Warn on bare_trait_objects by default

src/librustc/lint/builtin.rs

@@ -255,7 +255,7 @@ declare_lint! {
 
 declare_lint! {
     pub BARE_TRAIT_OBJECTS,
-    Allow,
+    Warn,
     "suggest using `dyn Trait` for trait objects"
 }
 

src/libstd/error.rs

@@ -94,7 +94,7 @@ pub trait Error: Debug + Display {
     ///         "I'm the superhero of errors"
     ///     }
     ///
-    ///     fn cause(&self) -> Option<&Error> {
+    ///     fn cause(&self) -> Option<&dyn Error> {
     ///         Some(&self.side)
     ///     }
     /// }
@@ -244,7 +244,7 @@ impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
     ///
     /// let an_error = AnError;
     /// assert!(0 == mem::size_of_val(&an_error));
-    /// let a_boxed_error = Box::<Error>::from(an_error);
+    /// let a_boxed_error = Box::<dyn Error>::from(an_error);
     /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
     /// ```
     fn from(err: E) -> Box<dyn Error + 'a> {
@@ -287,7 +287,7 @@ impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync +
     ///
     /// let an_error = AnError;
     /// assert!(0 == mem::size_of_val(&an_error));
-    /// let a_boxed_error = Box::<Error + Send + Sync>::from(an_error);
+    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(an_error);
     /// assert!(
     ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
     /// ```
@@ -309,7 +309,7 @@ impl From<String> for Box<dyn Error + Send + Sync> {
     /// use std::mem;
     ///
     /// let a_string_error = "a string error".to_string();
-    /// let a_boxed_error = Box::<Error + Send + Sync>::from(a_string_error);
+    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error);
     /// assert!(
     ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
     /// ```
@@ -344,7 +344,7 @@ impl From<String> for Box<dyn Error> {
     /// use std::mem;
     ///
     /// let a_string_error = "a string error".to_string();
-    /// let a_boxed_error = Box::<Error>::from(a_string_error);
+    /// let a_boxed_error = Box::<dyn Error>::from(a_string_error);
     /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
     /// ```
     fn from(str_err: String) -> Box<dyn Error> {
@@ -367,7 +367,7 @@ impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a> {
     /// use std::mem;
     ///
     /// let a_str_error = "a str error";
-    /// let a_boxed_error = Box::<Error + Send + Sync>::from(a_str_error);
+    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error);
     /// assert!(
     ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
     /// ```
@@ -389,7 +389,7 @@ impl From<&str> for Box<dyn Error> {
     /// use std::mem;
     ///
     /// let a_str_error = "a str error";
-    /// let a_boxed_error = Box::<Error>::from(a_str_error);
+    /// let a_boxed_error = Box::<dyn Error>::from(a_str_error);
     /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
     /// ```
     fn from(err: &str) -> Box<dyn Error> {
@@ -412,7 +412,7 @@ impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a> {
     /// use std::borrow::Cow;
     ///
     /// let a_cow_str_error = Cow::from("a str error");
-    /// let a_boxed_error = Box::<Error + Send + Sync>::from(a_cow_str_error);
+    /// let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error);
     /// assert!(
     ///     mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
     /// ```
@@ -436,7 +436,7 @@ impl<'a> From<Cow<'a, str>> for Box<dyn Error> {
     /// use std::borrow::Cow;
     ///
     /// let a_cow_str_error = Cow::from("a str error");
-    /// let a_boxed_error = Box::<Error>::from(a_cow_str_error);
+    /// let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error);
     /// assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
     /// ```
     fn from(err: Cow<'a, str>) -> Box<dyn Error> {

src/libstd/fs.rs

@@ -1976,7 +1976,7 @@ pub fn remove_dir_all<P: AsRef<Path>>(path: P) -> io::Result<()> {
 /// use std::path::Path;
 ///
 /// // one possible implementation of walking a directory only visiting files
-/// fn visit_dirs(dir: &Path, cb: &Fn(&DirEntry)) -> io::Result<()> {
+/// fn visit_dirs(dir: &Path, cb: &dyn Fn(&DirEntry)) -> io::Result<()> {
 ///     if dir.is_dir() {
 ///         for entry in fs::read_dir(dir)? {
 ///             let entry = entry?;

src/test/compile-fail/issue-23595-1.rs

@@ -5,7 +5,7 @@ use std::ops::{Index};
 trait Hierarchy {
     type Value;
     type ChildKey;
-    type Children = Index<Self::ChildKey, Output=Hierarchy>;
+    type Children = dyn Index<Self::ChildKey, Output=dyn Hierarchy>;
     //~^ ERROR: the value of the associated types `Value` (from the trait `Hierarchy`), `ChildKey`
 
     fn data(&self) -> Option<(Self::Value, Self::Children)>;

src/test/run-pass-fulldeps/pprust-expr-roundtrip.rs

@@ -62,7 +62,7 @@ fn make_x() -> P<Expr> {
 /// Iterate over exprs of depth up to `depth`. The goal is to explore all "interesting"
 /// combinations of expression nesting. For example, we explore combinations using `if`, but not
 /// `while` or `match`, since those should print and parse in much the same way as `if`.
-fn iter_exprs(depth: usize, f: &mut FnMut(P<Expr>)) {
+fn iter_exprs(depth: usize, f: &mut dyn FnMut(P<Expr>)) {
     if depth == 0 {
         f(make_x());
         return;

src/test/run-pass/alignment-gep-tup-like-1.rs

@@ -22,11 +22,11 @@ impl<A:Clone> Invokable<A> for Invoker<A> {
     }
 }
 
-fn f<A:Clone + 'static>(a: A, b: u16) -> Box<Invokable<A>+'static> {
+fn f<A:Clone + 'static>(a: A, b: u16) -> Box<dyn Invokable<A>+'static> {
     box Invoker {
         a: a,
         b: b,
-    } as (Box<Invokable<A>+'static>)
+    } as (Box<dyn Invokable<A>+'static>)
 }
 
 pub fn main() {

src/test/run-pass/associated-types/associated-types-doubleendediterator-object.rs

@@ -1,7 +1,7 @@
 // run-pass
 #![feature(box_syntax)]
 
-fn pairwise_sub(mut t: Box<DoubleEndedIterator<Item=isize>>) -> isize {
+fn pairwise_sub(mut t: Box<dyn DoubleEndedIterator<Item=isize>>) -> isize {
     let mut result = 0;
     loop {
         let front = t.next();

src/test/run-pass/associated-types/associated-types-eq-obj.rs

@@ -15,7 +15,7 @@ impl Foo for char {
     fn boo(&self) -> Bar { Bar }
 }
 
-fn baz(x: &Foo<A=Bar>) -> Bar {
+fn baz(x: &dyn Foo<A=Bar>) -> Bar {
     x.boo()
 }
 

src/test/run-pass/associated-types/associated-types-projection-in-object-type.rs

@@ -19,20 +19,20 @@ pub trait Subscriber {
 
 pub trait Publisher<'a> {
     type Output;
-    fn subscribe(&mut self, _: Box<Subscriber<Input=Self::Output> + 'a>);
+    fn subscribe(&mut self, _: Box<dyn Subscriber<Input=Self::Output> + 'a>);
 }
 
 pub trait Processor<'a> : Subscriber + Publisher<'a> { }
 
 impl<'a, P> Processor<'a> for P where P : Subscriber + Publisher<'a> { }
 
 struct MyStruct<'a> {
-    sub: Box<Subscriber<Input=u64> + 'a>
+    sub: Box<dyn Subscriber<Input=u64> + 'a>
 }
 
 impl<'a> Publisher<'a> for MyStruct<'a> {
     type Output = u64;
-    fn subscribe(&mut self, t : Box<Subscriber<Input=u64> + 'a>) {
+    fn subscribe(&mut self, t : Box<dyn Subscriber<Input=u64> + 'a>) {
         self.sub = t;
     }
 }

src/test/run-pass/autoref-autoderef/autoderef-method-on-trait.rs

@@ -11,6 +11,6 @@ impl double for usize {
 }
 
 pub fn main() {
-    let x: Box<_> = box (box 3usize as Box<double>);
+    let x: Box<_> = box (box 3usize as Box<dyn double>);
     assert_eq!(x.double(), 6);
 }

src/test/run-pass/borrowck/borrowck-trait-lifetime.rs

@@ -12,7 +12,7 @@ use std::marker;
 fn main() {
     trait T { fn foo(&self) {} }
 
-    fn f<'a, V: T>(v: &'a V) -> &'a T {
-        v as &'a T
+    fn f<'a, V: T>(v: &'a V) -> &'a dyn T {
+        v as &'a dyn T
     }
 }

src/test/run-pass/cast-rfc0401-vtable-kinds.rs

@@ -15,9 +15,9 @@ impl<T> Foo<T> for () {}
 impl Foo<u32> for u32 { fn foo(&self, _: u32) -> u32 { self+43 } }
 impl Bar for () {}
 
-unsafe fn round_trip_and_call<'a>(t: *const (Foo<u32>+'a)) -> u32 {
-    let foo_e : *const Foo<u16> = t as *const _;
-    let r_1 = foo_e as *mut Foo<u32>;
+unsafe fn round_trip_and_call<'a>(t: *const (dyn Foo<u32>+'a)) -> u32 {
+    let foo_e : *const dyn Foo<u16> = t as *const _;
+    let r_1 = foo_e as *mut dyn Foo<u32>;
 
     (&*r_1).foo(0)
 }
@@ -38,8 +38,8 @@ fn tuple_i32_to_u32<T:?Sized>(u: *const (i32, T)) -> *const (u32, T) {
 
 fn main() {
     let x = 4u32;
-    let y : &Foo<u32> = &x;
-    let fl = unsafe { round_trip_and_call(y as *const Foo<u32>) };
+    let y : &dyn Foo<u32> = &x;
+    let fl = unsafe { round_trip_and_call(y as *const dyn Foo<u32>) };
     assert_eq!(fl, (43+4));
 
     let s = FooS([0,1,2]);

src/test/run-pass/cast-rfc0401.rs

@@ -25,8 +25,8 @@ fn main()
     // coercion-cast
     let mut it = vec![137].into_iter();
     let itr: &mut vec::IntoIter<u32> = &mut it;
-    assert_eq!((itr as &mut Iterator<Item=u32>).next(), Some(137));
-    assert_eq!((itr as &mut Iterator<Item=u32>).next(), None);
+    assert_eq!((itr as &mut dyn Iterator<Item=u32>).next(), Some(137));
+    assert_eq!((itr as &mut dyn Iterator<Item=u32>).next(), None);
 
     assert_eq!(Some(4u32) as Option<u32>, Some(4u32));
     assert_eq!((1u32,2u32) as (u32,u32), (1,2));

src/test/run-pass/close-over-big-then-small-data.rs

@@ -24,11 +24,11 @@ impl<A:Clone> Invokable<A> for Invoker<A> {
     }
 }
 
-fn f<A:Clone + 'static>(a: A, b: u16) -> Box<Invokable<A>+'static> {
+fn f<A:Clone + 'static>(a: A, b: u16) -> Box<dyn Invokable<A>+'static> {
     box Invoker {
         a: a,
         b: b,
-    } as (Box<Invokable<A>+'static>)
+    } as (Box<dyn Invokable<A>+'static>)
 }
 
 pub fn main() {

src/test/run-pass/codegen-object-shim.rs

@@ -1,4 +1,4 @@
 fn main() {
-    assert_eq!((ToString::to_string as fn(&(ToString+'static)) -> String)(&"foo"),
+    assert_eq!((ToString::to_string as fn(&(dyn ToString+'static)) -> String)(&"foo"),
         String::from("foo"));
 }

src/test/run-pass/coerce/coerce-expect-unsized.rs

@@ -12,16 +12,16 @@ pub fn main() {
     let _: Box<[isize]> = Box::new({ [1, 2, 3] });
     let _: Box<[isize]> = Box::new(if true { [1, 2, 3] } else { [1, 3, 4] });
     let _: Box<[isize]> = Box::new(match true { true => [1, 2, 3], false => [1, 3, 4] });
-    let _: Box<Fn(isize) -> _> = Box::new({ |x| (x as u8) });
-    let _: Box<Debug> = Box::new(if true { false } else { true });
-    let _: Box<Debug> = Box::new(match true { true => 'a', false => 'b' });
+    let _: Box<dyn Fn(isize) -> _> = Box::new({ |x| (x as u8) });
+    let _: Box<dyn Debug> = Box::new(if true { false } else { true });
+    let _: Box<dyn Debug> = Box::new(match true { true => 'a', false => 'b' });
 
     let _: &[isize] = &{ [1, 2, 3] };
     let _: &[isize] = &if true { [1, 2, 3] } else { [1, 3, 4] };
     let _: &[isize] = &match true { true => [1, 2, 3], false => [1, 3, 4] };
-    let _: &Fn(isize) -> _ = &{ |x| (x as u8) };
-    let _: &Debug = &if true { false } else { true };
-    let _: &Debug = &match true { true => 'a', false => 'b' };
+    let _: &dyn Fn(isize) -> _ = &{ |x| (x as u8) };
+    let _: &dyn Debug = &if true { false } else { true };
+    let _: &dyn Debug = &match true { true => 'a', false => 'b' };
 
     let _: &str = &{ String::new() };
     let _: &str = &if true { String::from("...") } else { 5.to_string() };
@@ -31,12 +31,12 @@ pub fn main() {
     };
 
     let _: Box<[isize]> = Box::new([1, 2, 3]);
-    let _: Box<Fn(isize) -> _> = Box::new(|x| (x as u8));
+    let _: Box<dyn Fn(isize) -> _> = Box::new(|x| (x as u8));
 
     let _: Rc<RefCell<[isize]>> = Rc::new(RefCell::new([1, 2, 3]));
-    let _: Rc<RefCell<FnMut(isize) -> _>> = Rc::new(RefCell::new(|x| (x as u8)));
+    let _: Rc<RefCell<dyn FnMut(isize) -> _>> = Rc::new(RefCell::new(|x| (x as u8)));
 
-    let _: Vec<Box<Fn(isize) -> _>> = vec![
+    let _: Vec<Box<dyn Fn(isize) -> _>> = vec![
         Box::new(|x| (x as u8)),
         Box::new(|x| (x as i16 as u8)),
     ];

src/test/run-pass/consts/const-trait-to-trait.rs

@@ -8,17 +8,17 @@ struct Bar;
 impl Trait for Bar {}
 
 fn main() {
-    let x: &[&Trait] = &[{ &Bar }];
+    let x: &[&dyn Trait] = &[{ &Bar }];
 }
 
 // Issue #25748 - the cast causes an &Encoding -> &Encoding coercion:
 pub struct UTF8Encoding;
 pub const UTF_8: &'static UTF8Encoding = &UTF8Encoding;
 pub trait Encoding {}
 impl Encoding for UTF8Encoding {}
-pub fn f() -> &'static Encoding { UTF_8 as &'static Encoding }
+pub fn f() -> &'static dyn Encoding { UTF_8 as &'static dyn Encoding }
 
 // Root of the problem: &Trait -> &Trait coercions:
-const FOO: &'static Trait = &Bar;
-const BAR: &'static Trait = FOO;
+const FOO: &'static dyn Trait = &Bar;
+const BAR: &'static dyn Trait = FOO;
 fn foo() { let _x = BAR; }

src/test/run-pass/deriving/deriving-show.rs

@@ -17,7 +17,7 @@ enum Enum {
 }
 
 #[derive(Debug)]
-struct Pointers(*const Send, *mut Sync);
+struct Pointers(*const dyn Send, *mut dyn Sync);
 
 macro_rules! t {
     ($x:expr, $expected:expr) => {

src/test/run-pass/drop/drop-struct-as-object.rs

@@ -30,7 +30,7 @@ impl Drop for Cat {
 pub fn main() {
     {
         let x = box Cat {name: 22};
-        let nyan: Box<Dummy> = x as Box<Dummy>;
+        let nyan: Box<dyn Dummy> = x as Box<dyn Dummy>;
     }
     unsafe {
         assert_eq!(value, 22);

src/test/run-pass/dynamically-sized-types/dst-coerce-custom.rs

@@ -36,7 +36,7 @@ fn main() {
 
     // Trait objects.
     let a: Bar<i32> = Bar { x: &42 };
-    let b: Bar<Baz> = a;
+    let b: Bar<dyn Baz> = a;
     unsafe {
         assert_eq!((*b.x).get(), 42);
     }

src/test/run-pass/dynamically-sized-types/dst-coerce-rc.rs

@@ -26,17 +26,17 @@ fn main() {
     assert_eq!(b[2], 3);
 
     let a: Rc<i32> = Rc::new(42);
-    let b: Rc<Baz> = a.clone();
+    let b: Rc<dyn Baz> = a.clone();
     assert_eq!(b.get(), 42);
 
     let c: Weak<i32> = Rc::downgrade(&a);
-    let d: Weak<Baz> = c.clone();
+    let d: Weak<dyn Baz> = c.clone();
 
     let _c = b.clone();
 
     let a: Rc<RefCell<i32>> = Rc::new(RefCell::new(42));
-    let b: Rc<RefCell<Baz>> = a.clone();
+    let b: Rc<RefCell<dyn Baz>> = a.clone();
     assert_eq!(b.borrow().get(), 42);
     // FIXME
-    let c: Weak<RefCell<Baz>> = Rc::downgrade(&a) as Weak<_>;
+    let c: Weak<RefCell<dyn Baz>> = Rc::downgrade(&a) as Weak<_>;
 }

src/test/run-pass/dynamically-sized-types/dst-coercions.rs

@@ -9,20 +9,20 @@ trait T { fn dummy(&self) { } }
 impl T for S {}
 
 pub fn main() {
-    let x: &T = &S;
+    let x: &dyn T = &S;
     // Test we can convert from &-ptr to *-ptr of trait objects
-    let x: *const T = &S;
+    let x: *const dyn T = &S;
 
     // Test we can convert from &-ptr to *-ptr of struct pointer (not DST)
     let x: *const S = &S;
 
     // As above, but mut
-    let x: &mut T = &mut S;
-    let x: *mut T = &mut S;
+    let x: &mut dyn T = &mut S;
+    let x: *mut dyn T = &mut S;
 
     let x: *mut S = &mut S;
 
     // Test we can change the mutability from mut to const.
-    let x: &T = &mut S;
-    let x: *const T = &mut S;
+    let x: &dyn T = &mut S;
+    let x: *const dyn T = &mut S;
 }