std: Tweak the std::env OsString/String interface

This commit tweaks the interface of the `std::env` module to make it more
ergonomic for common usage:

* `env::var` was renamed to `env::var_os`
* `env::var_string` was renamed to `env::var`
* `env::args` was renamed to `env::args_os`
* `env::args` was re-added as a panicking iterator over string values
* `env::vars` was renamed to `env::vars_os`
* `env::vars` was re-added as a panicking iterator over string values.

This should make common usage (e.g. unicode values everywhere) more ergonomic
as well as "the default". This is also a breaking change due to the differences
of what's yielded from each of these functions, but migration should be fairly
easy as the defaults operate over `String` which is a common type to use.

[breaking-change]

21 files changed, 162 insertions, 80 deletions

diff --git a/src/compiletest/compiletest.rs b/src/compiletest/compiletest.rs
index 3c92fa02f20..385f1b9e791 100644
--- a/src/compiletest/compiletest.rs
+++ b/src/compiletest/compiletest.rs
@@ -14,7 +14,6 @@
 #![feature(collections)]
 #![feature(int_uint)]
 #![feature(io)]
-#![feature(os)]
 #![feature(path)]
 #![feature(rustc_private)]
 #![feature(slicing_syntax, unboxed_closures)]
@@ -48,8 +47,7 @@ pub mod common;
 pub mod errors;
 
 pub fn main() {
-    let args = env::args().map(|s| s.into_string().unwrap()).collect();;
-    let config = parse_config(args);
+    let config = parse_config(env::args().collect());
 
     if config.valgrind_path.is_none() && config.force_valgrind {
         panic!("Can't find Valgrind to run Valgrind tests");
diff --git a/src/compiletest/util.rs b/src/compiletest/util.rs
index 078eb7bba20..c046a89cba5 100644
--- a/src/compiletest/util.rs
+++ b/src/compiletest/util.rs
@@ -40,7 +40,7 @@ pub fn make_new_path(path: &str) -> String {
 
     // Windows just uses PATH as the library search path, so we have to
     // maintain the current value while adding our own
-    match env::var_string(lib_path_env_var()) {
+    match env::var(lib_path_env_var()) {
       Ok(curr) => {
         format!("{}{}{}", path, path_div(), curr)
       }
diff --git a/src/liblog/lib.rs b/src/liblog/lib.rs
index 15f50188919..1fedf49738c 100644
--- a/src/liblog/lib.rs
+++ b/src/liblog/lib.rs
@@ -397,7 +397,7 @@ fn enabled(level: u32,
 /// This is not threadsafe at all, so initialization is performed through a
 /// `Once` primitive (and this function is called from that primitive).
 fn init() {
-    let (mut directives, filter) = match env::var_string("RUST_LOG") {
+    let (mut directives, filter) = match env::var("RUST_LOG") {
         Ok(spec) => directive::parse_logging_spec(&spec[]),
         Err(..) => (Vec::new(), None),
     };
diff --git a/src/librustc/metadata/filesearch.rs b/src/librustc/metadata/filesearch.rs
index 1b2d82e68c1..3caa0f5b4db 100644
--- a/src/librustc/metadata/filesearch.rs
+++ b/src/librustc/metadata/filesearch.rs
@@ -207,7 +207,7 @@ static PATH_ENTRY_SEPARATOR: &'static str = ":";
 
 /// Returns RUST_PATH as a string, without default paths added
 pub fn get_rust_path() -> Option<String> {
-    env::var_string("RUST_PATH").ok()
+    env::var("RUST_PATH").ok()
 }
 
 /// Returns the value of RUST_PATH, as a list
diff --git a/src/librustc/middle/infer/region_inference/graphviz.rs b/src/librustc/middle/infer/region_inference/graphviz.rs
index 362919755c3..67875ae2252 100644
--- a/src/librustc/middle/infer/region_inference/graphviz.rs
+++ b/src/librustc/middle/infer/region_inference/graphviz.rs
@@ -61,13 +61,13 @@ pub fn maybe_print_constraints_for<'a, 'tcx>(region_vars: &RegionVarBindings<'a,
     }
 
     let requested_node : Option<ast::NodeId> =
-        env::var_string("RUST_REGION_GRAPH_NODE").ok().and_then(|s| s.parse().ok());
+        env::var("RUST_REGION_GRAPH_NODE").ok().and_then(|s| s.parse().ok());
 
     if requested_node.is_some() && requested_node != Some(subject_node) {
         return;
     }
 
-    let requested_output = env::var_string("RUST_REGION_GRAPH").ok();
+    let requested_output = env::var("RUST_REGION_GRAPH").ok();
     debug!("requested_output: {:?} requested_node: {:?}",
            requested_output, requested_node);
 
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 949fee45517..8340a49b92a 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1052,7 +1052,7 @@ pub fn get_unstable_features_setting() -> UnstableFeatures {
     // subverting the unstable features lints
     let bootstrap_secret_key = option_env!("CFG_BOOTSTRAP_KEY");
     // The matching key to the above, only known by the build system
-    let bootstrap_provided_key = env::var_string("RUSTC_BOOTSTRAP_KEY").ok();
+    let bootstrap_provided_key = env::var("RUSTC_BOOTSTRAP_KEY").ok();
     match (disable_unstable_features, bootstrap_secret_key, bootstrap_provided_key) {
         (_, Some(ref s), Some(ref p)) if s == p => UnstableFeatures::Cheat,
         (true, _, _) => UnstableFeatures::Disallow,
diff --git a/src/librustc_back/target/mod.rs b/src/librustc_back/target/mod.rs
index afb5c948f18..4d90c492fa2 100644
--- a/src/librustc_back/target/mod.rs
+++ b/src/librustc_back/target/mod.rs
@@ -384,7 +384,7 @@ impl Target {
             Path::new(target)
         };
 
-        let target_path = env::var("RUST_TARGET_PATH")
+        let target_path = env::var_os("RUST_TARGET_PATH")
                               .unwrap_or(OsString::from_str(""));
 
         // FIXME 16351: add a sane default search path?
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index d82c160fdee..12f5041cad1 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -464,7 +464,7 @@ pub fn phase_2_configure_and_expand(sess: &Session,
             // compiler, not for the target.
             let mut _old_path = OsString::from_str("");
             if cfg!(windows) {
-                _old_path = env::var("PATH").unwrap_or(_old_path);
+                _old_path = env::var_os("PATH").unwrap_or(_old_path);
                 let mut new_path = sess.host_filesearch(PathKind::All).get_dylib_search_paths();
                 new_path.extend(env::split_paths(&_old_path));
                 env::set_var("PATH", &env::join_paths(new_path.iter()).unwrap());
@@ -737,7 +737,7 @@ pub fn phase_5_run_llvm_passes(sess: &Session,
 pub fn phase_6_link_output(sess: &Session,
                            trans: &trans::CrateTranslation,
                            outputs: &OutputFilenames) {
-    let old_path = env::var("PATH").unwrap_or(OsString::from_str(""));
+    let old_path = env::var_os("PATH").unwrap_or(OsString::from_str(""));
     let mut new_path = sess.host_filesearch(PathKind::All).get_tools_search_paths();
     new_path.extend(env::split_paths(&old_path));
     env::set_var("PATH", &env::join_paths(new_path.iter()).unwrap());
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index ef6e84d3a76..b087c0c2aa1 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -771,7 +771,7 @@ pub fn monitor<F:FnOnce()+Send>(f: F) {
 
     // FIXME: Hacks on hacks. If the env is trying to override the stack size
     // then *don't* set it explicitly.
-    if env::var("RUST_MIN_STACK").is_none() {
+    if env::var_os("RUST_MIN_STACK").is_none() {
         cfg = cfg.stack_size(STACK_SIZE);
     }
 
@@ -835,8 +835,7 @@ pub fn diagnostics_registry() -> diagnostics::registry::Registry {
 }
 
 pub fn main() {
-    let args = env::args().map(|s| s.into_string().unwrap());
-    let result = run(args.collect());
+    let result = run(env::args().collect());
     std::env::set_exit_status(result as i32);
 }
 
diff --git a/src/librustc_trans/save/mod.rs b/src/librustc_trans/save/mod.rs
index e80564097df..cdcd917ee5e 100644
--- a/src/librustc_trans/save/mod.rs
+++ b/src/librustc_trans/save/mod.rs
@@ -1551,7 +1551,7 @@ pub fn process_crate(sess: &Session,
     info!("Dumping crate {}", cratename);
 
     // find a path to dump our data to
-    let mut root_path = match env::var_string("DXR_RUST_TEMP_FOLDER") {
+    let mut root_path = match env::var("DXR_RUST_TEMP_FOLDER") {
         Ok(val) => Path::new(val),
         Err(..) => match odir {
             Some(val) => val.join("dxr"),
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 0253aaa31ca..9d45caf7669 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -122,10 +122,10 @@ struct Output {
 }
 
 pub fn main() {
-    static STACK_SIZE: uint = 32000000; // 32MB
+    const STACK_SIZE: usize = 32000000; // 32MB
     let res = std::thread::Builder::new().stack_size(STACK_SIZE).scoped(move || {
-        let s = env::args().map(|s| s.into_string().unwrap());
-        main_args(&s.collect::<Vec<_>>())
+        let s = env::args().collect::<Vec<_>>();
+        main_args(&s)
     }).join();
     env::set_exit_status(res.ok().unwrap() as i32);
 }
diff --git a/src/libstd/dynamic_lib.rs b/src/libstd/dynamic_lib.rs
index bee9a0d0033..c5dd66630b4 100644
--- a/src/libstd/dynamic_lib.rs
+++ b/src/libstd/dynamic_lib.rs
@@ -101,7 +101,7 @@ impl DynamicLibrary {
     /// Returns the current search path for dynamic libraries being used by this
     /// process
     pub fn search_path() -> Vec<Path> {
-        match env::var(DynamicLibrary::envvar()) {
+        match env::var_os(DynamicLibrary::envvar()) {
             Some(var) => env::split_paths(&var).collect(),
             None => Vec::new(),
         }
diff --git a/src/libstd/env.rs b/src/libstd/env.rs
index e73797bc66c..ea18838211f 100644
--- a/src/libstd/env.rs
+++ b/src/libstd/env.rs
@@ -71,17 +71,29 @@ static ENV_LOCK: StaticMutex = MUTEX_INIT;
 
 /// An iterator over a snapshot of the environment variables of this process.
 ///
-/// This iterator is created through `std::env::vars()` and yields `(OsString,
-/// OsString)` pairs.
-pub struct Vars { inner: os_imp::Env }
+/// This iterator is created through `std::env::vars()` and yields `(String,
+/// String)` pairs.
+pub struct Vars { inner: VarsOs }
 
-/// Returns an iterator of (variable, value) pairs, for all the environment
-/// variables of the current process.
+/// An iterator over a snapshot of the environment variables of this process.
+///
+/// This iterator is created through `std::env::vars_os()` and yields
+/// `(OsString, OsString)` pairs.
+pub struct VarsOs { inner: os_imp::Env }
+
+/// Returns an iterator of (variable, value) pairs of strings, for all the
+/// environment variables of the current process.
 ///
 /// The returned iterator contains a snapshot of the process's environment
 /// variables at the time of this invocation, modifications to environment
 /// variables afterwards will not be reflected in the returned iterator.
 ///
+/// # Panics
+///
+/// While iterating, the returned iterator will panic if any key or value in the
+/// environment is not valid unicode. If this is not desired, consider using the
+/// `env::vars_os` function.
+///
 /// # Example
 ///
 /// ```rust
@@ -90,37 +102,50 @@ pub struct Vars { inner: os_imp::Env }
 /// // We will iterate through the references to the element returned by
 /// // env::vars();
 /// for (key, value) in env::vars() {
-///     println!("{:?}: {:?}", key, value);
+///     println!("{}: {}", key, value);
 /// }
 /// ```
 pub fn vars() -> Vars {
-    let _g = ENV_LOCK.lock();
-    Vars { inner: os_imp::env() }
-}
-
-impl Iterator for Vars {
-    type Item = (OsString, OsString);
-    fn next(&mut self) -> Option<(OsString, OsString)> { self.inner.next() }
-    fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
+    Vars { inner: vars_os() }
 }
 
-/// Fetches the environment variable `key` from the current process, returning
-/// None if the variable isn't set.
+/// Returns an iterator of (variable, value) pairs of OS strings, for all the
+/// environment variables of the current process.
+///
+/// The returned iterator contains a snapshot of the process's environment
+/// variables at the time of this invocation, modifications to environment
+/// variables afterwards will not be reflected in the returned iterator.
 ///
 /// # Example
 ///
 /// ```rust
 /// use std::env;
 ///
-/// let key = "HOME";
-/// match env::var(key) {
-///     Some(val) => println!("{}: {:?}", key, val),
-///     None => println!("{} is not defined in the environment.", key)
+/// // We will iterate through the references to the element returned by
+/// // env::vars_os();
+/// for (key, value) in env::vars_os() {
+///     println!("{:?}: {:?}", key, value);
 /// }
 /// ```
-pub fn var<K: ?Sized>(key: &K) -> Option<OsString> where K: AsOsStr {
+pub fn vars_os() -> VarsOs {
     let _g = ENV_LOCK.lock();
-    os_imp::getenv(key.as_os_str())
+    VarsOs { inner: os_imp::env() }
+}
+
+impl Iterator for Vars {
+    type Item = (String, String);
+    fn next(&mut self) -> Option<(String, String)> {
+        self.inner.next().map(|(a, b)| {
+            (a.into_string().unwrap(), b.into_string().unwrap())
+        })
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
+}
+
+impl Iterator for VarsOs {
+    type Item = (OsString, OsString);
+    fn next(&mut self) -> Option<(OsString, OsString)> { self.inner.next() }
+    fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
 }
 
 /// Fetches the environment variable `key` from the current process.
@@ -135,18 +160,37 @@ pub fn var<K: ?Sized>(key: &K) -> Option<OsString> where K: AsOsStr {
 /// use std::env;
 ///
 /// let key = "HOME";
-/// match env::var_string(key) {
+/// match env::var(key) {
 ///     Ok(val) => println!("{}: {:?}", key, val),
 ///     Err(e) => println!("couldn't interpret {}: {}", key, e),
 /// }
 /// ```
-pub fn var_string<K: ?Sized>(key: &K) -> Result<String, VarError> where K: AsOsStr {
-    match var(key) {
+pub fn var<K: ?Sized>(key: &K) -> Result<String, VarError> where K: AsOsStr {
+    match var_os(key) {
         Some(s) => s.into_string().map_err(VarError::NotUnicode),
         None => Err(VarError::NotPresent)
     }
 }
 
+/// Fetches the environment variable `key` from the current process, returning
+/// None if the variable isn't set.
+///
+/// # Example
+///
+/// ```rust
+/// use std::env;
+///
+/// let key = "HOME";
+/// match env::var_os(key) {
+///     Some(val) => println!("{}: {:?}", key, val),
+///     None => println!("{} is not defined in the environment.", key)
+/// }
+/// ```
+pub fn var_os<K: ?Sized>(key: &K) -> Option<OsString> where K: AsOsStr {
+    let _g = ENV_LOCK.lock();
+    os_imp::getenv(key.as_os_str())
+}
+
 /// Possible errors from the `env::var` method.
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub enum VarError {
@@ -190,7 +234,7 @@ impl Error for VarError {
 ///
 /// let key = "KEY";
 /// env::set_var(key, "VALUE");
-/// assert_eq!(env::var_string(key), Ok("VALUE".to_string()));
+/// assert_eq!(env::var(key), Ok("VALUE".to_string()));
 /// ```
 pub fn set_var<K: ?Sized, V: ?Sized>(k: &K, v: &V)
     where K: AsOsStr, V: AsOsStr
@@ -222,7 +266,7 @@ pub struct SplitPaths<'a> { inner: os_imp::SplitPaths<'a> }
 /// use std::env;
 ///
 /// let key = "PATH";
-/// match env::var(key) {
+/// match env::var_os(key) {
 ///     Some(paths) => {
 ///         for path in env::split_paths(&paths) {
 ///             println!("'{}'", path.display());
@@ -262,7 +306,7 @@ pub struct JoinPathsError {
 /// ```rust
 /// use std::env;
 ///
-/// if let Some(path) = env::var("PATH") {
+/// if let Some(path) = env::var_os("PATH") {
 ///     let mut paths = env::split_paths(&path).collect::<Vec<_>>();
 ///     paths.push(Path::new("/home/xyz/bin"));
 ///     let new_path = env::join_paths(paths.iter()).unwrap();
@@ -376,11 +420,17 @@ pub fn get_exit_status() -> i32 {
     EXIT_STATUS.load(Ordering::SeqCst) as i32
 }
 
-/// An iterator over the arguments of a process, yielding an `OsString` value
+/// An iterator over the arguments of a process, yielding an `String` value
 /// for each argument.
 ///
 /// This structure is created through the `std::env::args` method.
-pub struct Args { inner: os_imp::Args }
+pub struct Args { inner: ArgsOs }
+
+/// An iterator over the arguments of a process, yielding an `OsString` value
+/// for each argument.
+///
+/// This structure is created through the `std::env::args_os` method.
+pub struct ArgsOs { inner: os_imp::Args }
 
 /// Returns the arguments which this program was started with (normally passed
 /// via the command line).
@@ -389,6 +439,12 @@ pub struct Args { inner: os_imp::Args }
 /// set to arbitrary text, and it may not even exist, so this property should
 /// not be relied upon for security purposes.
 ///
+/// # Panics
+///
+/// The returned iterator will panic during iteration if any argument to the
+/// process is not valid unicode. If this is not desired it is recommended to
+/// use the `args_os` function instead.
+///
 /// # Example
 ///
 /// ```rust
@@ -396,14 +452,43 @@ pub struct Args { inner: os_imp::Args }
 ///
 /// // Prints each argument on a separate line
 /// for argument in env::args() {
-///     println!("{:?}", argument);
+///     println!("{}", argument);
 /// }
 /// ```
 pub fn args() -> Args {
-    Args { inner: os_imp::args() }
+    Args { inner: args_os() }
+}
+
+/// Returns the arguments which this program was started with (normally passed
+/// via the command line).
+///
+/// The first element is traditionally the path to the executable, but it can be
+/// set to arbitrary text, and it may not even exist, so this property should
+/// not be relied upon for security purposes.
+///
+/// # Example
+///
+/// ```rust
+/// use std::env;
+///
+/// // Prints each argument on a separate line
+/// for argument in env::args_os() {
+///     println!("{:?}", argument);
+/// }
+/// ```
+pub fn args_os() -> ArgsOs {
+    ArgsOs { inner: os_imp::args() }
 }
 
 impl Iterator for Args {
+    type Item = String;
+    fn next(&mut self) -> Option<String> {
+        self.inner.next().map(|s| s.into_string().unwrap())
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
+}
+
+impl Iterator for ArgsOs {
     type Item = OsString;
     fn next(&mut self) -> Option<OsString> { self.inner.next() }
     fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
@@ -706,7 +791,7 @@ mod tests {
         let n = format!("TEST{}", rng.gen_ascii_chars().take(10)
                                      .collect::<String>());
         let n = OsString::from_string(n);
-        assert!(var(&n).is_none());
+        assert!(var_os(&n).is_none());
         n
     }
 
@@ -718,7 +803,7 @@ mod tests {
     fn test_set_var() {
         let n = make_rand_name();
         set_var(&n, "VALUE");
-        eq(var(&n), Some("VALUE"));
+        eq(var_os(&n), Some("VALUE"));
     }
 
     #[test]
@@ -726,7 +811,7 @@ mod tests {
         let n = make_rand_name();
         set_var(&n, "VALUE");
         remove_var(&n);
-        eq(var(&n), None);
+        eq(var_os(&n), None);
     }
 
     #[test]
@@ -734,9 +819,9 @@ mod tests {
         let n = make_rand_name();
         set_var(&n, "1");
         set_var(&n, "2");
-        eq(var(&n), Some("2"));
+        eq(var_os(&n), Some("2"));
         set_var(&n, "");
-        eq(var(&n), Some(""));
+        eq(var_os(&n), Some(""));
     }
 
     #[test]
@@ -749,7 +834,7 @@ mod tests {
         }
         let n = make_rand_name();
         set_var(&n, s.as_slice());
-        eq(var(&n), Some(s.as_slice()));
+        eq(var_os(&n), Some(s.as_slice()));
     }
 
     #[test]
@@ -767,22 +852,22 @@ mod tests {
         let n = make_rand_name();
         let s = repeat("x").take(10000).collect::<String>();
         set_var(&n, &s);
-        eq(var(&n), Some(s.as_slice()));
+        eq(var_os(&n), Some(s.as_slice()));
         remove_var(&n);
-        eq(var(&n), None);
+        eq(var_os(&n), None);
     }
 
     #[test]
     fn test_env_set_var() {
         let n = make_rand_name();
 
-        let mut e = vars();
+        let mut e = vars_os();
         set_var(&n, "VALUE");
         assert!(!e.any(|(k, v)| {
             &*k == &*n && &*v == "VALUE"
         }));
 
-        assert!(vars().any(|(k, v)| {
+        assert!(vars_os().any(|(k, v)| {
             &*k == &*n && &*v == "VALUE"
         }));
     }
diff --git a/src/libstd/os.rs b/src/libstd/os.rs
index 526b5edd4cb..ca7183a97d4 100644
--- a/src/libstd/os.rs
+++ b/src/libstd/os.rs
@@ -125,7 +125,7 @@ pub fn getcwd() -> IoResult<Path> {
 #[deprecated(since = "1.0.0", reason = "use env::vars instead")]
 #[unstable(feature = "os")]
 pub fn env() -> Vec<(String,String)> {
-    env::vars().map(|(k, v)| {
+    env::vars_os().map(|(k, v)| {
         (k.to_string_lossy().into_owned(), v.to_string_lossy().into_owned())
     }).collect()
 }
@@ -135,7 +135,7 @@ pub fn env() -> Vec<(String,String)> {
 #[deprecated(since = "1.0.0", reason = "use env::vars instead")]
 #[unstable(feature = "os")]
 pub fn env_as_bytes() -> Vec<(Vec<u8>, Vec<u8>)> {
-    env::vars().map(|(k, v)| (byteify(k), byteify(v))).collect()
+    env::vars_os().map(|(k, v)| (byteify(k), byteify(v))).collect()
 }
 
 /// Fetches the environment variable `n` from the current process, returning
@@ -159,10 +159,10 @@ pub fn env_as_bytes() -> Vec<(Vec<u8>, Vec<u8>)> {
 ///     None => println!("{} is not defined in the environment.", key)
 /// }
 /// ```
-#[deprecated(since = "1.0.0", reason = "use env::var or env::var_string instead")]
+#[deprecated(since = "1.0.0", reason = "use env::var or env::var_os instead")]
 #[unstable(feature = "os")]
 pub fn getenv(n: &str) -> Option<String> {
-    env::var_string(n).ok()
+    env::var(n).ok()
 }
 
 /// Fetches the environment variable `n` byte vector from the current process,
@@ -174,7 +174,7 @@ pub fn getenv(n: &str) -> Option<String> {
 #[deprecated(since = "1.0.0", reason = "use env::var instead")]
 #[unstable(feature = "os")]
 pub fn getenv_as_bytes(n: &str) -> Option<Vec<u8>> {
-    env::var(n).map(byteify)
+    env::var_os(n).map(byteify)
 }
 
 #[cfg(unix)]
diff --git a/src/libstd/rt/backtrace.rs b/src/libstd/rt/backtrace.rs
index 2af5a486d0d..ced84d7551e 100644
--- a/src/libstd/rt/backtrace.rs
+++ b/src/libstd/rt/backtrace.rs
@@ -29,7 +29,7 @@ pub fn log_enabled() -> bool {
         _ => {}
     }
 
-    let val = match env::var("RUST_BACKTRACE") {
+    let val = match env::var_os("RUST_BACKTRACE") {
         Some(..) => 2,
         None => 1,
     };
diff --git a/src/libstd/rt/util.rs b/src/libstd/rt/util.rs
index 703dca4d29b..bb57d19ed26 100644
--- a/src/libstd/rt/util.rs
+++ b/src/libstd/rt/util.rs
@@ -52,7 +52,7 @@ pub fn min_stack() -> uint {
         0 => {}
         n => return n - 1,
     }
-    let amt = env::var_string("RUST_MIN_STACK").ok().and_then(|s| s.parse().ok());
+    let amt = env::var("RUST_MIN_STACK").ok().and_then(|s| s.parse().ok());
     let amt = amt.unwrap_or(2 * 1024 * 1024);
     // 0 is our sentinel value, so ensure that we'll never see 0 after
     // initialization has run
@@ -63,7 +63,7 @@ pub fn min_stack() -> uint {
 /// Get's the number of scheduler threads requested by the environment
 /// either `RUST_THREADS` or `num_cpus`.
 pub fn default_sched_threads() -> uint {
-    match env::var_string("RUST_THREADS") {
+    match env::var("RUST_THREADS") {
         Ok(nstr) => {
             let opt_n: Option<uint> = nstr.parse().ok();
             match opt_n {
diff --git a/src/libsyntax/ext/env.rs b/src/libsyntax/ext/env.rs
index ef9d3799879..5d56707c87a 100644
--- a/src/libsyntax/ext/env.rs
+++ b/src/libsyntax/ext/env.rs
@@ -30,7 +30,7 @@ pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenT
         Some(v) => v
     };
 
-    let e = match env::var_string(&var[]) {
+    let e = match env::var(&var[]) {
       Err(..) => {
           cx.expr_path(cx.path_all(sp,
                                    true,
@@ -101,7 +101,7 @@ pub fn expand_env<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
         }
     }
 
-    let e = match env::var_string(&var[]) {
+    let e = match env::var(&var[]) {
         Err(_) => {
             cx.span_err(sp, &msg);
             cx.expr_usize(sp, 0)
diff --git a/src/libterm/terminfo/mod.rs b/src/libterm/terminfo/mod.rs
index 0a1439ebee0..758191a6e11 100644
--- a/src/libterm/terminfo/mod.rs
+++ b/src/libterm/terminfo/mod.rs
@@ -172,7 +172,7 @@ impl<T: Writer+Send> TerminfoTerminal<T> {
     /// Returns `None` whenever the terminal cannot be created for some
     /// reason.
     pub fn new(out: T) -> Option<Box<Terminal<T>+Send+'static>> {
-        let term = match env::var_string("TERM") {
+        let term = match env::var("TERM") {
             Ok(t) => t,
             Err(..) => {
                 debug!("TERM environment variable not defined");
@@ -182,7 +182,7 @@ impl<T: Writer+Send> TerminfoTerminal<T> {
 
         let entry = open(&term[]);
         if entry.is_err() {
-            if env::var_string("MSYSCON").ok().map_or(false, |s| {
+            if env::var("MSYSCON").ok().map_or(false, |s| {
                     "mintty.exe" == s
                 }) {
                 // msys terminal
diff --git a/src/libterm/terminfo/searcher.rs b/src/libterm/terminfo/searcher.rs
index 6ee477fc808..fd6e6a843e1 100644
--- a/src/libterm/terminfo/searcher.rs
+++ b/src/libterm/terminfo/searcher.rs
@@ -28,14 +28,14 @@ pub fn get_dbpath_for_term(term: &str) -> Option<Box<Path>> {
     let first_char = term.char_at(0);
 
     // Find search directory
-    match env::var_string("TERMINFO") {
+    match env::var("TERMINFO") {
         Ok(dir) => dirs_to_search.push(Path::new(dir)),
         Err(..) => {
             if homedir.is_some() {
                 // ncurses compatibility;
                 dirs_to_search.push(homedir.unwrap().join(".terminfo"))
             }
-            match env::var_string("TERMINFO_DIRS") {
+            match env::var("TERMINFO_DIRS") {
                 Ok(dirs) => for i in dirs.split(':') {
                     if i == "" {
                         dirs_to_search.push(Path::new("/usr/share/terminfo"));
diff --git a/src/libtest/lib.rs b/src/libtest/lib.rs
index f3edd90b4fa..e7a70ed0d69 100644
--- a/src/libtest/lib.rs
+++ b/src/libtest/lib.rs
@@ -385,7 +385,7 @@ pub fn parse_opts(args: &[String]) -> Option<OptRes> {
 
     let mut nocapture = matches.opt_present("nocapture");
     if !nocapture {
-        nocapture = env::var("RUST_TEST_NOCAPTURE").is_some();
+        nocapture = env::var("RUST_TEST_NOCAPTURE").is_ok();
     }
 
     let color = match matches.opt_str("color").as_ref().map(|s| &**s) {
@@ -811,7 +811,7 @@ fn run_tests<F>(opts: &TestOpts,
 
 fn get_concurrency() -> uint {
     use std::rt;
-    match env::var_string("RUST_TEST_TASKS") {
+    match env::var("RUST_TEST_TASKS") {
         Ok(s) => {
             let opt_n: Option<uint> = s.parse().ok();
             match opt_n {
diff --git a/src/test/run-pass/env-vars.rs b/src/test/run-pass/env-vars.rs
index 892041b9648..659e5b3a8c2 100644
--- a/src/test/run-pass/env-vars.rs
+++ b/src/test/run-pass/env-vars.rs
@@ -11,8 +11,8 @@
 use std::env::*;
 
 fn main() {
-    for (k, v) in vars() {
-        let v2 = var(&k);
+    for (k, v) in vars_os() {
+        let v2 = var_os(&k);
         // MingW seems to set some funky environment variables like
         // "=C:=C:\MinGW\msys\1.0\bin" and "!::=::\" that are returned
         // from vars() but not visible from var().