Change:
$ RUST_BACKTRACE=1 rustc $ cat $ rustc --version --verbose
Looks like this was fixed. Output with current nightly as per playground:
Yeah, this was fixed. Marking as E-needstest.

Discussion:
<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. fn main() { let value = 1; match SomeStruct(value) { StructConst1(_) => { }, //~^ ERROR expected tuple struct/variant, found constant `StructConst1` _ => { }, } struct SomeStruct(u8); const StructConst1 : SomeStruct = SomeStruct(1); const StructConst2 : SomeStruct = SomeStruct(2); } </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![feature(associated_consts)] trait Foo { const BAR: i32; fn foo(self) -> &'static i32 { //~^ ERROR the trait bound `Self: std::marker::Sized` is not satisfied &<Self>::BAR } } fn main() {} </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. macro_rules! get_opt { ($tgt:expr, $field:ident) => { if $tgt.has_$field() {} } } fn main() { get_opt!(bar, foo); //~^ ERROR expected `{`, found `foo` } </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. fn main() { let a = |r: f64| if r != 0.0(r != 0.0) { 1.0 } else { 0.0 }; //~^ ERROR expected function, found `{float}` } </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. // #45662 #![feature(repr_align)] #![feature(attr_literals)] #[repr(align(16))] pub struct A { y: i64, } pub extern "C" fn foo(x: A) {} fn main() {} </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![feature(conservative_impl_trait)] use std::iter::once; struct Foo { x: i32, } impl Foo { fn inside(&self) -> impl Iterator<Item = &i32> { once(&self.x) } } fn main() { println!("hi"); } </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![feature(unsize, coerce_unsized)] #[repr(packed)] struct UnalignedPtr<'a, T: ?Sized> where T: 'a, { data: &'a T, } fn main() { impl<'a, T, U> std::ops::CoerceUnsized<UnalignedPtr<'a, U>> for UnalignedPtr<'a, T> where T: std::marker::Unsize<U> + ?Sized, U: ?Sized, { } let arr = [1, 2, 3]; let arr_unaligned: UnalignedPtr<[i32; 3]> = UnalignedPtr { data: &arr }; let arr_unaligned: UnalignedPtr<[i32]> = arr_unaligned; } </ins>

<ins> // Copyright 2017 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. // #42164 #![feature(decl_macro)] #![allow(dead_code)] pub macro m($inner_str:expr) { #[doc = $inner_str] struct S; } macro_rules! define_f { ($name:expr) => { #[export_name = $name] fn f() {} } } fn main() { define_f!(concat!("exported_", "f")); m!(stringify!(foo)); } </ins>