Auto merge of #62902 - Mark-Simulacrum:rollup-mxfk0mm, r=Mark-Simulacrum

Rollup of 14 pull requests

Successful merges:

 - #60951 (more specific errors in src/librustc/mir/interpret/error.rs)
 - #62523 (Delay bug to resolve HRTB ICE)
 - #62656 (explain how to search in slice without owned data)
 - #62791 (Handle more cases of typos misinterpreted as type ascription)
 - #62804 (rustc_typeck: improve diagnostics for _ const/static declarations)
 - #62808 (Revert "Disable stack probing for gnux32.")
 - #62817 (Tweak span for variant not found error)
 - #62842 (Add tests for issue-58887)
 - #62851 (move unescape module to rustc_lexer)
 - #62859 (Place::as_place_ref is now Place::as_ref)
 - #62869 (add rustc_private as a proper language feature gate)
 - #62880 (normalize use of backticks in compiler messages for librustc_allocator)
 - #62885 (Change "OSX" to "macOS")
 - #62889 (Update stage0.txt)

Failed merges:

r? @ghost

39 files changed, 368 insertions, 63 deletions

diff --git a/src/test/ui/allocator/two-allocators.rs b/src/test/ui/allocator/two-allocators.rs
index 10fb03c3930..0f81fc41823 100644
--- a/src/test/ui/allocator/two-allocators.rs
+++ b/src/test/ui/allocator/two-allocators.rs
@@ -4,6 +4,6 @@ use std::alloc::System;
 static A: System = System;
 #[global_allocator]
 static B: System = System;
-//~^ ERROR: cannot define more than one #[global_allocator]
+//~^ ERROR: cannot define more than one `#[global_allocator]`
 
 fn main() {}
diff --git a/src/test/ui/allocator/two-allocators.stderr b/src/test/ui/allocator/two-allocators.stderr
index da247f6c316..6b0c2b2a25d 100644
--- a/src/test/ui/allocator/two-allocators.stderr
+++ b/src/test/ui/allocator/two-allocators.stderr
@@ -1,4 +1,4 @@
-error: cannot define more than one #[global_allocator]
+error: cannot define more than one `#[global_allocator]`
   --> $DIR/two-allocators.rs:6:1
    |
 LL | static B: System = System;
diff --git a/src/test/ui/codemap_tests/bad-format-args.stderr b/src/test/ui/codemap_tests/bad-format-args.stderr
index c424eb08a7a..5b01314d8ad 100644
--- a/src/test/ui/codemap_tests/bad-format-args.stderr
+++ b/src/test/ui/codemap_tests/bad-format-args.stderr
@@ -10,13 +10,13 @@ error: expected token: `,`
   --> $DIR/bad-format-args.rs:3:16
    |
 LL |     format!("" 1);
-   |                ^
+   |                ^ expected `,`
 
 error: expected token: `,`
   --> $DIR/bad-format-args.rs:4:19
    |
 LL |     format!("", 1 1);
-   |                   ^
+   |                   ^ expected `,`
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/error-codes/E0121.stderr b/src/test/ui/error-codes/E0121.stderr
index 1a16aab6a41..beb8941320b 100644
--- a/src/test/ui/error-codes/E0121.stderr
+++ b/src/test/ui/error-codes/E0121.stderr
@@ -11,7 +11,10 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
   --> $DIR/E0121.rs:3:13
    |
 LL | static BAR: _ = "test";
-   |             ^ not allowed in type signatures
+   |             ^
+   |             |
+   |             not allowed in type signatures
+   |             help: replace `_` with the correct type: `&'static str`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/existential-type/issue-58887.rs b/src/test/ui/existential-type/issue-58887.rs
new file mode 100644
index 00000000000..f038648ec21
--- /dev/null
+++ b/src/test/ui/existential-type/issue-58887.rs
@@ -0,0 +1,23 @@
+#![feature(existential_type)]
+
+trait UnwrapItemsExt {
+    type Iter;
+    fn unwrap_items(self) -> Self::Iter;
+}
+
+impl<I, T, E> UnwrapItemsExt for I
+where
+    I: Iterator<Item = Result<T, E>>,
+    E: std::fmt::Debug,
+{
+    existential type Iter: Iterator<Item = T>;
+    //~^ ERROR: could not find defining uses
+
+    fn unwrap_items(self) -> Self::Iter {
+    //~^ ERROR: type parameter `T` is part of concrete type
+    //~| ERROR: type parameter `E` is part of concrete type
+        self.map(|x| x.unwrap())
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/existential-type/issue-58887.stderr b/src/test/ui/existential-type/issue-58887.stderr
new file mode 100644
index 00000000000..800f4b7e059
--- /dev/null
+++ b/src/test/ui/existential-type/issue-58887.stderr
@@ -0,0 +1,30 @@
+error: type parameter `T` is part of concrete type but not used in parameter list for existential type
+  --> $DIR/issue-58887.rs:16:41
+   |
+LL |       fn unwrap_items(self) -> Self::Iter {
+   |  _________________________________________^
+LL | |
+LL | |
+LL | |         self.map(|x| x.unwrap())
+LL | |     }
+   | |_____^
+
+error: type parameter `E` is part of concrete type but not used in parameter list for existential type
+  --> $DIR/issue-58887.rs:16:41
+   |
+LL |       fn unwrap_items(self) -> Self::Iter {
+   |  _________________________________________^
+LL | |
+LL | |
+LL | |         self.map(|x| x.unwrap())
+LL | |     }
+   | |_____^
+
+error: could not find defining uses
+  --> $DIR/issue-58887.rs:13:5
+   |
+LL |     existential type Iter: Iterator<Item = T>;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
diff --git a/src/test/ui/feature-gate/rustc-private.rs b/src/test/ui/feature-gate/rustc-private.rs
new file mode 100644
index 00000000000..7b8944bb0a0
--- /dev/null
+++ b/src/test/ui/feature-gate/rustc-private.rs
@@ -0,0 +1,5 @@
+// gate-test-rustc_private
+
+extern crate libc; //~ ERROR  use of unstable library feature 'rustc_private'
+
+fn main() {}
diff --git a/src/test/ui/feature-gate/rustc-private.stderr b/src/test/ui/feature-gate/rustc-private.stderr
new file mode 100644
index 00000000000..be320718145
--- /dev/null
+++ b/src/test/ui/feature-gate/rustc-private.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
+  --> $DIR/rustc-private.rs:3:1
+   |
+LL | extern crate libc;
+   | ^^^^^^^^^^^^^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/27812
+   = help: add `#![feature(rustc_private)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/hrtb/issue-62203-hrtb-ice.rs b/src/test/ui/hrtb/issue-62203-hrtb-ice.rs
new file mode 100644
index 00000000000..454d7e5e9cd
--- /dev/null
+++ b/src/test/ui/hrtb/issue-62203-hrtb-ice.rs
@@ -0,0 +1,50 @@
+trait T0<'a, A> {
+    type O;
+}
+
+struct L<T> {
+    f: T,
+}
+
+// explicitly named variants of what one would normally denote by the
+// unit type `()`. Why do this? So that we can differentiate them in
+// the diagnostic output.
+struct Unit1;
+struct Unit2;
+struct Unit3;
+struct Unit4;
+
+impl<'a, A, T> T0<'a, A> for L<T>
+where
+    T: FnMut(A) -> Unit3,
+{
+    type O = T::Output;
+}
+
+trait T1: for<'r> Ty<'r> {
+    fn m<'a, B: Ty<'a>, F>(&self, f: F) -> Unit1
+    where
+        F: for<'r> T0<'r, (<Self as Ty<'r>>::V,), O = <B as Ty<'r>>::V>,
+    {
+        unimplemented!();
+    }
+}
+
+trait Ty<'a> {
+    type V;
+}
+
+fn main() {
+    let v = Unit2.m(
+        //~^ ERROR type mismatch
+        //~| ERROR type mismatch
+        L {
+            f : |x| { drop(x); Unit4 }
+        });
+}
+
+impl<'a> Ty<'a> for Unit2 {
+    type V = &'a u8;
+}
+
+impl T1 for Unit2 {}
diff --git a/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr b/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr
new file mode 100644
index 00000000000..c2d0e0c2a26
--- /dev/null
+++ b/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr
@@ -0,0 +1,22 @@
+error[E0271]: type mismatch resolving `for<'r> <L<[closure@$DIR/issue-62203-hrtb-ice.rs:42:17: 42:39]> as T0<'r, (<Unit2 as Ty<'r>>::V,)>>::O == <_ as Ty<'r>>::V`
+  --> $DIR/issue-62203-hrtb-ice.rs:38:19
+   |
+LL |     let v = Unit2.m(
+   |                   ^ expected struct `Unit4`, found associated type
+   |
+   = note: expected type `Unit4`
+              found type `<_ as Ty<'_>>::V`
+
+error[E0271]: type mismatch resolving `<[closure@$DIR/issue-62203-hrtb-ice.rs:42:17: 42:39] as std::ops::FnOnce<((&u8,),)>>::Output == Unit3`
+  --> $DIR/issue-62203-hrtb-ice.rs:38:19
+   |
+LL |     let v = Unit2.m(
+   |                   ^ expected struct `Unit4`, found struct `Unit3`
+   |
+   = note: expected type `Unit4`
+              found type `Unit3`
+   = note: required because of the requirements on the impl of `for<'r> T0<'r, (<Unit2 as Ty<'r>>::V,)>` for `L<[closure@$DIR/issue-62203-hrtb-ice.rs:42:17: 42:39]>`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/src/test/ui/issues/issue-22644.stderr b/src/test/ui/issues/issue-22644.stderr
index 4f0dc0a4887..0fe167963c3 100644
--- a/src/test/ui/issues/issue-22644.stderr
+++ b/src/test/ui/issues/issue-22644.stderr
@@ -87,15 +87,12 @@ error: expected type, found `4`
   --> $DIR/issue-22644.rs:34:28
    |
 LL |     println!("{}", a: &mut 4);
-   |                            ^ expecting a type here because of type ascription
+   |                     -      ^ expected type
+   |                     |
+   |                     tried to parse a type due to this type ascription
    |
    = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-note: this expression expects an ascribed type after the colon
-  --> $DIR/issue-22644.rs:34:20
-   |
-LL |     println!("{}", a: &mut 4);
-   |                    ^
-   = help: this might be indicative of a syntax error elsewhere
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to 9 previous errors
 
diff --git a/src/test/ui/issues/issue-34255-1.stderr b/src/test/ui/issues/issue-34255-1.stderr
index 0218a7abeaa..acb093b5142 100644
--- a/src/test/ui/issues/issue-34255-1.stderr
+++ b/src/test/ui/issues/issue-34255-1.stderr
@@ -2,15 +2,12 @@ error: expected type, found `42`
   --> $DIR/issue-34255-1.rs:8:24
    |
 LL |     Test::Drill(field: 42);
-   |                        ^^ expecting a type here because of type ascription
+   |                      - ^^ expected type
+   |                      |
+   |                      tried to parse a type due to this type ascription
    |
    = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-note: this expression expects an ascribed type after the colon
-  --> $DIR/issue-34255-1.rs:8:17
-   |
-LL |     Test::Drill(field: 42);
-   |                 ^^^^^
-   = help: this might be indicative of a syntax error elsewhere
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-39616.stderr b/src/test/ui/issues/issue-39616.stderr
index e24ffcdb0d9..75eb55fa50b 100644
--- a/src/test/ui/issues/issue-39616.stderr
+++ b/src/test/ui/issues/issue-39616.stderr
@@ -2,7 +2,7 @@ error: expected type, found `0`
   --> $DIR/issue-39616.rs:1:12
    |
 LL | fn foo(a: [0; 1]) {}
-   |            ^
+   |            ^ expected type
 
 error: expected one of `)`, `,`, `->`, `where`, or `{`, found `]`
   --> $DIR/issue-39616.rs:1:16
diff --git a/src/test/ui/issues/issue-44406.stderr b/src/test/ui/issues/issue-44406.stderr
index 14b3b8cc5c8..108542c9b6f 100644
--- a/src/test/ui/issues/issue-44406.stderr
+++ b/src/test/ui/issues/issue-44406.stderr
@@ -15,7 +15,10 @@ LL |         bar(baz: $rest)
    |                - help: try using a semicolon: `;`
 ...
 LL |     foo!(true);
-   |          ^^^^ expecting a type here because of type ascription
+   |          ^^^^ expected type
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/lifetime_starts_expressions.stderr b/src/test/ui/lifetime_starts_expressions.stderr
index 84e4c87ebc4..bacba10b55f 100644
--- a/src/test/ui/lifetime_starts_expressions.stderr
+++ b/src/test/ui/lifetime_starts_expressions.stderr
@@ -12,15 +12,12 @@ error: expected type, found keyword `loop`
   --> $DIR/lifetime_starts_expressions.rs:6:26
    |
 LL |     loop { break 'label: loop { break 'label 42; }; }
-   |                          ^^^^ expecting a type here because of type ascription
+   |                        - ^^^^ expected type
+   |                        |
+   |                        tried to parse a type due to this type ascription
    |
    = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-note: this expression expects an ascribed type after the colon
-  --> $DIR/lifetime_starts_expressions.rs:6:12
-   |
-LL |     loop { break 'label: loop { break 'label 42; }; }
-   |            ^^^^^^^^^^^^
-   = help: this might be indicative of a syntax error elsewhere
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/macros/missing-comma.stderr b/src/test/ui/macros/missing-comma.stderr
index d5b6d86b20f..f96848f8239 100644
--- a/src/test/ui/macros/missing-comma.stderr
+++ b/src/test/ui/macros/missing-comma.stderr
@@ -2,7 +2,7 @@ error: expected token: `,`
   --> $DIR/missing-comma.rs:19:19
    |
 LL |     println!("{}" a);
-   |                   ^
+   |                   ^ expected `,`
 
 error: no rules expected the token `b`
   --> $DIR/missing-comma.rs:21:12
diff --git a/src/test/ui/parser/issue-33262.stderr b/src/test/ui/parser/issue-33262.stderr
index c2491df903b..2aff3283935 100644
--- a/src/test/ui/parser/issue-33262.stderr
+++ b/src/test/ui/parser/issue-33262.stderr
@@ -2,7 +2,7 @@ error: expected type, found `{`
   --> $DIR/issue-33262.rs:4:22
    |
 LL |     for i in 0..a as { }
-   |                      ^
+   |                      ^ expected type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/parser/macro/trait-object-macro-matcher.stderr b/src/test/ui/parser/macro/trait-object-macro-matcher.stderr
index 19c5c82f82c..f02f60e4bfb 100644
--- a/src/test/ui/parser/macro/trait-object-macro-matcher.stderr
+++ b/src/test/ui/parser/macro/trait-object-macro-matcher.stderr
@@ -2,7 +2,7 @@ error: expected type, found `'static`
   --> $DIR/trait-object-macro-matcher.rs:9:8
    |
 LL |     m!('static);
-   |        ^^^^^^^
+   |        ^^^^^^^ expected type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/parser/recover-enum2.stderr b/src/test/ui/parser/recover-enum2.stderr
index 9ed2e6f5eb6..2311887a6fb 100644
--- a/src/test/ui/parser/recover-enum2.stderr
+++ b/src/test/ui/parser/recover-enum2.stderr
@@ -2,7 +2,7 @@ error: expected type, found `{`
   --> $DIR/recover-enum2.rs:6:18
    |
 LL |             abc: {},
-   |                  ^
+   |                  ^ expected type
 
 error: expected one of `!`, `(`, `)`, `+`, `,`, `::`, or `<`, found `{`
   --> $DIR/recover-enum2.rs:25:22
diff --git a/src/test/ui/parser/recover-from-bad-variant.stderr b/src/test/ui/parser/recover-from-bad-variant.stderr
index d525bd3f4c6..b46d3ca9c23 100644
--- a/src/test/ui/parser/recover-from-bad-variant.stderr
+++ b/src/test/ui/parser/recover-from-bad-variant.stderr
@@ -2,15 +2,12 @@ error: expected type, found `3`
   --> $DIR/recover-from-bad-variant.rs:7:26
    |
 LL |     let x = Enum::Foo(a: 3, b: 4);
-   |                          ^ expecting a type here because of type ascription
+   |                        - ^ expected type
+   |                        |
+   |                        tried to parse a type due to this type ascription
    |
    = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-note: this expression expects an ascribed type after the colon
-  --> $DIR/recover-from-bad-variant.rs:7:23
-   |
-LL |     let x = Enum::Foo(a: 3, b: 4);
-   |                       ^
-   = help: this might be indicative of a syntax error elsewhere
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error[E0532]: expected tuple struct/variant, found struct variant `Enum::Foo`
   --> $DIR/recover-from-bad-variant.rs:10:9
diff --git a/src/test/ui/parser/removed-syntax-mut-vec-ty.stderr b/src/test/ui/parser/removed-syntax-mut-vec-ty.stderr
index a759716b5a9..02b518e2516 100644
--- a/src/test/ui/parser/removed-syntax-mut-vec-ty.stderr
+++ b/src/test/ui/parser/removed-syntax-mut-vec-ty.stderr
@@ -2,7 +2,7 @@ error: expected type, found keyword `mut`
   --> $DIR/removed-syntax-mut-vec-ty.rs:1:11
    |
 LL | type v = [mut isize];
-   |           ^^^
+   |           ^^^ expected type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/parser/removed-syntax-record.stderr b/src/test/ui/parser/removed-syntax-record.stderr
index 730d5e2712b..0a1655840b5 100644
--- a/src/test/ui/parser/removed-syntax-record.stderr
+++ b/src/test/ui/parser/removed-syntax-record.stderr
@@ -2,7 +2,7 @@ error: expected type, found `{`
   --> $DIR/removed-syntax-record.rs:1:10
    |
 LL | type t = { f: () };
-   |          ^
+   |          ^ expected type
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/parser/trait-object-lifetime-parens.stderr b/src/test/ui/parser/trait-object-lifetime-parens.stderr
index a31b7aea8fe..7ffc26e9ede 100644
--- a/src/test/ui/parser/trait-object-lifetime-parens.stderr
+++ b/src/test/ui/parser/trait-object-lifetime-parens.stderr
@@ -29,7 +29,7 @@ error: expected type, found `'a`
   --> $DIR/trait-object-lifetime-parens.rs:9:17
    |
 LL |     let _: Box<('a) + Trait>;
-   |         -       ^^
+   |         -       ^^ expected type
    |         |
    |         while parsing the type for `_`
 
diff --git a/src/test/ui/suggestions/suggest-variants.stderr b/src/test/ui/suggestions/suggest-variants.stderr
index ef0ba70c340..b4338e20554 100644
--- a/src/test/ui/suggestions/suggest-variants.stderr
+++ b/src/test/ui/suggestions/suggest-variants.stderr
@@ -23,9 +23,7 @@ LL | enum Shape {
    | ---------- variant `Rombus` not found here
 ...
 LL |     println!("My shape is {:?}", Shape::Rombus{ size: 5});
-   |                                  -------^^^^^^
-   |                                  |
-   |                                  variant not found in `Shape`
+   |                                         ^^^^^^ variant not found in `Shape`
 
 error[E0599]: no variant or associated item named `Squareee` found for type `Shape` in the current scope
   --> $DIR/suggest-variants.rs:15:12
diff --git a/src/test/ui/suggestions/type-ascription-instead-of-method.stderr b/src/test/ui/suggestions/type-ascription-instead-of-method.stderr
index 15ec087b1cc..4a8d2f57d89 100644
--- a/src/test/ui/suggestions/type-ascription-instead-of-method.stderr
+++ b/src/test/ui/suggestions/type-ascription-instead-of-method.stderr
@@ -2,9 +2,12 @@ error: expected type, found `"foo"`
   --> $DIR/type-ascription-instead-of-method.rs:2:13
    |
 LL |     Box:new("foo".to_string())
-   |        -    ^^^^^ expecting a type here because of type ascription
+   |        -    ^^^^^ expected type
    |        |
-   |        help: maybe you meant to write a path separator here: `::`
+   |        help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/suggestions/type-ascription-instead-of-variant.stderr b/src/test/ui/suggestions/type-ascription-instead-of-variant.stderr
index 5719a667a84..7e9a31c06c8 100644
--- a/src/test/ui/suggestions/type-ascription-instead-of-variant.stderr
+++ b/src/test/ui/suggestions/type-ascription-instead-of-variant.stderr
@@ -2,9 +2,12 @@ error: expected type, found `""`
   --> $DIR/type-ascription-instead-of-variant.rs:2:25
    |
 LL |     let _ = Option:Some("");
-   |                   -     ^^ expecting a type here because of type ascription
+   |                   -     ^^ expected type
    |                   |
-   |                   help: maybe you meant to write a path separator here: `::`
+   |                   help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/type/ascription/issue-34255-1.rs b/src/test/ui/type/ascription/issue-34255-1.rs
new file mode 100644
index 00000000000..c11a248d3c7
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-34255-1.rs
@@ -0,0 +1,15 @@
+struct Reactor {
+    input_cells: Vec<usize>,
+}
+
+impl Reactor {
+    pub fn new() -> Self {
+        input_cells: Vec::new()
+        //~^ ERROR cannot find value `input_cells` in this scope
+        //~| ERROR parenthesized type parameters may only be used with a `Fn` trait
+        //~| ERROR wrong number of type arguments: expected 1, found 0
+        //~| WARNING this was previously accepted by the compiler but is being phased out
+    }
+}
+
+// This case isn't currently being handled gracefully, including for completeness.
diff --git a/src/test/ui/type/ascription/issue-34255-1.stderr b/src/test/ui/type/ascription/issue-34255-1.stderr
new file mode 100644
index 00000000000..531455b82b4
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-34255-1.stderr
@@ -0,0 +1,30 @@
+error[E0425]: cannot find value `input_cells` in this scope
+  --> $DIR/issue-34255-1.rs:7:9
+   |
+LL |         input_cells: Vec::new()
+   |         ^^^^^^^^^^^ a field by this name exists in `Self`
+
+error: parenthesized type parameters may only be used with a `Fn` trait
+  --> $DIR/issue-34255-1.rs:7:30
+   |
+LL |         input_cells: Vec::new()
+   |                              ^^
+   |
+   = note: `#[deny(parenthesized_params_in_types_and_modules)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #42238 <https://github.com/rust-lang/rust/issues/42238>
+
+error[E0601]: `main` function not found in crate `issue_34255_1`
+   |
+   = note: consider adding a `main` function to `$DIR/issue-34255-1.rs`
+
+error[E0107]: wrong number of type arguments: expected 1, found 0
+  --> $DIR/issue-34255-1.rs:7:22
+   |
+LL |         input_cells: Vec::new()
+   |                      ^^^^^^^^^^ expected 1 type argument
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0107, E0425, E0601.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/type/ascription/issue-47666.rs b/src/test/ui/type/ascription/issue-47666.rs
new file mode 100644
index 00000000000..ceb1dd89dae
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-47666.rs
@@ -0,0 +1,5 @@
+fn main() {
+    let _ = Option:Some(vec![0, 1]); //~ ERROR expected type, found
+}
+
+// This case isn't currently being handled gracefully due to the macro invocation.
diff --git a/src/test/ui/type/ascription/issue-47666.stderr b/src/test/ui/type/ascription/issue-47666.stderr
new file mode 100644
index 00000000000..7aa899f795c
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-47666.stderr
@@ -0,0 +1,13 @@
+error: expected type, found reserved keyword `box`
+  --> $DIR/issue-47666.rs:2:25
+   |
+LL |     let _ = Option:Some(vec![0, 1]);
+   |                         ^^^^^^^^^^
+   |                         |
+   |                         expected type
+   |                         in this macro invocation
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/ascription/issue-54516.rs b/src/test/ui/type/ascription/issue-54516.rs
new file mode 100644
index 00000000000..6d65760e299
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-54516.rs
@@ -0,0 +1,6 @@
+use std::collections::BTreeMap;
+
+fn main() {
+    println!("{}", std::mem:size_of::<BTreeMap<u32, u32>>());
+    //~^ ERROR expected token: `,`
+}
diff --git a/src/test/ui/type/ascription/issue-54516.stderr b/src/test/ui/type/ascription/issue-54516.stderr
new file mode 100644
index 00000000000..a846f3bc320
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-54516.stderr
@@ -0,0 +1,13 @@
+error: expected token: `,`
+  --> $DIR/issue-54516.rs:4:58
+   |
+LL |     println!("{}", std::mem:size_of::<BTreeMap<u32, u32>>());
+   |                            -                             ^ expected `,`
+   |                            |
+   |                            help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/ascription/issue-60933.rs b/src/test/ui/type/ascription/issue-60933.rs
new file mode 100644
index 00000000000..8fb06c887bd
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-60933.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let u: usize = std::mem:size_of::<u32>();
+    //~^ ERROR expected one of
+}
diff --git a/src/test/ui/type/ascription/issue-60933.stderr b/src/test/ui/type/ascription/issue-60933.stderr
new file mode 100644
index 00000000000..c2fc7bbcfc8
--- /dev/null
+++ b/src/test/ui/type/ascription/issue-60933.stderr
@@ -0,0 +1,13 @@
+error: expected one of `!`, `::`, or `;`, found `(`
+  --> $DIR/issue-60933.rs:2:43
+   |
+LL |     let u: usize = std::mem:size_of::<u32>();
+   |                            -              ^ expected one of `!`, `::`, or `;` here
+   |                            |
+   |                            help: maybe write a path separator here: `::`
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/type/type-ascription-instead-of-initializer.stderr b/src/test/ui/type/type-ascription-instead-of-initializer.stderr
index a22d25697d8..3fe676de59d 100644
--- a/src/test/ui/type/type-ascription-instead-of-initializer.stderr
+++ b/src/test/ui/type/type-ascription-instead-of-initializer.stderr
@@ -2,7 +2,7 @@ error: expected type, found `10`
   --> $DIR/type-ascription-instead-of-initializer.rs:2:31
    |
 LL |     let x: Vec::with_capacity(10, 20);
-   |         --                    ^^
+   |         --                    ^^ expected type
    |         ||
    |         |help: use `=` if you meant to assign
    |         while parsing the type for `x`
diff --git a/src/test/ui/type/type-ascription-instead-of-statement-end.stderr b/src/test/ui/type/type-ascription-instead-of-statement-end.stderr
index 1f8989db814..8fbcb3969a7 100644
--- a/src/test/ui/type/type-ascription-instead-of-statement-end.stderr
+++ b/src/test/ui/type/type-ascription-instead-of-statement-end.stderr
@@ -4,21 +4,21 @@ error: expected type, found `0`
 LL |     println!("test"):
    |                     - help: try using a semicolon: `;`
 LL |     0;
-   |     ^ expecting a type here because of type ascription
+   |     ^ expected type
+   |
+   = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: expected type, found `0`
   --> $DIR/type-ascription-instead-of-statement-end.rs:9:23
    |
 LL |     println!("test"): 0;
-   |                       ^ expecting a type here because of type ascription
+   |                     - ^ expected type
+   |                     |
+   |                     tried to parse a type due to this type ascription
    |
    = note: `#![feature(type_ascription)]` lets you annotate an expression with a type: `<expr>: <type>`
-note: this expression expects an ascribed type after the colon
-  --> $DIR/type-ascription-instead-of-statement-end.rs:9:5
-   |
-LL |     println!("test"): 0;
-   |     ^^^^^^^^^^^^^^^^
-   = help: this might be indicative of a syntax error elsewhere
+   = note: for more information, see https://github.com/rust-lang/rust/issues/23416
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
index ddaa5de4d3e..2b4d9966c3d 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
@@ -23,13 +23,19 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
   --> $DIR/typeck_type_placeholder_item.rs:11:15
    |
 LL | static TEST3: _ = "test";
-   |               ^ not allowed in type signatures
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace `_` with the correct type: `&'static str`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:14:15
    |
 LL | static TEST4: _ = 145;
-   |               ^ not allowed in type signatures
+   |               ^
+   |               |
+   |               not allowed in type signatures
+   |               help: replace `_` with the correct type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:17:16
@@ -122,13 +128,19 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
   --> $DIR/typeck_type_placeholder_item.rs:64:22
    |
 LL |     static FN_TEST3: _ = "test";
-   |                      ^ not allowed in type signatures
+   |                      ^
+   |                      |
+   |                      not allowed in type signatures
+   |                      help: replace `_` with the correct type: `&'static str`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:67:22
    |
 LL |     static FN_TEST4: _ = 145;
-   |                      ^ not allowed in type signatures
+   |                      ^
+   |                      |
+   |                      not allowed in type signatures
+   |                      help: replace `_` with the correct type: `i32`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:70:23
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item_help.rs b/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
index 5f4cb4c1316..905fc35350e 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
+++ b/src/test/ui/typeck/typeck_type_placeholder_item_help.rs
@@ -4,6 +4,24 @@
 fn test1() -> _ { Some(42) }
 //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
 
+const TEST2: _ = 42u32;
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+
+const TEST3: _ = Some(42);
+//~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+
+trait Test4 {
+    const TEST4: _ = 42;
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+}
+
+struct Test5;
+
+impl Test5 {
+    const TEST5: _ = 13;
+    //~^ ERROR the type placeholder `_` is not allowed within types on item signatures
+}
+
 pub fn main() {
     let _: Option<usize> = test1();
     let _: f64 = test1();
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr b/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
index 7fb5549825c..c5b9566290c 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item_help.stderr
@@ -7,6 +7,42 @@ LL | fn test1() -> _ { Some(42) }
    |               not allowed in type signatures
    |               help: replace `_` with the correct return type: `std::option::Option<i32>`
 
-error: aborting due to previous error
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item_help.rs:7:14
+   |
+LL | const TEST2: _ = 42u32;
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace `_` with the correct type: `u32`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item_help.rs:10:14
+   |
+LL | const TEST3: _ = Some(42);
+   |              ^
+   |              |
+   |              not allowed in type signatures
+   |              help: replace `_` with the correct type: `std::option::Option<i32>`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item_help.rs:14:18
+   |
+LL |     const TEST4: _ = 42;
+   |                  ^
+   |                  |
+   |                  not allowed in type signatures
+   |                  help: replace `_` with the correct type: `i32`
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/typeck_type_placeholder_item_help.rs:21:18
+   |
+LL |     const TEST5: _ = 13;
+   |                  ^
+   |                  |
+   |                  not allowed in type signatures
+   |                  help: replace `_` with the correct type: `i32`
+
+error: aborting due to 5 previous errors
 
 For more information about this error, try `rustc --explain E0121`.