Add Deno.version.gnArgs (#1845)

To display specific build args passed to GN.

BUILD.gn

@@ -221,6 +221,10 @@ bundle("main_bundle") {
   deps = [
     ":deno_runtime_declaration",
     ":msg_ts",
+    ":write_gn_args",
+  ]
+  data = [
+    "$target_gen_dir/gn_args.txt",
   ]
 }
 
@@ -260,3 +264,11 @@ snapshot("snapshot_compiler") {
     ":compiler_bundle",
   ]
 }
+
+action("write_gn_args") {
+  script = "//tools/write_gn_args.py"
+  outputs = [
+    "$target_gen_dir/gn_args.txt",
+  ]
+  args = [ rebase_path(outputs[0], root_build_dir) ]
+}

js/version.ts

@@ -3,12 +3,14 @@ interface Version {
   deno: string;
   v8: string;
   typescript: string;
+  gnArgs: string;
 }
 
 export const version: Version = {
   deno: "",
   v8: "",
-  typescript: "TS_VERSION" // This string will be replaced by rollup
+  typescript: "TS_VERSION", // This string will be replaced by rollup
+  gnArgs: `GN_ARGS` // This string will be replaced by rollup
 };
 
 /**

js/version_test.ts

@@ -6,3 +6,7 @@ test(function version() {
   assert(pattern.test(Deno.version.v8));
   assert(pattern.test(Deno.version.typescript));
 });
+
+test(function versionGnArgs() {
+  assert(Deno.version.gnArgs.length > 100);
+});

rollup.config.js

@@ -20,6 +20,7 @@ const typescriptPath = path.resolve(
   __dirname,
   "third_party/node_modules/typescript/lib/typescript.js"
 );
+const gnArgs = fs.readFileSync("gen/gn_args.txt", "utf-8").trim();
 
 // We will allow generated modules to be resolvable by TypeScript based on
 // the current build path
@@ -228,7 +229,8 @@ export default function makeConfig(commandOptions) {
 
       // replace strings
       replace({
-        TS_VERSION: typescript.version
+        TS_VERSION: typescript.version,
+        GN_ARGS: gnArgs
       }),
 
       // would prefer to use `rollup-plugin-virtual` to inject the empty module, but there

tools/setup.py

@@ -2,7 +2,7 @@
 # Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import third_party
 from util import build_mode, build_path, enable_ansi_colors, root_path, run
-from util import shell_quote
+from util import shell_quote, run_output
 import os
 import re
 import sys

tools/write_gn_args.py

@@ -0,0 +1,16 @@
+# Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import os
+import sys
+import third_party
+from util import run_output, build_path
+
+out_filename = sys.argv[1]
+
+args_list = run_output([
+    third_party.gn_path, "args",
+    build_path(), "--list", "--short", "--overrides-only"
+],
+                       env=third_party.google_env())
+
+with open(out_filename, "w") as f:
+    f.write(args_list)