use fmt::Result where applicable

src/libstd/path.rs

@@ -1460,7 +1460,7 @@ impl<P: AsRef<Path>> iter::Extend<P> for PathBuf {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for PathBuf {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(&**self, formatter)
     }
 }

src/libstd/sys/redox/syscall/error.rs

@@ -48,13 +48,13 @@ impl Error {
 }
 
 impl fmt::Debug for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str(self.text())
     }
 }
 
 impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str(self.text())
     }
 }

src/libstd/sys_common/wtf8.rs

@@ -56,7 +56,7 @@ pub struct CodePoint {
 /// Example: `U+1F4A9`
 impl fmt::Debug for CodePoint {
     #[inline]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         write!(formatter, "U+{:04X}", self.value)
     }
 }
@@ -144,7 +144,7 @@ impl ops::DerefMut for Wtf8Buf {
 /// Example: `"a\u{D800}"` for a string with code points [U+0061, U+D800]
 impl fmt::Debug for Wtf8Buf {
     #[inline]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         fmt::Debug::fmt(&**self, formatter)
     }
 }