Reduce code bloat from conversion traits in function parameters

src/librustc_back/tempdir.rs

@@ -38,8 +38,12 @@ impl TempDir {
     #[allow(deprecated)] // rand usage
     pub fn new_in<P: AsRef<Path>>(tmpdir: P, prefix: &str)
                                   -> io::Result<TempDir> {
+        Self::_new_in(tmpdir.as_ref(), prefix)
+    }
+
+    fn _new_in(tmpdir: &Path, prefix: &str) -> io::Result<TempDir> {
         let storage;
-        let mut tmpdir = tmpdir.as_ref();
+        let mut tmpdir = tmpdir;
         if !tmpdir.is_absolute() {
             let cur_dir = try!(env::current_dir());
             storage = cur_dir.join(tmpdir);

src/libstd/env.rs

@@ -174,6 +174,10 @@ impl Iterator for VarsOs {
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn var<K: AsRef<OsStr>>(key: K) -> Result<String, VarError> {
+    _var(key.as_ref())
+}
+
+fn _var(key: &OsStr) -> Result<String, VarError> {
     match var_os(key) {
         Some(s) => s.into_string().map_err(VarError::NotUnicode),
         None => Err(VarError::NotPresent)
@@ -196,8 +200,12 @@ pub fn var<K: AsRef<OsStr>>(key: K) -> Result<String, VarError> {
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn var_os<K: AsRef<OsStr>>(key: K) -> Option<OsString> {
+    _var_os(key.as_ref())
+}
+
+fn _var_os(key: &OsStr) -> Option<OsString> {
     let _g = ENV_LOCK.lock();
-    os_imp::getenv(key.as_ref())
+    os_imp::getenv(key)
 }
 
 /// Possible errors from the `env::var` method.
@@ -263,8 +271,12 @@ impl Error for VarError {
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn set_var<K: AsRef<OsStr>, V: AsRef<OsStr>>(k: K, v: V) {
+    _set_var(k.as_ref(), v.as_ref())
+}
+
+fn _set_var(k: &OsStr, v: &OsStr) {
     let _g = ENV_LOCK.lock();
-    os_imp::setenv(k.as_ref(), v.as_ref())
+    os_imp::setenv(k, v)
 }
 
 /// Removes an environment variable from the environment of the currently running process.
@@ -294,8 +306,12 @@ pub fn set_var<K: AsRef<OsStr>, V: AsRef<OsStr>>(k: K, v: V) {
 /// ```
 #[stable(feature = "env", since = "1.0.0")]
 pub fn remove_var<K: AsRef<OsStr>>(k: K) {
+    _remove_var(k.as_ref())
+}
+
+fn _remove_var(k: &OsStr) {
     let _g = ENV_LOCK.lock();
-    os_imp::unsetenv(k.as_ref())
+    os_imp::unsetenv(k)
 }
 
 /// An iterator over `Path` instances for parsing an environment variable

src/libstd/ffi/c_str.rs

@@ -181,7 +181,10 @@ impl CString {
     /// the position of the nul byte.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new<T: Into<Vec<u8>>>(t: T) -> Result<CString, NulError> {
-        let bytes = t.into();
+        Self::_new(t.into())
+    }
+
+    fn _new(bytes: Vec<u8>) -> Result<CString, NulError> {
         match bytes.iter().position(|x| *x == 0) {
             Some(i) => Err(NulError(i, bytes)),
             None => Ok(unsafe { CString::from_vec_unchecked(bytes) }),

src/libstd/ffi/os_str.rs

@@ -73,18 +73,18 @@ impl OsString {
     /// convert; non UTF-8 data will produce `None`.
     #[unstable(feature = "convert", reason = "recently added", issue = "27704")]
     pub fn from_bytes<B>(bytes: B) -> Option<OsString> where B: Into<Vec<u8>> {
-        #[cfg(unix)]
-        fn from_bytes_inner(vec: Vec<u8>) -> Option<OsString> {
-            use os::unix::ffi::OsStringExt;
-            Some(OsString::from_vec(vec))
-        }
+        Self::_from_bytes(bytes.into())
+    }
 
-        #[cfg(windows)]
-        fn from_bytes_inner(vec: Vec<u8>) -> Option<OsString> {
-            String::from_utf8(vec).ok().map(OsString::from)
-        }
+    #[cfg(unix)]
+    fn _from_bytes(vec: Vec<u8>) -> Option<OsString> {
+        use os::unix::ffi::OsStringExt;
+        Some(OsString::from_vec(vec))
+    }
 
-        from_bytes_inner(bytes.into())
+    #[cfg(windows)]
+    fn _from_bytes(vec: Vec<u8>) -> Option<OsString> {
+        String::from_utf8(vec).ok().map(OsString::from)
     }
 
     /// Converts to an `OsStr` slice.

src/libstd/fs.rs

@@ -184,7 +184,7 @@ impl File {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn open<P: AsRef<Path>>(path: P) -> io::Result<File> {
-        OpenOptions::new().read(true).open(path)
+        OpenOptions::new().read(true).open(path.as_ref())
     }
 
     /// Opens a file in write-only mode.
@@ -206,7 +206,7 @@ impl File {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn create<P: AsRef<Path>>(path: P) -> io::Result<File> {
-        OpenOptions::new().write(true).create(true).truncate(true).open(path)
+        OpenOptions::new().write(true).create(true).truncate(true).open(path.as_ref())
     }
 
     /// Attempts to sync all OS-internal metadata to disk.
@@ -494,7 +494,10 @@ impl OpenOptions {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
-        let path = path.as_ref();
+        self._open(path.as_ref())
+    }
+
+    fn _open(&self, path: &Path) -> io::Result<File> {
         let inner = try!(fs_imp::File::open(path, &self.0));
         Ok(File { inner: inner })
     }
@@ -1048,7 +1051,10 @@ pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
-    let path = path.as_ref();
+    _remove_dir_all(path.as_ref())
+}
+
+fn _remove_dir_all(path: &Path) -> io::Result<()> {
     for child in try!(read_dir(path)) {
         let child = try!(child).path();
         let stat = try!(symlink_metadata(&*child));
@@ -1113,6 +1119,10 @@ pub fn read_dir<P: AsRef<Path>>(path: P) -> io::Result<ReadDir> {
                      as symlinks differently",
            issue = "27707")]
 pub fn walk_dir<P: AsRef<Path>>(path: P) -> io::Result<WalkDir> {
+    _walk_dir(path.as_ref())
+}
+
+fn _walk_dir(path: &Path) -> io::Result<WalkDir> {
     let start = try!(read_dir(path));
     Ok(WalkDir { cur: Some(start), stack: Vec::new() })
 }
@@ -1272,7 +1282,10 @@ impl DirBuilder {
     /// Create the specified directory with the options configured in this
     /// builder.
     pub fn create<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
-        let path = path.as_ref();
+        self._create(path.as_ref())
+    }
+
+    fn _create(&self, path: &Path) -> io::Result<()> {
         if self.recursive {
             self.create_dir_all(path)
         } else {

src/libstd/io/error.rs

@@ -191,10 +191,14 @@ impl Error {
     pub fn new<E>(kind: ErrorKind, error: E) -> Error
         where E: Into<Box<error::Error+Send+Sync>>
     {
+        Self::_new(kind, error.into())
+    }
+
+    fn _new(kind: ErrorKind, error: Box<error::Error+Send+Sync>) -> Error {
         Error {
             repr: Repr::Custom(Box::new(Custom {
                 kind: kind,
-                error: error.into(),
+                error: error,
             }))
         }
     }

src/libstd/path.rs

@@ -965,8 +965,10 @@ impl PathBuf {
     /// * if `path` has a prefix but no root, it replaces `self`.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn push<P: AsRef<Path>>(&mut self, path: P) {
-        let path = path.as_ref();
+        self._push(path.as_ref())
+    }
 
+    fn _push(&mut self, path: &Path) {
         // in general, a separator is needed if the rightmost byte is not a separator
         let mut need_sep = self.as_mut_vec().last().map(|c| !is_sep_byte(*c)).unwrap_or(false);
 
@@ -1033,11 +1035,15 @@ impl PathBuf {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn set_file_name<S: AsRef<OsStr>>(&mut self, file_name: S) {
+        self._set_file_name(file_name.as_ref())
+    }
+
+    fn _set_file_name(&mut self, file_name: &OsStr) {
         if self.file_name().is_some() {
             let popped = self.pop();
             debug_assert!(popped);
         }
-        self.push(file_name.as_ref());
+        self.push(file_name);
     }
 
     /// Updates `self.extension()` to `extension`.
@@ -1048,14 +1054,17 @@ impl PathBuf {
     /// is added; otherwise it is replaced.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn set_extension<S: AsRef<OsStr>>(&mut self, extension: S) -> bool {
+        self._set_extension(extension.as_ref())
+    }
+
+    fn _set_extension(&mut self, extension: &OsStr) -> bool {
         if self.file_name().is_none() { return false; }
 
         let mut stem = match self.file_stem() {
             Some(stem) => stem.to_os_string(),
             None => OsString::new(),
         };
 
-        let extension = extension.as_ref();
         if !os_str_as_u8_slice(extension).is_empty() {
             stem.push(".");
             stem.push(extension);
@@ -1106,7 +1115,7 @@ impl<P: AsRef<Path>> iter::FromIterator<P> for PathBuf {
 impl<P: AsRef<Path>> iter::Extend<P> for PathBuf {
     fn extend<I: IntoIterator<Item = P>>(&mut self, iter: I) {
         for p in iter {
-            self.push(p)
+            self.push(p.as_ref())
         }
     }
 }
@@ -1452,7 +1461,11 @@ impl Path {
                issue = "23284")]
     pub fn relative_from<'a, P: ?Sized + AsRef<Path>>(&'a self, base: &'a P) -> Option<&Path>
     {
-        iter_after(self.components(), base.as_ref().components()).map(|c| c.as_path())
+        self._relative_from(base.as_ref())
+    }
+
+    fn _relative_from<'a>(&'a self, base: &'a Path) -> Option<&'a Path> {
+        iter_after(self.components(), base.components()).map(|c| c.as_path())
     }
 
     /// Determines whether `base` is a prefix of `self`.
@@ -1472,7 +1485,11 @@ impl Path {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn starts_with<P: AsRef<Path>>(&self, base: P) -> bool {
-        iter_after(self.components(), base.as_ref().components()).is_some()
+        self._starts_with(base.as_ref())
+    }
+
+    fn _starts_with(&self, base: &Path) -> bool {
+        iter_after(self.components(), base.components()).is_some()
     }
 
     /// Determines whether `child` is a suffix of `self`.
@@ -1490,7 +1507,11 @@ impl Path {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn ends_with<P: AsRef<Path>>(&self, child: P) -> bool {
-        iter_after(self.components().rev(), child.as_ref().components().rev()).is_some()
+        self._ends_with(child.as_ref())
+    }
+
+    fn _ends_with(&self, child: &Path) -> bool {
+        iter_after(self.components().rev(), child.components().rev()).is_some()
     }
 
     /// Extracts the stem (non-extension) portion of `self.file_name()`.
@@ -1552,6 +1573,10 @@ impl Path {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn join<P: AsRef<Path>>(&self, path: P) -> PathBuf {
+        self._join(path.as_ref())
+    }
+
+    fn _join(&self, path: &Path) -> PathBuf {
         let mut buf = self.to_path_buf();
         buf.push(path);
         buf
@@ -1571,6 +1596,10 @@ impl Path {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_file_name<S: AsRef<OsStr>>(&self, file_name: S) -> PathBuf {
+        self._with_file_name(file_name.as_ref())
+    }
+
+    fn _with_file_name(&self, file_name: &OsStr) -> PathBuf {
         let mut buf = self.to_path_buf();
         buf.set_file_name(file_name);
         buf
@@ -1590,6 +1619,10 @@ impl Path {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_extension<S: AsRef<OsStr>>(&self, extension: S) -> PathBuf {
+        self._with_extension(extension.as_ref())
+    }
+
+    fn _with_extension(&self, extension: &OsStr) -> PathBuf {
         let mut buf = self.to_path_buf();
         buf.set_extension(extension);
         buf