Merge pull request #1259 from serde-rs/build

Build script that does nothing

serde/Cargo.toml

@@ -10,7 +10,8 @@ documentation = "https://docs.serde.rs/serde/"
 keywords = ["serde", "serialization", "no_std"]
 categories = ["encoding"]
 readme = "README.md"
-include = ["Cargo.toml", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+include = ["Cargo.toml", "build.rs", "src/**/*.rs", "README.md", "LICENSE-APACHE", "LICENSE-MIT"]
+build = "build.rs"
 
 [badges]
 travis-ci = { repository = "serde-rs/serde" }

serde/build.rs

@@ -0,0 +1,41 @@
+use std::env;
+use std::process::Command;
+use std::str::{self, FromStr};
+
+fn main() {
+    let rustc = match env::var_os("RUSTC") {
+        Some(rustc) => rustc,
+        None => return,
+    };
+
+    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,
+    };
+
+    // 128-bit integers stabilized in Rust 1.26:
+    // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
+    if minor >= 26 {
+        println!("cargo:rustc-cfg=integer128");
+    }
+}