use option_env! instead of env!

Author: nikomatsakis

src/librustc/back/rpath.rs

@@ -133,7 +133,7 @@ pub fn get_rpath_relative_to_output(os: abi::Os,
 }
 
 pub fn get_install_prefix_rpath(sysroot: &Path, target_triple: &str) -> ~str {
-    let install_prefix = env!("CFG_PREFIX");
+    let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
 
     let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
     let mut path = Path::new(install_prefix);
@@ -171,7 +171,7 @@ mod test {
     fn test_prefix_rpath() {
         let sysroot = filesearch::get_or_default_sysroot();
         let res = get_install_prefix_rpath(&sysroot, "triple");
-        let mut d = Path::new(env!("CFG_PREFIX"));
+        let mut d = Path::new((option_env!("CFG_PREFIX")).expect("CFG_PREFIX"));
         d.push("lib");
         d.push(filesearch::rustlibdir());
         d.push("triple/lib");

src/librustc/driver/driver.rs

@@ -802,7 +802,8 @@ pub fn host_triple() -> &'static str {
     // Instead of grabbing the host triple (for the current host), we grab (at
     // compile time) the target triple that this rustc is built with and
     // calling that (at runtime) the host triple.
-    env!("CFG_COMPILER_HOST_TRIPLE")
+    (option_env!("CFG_COMPILER_HOST_TRIPLE")).
+        expect("CFG_COMPILER_HOST_TRIPLE")
 }
 
 pub fn build_session_options(matches: &getopts::Matches) -> session::Options {

src/librustc/middle/trans/debuginfo.rs

@@ -984,7 +984,8 @@ fn compile_unit_metadata(cx: &CrateContext) {
     };
 
     debug!("compile_unit_metadata: {:?}", compile_unit_name);
-    let producer = format!("rustc version {}", env!("CFG_VERSION"));
+    let producer = format!("rustc version {}",
+                           (option_env!("CFG_VERSION")).expect("CFG_VERSION"));
 
     compile_unit_name.with_ref(|compile_unit_name| {
         work_dir.as_vec().with_c_str(|work_dir| {