required_types() doesn't contain
SOURCE_TARGET_RELATIVE and throw an error if it does? I think it's better to be
really obvious that this doesn't work.

[Petr Hosek, 2016/10/11 00:59:49]

Done.

   SubstitutionWriter::ApplyListToSourcesAsString(
-      scope->settings(), subst, input_files, &result_files);
+      nullptr, scope->settings(), subst, input_files, &result_files);
 
   // Convert the list of strings to the return Value.
   Value ret(function, Value::LIST);