Deny bare trait objects in src/libstd

src/libstd/error.rs

@@ -138,7 +138,7 @@ pub trait Error: Debug + Display {
     /// }
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    fn cause(&self) -> Option<&Error> { None }
+    fn cause(&self) -> Option<&dyn Error> { None }
 
     /// Get the `TypeId` of `self`
     #[doc(hidden)]
@@ -151,22 +151,22 @@ pub trait Error: Debug + Display {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + 'a> From<E> for Box<Error + 'a> {
-    fn from(err: E) -> Box<Error + 'a> {
+impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
+    fn from(err: E) -> Box<dyn Error + 'a> {
         Box::new(err)
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<Error + Send + Sync + 'a> {
-    fn from(err: E) -> Box<Error + Send + Sync + 'a> {
+impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync + 'a> {
+    fn from(err: E) -> Box<dyn Error + Send + Sync + 'a> {
         Box::new(err)
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl From<String> for Box<Error + Send + Sync> {
-    fn from(err: String) -> Box<Error + Send + Sync> {
+impl From<String> for Box<dyn Error + Send + Sync> {
+    fn from(err: String) -> Box<dyn Error + Send + Sync> {
         #[derive(Debug)]
         struct StringError(String);
 
@@ -185,38 +185,38 @@ impl From<String> for Box<Error + Send + Sync> {
 }
 
 #[stable(feature = "string_box_error", since = "1.6.0")]
-impl From<String> for Box<Error> {
-    fn from(str_err: String) -> Box<Error> {
-        let err1: Box<Error + Send + Sync> = From::from(str_err);
-        let err2: Box<Error> = err1;
+impl From<String> for Box<dyn Error> {
+    fn from(str_err: String) -> Box<dyn Error> {
+        let err1: Box<dyn Error + Send + Sync> = From::from(str_err);
+        let err2: Box<dyn Error> = err1;
         err2
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, 'b> From<&'b str> for Box<Error + Send + Sync + 'a> {
-    fn from(err: &'b str) -> Box<Error + Send + Sync + 'a> {
+impl<'a, 'b> From<&'b str> for Box<dyn Error + Send + Sync + 'a> {
+    fn from(err: &'b str) -> Box<dyn Error + Send + Sync + 'a> {
         From::from(String::from(err))
     }
 }
 
 #[stable(feature = "string_box_error", since = "1.6.0")]
-impl<'a> From<&'a str> for Box<Error> {
-    fn from(err: &'a str) -> Box<Error> {
+impl<'a> From<&'a str> for Box<dyn Error> {
+    fn from(err: &'a str) -> Box<dyn Error> {
         From::from(String::from(err))
     }
 }
 
 #[stable(feature = "cow_box_error", since = "1.22.0")]
-impl<'a, 'b> From<Cow<'b, str>> for Box<Error + Send + Sync + 'a> {
-    fn from(err: Cow<'b, str>) -> Box<Error + Send + Sync + 'a> {
+impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> {
+    fn from(err: Cow<'b, str>) -> Box<dyn Error + Send + Sync + 'a> {
         From::from(String::from(err))
     }
 }
 
 #[stable(feature = "cow_box_error", since = "1.22.0")]
-impl<'a> From<Cow<'a, str>> for Box<Error> {
-    fn from(err: Cow<'a, str>) -> Box<Error> {
+impl<'a> From<Cow<'a, str>> for Box<dyn Error> {
+    fn from(err: Cow<'a, str>) -> Box<dyn Error> {
         From::from(String::from(err))
     }
 }
@@ -327,7 +327,7 @@ impl<T: Error> Error for Box<T> {
         Error::description(&**self)
     }
 
-    fn cause(&self) -> Option<&Error> {
+    fn cause(&self) -> Option<&dyn Error> {
         Error::cause(&**self)
     }
 }
@@ -368,7 +368,7 @@ impl Error for char::ParseCharError {
 }
 
 // copied from any.rs
-impl Error + 'static {
+impl dyn Error + 'static {
     /// Returns true if the boxed type is the same as `T`
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
@@ -390,7 +390,7 @@ impl Error + 'static {
     pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
         if self.is::<T>() {
             unsafe {
-                Some(&*(self as *const Error as *const T))
+                Some(&*(self as *const dyn Error as *const T))
             }
         } else {
             None
@@ -404,68 +404,68 @@ impl Error + 'static {
     pub fn downcast_mut<T: Error + 'static>(&mut self) -> Option<&mut T> {
         if self.is::<T>() {
             unsafe {
-                Some(&mut *(self as *mut Error as *mut T))
+                Some(&mut *(self as *mut dyn Error as *mut T))
             }
         } else {
             None
         }
     }
 }
 
-impl Error + 'static + Send {
+impl dyn Error + 'static + Send {
     /// Forwards to the method defined on the type `Any`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn is<T: Error + 'static>(&self) -> bool {
-        <Error + 'static>::is::<T>(self)
+        <dyn Error + 'static>::is::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
-        <Error + 'static>::downcast_ref::<T>(self)
+        <dyn Error + 'static>::downcast_ref::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_mut<T: Error + 'static>(&mut self) -> Option<&mut T> {
-        <Error + 'static>::downcast_mut::<T>(self)
+        <dyn Error + 'static>::downcast_mut::<T>(self)
     }
 }
 
-impl Error + 'static + Send + Sync {
+impl dyn Error + 'static + Send + Sync {
     /// Forwards to the method defined on the type `Any`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn is<T: Error + 'static>(&self) -> bool {
-        <Error + 'static>::is::<T>(self)
+        <dyn Error + 'static>::is::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T> {
-        <Error + 'static>::downcast_ref::<T>(self)
+        <dyn Error + 'static>::downcast_ref::<T>(self)
     }
 
     /// Forwards to the method defined on the type `Any`.
     #[stable(feature = "error_downcast", since = "1.3.0")]
     #[inline]
     pub fn downcast_mut<T: Error + 'static>(&mut self) -> Option<&mut T> {
-        <Error + 'static>::downcast_mut::<T>(self)
+        <dyn Error + 'static>::downcast_mut::<T>(self)
     }
 }
 
-impl Error {
+impl dyn Error {
     #[inline]
     #[stable(feature = "error_downcast", since = "1.3.0")]
     /// Attempt to downcast the box to a concrete type.
-    pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<Error>> {
+    pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error>> {
         if self.is::<T>() {
             unsafe {
-                let raw: *mut Error = Box::into_raw(self);
+                let raw: *mut dyn Error = Box::into_raw(self);
                 Ok(Box::from_raw(raw as *mut T))
             }
         } else {
@@ -474,30 +474,30 @@ impl Error {
     }
 }
 
-impl Error + Send {
+impl dyn Error + Send {
     #[inline]
     #[stable(feature = "error_downcast", since = "1.3.0")]
     /// Attempt to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>)
-                                        -> Result<Box<T>, Box<Error + Send>> {
-        let err: Box<Error> = self;
-        <Error>::downcast(err).map_err(|s| unsafe {
+                                        -> Result<Box<T>, Box<dyn Error + Send>> {
+        let err: Box<dyn Error> = self;
+        <dyn Error>::downcast(err).map_err(|s| unsafe {
             // reapply the Send marker
-            transmute::<Box<Error>, Box<Error + Send>>(s)
+            transmute::<Box<dyn Error>, Box<dyn Error + Send>>(s)
         })
     }
 }
 
-impl Error + Send + Sync {
+impl dyn Error + Send + Sync {
     #[inline]
     #[stable(feature = "error_downcast", since = "1.3.0")]
     /// Attempt to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>)
                                         -> Result<Box<T>, Box<Self>> {
-        let err: Box<Error> = self;
-        <Error>::downcast(err).map_err(|s| unsafe {
+        let err: Box<dyn Error> = self;
+        <dyn Error>::downcast(err).map_err(|s| unsafe {
             // reapply the Send+Sync marker
-            transmute::<Box<Error>, Box<Error + Send + Sync>>(s)
+            transmute::<Box<dyn Error>, Box<dyn Error + Send + Sync>>(s)
         })
     }
 }
@@ -533,13 +533,13 @@ mod tests {
     #[test]
     fn downcasting() {
         let mut a = A;
-        let a = &mut a as &mut (Error + 'static);
+        let a = &mut a as &mut (dyn Error + 'static);
         assert_eq!(a.downcast_ref::<A>(), Some(&A));
         assert_eq!(a.downcast_ref::<B>(), None);
         assert_eq!(a.downcast_mut::<A>(), Some(&mut A));
         assert_eq!(a.downcast_mut::<B>(), None);
 
-        let a: Box<Error> = Box::new(A);
+        let a: Box<dyn Error> = Box::new(A);
         match a.downcast::<B>() {
             Ok(..) => panic!("expected error"),
             Err(e) => assert_eq!(*e.downcast::<A>().unwrap(), A),

src/libstd/ffi/c_str.rs

@@ -883,7 +883,7 @@ impl Error for IntoStringError {
         "C string contained non-utf8 bytes"
     }
 
-    fn cause(&self) -> Option<&Error> {
+    fn cause(&self) -> Option<&dyn Error> {
         Some(&self.error)
     }
 }

src/libstd/io/error.rs

@@ -83,7 +83,7 @@ enum Repr {
 #[derive(Debug)]
 struct Custom {
     kind: ErrorKind,
-    error: Box<error::Error+Send+Sync>,
+    error: Box<dyn error::Error+Send+Sync>,
 }
 
 /// A list specifying general categories of I/O error.
@@ -250,12 +250,12 @@ impl Error {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn new<E>(kind: ErrorKind, error: E) -> Error
-        where E: Into<Box<error::Error+Send+Sync>>
+        where E: Into<Box<dyn error::Error+Send+Sync>>
     {
         Self::_new(kind, error.into())
     }
 
-    fn _new(kind: ErrorKind, error: Box<error::Error+Send+Sync>) -> Error {
+    fn _new(kind: ErrorKind, error: Box<dyn error::Error+Send+Sync>) -> Error {
         Error {
             repr: Repr::Custom(Box::new(Custom {
                 kind,
@@ -373,7 +373,7 @@ impl Error {
     /// }
     /// ```
     #[stable(feature = "io_error_inner", since = "1.3.0")]
-    pub fn get_ref(&self) -> Option<&(error::Error+Send+Sync+'static)> {
+    pub fn get_ref(&self) -> Option<&(dyn error::Error+Send+Sync+'static)> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
@@ -444,7 +444,7 @@ impl Error {
     /// }
     /// ```
     #[stable(feature = "io_error_inner", since = "1.3.0")]
-    pub fn get_mut(&mut self) -> Option<&mut (error::Error+Send+Sync+'static)> {
+    pub fn get_mut(&mut self) -> Option<&mut (dyn error::Error+Send+Sync+'static)> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
@@ -478,7 +478,7 @@ impl Error {
     /// }
     /// ```
     #[stable(feature = "io_error_inner", since = "1.3.0")]
-    pub fn into_inner(self) -> Option<Box<error::Error+Send+Sync>> {
+    pub fn into_inner(self) -> Option<Box<dyn error::Error+Send+Sync>> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,
@@ -551,7 +551,7 @@ impl error::Error for Error {
         }
     }
 
-    fn cause(&self) -> Option<&error::Error> {
+    fn cause(&self) -> Option<&dyn error::Error> {
         match self.repr {
             Repr::Os(..) => None,
             Repr::Simple(..) => None,

src/libstd/io/mod.rs

@@ -1972,7 +1972,7 @@ impl<T: BufRead> BufRead for Take<T> {
     }
 }
 
-fn read_one_byte(reader: &mut Read) -> Option<Result<u8>> {
+fn read_one_byte(reader: &mut dyn Read) -> Option<Result<u8>> {
     let mut buf = [0];
     loop {
         return match reader.read(&mut buf) {
@@ -2081,7 +2081,7 @@ impl std_error::Error for CharsError {
             CharsError::Other(ref e) => std_error::Error::description(e),
         }
     }
-    fn cause(&self) -> Option<&std_error::Error> {
+    fn cause(&self) -> Option<&dyn std_error::Error> {
         match *self {
             CharsError::NotUtf8 => None,
             CharsError::Other(ref e) => e.cause(),

src/libstd/io/stdio.rs

@@ -21,7 +21,7 @@ use thread::LocalKey;
 
 /// Stdout used by print! and println! macros
 thread_local! {
-    static LOCAL_STDOUT: RefCell<Option<Box<Write + Send>>> = {
+    static LOCAL_STDOUT: RefCell<Option<Box<dyn Write + Send>>> = {
         RefCell::new(None)
     }
 }
@@ -624,7 +624,7 @@ impl<'a> fmt::Debug for StderrLock<'a> {
                      with a more general mechanism",
            issue = "0")]
 #[doc(hidden)]
-pub fn set_panic(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
+pub fn set_panic(sink: Option<Box<dyn Write + Send>>) -> Option<Box<dyn Write + Send>> {
     use panicking::LOCAL_STDERR;
     use mem;
     LOCAL_STDERR.with(move |slot| {
@@ -648,7 +648,7 @@ pub fn set_panic(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
                      with a more general mechanism",
            issue = "0")]
 #[doc(hidden)]
-pub fn set_print(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
+pub fn set_print(sink: Option<Box<dyn Write + Send>>) -> Option<Box<dyn Write + Send>> {
     use mem;
     LOCAL_STDOUT.with(move |slot| {
         mem::replace(&mut *slot.borrow_mut(), sink)
@@ -670,7 +670,7 @@ pub fn set_print(sink: Option<Box<Write + Send>>) -> Option<Box<Write + Send>> {
 /// However, if the actual I/O causes an error, this function does panic.
 fn print_to<T>(
     args: fmt::Arguments,
-    local_s: &'static LocalKey<RefCell<Option<Box<Write+Send>>>>,
+    local_s: &'static LocalKey<RefCell<Option<Box<dyn Write+Send>>>>,
     global_s: fn() -> T,
     label: &str,
 )

src/libstd/io/util.rs

@@ -223,7 +223,7 @@ mod tests {
         assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
 
         let mut r = repeat(0).take(1 << 17);
-        assert_eq!(copy(&mut r as &mut Read, &mut w as &mut Write).unwrap(), 1 << 17);
+        assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
     }
 
     #[test]

src/libstd/lib.rs

@@ -221,6 +221,7 @@
 // Don't link to std. We are std.
 #![no_std]
 
+#![deny(bare_trait_objects)]
 #![deny(missing_docs)]
 #![deny(missing_debug_implementations)]