rollup merge of #22188: alexcrichton/envv2

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]

1 files changed, 2 insertions, 2 deletions

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)