auto merge of #15493 : brson/rust/tostr, r=pcwalton

This updates https://github.com/rust-lang/rust/pull/15075.

Rename `ToStr::to_str` to `ToString::to_string`. The naive renaming ends up with two `to_string` functions defined on strings in the prelude (the other defined via `collections::str::StrAllocating`). To remedy this I removed `StrAllocating::to_string`, making all conversions from `&str` to `String` go through `Show`. This has a measurable impact on the speed of this conversion, but the sense I get from others is that it's best to go ahead and unify `to_string` and address performance for all `to_string` conversions in `core::fmt`. `String::from_str(...)` still works as a manual fast-path.

Note that the patch was done with a script, and ended up renaming a number of other `*_to_str` functions, particularly inside of rustc. All the ones I saw looked correct, and I didn't notice any additional API breakage.

Closes #15046.

2 files changed, 3 insertions, 3 deletions

diff --git a/src/libstd/path/posix.rs b/src/libstd/path/posix.rs
index d98cfb7d8ee..5c6e140bd29 100644
--- a/src/libstd/path/posix.rs
+++ b/src/libstd/path/posix.rs
@@ -545,7 +545,7 @@ mod tests {
             ($path:expr, $disp:ident, $exp:expr) => (
                 {
                     let path = Path::new($path);
-                    assert!(path.$disp().to_str().as_slice() == $exp);
+                    assert!(path.$disp().to_string().as_slice() == $exp);
                 }
             )
         )
diff --git a/src/libstd/path/windows.rs b/src/libstd/path/windows.rs
index 113b0410875..206f75739e8 100644
--- a/src/libstd/path/windows.rs
+++ b/src/libstd/path/windows.rs
@@ -1314,9 +1314,9 @@ mod tests {
     #[test]
     fn test_display_str() {
         let path = Path::new("foo");
-        assert_eq!(path.display().to_str(), "foo".to_string());
+        assert_eq!(path.display().to_string(), "foo".to_string());
         let path = Path::new(b"\\");
-        assert_eq!(path.filename_display().to_str(), "".to_string());
+        assert_eq!(path.filename_display().to_string(), "".to_string());
 
         let path = Path::new("foo");
         let mo = path.display().as_maybe_owned();