Use version_check crate instead of handcrafted version parsing

serde/Cargo.toml

@@ -23,6 +23,9 @@ serde_derive = { version = "1.0", optional = true, path = "../serde_derive" }
 [dev-dependencies]
 serde_derive = { version = "1.0", path = "../serde_derive" }
 
+[build-dependencies]
+version_check = "0.1.3"
+
 
 ### FEATURES #################################################################
 

serde/build.rs

@@ -1,39 +1,13 @@
-use std::env;
-use std::process::Command;
-use std::str::{self, FromStr};
+extern crate version_check;
 
 fn main() {
-    let rustc = match env::var_os("RUSTC") {
-        Some(rustc) => rustc,
-        None => return,
+    match version_check::is_min_version("1.26.0") {
+        Some((true, _)) => {
+            println!("cargo:rustc-cfg=integer128");
+        },
+        Some((false, _)) => {}
+        None => {
+            println!("could not figure out the rustc version");
+        },
     };
-
-    let output = match Command::new(rustc).arg("--version").output() {
-        Ok(output) => output,
-        Err(_) => return,
-    };
-
-    let version = match str::from_utf8(&output.stdout) {
-        Ok(version) => version,
-        Err(_) => return,
-    };
-
-    let mut pieces = version.split('.');
-    if pieces.next() != Some("rustc 1") {
-        return;
-    }
-
-    let next = match pieces.next() {
-        Some(next) => next,
-        None => return,
-    };
-
-    let minor = match u32::from_str(next) {
-        Ok(minor) => minor,
-        Err(_) => return,
-    };
-
-    if minor >= 26 {
-        println!("cargo:rustc-cfg=integer128");
-    }
 }