rollup merge of #23879: seanmonstar/del-from-error

Conflicts:
	src/libcore/error.rs

10 files changed, 26 insertions, 78 deletions

diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 48dce3d8815..f3c0dd0c3dc 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -51,7 +51,7 @@ use core::prelude::*;
 use core::any::Any;
 use core::cmp::Ordering;
 use core::default::Default;
-use core::error::{Error, FromError};
+use core::error::Error;
 use core::fmt;
 use core::hash::{self, Hash};
 use core::mem;
@@ -308,8 +308,8 @@ impl<I: DoubleEndedIterator + ?Sized> DoubleEndedIterator for Box<I> {
 impl<I: ExactSizeIterator + ?Sized> ExactSizeIterator for Box<I> {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + 'a> FromError<E> for Box<Error + 'a> {
-    fn from_error(err: E) -> Box<Error + 'a> {
+impl<'a, E: Error + 'a> From<E> for Box<Error + 'a> {
+    fn from(err: E) -> Box<Error + 'a> {
         Box::new(err)
     }
 }
diff --git a/src/libcore/convert.rs b/src/libcore/convert.rs
index 4a99f1a756a..62ca8c47ab6 100644
--- a/src/libcore/convert.rs
+++ b/src/libcore/convert.rs
@@ -95,6 +95,13 @@ impl<'a, T: ?Sized, U: ?Sized> AsMut<U> for &'a mut T where T: AsMut<U> {
 //     }
 // }
 
+// From itself is always itself
+impl<T> From<T> for T {
+    fn from(t: T) -> T {
+        t
+    }
+}
+
 // From implies Into
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T, U> Into<U> for T where U: From<T> {
diff --git a/src/libcore/error.rs b/src/libcore/error.rs
index 9430aa00668..24035b7d9a8 100644
--- a/src/libcore/error.rs
+++ b/src/libcore/error.rs
@@ -33,49 +33,6 @@
 //! high-level module to provide its own errors that do not commit to any
 //! particular implementation, but also reveal some of its implementation for
 //! debugging via `cause` chains.
-//!
-//! # The `FromError` trait
-//!
-//! `FromError` is a simple trait that expresses conversions between different
-//! error types. To provide maximum flexibility, it does not require either of
-//! the types to actually implement the `Error` trait, although this will be the
-//! common case.
-//!
-//! The main use of this trait is in the `try!` macro, which uses it to
-//! automatically convert a given error to the error specified in a function's
-//! return type.
-//!
-//! For example,
-//!
-//! ```
-//! #![feature(core)]
-//! use std::error::FromError;
-//! use std::{io, str};
-//! use std::fs::File;
-//!
-//! enum MyError {
-//!     Io(io::Error),
-//!     Utf8(str::Utf8Error),
-//! }
-//!
-//! impl FromError<io::Error> for MyError {
-//!     fn from_error(err: io::Error) -> MyError { MyError::Io(err) }
-//! }
-//!
-//! impl FromError<str::Utf8Error> for MyError {
-//!     fn from_error(err: str::Utf8Error) -> MyError { MyError::Utf8(err) }
-//! }
-//!
-//! #[allow(unused_variables)]
-//! fn open_and_map() -> Result<(), MyError> {
-//!     let b = b"foo.txt";
-//!     let s = try!(str::from_utf8(b));
-//!     let f = try!(File::open(s));
-//!
-//!     // do something interesting here...
-//!     Ok(())
-//! }
-//! ```
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
@@ -97,19 +54,3 @@ pub trait Error: Debug + Display {
     #[stable(feature = "rust1", since = "1.0.0")]
     fn cause(&self) -> Option<&Error> { None }
 }
-
-/// A trait for types that can be converted from a given error type `E`.
-#[stable(feature = "rust1", since = "1.0.0")]
-pub trait FromError<E> {
-    /// Perform the conversion.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    fn from_error(err: E) -> Self;
-}
-
-// Any type is convertable from itself
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<E> FromError<E> for E {
-    fn from_error(err: E) -> E {
-        err
-    }
-}
diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index d5a7c1d6b26..19626aa5056 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -156,7 +156,7 @@ macro_rules! debug_assert_eq {
 
 /// Short circuiting evaluation on Err
 ///
-/// `libstd` contains a more general `try!` macro that uses `FromError`.
+/// `libstd` contains a more general `try!` macro that uses `From<E>`.
 #[macro_export]
 macro_rules! try {
     ($e:expr) => ({
diff --git a/src/libserialize/json.rs b/src/libserialize/json.rs
index c47568520a0..cdfe212bf23 100644
--- a/src/libserialize/json.rs
+++ b/src/libserialize/json.rs
@@ -367,8 +367,8 @@ impl std::error::Error for EncoderError {
     fn description(&self) -> &str { "encoder error" }
 }
 
-impl std::error::FromError<fmt::Error> for EncoderError {
-    fn from_error(err: fmt::Error) -> EncoderError { EncoderError::FmtError(err) }
+impl From<fmt::Error> for EncoderError {
+    fn from(err: fmt::Error) -> EncoderError { EncoderError::FmtError(err) }
 }
 
 pub type EncodeResult = Result<(), EncoderError>;
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index a00f7708025..f5c7d1d18d5 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -12,7 +12,7 @@
 
 use convert::Into;
 use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
-use error::{Error, FromError};
+use error::Error;
 use fmt;
 use io;
 use iter::Iterator;
@@ -298,8 +298,8 @@ impl fmt::Display for NulError {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl FromError<NulError> for io::Error {
-    fn from_error(_: NulError) -> io::Error {
+impl From<NulError> for io::Error {
+    fn from(_: NulError) -> io::Error {
         io::Error::new(io::ErrorKind::InvalidInput,
                        "data provided contains a nul byte", None)
     }
@@ -307,8 +307,8 @@ impl FromError<NulError> for io::Error {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow(deprecated)]
-impl FromError<NulError> for old_io::IoError {
-    fn from_error(_: NulError) -> old_io::IoError {
+impl From<NulError> for old_io::IoError {
+    fn from(_: NulError) -> old_io::IoError {
         old_io::IoError {
             kind: old_io::IoErrorKind::InvalidInput,
             desc: "data provided contains a nul byte",
diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index 8eea06bf6b0..628ad839c16 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -16,7 +16,7 @@ use prelude::v1::*;
 use io::prelude::*;
 
 use cmp;
-use error::{self, FromError};
+use error;
 use fmt;
 use io::{self, DEFAULT_BUF_SIZE, Error, ErrorKind};
 use ptr;
@@ -264,8 +264,8 @@ impl<W> IntoInnerError<W> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<W> FromError<IntoInnerError<W>> for Error {
-    fn from_error(iie: IntoInnerError<W>) -> Error { iie.1 }
+impl<W> From<IntoInnerError<W>> for Error {
+    fn from(iie: IntoInnerError<W>) -> Error { iie.1 }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index 645bc5db753..b3d1adb4421 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -101,7 +101,7 @@ macro_rules! try {
     ($expr:expr) => (match $expr {
         $crate::result::Result::Ok(val) => val,
         $crate::result::Result::Err(err) => {
-            return $crate::result::Result::Err($crate::error::FromError::from_error(err))
+            return $crate::result::Result::Err($crate::convert::From::from(err))
         }
     })
 }
diff --git a/src/libstd/os.rs b/src/libstd/os.rs
index 2e3f47fea86..4ae3ad29c73 100644
--- a/src/libstd/os.rs
+++ b/src/libstd/os.rs
@@ -40,7 +40,7 @@ use boxed::Box;
 use clone::Clone;
 use convert::From;
 use env;
-use error::{FromError, Error};
+use error::Error;
 use ffi::{OsString, OsStr};
 use fmt;
 use iter::Iterator;
diff --git a/src/libstd/sync/poison.rs b/src/libstd/sync/poison.rs
index c07c83d37f4..cea2def30f1 100644
--- a/src/libstd/sync/poison.rs
+++ b/src/libstd/sync/poison.rs
@@ -11,7 +11,7 @@
 use prelude::v1::*;
 
 use cell::UnsafeCell;
-use error::{Error, FromError};
+use error::{Error};
 use fmt;
 use thread;
 
@@ -144,8 +144,8 @@ impl<T> PoisonError<T> {
     pub fn get_mut(&mut self) -> &mut T { &mut self.guard }
 }
 
-impl<T> FromError<PoisonError<T>> for TryLockError<T> {
-    fn from_error(err: PoisonError<T>) -> TryLockError<T> {
+impl<T> From<PoisonError<T>> for TryLockError<T> {
+    fn from(err: PoisonError<T>) -> TryLockError<T> {
         TryLockError::Poisoned(err)
     }
 }