Rollup of 7 pull requests

src/ci/docker/dist-x86_64-linux/build-curl.sh

@@ -3,9 +3,11 @@
 set -ex
 source shared.sh
 
-VERSION=7.51.0
+VERSION=7.66.0
 
-curl http://cool.haxx.se/download/curl-$VERSION.tar.bz2 | tar xjf -
+curl https://rust-lang-ci-mirrors.s3-us-west-1.amazonaws.com/rustc/curl-$VERSION.tar.xz \
+  | xz --decompress \
+  | tar xf -
 
 mkdir curl-build
 cd curl-build

src/liballoc/tests/vec.rs

@@ -1281,3 +1281,51 @@ fn test_stable_push_pop() {
     v.pop().unwrap();
     assert_eq!(*v0, 13);
 }
+
+// https://github.com/rust-lang/rust/pull/49496 introduced specialization based on:
+//
+// ```
+// unsafe impl<T: ?Sized> IsZero for *mut T {
+//     fn is_zero(&self) -> bool {
+//         (*self).is_null()
+//     }
+// }
+// ```
+//
+// … to call `RawVec::with_capacity_zeroed` for creating `Vec<*mut T>`,
+// which is incorrect for fat pointers since `<*mut T>::is_null` only looks at the data component.
+// That is, a fat pointer can be “null” without being made entirely of zero bits.
+#[test]
+fn vec_macro_repeating_null_raw_fat_pointer() {
+    let raw_dyn = &mut (|| ()) as &mut dyn Fn() as *mut dyn Fn();
+    let vtable = dbg!(ptr_metadata(raw_dyn));
+    let null_raw_dyn = ptr_from_raw_parts(std::ptr::null_mut(), vtable);
+    assert!(null_raw_dyn.is_null());
+
+    let vec = vec![null_raw_dyn; 1];
+    dbg!(ptr_metadata(vec[0]));
+    assert!(vec[0] == null_raw_dyn);
+
+    // Polyfill for https://github.com/rust-lang/rfcs/pull/2580
+
+    fn ptr_metadata(ptr: *mut dyn Fn()) -> *mut () {
+        unsafe {
+            std::mem::transmute::<*mut dyn Fn(), DynRepr>(ptr).vtable
+        }
+    }
+
+    fn ptr_from_raw_parts(data: *mut (), vtable: *mut()) -> *mut dyn Fn() {
+        unsafe {
+            std::mem::transmute::<DynRepr, *mut dyn Fn()>(DynRepr {
+                data,
+                vtable
+            })
+        }
+    }
+
+    #[repr(C)]
+    struct DynRepr {
+        data: *mut (),
+        vtable: *mut (),
+    }
+}

src/liballoc/vec.rs

@@ -1734,20 +1734,45 @@ impl_is_zero!(char, |x| x == '\0');
 impl_is_zero!(f32, |x: f32| x.to_bits() == 0);
 impl_is_zero!(f64, |x: f64| x.to_bits() == 0);
 
-unsafe impl<T: ?Sized> IsZero for *const T {
+unsafe impl<T> IsZero for *const T {
     #[inline]
     fn is_zero(&self) -> bool {
         (*self).is_null()
     }
 }
 
-unsafe impl<T: ?Sized> IsZero for *mut T {
+unsafe impl<T> IsZero for *mut T {
     #[inline]
     fn is_zero(&self) -> bool {
         (*self).is_null()
     }
 }
 
+// `Option<&T>`, `Option<&mut T>` and `Option<Box<T>>` are guaranteed to represent `None` as null.
+// For fat pointers, the bytes that would be the pointer metadata in the `Some` variant
+// are padding in the `None` variant, so ignoring them and zero-initializing instead is ok.
+
+unsafe impl<T: ?Sized> IsZero for Option<&T> {
+    #[inline]
+    fn is_zero(&self) -> bool {
+        self.is_none()
+    }
+}
+
+unsafe impl<T: ?Sized> IsZero for Option<&mut T> {
+    #[inline]
+    fn is_zero(&self) -> bool {
+        self.is_none()
+    }
+}
+
+unsafe impl<T: ?Sized> IsZero for Option<Box<T>> {
+    #[inline]
+    fn is_zero(&self) -> bool {
+        self.is_none()
+    }
+}
+
 
 ////////////////////////////////////////////////////////////////////////////////
 // Common trait implementations for Vec

src/libcore/option.rs

@@ -46,7 +46,7 @@
 //! # Options and pointers ("nullable" pointers)
 //!
 //! Rust's pointer types must always point to a valid location; there are
-//! no "null" pointers. Instead, Rust has *optional* pointers, like
+//! no "null" references. Instead, Rust has *optional* pointers, like
 //! the optional owned box, [`Option`]`<`[`Box<T>`]`>`.
 //!
 //! The following example uses [`Option`] to create an optional box of

src/librustc/error_codes.rs

@@ -1580,6 +1580,47 @@ where
 ```
 "##,
 
+E0495: r##"
+A lifetime cannot be determined in the given situation.
+
+Erroneous code example:
+
+```compile_fail,E0495
+fn transmute_lifetime<'a, 'b, T>(t: &'a (T,)) -> &'b T {
+    match (&t,) { // error!
+        ((u,),) => u,
+    }
+}
+
+let y = Box::new((42,));
+let x = transmute_lifetime(&y);
+```
+
+In this code, you have two ways to solve this issue:
+ 1. Enforce that `'a` lives at least as long as `'b`.
+ 2. Use the same lifetime requirement for both input and output values.
+
+So for the first solution, you can do it by replacing `'a` with `'a: 'b`:
+
+```
+fn transmute_lifetime<'a: 'b, 'b, T>(t: &'a (T,)) -> &'b T {
+    match (&t,) { // ok!
+        ((u,),) => u,
+    }
+}
+```
+
+In the second you can do it by simply removing `'b` so they both use `'a`:
+
+```
+fn transmute_lifetime<'a, T>(t: &'a (T,)) -> &'a T {
+    match (&t,) { // ok!
+        ((u,),) => u,
+    }
+}
+```
+"##,
+
 E0496: r##"
 A lifetime name is shadowing another lifetime name. Erroneous code example:
 
@@ -2275,8 +2316,6 @@ rejected in your own crates.
     E0488, // lifetime of variable does not enclose its declaration
     E0489, // type/lifetime parameter not in scope here
     E0490, // a value of type `..` is borrowed for too long
-    E0495, // cannot infer an appropriate lifetime due to conflicting
-           // requirements
     E0566, // conflicting representation hints
     E0623, // lifetime mismatch where both parameters are anonymous regions
     E0628, // generators cannot have explicit parameters

src/libsyntax/error_codes.rs

@@ -144,6 +144,25 @@ fn deprecated_function() {}
 ```
 "##,
 
+E0550: r##"
+More than one `deprecated` attribute has been put on an item.
+
+Erroneous code example:
+
+```compile_fail,E0550
+#[deprecated(note = "because why not?")]
+#[deprecated(note = "right?")] // error!
+fn the_banished() {}
+```
+
+The `deprecated` attribute can only be present **once** on an item.
+
+```
+#[deprecated(note = "because why not, right?")]
+fn the_banished() {} // ok!
+```
+"##,
+
 E0552: r##"
 A unrecognized representation attribute was used.
 
@@ -435,7 +454,6 @@ features in the `-Z allow_features` flag.
     // rustc_deprecated attribute must be paired with either stable or unstable
     // attribute
     E0549,
-    E0550, // multiple deprecated attributes
     E0551, // incorrect meta item
     E0553, // multiple rustc_const_unstable attributes
 //  E0555, // replaced with a generic attribute input check

src/test/ui/associated-types/cache/project-fn-ret-contravariant.transmute.stderr

@@ -23,3 +23,4 @@ LL |    bar(foo, x)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/associated-types/cache/project-fn-ret-invariant.transmute.stderr

@@ -19,3 +19,4 @@ LL | fn baz<'a,'b>(x: Type<'a>) -> Type<'static> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/c-variadic/variadic-ffi-4.stderr

@@ -209,4 +209,5 @@ LL | | }
 
 error: aborting due to 8 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0495.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/consts/issue-64662.rs

@@ -0,0 +1,10 @@
+enum Foo {
+    A = foo(), //~ ERROR: type annotations needed
+    B = foo(), //~ ERROR: type annotations needed
+}
+
+const fn foo<T>() -> isize {
+    0
+}
+
+fn main() {}

src/test/ui/consts/issue-64662.stderr

@@ -0,0 +1,15 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-64662.rs:2:9
+   |
+LL |     A = foo(),
+   |         ^^^ cannot infer type for `T`
+
+error[E0282]: type annotations needed
+  --> $DIR/issue-64662.rs:3:9
+   |
+LL |     B = foo(),
+   |         ^^^ cannot infer type for `T`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0282`.

src/test/ui/deprecation/deprecation-sanity.stderr

@@ -54,5 +54,5 @@ LL | #[deprecated(since = "a", since = "b", note = "c")]
 
 error: aborting due to 9 previous errors
 
-Some errors have detailed explanations: E0538, E0541, E0565.
+Some errors have detailed explanations: E0538, E0541, E0550, E0565.
 For more information about an error, try `rustc --explain E0538`.

src/test/ui/error-codes/E0621-does-not-trigger-for-closures.stderr

@@ -27,3 +27,4 @@ LL |     invoke(&x, |a, b| if a > b { a } else { b });
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/impl-header-lifetime-elision/dyn-trait.stderr

@@ -19,3 +19,4 @@ LL | fn with_dyn_debug_static<'a>(x: Box<dyn Debug + 'a>) {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/in-band-lifetimes/mismatched_trait_impl-2.stderr

@@ -18,3 +18,4 @@ LL | |     }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr

@@ -32,3 +32,4 @@ LL |         x
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/issues/issue-16683.stderr

@@ -27,3 +27,4 @@ LL | trait T<'a> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/issues/issue-17758.stderr

@@ -28,3 +28,4 @@ LL | trait Foo<'a> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/issues/issue-20831-debruijn.stderr

@@ -94,4 +94,5 @@ LL | impl<'a> Publisher<'a> for MyStruct<'a> {
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0495.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/issues/issue-52213.stderr

@@ -25,3 +25,4 @@ LL |         ((u,),) => u,
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/issues/issue-55796.stderr

@@ -42,3 +42,4 @@ LL |         Box::new(self.in_edges(u).map(|e| e.target()))
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/nll/issue-55394.stderr

@@ -27,3 +27,4 @@ LL | impl Foo<'_> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/nll/normalization-bounds-error.stderr

@@ -20,3 +20,4 @@ LL | fn visit_seq<'d, 'a: 'd>() -> <&'a () as Visitor<'d>>::Value {}
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/nll/type-alias-free-regions.stderr

@@ -50,3 +50,4 @@ LL | impl<'a> FromTuple<'a> for C<'a> {
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/nll/user-annotations/constant-in-expr-inherent-1.stderr

@@ -21,3 +21,4 @@ LL |     <Foo<'a>>::C
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/nll/user-annotations/constant-in-expr-trait-item-3.stderr

@@ -21,3 +21,4 @@ LL |     T::C
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/object-lifetime/object-lifetime-default-elision.stderr

@@ -50,3 +50,4 @@ LL | fn load3<'a,'b>(ss: &'a dyn SomeTrait) -> &'b dyn SomeTrait {
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/region-object-lifetime-2.stderr

@@ -27,3 +27,4 @@ LL |     x.borrowed()
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/region-object-lifetime-4.stderr

@@ -27,3 +27,4 @@ LL |     x.borrowed()
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/region-object-lifetime-in-coercion.stderr

@@ -48,4 +48,5 @@ LL | fn d<'a,'b>(v: &'a [u8]) -> Box<dyn Foo+'b> {
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0621`.
+Some errors have detailed explanations: E0495, E0621.
+For more information about an error, try `rustc --explain E0495`.

src/test/ui/regions/regions-addr-of-self.stderr

@@ -26,3 +26,4 @@ LL |         let p: &'static mut usize = &mut self.cats_chased;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-addr-of-upvar-self.stderr

@@ -23,3 +23,4 @@ LL |             let p: &'static mut usize = &mut self.food;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-assoc-type-region-bound-in-trait-not-met.stderr

@@ -46,3 +46,4 @@ LL | impl<'a,'b> Foo<'b> for &'a i64 {
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-assoc-type-static-bound-in-trait-not-met.stderr

@@ -21,3 +21,4 @@ LL | impl<'a> Foo for &'a i32 {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-close-object-into-object-2.stderr

@@ -21,3 +21,4 @@ LL |     box B(&*v) as Box<dyn X>
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-close-object-into-object-4.stderr

@@ -21,3 +21,4 @@ LL |     box B(&*v) as Box<dyn X>
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-close-over-type-parameter-multiple.stderr

@@ -25,3 +25,4 @@ LL | fn make_object_bad<'a,'b,'c,A:SomeTrait+'a+'b>(v: A) -> Box<dyn SomeTrait +
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.

src/test/ui/regions/regions-creating-enums4.stderr

@@ -23,3 +23,4 @@ LL | fn mk_add_bad2<'a,'b>(x: &'a Ast<'a>, y: &'a Ast<'a>, z: &Ast) -> Ast<'b> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0495`.