Checkin build mod

build.rs

+// Copyright 2015-2018 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+extern crate vergen;
+
+use vergen::{ConstantsFlags, Vergen};
+
+const ERROR_MSG: &'static str = "Failed to generate metadata files";
+
+fn main() {
+	let vergen = Vergen::new(ConstantsFlags::all()).expect(ERROR_MSG);
+
+	for (k, v) in vergen.build_info() {
+		println!("cargo:rustc-env={}={}", k.name(), v);
+	}
+
+	println!("cargo:rerun-if-changed=.git/HEAD");
+}