auto merge of #18463 : japaric/rust/bytes2, r=alexcrichton

- The `BytesContainer::container_into_owned_bytes` method has been removed

- Methods that used to take `BytesContainer` implementors by value, now take them by reference. In particular, this breaks some uses of Path:

``` rust
Path::new("foo")  // Still works
path.join(another_path) -> path.join(&another_path)
```

[breaking-change]

---

Re: `container_into_owned_bytes`, I've removed it because

- Nothing in the whole repository uses it
- Takes `self` by value, which is incompatible with unsized types (`str`)

The alternative to removing this method is to split `BytesContainer` into `BytesContainer for Sized?` and `SizedBytesContainer: BytesContainer + Sized`, where the second trait only contains the `container_into_owned_bytes` method. I tried this alternative [in another branch](https://github.com/japaric/rust/commits/bytes) and it works, but it seemed better not to create a new trait for an unused method.

Re: Breakage of `Path` methods

We could use the idea that @alexcrichton proposed in #18457 (add blanket `impl BytesContainer for &T where T: BytesContainer` + keep taking `T: BytesContainer` by value in `Path` methods) to avoid breaking any code.

r? @aturon 
cc #16918

src/compiletest/runtest.rs

@@ -627,7 +627,7 @@ fn find_rust_src_root(config: &Config) -> Option<Path> {
     let path_postfix = Path::new("src/etc/lldb_batchmode.py");
 
     while path.pop() {
-        if path.join(path_postfix.clone()).is_file() {
+        if path.join(&path_postfix).is_file() {
             return Some(path);
         }
     }

src/librustc/driver/session.rs

@@ -231,7 +231,7 @@ pub fn build_session_(sopts: config::Options,
         if path.is_absolute() {
             path.clone()
         } else {
-            os::getcwd().join(path.clone())
+            os::getcwd().join(&path)
         }
     );
 

src/libstd/io/process.rs

@@ -918,7 +918,7 @@ mod tests {
         let prog = pwd_cmd().cwd(&parent_dir).spawn().unwrap();
 
         let output = String::from_utf8(prog.wait_with_output().unwrap().output).unwrap();
-        let child_dir = Path::new(output.as_slice().trim().into_string());
+        let child_dir = Path::new(output.as_slice().trim());
 
         let parent_stat = parent_dir.stat().unwrap();
         let child_stat = child_dir.stat().unwrap();

src/libstd/path/mod.rs

@@ -67,6 +67,7 @@ println!("path exists: {}", path.exists());
 
 #![experimental]
 
+use core::kinds::Sized;
 use c_str::CString;
 use clone::Clone;
 use fmt;
@@ -626,7 +627,7 @@ pub trait GenericPath: Clone + GenericPathUnsafe {
     /// ```
     #[inline]
     fn push_many<T: BytesContainer>(&mut self, paths: &[T]) {
-        let t: Option<T> = None;
+        let t: Option<&T> = None;
         if BytesContainer::is_str(t) {
             for p in paths.iter() {
                 self.push(p.container_as_str().unwrap())
@@ -791,14 +792,9 @@ pub trait GenericPath: Clone + GenericPathUnsafe {
 }
 
 /// A trait that represents something bytes-like (e.g. a &[u8] or a &str)
-pub trait BytesContainer {
+pub trait BytesContainer for Sized? {
     /// Returns a &[u8] representing the receiver
     fn container_as_bytes<'a>(&'a self) -> &'a [u8];
-    /// Consumes the receiver and converts it into Vec<u8>
-    #[inline]
-    fn container_into_owned_bytes(self) -> Vec<u8> {
-        self.container_as_bytes().to_vec()
-    }
     /// Returns the receiver interpreted as a utf-8 string, if possible
     #[inline]
     fn container_as_str<'a>(&'a self) -> Option<&'a str> {
@@ -807,7 +803,7 @@ pub trait BytesContainer {
     /// Returns whether .container_as_str() is guaranteed to not fail
     // FIXME (#8888): Remove unused arg once ::<for T> works
     #[inline]
-    fn is_str(_: Option<Self>) -> bool { false }
+    fn is_str(_: Option<&Self>) -> bool { false }
 }
 
 /// A trait that represents the unsafe operations on GenericPaths
@@ -859,48 +855,44 @@ impl<'a, P: GenericPath> Display<'a, P> {
     }
 }
 
-impl<'a> BytesContainer for &'a str {
+impl BytesContainer for str {
     #[inline]
-    fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
+    fn container_as_bytes(&self) -> &[u8] {
         self.as_bytes()
     }
     #[inline]
-    fn container_as_str<'a>(&'a self) -> Option<&'a str> {
-        Some(*self)
+    fn container_as_str(&self) -> Option<&str> {
+        Some(self)
     }
     #[inline]
-    fn is_str(_: Option<&'a str>) -> bool { true }
+    fn is_str(_: Option<&str>) -> bool { true }
 }
 
 impl BytesContainer for String {
     #[inline]
-    fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
+    fn container_as_bytes(&self) -> &[u8] {
         self.as_bytes()
     }
     #[inline]
-    fn container_as_str<'a>(&'a self) -> Option<&'a str> {
+    fn container_as_str(&self) -> Option<&str> {
         Some(self.as_slice())
     }
     #[inline]
-    fn is_str(_: Option<String>) -> bool { true }
+    fn is_str(_: Option<&String>) -> bool { true }
 }
 
-impl<'a> BytesContainer for &'a [u8] {
+impl BytesContainer for [u8] {
     #[inline]
-    fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
-        *self
+    fn container_as_bytes(&self) -> &[u8] {
+        self
     }
 }
 
 impl BytesContainer for Vec<u8> {
     #[inline]
-    fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
+    fn container_as_bytes(&self) -> &[u8] {
         self.as_slice()
     }
-    #[inline]
-    fn container_into_owned_bytes(self) -> Vec<u8> {
-        self
-    }
 }
 
 impl BytesContainer for CString {
@@ -920,7 +912,20 @@ impl<'a> BytesContainer for str::MaybeOwned<'a> {
         Some(self.as_slice())
     }
     #[inline]
-    fn is_str(_: Option<str::MaybeOwned>) -> bool { true }
+    fn is_str(_: Option<&str::MaybeOwned>) -> bool { true }
+}
+
+impl<'a, Sized? T: BytesContainer> BytesContainer for &'a T {
+    #[inline]
+    fn container_as_bytes(&self) -> &[u8] {
+        (**self).container_as_bytes()
+    }
+    #[inline]
+    fn container_as_str(&self) -> Option<&str> {
+        (**self).container_as_str()
+    }
+    #[inline]
+    fn is_str(_: Option<& &'a T>) -> bool { BytesContainer::is_str(None::<&T>) }
 }
 
 #[inline(always)]

src/libstd/path/posix.rs

@@ -117,17 +117,6 @@ impl BytesContainer for Path {
     fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
         self.as_vec()
     }
-    #[inline]
-    fn container_into_owned_bytes(self) -> Vec<u8> {
-        self.into_vec()
-    }
-}
-
-impl<'a> BytesContainer for &'a Path {
-    #[inline]
-    fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
-        self.as_vec()
-    }
 }
 
 impl GenericPathUnsafe for Path {

src/libstd/path/windows.rs

@@ -144,23 +144,6 @@ impl<S: hash::Writer> hash::Hash<S> for Path {
 }
 
 impl BytesContainer for Path {
-    #[inline]
-    fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
-        self.as_vec()
-    }
-    #[inline]
-    fn container_into_owned_bytes(self) -> Vec<u8> {
-        self.into_vec()
-    }
-    #[inline]
-    fn container_as_str<'a>(&'a self) -> Option<&'a str> {
-        self.as_str()
-    }
-    #[inline]
-    fn is_str(_: Option<Path>) -> bool { true }
-}
-
-impl<'a> BytesContainer for &'a Path {
     #[inline]
     fn container_as_bytes<'a>(&'a self) -> &'a [u8] {
         self.as_vec()
@@ -170,7 +153,7 @@ impl<'a> BytesContainer for &'a Path {
         self.as_str()
     }
     #[inline]
-    fn is_str(_: Option<&'a Path>) -> bool { true }
+    fn is_str(_: Option<&Path>) -> bool { true }
 }
 
 impl GenericPathUnsafe for Path {

src/libterm/terminfo/searcher.rs

@@ -41,7 +41,7 @@ pub fn get_dbpath_for_term(term: &str) -> Option<Box<Path>> {
                     if i == "" {
                         dirs_to_search.push(Path::new("/usr/share/terminfo"));
                     } else {
-                        dirs_to_search.push(Path::new(i.to_string()));
+                        dirs_to_search.push(Path::new(i));
                     }
                 },
                 // Found nothing in TERMINFO_DIRS, use the default paths:

src/test/run-pass/process-spawn-with-unicode-params.rs

@@ -48,7 +48,7 @@ fn main() {
 
         let child_filestem = Path::new(child_name);
         let child_filename = child_filestem.with_extension(my_ext);
-        let child_path     = cwd.join(child_filename.clone());
+        let child_path     = cwd.join(child_filename);
 
         // make a separate directory for the child
         drop(fs::mkdir(&cwd, io::USER_RWX).is_ok());