Auto merge of #64666 - Centril:rollup-tp98vlr, r=Centril

Rollup of 9 pull requests

Successful merges:

 - #63907 (Add explanation to type mismatch involving type params and assoc types)
 - #64615 (rustbuild: Turn down compression on exe installers)
 - #64617 (rustbuild: Turn down compression on msi installers)
 - #64618 (rustbuild: Improve output of `dist` step)
 - #64619 (Fixes #63962. Hint about missing tuple parentheses in patterns)
 - #64634 (Update to LLVM 9.0.0)
 - #64635 (Allow using fn pointers in const fn with unleash miri)
 - #64660 (unify errors for tuple/struct variants)
 - #64664 (fully remove AstBuilder)

Failed merges:

r? @ghost

35 files changed, 426 insertions, 9 deletions

diff --git a/src/test/ui/associated-const/associated-const-generic-obligations.stderr b/src/test/ui/associated-const/associated-const-generic-obligations.stderr
index eeee26a7567..ca6118cb3ba 100644
--- a/src/test/ui/associated-const/associated-const-generic-obligations.stderr
+++ b/src/test/ui/associated-const/associated-const-generic-obligations.stderr
@@ -9,6 +9,8 @@ LL |     const FROM: &'static str = "foo";
    |
    = note: expected type `<T as Foo>::Out`
               found type `&'static str`
+   = note: consider constraining the associated type `<T as Foo>::Out` to `&'static str` or calling a method that returns `<T as Foo>::Out`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/associated-types/associated-types-eq-3.stderr b/src/test/ui/associated-types/associated-types-eq-3.stderr
index 0f8c5257d44..c9d88b7af07 100644
--- a/src/test/ui/associated-types/associated-types-eq-3.stderr
+++ b/src/test/ui/associated-types/associated-types-eq-3.stderr
@@ -6,6 +6,8 @@ LL |     let _: Bar = x.boo();
    |
    = note: expected type `Bar`
               found type `<I as Foo>::A`
+   = note: consider constraining the associated type `<I as Foo>::A` to `Bar`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error[E0271]: type mismatch resolving `<isize as Foo>::A == Bar`
   --> $DIR/associated-types-eq-3.rs:38:5
diff --git a/src/test/ui/associated-types/associated-types-issue-20346.stderr b/src/test/ui/associated-types/associated-types-issue-20346.stderr
index 7d6c025d69d..e037bd851ca 100644
--- a/src/test/ui/associated-types/associated-types-issue-20346.stderr
+++ b/src/test/ui/associated-types/associated-types-issue-20346.stderr
@@ -9,6 +9,8 @@ LL |     is_iterator_of::<Option<T>, _>(&adapter);
    |
    = note: expected type `T`
               found type `std::option::Option<T>`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/associated-types/associated-types-multiple-types-one-trait.stderr b/src/test/ui/associated-types/associated-types-multiple-types-one-trait.stderr
index 4a2a6d03c60..d6328a64c7c 100644
--- a/src/test/ui/associated-types/associated-types-multiple-types-one-trait.stderr
+++ b/src/test/ui/associated-types/associated-types-multiple-types-one-trait.stderr
@@ -9,6 +9,8 @@ LL | fn want_y<T:Foo<Y=i32>>(t: &T) { }
    |
    = note: expected type `<T as Foo>::Y`
               found type `i32`
+   = note: consider constraining the associated type `<T as Foo>::Y` to `i32` or calling a method that returns `<T as Foo>::Y`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error[E0271]: type mismatch resolving `<T as Foo>::X == u32`
   --> $DIR/associated-types-multiple-types-one-trait.rs:18:5
@@ -21,6 +23,8 @@ LL | fn want_x<T:Foo<X=u32>>(t: &T) { }
    |
    = note: expected type `<T as Foo>::X`
               found type `u32`
+   = note: consider constraining the associated type `<T as Foo>::X` to `u32` or calling a method that returns `<T as Foo>::X`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/compare-method/reordered-type-param.stderr b/src/test/ui/compare-method/reordered-type-param.stderr
index a33908c01c8..8176e96d6de 100644
--- a/src/test/ui/compare-method/reordered-type-param.stderr
+++ b/src/test/ui/compare-method/reordered-type-param.stderr
@@ -9,6 +9,8 @@ LL |   fn b<F:Clone,G>(&self, _x: G) -> G { panic!() }
    |
    = note: expected type `fn(&E, F) -> F`
               found type `fn(&E, G) -> G`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/consts/const-eval/const_fn_ptr.rs b/src/test/ui/consts/const-eval/const_fn_ptr.rs
new file mode 100644
index 00000000000..498f801db81
--- /dev/null
+++ b/src/test/ui/consts/const-eval/const_fn_ptr.rs
@@ -0,0 +1,37 @@
+// run-pass
+// compile-flags: -Zunleash-the-miri-inside-of-you
+#![feature(const_fn)]
+
+fn double(x: usize) -> usize { x * 2 }
+const fn double_const(x: usize) -> usize { x * 2 }
+
+const X: fn(usize) -> usize = double;
+const X_const: fn(usize) -> usize = double_const;
+
+const fn bar(x: usize) -> usize {
+    X(x)
+}
+
+const fn bar_const(x: usize) -> usize {
+    X_const(x)
+}
+
+const fn foo(x: fn(usize) -> usize, y: usize)  -> usize {
+    x(y)
+}
+
+fn main() {
+    const Y: usize = bar_const(2);
+    assert_eq!(Y, 4);
+    let y = bar_const(2);
+    assert_eq!(y, 4);
+    let y = bar(2);
+    assert_eq!(y, 4);
+
+    const Z: usize = foo(double_const, 2);
+    assert_eq!(Z, 4);
+    let z = foo(double_const, 2);
+    assert_eq!(z, 4);
+    let z = foo(double, 2);
+    assert_eq!(z, 4);
+}
diff --git a/src/test/ui/consts/const-eval/const_fn_ptr.stderr b/src/test/ui/consts/const-eval/const_fn_ptr.stderr
new file mode 100644
index 00000000000..41452ee59eb
--- /dev/null
+++ b/src/test/ui/consts/const-eval/const_fn_ptr.stderr
@@ -0,0 +1,152 @@
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:25:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:25:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:25:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:27:5
+   |
+LL |     assert_eq!(y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:27:5
+   |
+LL |     assert_eq!(y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:27:5
+   |
+LL |     assert_eq!(y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:29:5
+   |
+LL |     assert_eq!(y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:29:5
+   |
+LL |     assert_eq!(y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:29:5
+   |
+LL |     assert_eq!(y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:32:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:32:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:32:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:34:5
+   |
+LL |     assert_eq!(z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:34:5
+   |
+LL |     assert_eq!(z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:34:5
+   |
+LL |     assert_eq!(z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:36:5
+   |
+LL |     assert_eq!(z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:36:5
+   |
+LL |     assert_eq!(z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr.rs:36:5
+   |
+LL |     assert_eq!(z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: constant `X_const` should have an upper case name
+  --> $DIR/const_fn_ptr.rs:9:7
+   |
+LL | const X_const: fn(usize) -> usize = double_const;
+   |       ^^^^^^^ help: convert the identifier to upper case: `X_CONST`
+   |
+   = note: `#[warn(non_upper_case_globals)]` on by default
+
diff --git a/src/test/ui/consts/const-eval/const_fn_ptr_fail.rs b/src/test/ui/consts/const-eval/const_fn_ptr_fail.rs
new file mode 100644
index 00000000000..14bd6558e7f
--- /dev/null
+++ b/src/test/ui/consts/const-eval/const_fn_ptr_fail.rs
@@ -0,0 +1,13 @@
+// run-pass
+// compile-flags: -Zunleash-the-miri-inside-of-you
+#![feature(const_fn)]
+#![allow(unused)]
+
+fn double(x: usize) -> usize { x * 2 }
+const X: fn(usize) -> usize = double;
+
+const fn bar(x: usize) -> usize {
+    X(x) // FIXME: this should error someday
+}
+
+fn main() {}
diff --git a/src/test/ui/consts/const-eval/const_fn_ptr_fail2.rs b/src/test/ui/consts/const-eval/const_fn_ptr_fail2.rs
new file mode 100644
index 00000000000..74c60f9a2a5
--- /dev/null
+++ b/src/test/ui/consts/const-eval/const_fn_ptr_fail2.rs
@@ -0,0 +1,26 @@
+// compile-flags: -Zunleash-the-miri-inside-of-you
+#![feature(const_fn)]
+#![allow(const_err)]
+
+fn double(x: usize) -> usize { x * 2 }
+const X: fn(usize) -> usize = double;
+
+const fn bar(x: fn(usize) -> usize, y: usize) -> usize {
+    x(y)
+}
+
+const Y: usize = bar(X, 2); // FIXME: should fail to typeck someday
+const Z: usize = bar(double, 2); // FIXME: should fail to typeck someday
+
+fn main() {
+    assert_eq!(Y, 4);
+    //~^ ERROR evaluation of constant expression failed
+    //~^^ WARN skipping const checks
+    //~^^^ WARN skipping const checks
+    //~^^^^ WARN skipping const checks
+    assert_eq!(Z, 4);
+    //~^ ERROR evaluation of constant expression failed
+    //~^^ WARN skipping const checks
+    //~^^^ WARN skipping const checks
+    //~^^^^ WARN skipping const checks
+}
diff --git a/src/test/ui/consts/const-eval/const_fn_ptr_fail2.stderr b/src/test/ui/consts/const-eval/const_fn_ptr_fail2.stderr
new file mode 100644
index 00000000000..611cc5313c0
--- /dev/null
+++ b/src/test/ui/consts/const-eval/const_fn_ptr_fail2.stderr
@@ -0,0 +1,71 @@
+warning: skipping const checks
+  --> $DIR/const_fn_ptr_fail2.rs:16:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr_fail2.rs:16:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr_fail2.rs:16:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr_fail2.rs:21:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr_fail2.rs:21:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: this warning originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+warning: skipping const checks
+  --> $DIR/const_fn_ptr_fail2.rs:21:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = 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[E0080]: evaluation of constant expression failed
+  --> $DIR/const_fn_ptr_fail2.rs:16:5
+   |
+LL |     assert_eq!(Y, 4);
+   |     ^^^^^^^^^^^-^^^^^
+   |                |
+   |                referenced constant has errors
+   |
+   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
+
+error[E0080]: evaluation of constant expression failed
+  --> $DIR/const_fn_ptr_fail2.rs:21:5
+   |
+LL |     assert_eq!(Z, 4);
+   |     ^^^^^^^^^^^-^^^^^
+   |                |
+   |                referenced constant has errors
+   |
+   = note: this error 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 2 previous errors
+
+For more information about this error, try `rustc --explain E0080`.
diff --git a/src/test/ui/empty/empty-struct-tuple-pat.stderr b/src/test/ui/empty/empty-struct-tuple-pat.stderr
index 777b9d4a4ac..6c15e7bf282 100644
--- a/src/test/ui/empty/empty-struct-tuple-pat.stderr
+++ b/src/test/ui/empty/empty-struct-tuple-pat.stderr
@@ -20,15 +20,16 @@ error[E0532]: expected unit struct/variant or constant, found tuple variant `E::
   --> $DIR/empty-struct-tuple-pat.rs:29:9
    |
 LL |         E::Empty4 => ()
-   |         ^^^^^^^^^ not a unit struct/variant or constant
+   |         ^^^^^^^^^ did you mean `E::Empty4 ( /* fields */ )`?
 
 error[E0532]: expected unit struct/variant or constant, found tuple variant `XE::XEmpty5`
   --> $DIR/empty-struct-tuple-pat.rs:33:9
    |
 LL |         XE::XEmpty5 => (),
    |         ^^^^-------
-   |             |
-   |             help: a unit variant with a similar name exists: `XEmpty4`
+   |         |   |
+   |         |   help: a unit variant with a similar name exists: `XEmpty4`
+   |         did you mean `XE::XEmpty5 ( /* fields */ )`?
 
 error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/error-codes/E0023.rs b/src/test/ui/error-codes/E0023.rs
index 2a97e9048a4..dc421e060e8 100644
--- a/src/test/ui/error-codes/E0023.rs
+++ b/src/test/ui/error-codes/E0023.rs
@@ -1,6 +1,7 @@
 enum Fruit {
     Apple(String, String),
     Pear(u32),
+    Orange((String, String)),
 }
 
 
@@ -10,5 +11,6 @@ fn main() {
         Fruit::Apple(a) => {}, //~ ERROR E0023
         Fruit::Apple(a, b, c) => {}, //~ ERROR E0023
         Fruit::Pear(1, 2) => {}, //~ ERROR E0023
+        Fruit::Orange(a, b) => {}, //~ ERROR E0023
     }
 }
diff --git a/src/test/ui/error-codes/E0023.stderr b/src/test/ui/error-codes/E0023.stderr
index d04e494c258..8ae7d01ed5f 100644
--- a/src/test/ui/error-codes/E0023.stderr
+++ b/src/test/ui/error-codes/E0023.stderr
@@ -1,5 +1,5 @@
 error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
-  --> $DIR/E0023.rs:10:9
+  --> $DIR/E0023.rs:11:9
    |
 LL |     Apple(String, String),
    |     --------------------- tuple variant defined here
@@ -8,7 +8,7 @@ LL |         Fruit::Apple(a) => {},
    |         ^^^^^^^^^^^^^^^ expected 2 fields, found 1
 
 error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 2 fields
-  --> $DIR/E0023.rs:11:9
+  --> $DIR/E0023.rs:12:9
    |
 LL |     Apple(String, String),
    |     --------------------- tuple variant defined here
@@ -17,7 +17,7 @@ LL |         Fruit::Apple(a, b, c) => {},
    |         ^^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 3
 
 error[E0023]: this pattern has 2 fields, but the corresponding tuple variant has 1 field
-  --> $DIR/E0023.rs:12:9
+  --> $DIR/E0023.rs:13:9
    |
 LL |     Pear(u32),
    |     --------- tuple variant defined here
@@ -25,6 +25,19 @@ LL |     Pear(u32),
 LL |         Fruit::Pear(1, 2) => {},
    |         ^^^^^^^^^^^^^^^^^ expected 1 field, found 2
 
-error: aborting due to 3 previous errors
+error[E0023]: this pattern has 2 fields, but the corresponding tuple variant has 1 field
+  --> $DIR/E0023.rs:14:9
+   |
+LL |     Orange((String, String)),
+   |     ------------------------ tuple variant defined here
+...
+LL |         Fruit::Orange(a, b) => {},
+   |         ^^^^^^^^^^^^^^^^^^^ expected 1 field, found 2
+help: missing parenthesis
+   |
+LL |         Fruit::Orange((a, b)) => {},
+   |                       ^    ^
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0023`.
diff --git a/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr b/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr
index c2d0e0c2a26..fd6fce938b2 100644
--- a/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr
+++ b/src/test/ui/hrtb/issue-62203-hrtb-ice.stderr
@@ -6,6 +6,8 @@ LL |     let v = Unit2.m(
    |
    = note: expected type `Unit4`
               found type `<_ as Ty<'_>>::V`
+   = note: consider constraining the associated type `<_ as Ty<'_>>::V` to `Unit4`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 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
diff --git a/src/test/ui/impl-trait/bound-normalization-fail.stderr b/src/test/ui/impl-trait/bound-normalization-fail.stderr
index 2c4c61a0957..99c6a8cdd6d 100644
--- a/src/test/ui/impl-trait/bound-normalization-fail.stderr
+++ b/src/test/ui/impl-trait/bound-normalization-fail.stderr
@@ -14,6 +14,8 @@ LL |     fn foo_fail<T: Trait>() -> impl FooLike<Output=T::Assoc> {
    |
    = note: expected type `()`
               found type `<T as impl_trait::Trait>::Assoc`
+   = note: consider constraining the associated type `<T as impl_trait::Trait>::Assoc` to `()`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
    = note: the return type of a function must have a statically known size
 
 error: `impl Trait` return type cannot contain a projection or `Self` that references lifetimes from a parent scope
@@ -30,6 +32,8 @@ LL |     fn foo2_fail<'a, T: Trait<'a>>() -> impl FooLike<Output=T::Assoc> {
    |
    = note: expected type `()`
               found type `<T as lifetimes::Trait<'static>>::Assoc`
+   = note: consider constraining the associated type `<T as lifetimes::Trait<'static>>::Assoc` to `()`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
    = note: the return type of a function must have a statically known size
 
 error: aborting due to 3 previous errors
diff --git a/src/test/ui/impl-trait/equality2.stderr b/src/test/ui/impl-trait/equality2.stderr
index 3e6181adec0..e30e2626e9f 100644
--- a/src/test/ui/impl-trait/equality2.stderr
+++ b/src/test/ui/impl-trait/equality2.stderr
@@ -15,6 +15,8 @@ LL |     let _: i32 = Leak::leak(hide(0_i32));
    |
    = note: expected type `i32`
               found type `<impl Foo as Leak>::T`
+   = note: consider constraining the associated type `<impl Foo as Leak>::T` to `i32`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error[E0308]: mismatched types
   --> $DIR/equality2.rs:38:10
diff --git a/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr b/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr
index 357e6b026e2..e4d0a731ebf 100644
--- a/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr
+++ b/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr
@@ -9,6 +9,8 @@ LL |     fn foo<B: Debug>(&self, a: &impl Debug, b: &B) { }
    |
    = note: expected type `fn(&(), &B, &impl Debug)`
               found type `fn(&(), &impl Debug, &B)`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/universal-mismatched-type.stderr b/src/test/ui/impl-trait/universal-mismatched-type.stderr
index d223b9672cf..d92c3f034e5 100644
--- a/src/test/ui/impl-trait/universal-mismatched-type.stderr
+++ b/src/test/ui/impl-trait/universal-mismatched-type.stderr
@@ -8,6 +8,8 @@ LL |     x
    |
    = note: expected type `std::string::String`
               found type `impl Debug`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/universal-two-impl-traits.stderr b/src/test/ui/impl-trait/universal-two-impl-traits.stderr
index 145d6a8431b..98a70f268cf 100644
--- a/src/test/ui/impl-trait/universal-two-impl-traits.stderr
+++ b/src/test/ui/impl-trait/universal-two-impl-traits.stderr
@@ -6,6 +6,8 @@ LL |     a = y;
    |
    = note: expected type `impl Debug` (type parameter)
               found type `impl Debug` (type parameter)
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-13853.stderr b/src/test/ui/issues/issue-13853.stderr
index c57ca3e25d9..3f2d0aa87ad 100644
--- a/src/test/ui/issues/issue-13853.stderr
+++ b/src/test/ui/issues/issue-13853.stderr
@@ -9,6 +9,8 @@ LL |         self.iter()
    |
    = note: expected type `I`
               found type `std::slice::Iter<'_, N>`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0599]: no method named `iter` found for type `&G` in the current scope
   --> $DIR/issue-13853.rs:27:23
diff --git a/src/test/ui/issues/issue-20225.stderr b/src/test/ui/issues/issue-20225.stderr
index 5ab23cb55bc..4c464e6d4f6 100644
--- a/src/test/ui/issues/issue-20225.stderr
+++ b/src/test/ui/issues/issue-20225.stderr
@@ -6,6 +6,8 @@ LL |   extern "rust-call" fn call(&self, (_,): (T,)) {}
    |
    = note: expected type `extern "rust-call" fn(&Foo, (&'a T,))`
               found type `extern "rust-call" fn(&Foo, (T,))`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0053]: method `call_mut` has an incompatible type for trait
   --> $DIR/issue-20225.rs:12:3
@@ -15,6 +17,8 @@ LL |   extern "rust-call" fn call_mut(&mut self, (_,): (T,)) {}
    |
    = note: expected type `extern "rust-call" fn(&mut Foo, (&'a T,))`
               found type `extern "rust-call" fn(&mut Foo, (T,))`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0053]: method `call_once` has an incompatible type for trait
   --> $DIR/issue-20225.rs:20:3
@@ -24,6 +28,8 @@ LL |   extern "rust-call" fn call_once(self, (_,): (T,)) {}
    |
    = note: expected type `extern "rust-call" fn(Foo, (&'a T,))`
               found type `extern "rust-call" fn(Foo, (T,))`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/issues/issue-24204.stderr b/src/test/ui/issues/issue-24204.stderr
index eb9aada389f..9658f6980be 100644
--- a/src/test/ui/issues/issue-24204.stderr
+++ b/src/test/ui/issues/issue-24204.stderr
@@ -9,6 +9,7 @@ LL | fn test<T: Trait<B=i32>>(b: i32) -> T where T::A: MultiDispatch<i32> { T::n
    |
    = note: expected type `<<T as Trait>::A as MultiDispatch<i32>>::O`
               found type `T`
+   = note: you might be missing a type parameter or trait bound
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-2951.stderr b/src/test/ui/issues/issue-2951.stderr
index 58e28c1a9dc..a6ccc4835fa 100644
--- a/src/test/ui/issues/issue-2951.stderr
+++ b/src/test/ui/issues/issue-2951.stderr
@@ -6,6 +6,8 @@ LL |     xx = y;
    |
    = note: expected type `T`
               found type `U`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-32004.stderr b/src/test/ui/issues/issue-32004.stderr
index f8c418b25a0..b56fa949acb 100644
--- a/src/test/ui/issues/issue-32004.stderr
+++ b/src/test/ui/issues/issue-32004.stderr
@@ -3,8 +3,9 @@ error[E0532]: expected unit struct/variant or constant, found tuple variant `Foo
    |
 LL |         Foo::Bar => {}
    |         ^^^^^---
-   |              |
-   |              help: a unit variant with a similar name exists: `Baz`
+   |         |    |
+   |         |    help: a unit variant with a similar name exists: `Baz`
+   |         did you mean `Foo::Bar ( /* fields */ )`?
 
 error[E0532]: expected tuple struct/variant, found unit struct `S`
   --> $DIR/issue-32004.rs:16:9
diff --git a/src/test/ui/issues/issue-32323.stderr b/src/test/ui/issues/issue-32323.stderr
index 6256dc0c550..9c11a02923c 100644
--- a/src/test/ui/issues/issue-32323.stderr
+++ b/src/test/ui/issues/issue-32323.stderr
@@ -8,6 +8,8 @@ LL | pub fn f<'a, T: Tr<'a>>() -> <T as Tr<'a>>::Out {}
    |
    = note: expected type `<T as Tr<'a>>::Out`
               found type `()`
+   = note: consider constraining the associated type `<T as Tr<'a>>::Out` to `()` or calling a method that returns `<T as Tr<'a>>::Out`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-63983.rs b/src/test/ui/issues/issue-63983.rs
new file mode 100644
index 00000000000..c1c79091fc8
--- /dev/null
+++ b/src/test/ui/issues/issue-63983.rs
@@ -0,0 +1,15 @@
+enum MyEnum {
+    Tuple(i32),
+    Struct{ s: i32 },
+}
+
+fn foo(en: MyEnum) {
+    match en {
+        MyEnum::Tuple => "",
+        //~^ ERROR expected unit struct/variant or constant, found tuple variant `MyEnum::Tuple`
+        MyEnum::Struct => "",
+        //~^ ERROR expected unit struct/variant or constant, found struct variant `MyEnum::Struct`
+    };
+}
+
+fn main() {}
diff --git a/src/test/ui/issues/issue-63983.stderr b/src/test/ui/issues/issue-63983.stderr
new file mode 100644
index 00000000000..67acd1d57c2
--- /dev/null
+++ b/src/test/ui/issues/issue-63983.stderr
@@ -0,0 +1,15 @@
+error[E0532]: expected unit struct/variant or constant, found tuple variant `MyEnum::Tuple`
+  --> $DIR/issue-63983.rs:8:9
+   |
+LL |         MyEnum::Tuple => "",
+   |         ^^^^^^^^^^^^^ did you mean `MyEnum::Tuple ( /* fields */ )`?
+
+error[E0532]: expected unit struct/variant or constant, found struct variant `MyEnum::Struct`
+  --> $DIR/issue-63983.rs:10:9
+   |
+LL |         MyEnum::Struct => "",
+   |         ^^^^^^^^^^^^^^ did you mean `MyEnum::Struct { /* fields */ }`?
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0532`.
diff --git a/src/test/ui/mismatched_types/issue-35030.stderr b/src/test/ui/mismatched_types/issue-35030.stderr
index f0306701613..4a9afb9d249 100644
--- a/src/test/ui/mismatched_types/issue-35030.stderr
+++ b/src/test/ui/mismatched_types/issue-35030.stderr
@@ -6,6 +6,8 @@ LL |         Some(true)
    |
    = note: expected type `bool` (type parameter)
               found type `bool` (bool)
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/specialization/specialization-default-projection.stderr b/src/test/ui/specialization/specialization-default-projection.stderr
index ab0bdc44cff..43cebd7f9c2 100644
--- a/src/test/ui/specialization/specialization-default-projection.stderr
+++ b/src/test/ui/specialization/specialization-default-projection.stderr
@@ -9,6 +9,8 @@ LL |     ()
    |
    = note: expected type `<T as Foo>::Assoc`
               found type `()`
+   = note: consider constraining the associated type `<T as Foo>::Assoc` to `()` or calling a method that returns `<T as Foo>::Assoc`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error[E0308]: mismatched types
   --> $DIR/specialization-default-projection.rs:28:5
@@ -23,6 +25,8 @@ LL |     generic::<()>()
    |
    = note: expected type `()`
               found type `<() as Foo>::Assoc`
+   = note: consider constraining the associated type `<() as Foo>::Assoc` to `()`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/specialization/specialization-default-types.stderr b/src/test/ui/specialization/specialization-default-types.stderr
index 1192b0e5cfa..932087421fb 100644
--- a/src/test/ui/specialization/specialization-default-types.stderr
+++ b/src/test/ui/specialization/specialization-default-types.stderr
@@ -8,6 +8,8 @@ LL |         Box::new(self)
    |
    = note: expected type `<T as Example>::Output`
               found type `std::boxed::Box<T>`
+   = note: consider constraining the associated type `<T as Example>::Output` to `std::boxed::Box<T>` or calling a method that returns `<T as Example>::Output`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error[E0308]: mismatched types
   --> $DIR/specialization-default-types.rs:25:5
@@ -19,6 +21,8 @@ LL |     Example::generate(t)
    |
    = note: expected type `std::boxed::Box<T>`
               found type `<T as Example>::Output`
+   = note: consider constraining the associated type `<T as Example>::Output` to `std::boxed::Box<T>`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/structs/struct-path-self-type-mismatch.stderr b/src/test/ui/structs/struct-path-self-type-mismatch.stderr
index 72c6d7ae22b..b905cd1a294 100644
--- a/src/test/ui/structs/struct-path-self-type-mismatch.stderr
+++ b/src/test/ui/structs/struct-path-self-type-mismatch.stderr
@@ -12,6 +12,8 @@ LL |             inner: u
    |
    = note: expected type `T`
               found type `U`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0308]: mismatched types
   --> $DIR/struct-path-self-type-mismatch.rs:13:9
@@ -27,6 +29,8 @@ LL | |         }
    |
    = note: expected type `Foo<U>`
               found type `Foo<T>`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
index ee73622cb7b..a0a617fdbbc 100644
--- a/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
+++ b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
@@ -6,6 +6,8 @@ LL |         Self::TSVariant(());
    |
    = note: expected type `T`
               found type `()`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0109]: type arguments are not allowed for this type
   --> $DIR/enum-variant-generic-args.rs:15:27
@@ -27,6 +29,8 @@ LL |         Self::<()>::TSVariant(());
    |
    = note: expected type `T`
               found type `()`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0109]: type arguments are not allowed for this type
   --> $DIR/enum-variant-generic-args.rs:20:16
@@ -48,6 +52,8 @@ LL |         Self::SVariant { v: () };
    |
    = note: expected type `T`
               found type `()`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0109]: type arguments are not allowed for this type
   --> $DIR/enum-variant-generic-args.rs:28:26
@@ -63,6 +69,8 @@ LL |         Self::SVariant::<()> { v: () };
    |
    = note: expected type `T`
               found type `()`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0109]: type arguments are not allowed for this type
   --> $DIR/enum-variant-generic-args.rs:31:16
@@ -78,6 +86,8 @@ LL |         Self::<()>::SVariant { v: () };
    |
    = note: expected type `T`
               found type `()`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0109]: type arguments are not allowed for this type
   --> $DIR/enum-variant-generic-args.rs:34:16
@@ -99,6 +109,8 @@ LL |         Self::<()>::SVariant::<()> { v: () };
    |
    = note: expected type `T`
               found type `()`
+   = help: type parameters must be constrained to match other types
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error[E0109]: type arguments are not allowed for this type
   --> $DIR/enum-variant-generic-args.rs:41:26
diff --git a/src/test/ui/type/type-parameter-names.stderr b/src/test/ui/type/type-parameter-names.stderr
index 9acae5c376d..3397eec9e05 100644
--- a/src/test/ui/type/type-parameter-names.stderr
+++ b/src/test/ui/type/type-parameter-names.stderr
@@ -8,6 +8,8 @@ LL |     x
    |
    = note: expected type `Bar`
               found type `Foo`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/type/type-params-in-different-spaces-1.stderr b/src/test/ui/type/type-params-in-different-spaces-1.stderr
index 0448a28ea8e..a10bf4e0b77 100644
--- a/src/test/ui/type/type-params-in-different-spaces-1.stderr
+++ b/src/test/ui/type/type-params-in-different-spaces-1.stderr
@@ -6,6 +6,8 @@ LL |         *self + rhs
    |
    = note: expected type `Self`
               found type `T`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/type/type-params-in-different-spaces-3.stderr b/src/test/ui/type/type-params-in-different-spaces-3.stderr
index e25f79947c7..9f0fa5a0ea1 100644
--- a/src/test/ui/type/type-params-in-different-spaces-3.stderr
+++ b/src/test/ui/type/type-params-in-different-spaces-3.stderr
@@ -8,6 +8,8 @@ LL |         u
    |
    = note: expected type `Self`
               found type `X`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 
 error: aborting due to previous error