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]

Author: alexcrichton

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");

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)
       }

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),
     };

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

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);
 

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,

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?

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());

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);
 }
 

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"),