auto merge of #15353 : aturon/rust/env-hashmap, r=alexcrichton

This commit adds `env_insert` and `env_remove` methods to the `Command`
builder, easing updates to the environment variables for the child
process. The existing method, `env`, is still available for overriding
the entire environment in one shot (after which the `env_insert` and
`env_remove` methods can be used to make further adjustments).

To support these new methods, the internal `env` representation for
`Command` has been changed to an optional `HashMap` holding owned
`CString`s (to support non-utf8 data). The `HashMap` is only
materialized if the environment is updated. The implementation does not
try hard to avoid allocation, since the cost of launching a process will
dwarf any allocation cost.

This patch also adds `PartialOrd`, `Eq`, and `Hash` implementations for
`CString`.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/test/run-pass/process-spawn-with-unicode-params.rs b/src/test/run-pass/process-spawn-with-unicode-params.rs
index 70839c18847..de86ca179b7 100644
--- a/src/test/run-pass/process-spawn-with-unicode-params.rs
+++ b/src/test/run-pass/process-spawn-with-unicode-params.rs
@@ -58,7 +58,7 @@ fn main() {
         let p = Command::new(&child_path)
                         .arg(arg)
                         .cwd(&cwd)
-                        .env(my_env.append_one(env).as_slice())
+                        .env_set_all(my_env.append_one(env).as_slice())
                         .spawn().unwrap().wait_with_output().unwrap();
 
         // display the output