Detect rust compiler version in Parity build script, closes 4742 (#4907)

* Detect rust compiler version in Parity build script, closes #4742

* updated required compiler version message

* fixed typo

Cargo.toml

@@ -4,6 +4,7 @@ name = "parity"
 version = "1.7.0"
 license = "GPL-3.0"
 authors = ["Parity Technologies <[email protected]>"]
+build = "build.rs"
 
 [dependencies]
 log = "0.3"
@@ -52,6 +53,9 @@ ethcore-dapps = { path = "dapps", optional = true }
 clippy = { version = "0.0.103", optional = true}
 ethcore-secretstore = { path = "secret_store", optional = true }
 
+[build-dependencies]
+rustc_version = "0.2"
+
 [dev-dependencies]
 ethcore-ipc-tests = { path = "ipc/tests" }
 

build.rs

@@ -0,0 +1,35 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity 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.
+
+// Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+extern crate rustc_version;
+
+const MIN_RUSTC_VERSION: &'static str = "1.15.1";
+
+fn main() {
+	let is = rustc_version::version().unwrap();
+	let required = MIN_RUSTC_VERSION.parse().unwrap();
+	assert!(is >= required, format!("
+
+It looks like you are compiling Parity with an old rustc compiler {}.
+Parity requires version {}. Please update your compiler.
+If you use rustup, try this:
+
+    rustup update stable
+
+and try building Parity again.
+
+", is, required));
+}