Auto-generate v8 version based on tags.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 6534eea85948104dffd43635282a3d14f370bc82..b9cabf05fb3ebbcd967608ca64500fc476009c2d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -341,6 +341,24 @@ action("run_mksnapshot") {
   }
 }
 
+action("generate_v8_version") {
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+
+  script = "tools/push-to-trunk/generate_version.py"
+
+  sources = [
+    "src/version.cc",
+  ]
+
+  outputs = [
+    "$target_gen_dir/version.cc"
+  ]
+
+  args = [
+    rebase_path("$target_gen_dir/version.cc", root_build_dir),
+  ]
+}
+
 
 ###############################################################################
 # Source Sets (aka static libraries)
@@ -945,7 +963,7 @@ source_set("v8_base") {
     "src/v8threads.h",
     "src/variables.cc",
     "src/variables.h",
-    "src/version.cc",
+    "$target_gen_dir/version.cc",

[Michael Achenbach, 2015/01/07 14:01:15]

I'm not so happy about the sorting. Should it just be on top?

[Jakob Kummerow, 2015/01/07 16:20:59]

I'm not too happy about it either. Keeping version.cc next to version.h has its
appeal, but I think we should preserve alphabetical ordering. Let's put it at
the top or the bottom of the list. (Same in v8.gyp.)

     "src/version.h",
     "src/vm-state-inl.h",
     "src/vm-state.h",
@@ -1217,7 +1235,7 @@ source_set("v8_base") {
   }
 
   defines = []
-  deps = [ ":v8_libbase" ]
+  deps = [ ":v8_libbase", ":generate_v8_version" ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.