Auto merge of #105686 - matthiaskrgr:rollup-bedfk3j, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #103644 (Add docs for question mark operator for Option)
 - #105161 (Refine when invalid prefix case error arises)
 - #105491 (Illegal sized bounds: only suggest mutability change if needed)
 - #105502 (Suggest impl in the scenario of typo with fn)
 - #105523 (Suggest `collect`ing into `Vec<_>`)
 - #105595 (Suggest dereferencing receiver arguments properly)
 - #105611 (fold instead of obliterating args)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

41 files changed, 380 insertions, 57 deletions

diff --git a/src/test/ui/array-slice-vec/infer_array_len.stderr b/src/test/ui/array-slice-vec/infer_array_len.stderr
index 919550cac30..c2a509a1963 100644
--- a/src/test/ui/array-slice-vec/infer_array_len.stderr
+++ b/src/test/ui/array-slice-vec/infer_array_len.stderr
@@ -6,8 +6,8 @@ LL |     let [_, _] = a.into();
    |
 help: consider giving this pattern a type
    |
-LL |     let [_, _]: _ = a.into();
-   |               +++
+LL |     let [_, _]: /* Type */ = a.into();
+   |               ++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closure-expected-type/expect-two-infer-vars-supply-ty-with-bound-region.stderr b/src/test/ui/closure-expected-type/expect-two-infer-vars-supply-ty-with-bound-region.stderr
index d5432755cfe..7a04ed7381e 100644
--- a/src/test/ui/closure-expected-type/expect-two-infer-vars-supply-ty-with-bound-region.stderr
+++ b/src/test/ui/closure-expected-type/expect-two-infer-vars-supply-ty-with-bound-region.stderr
@@ -6,8 +6,8 @@ LL |     with_closure(|x: u32, y| {});
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |     with_closure(|x: u32, y: _| {});
-   |                            +++
+LL |     with_closure(|x: u32, y: /* Type */| {});
+   |                            ++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/closures/issue-52437.stderr b/src/test/ui/closures/issue-52437.stderr
index 4c24a54bbbe..9ba24c7a886 100644
--- a/src/test/ui/closures/issue-52437.stderr
+++ b/src/test/ui/closures/issue-52437.stderr
@@ -12,8 +12,8 @@ LL |     [(); &(&'static: loop { |x| {}; }) as *const _ as usize]
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |     [(); &(&'static: loop { |x: _| {}; }) as *const _ as usize]
-   |                               +++
+LL |     [(); &(&'static: loop { |x: /* Type */| {}; }) as *const _ as usize]
+   |                               ++++++++++++
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/const-generics/generic_arg_infer/issue-91614.stderr b/src/test/ui/const-generics/generic_arg_infer/issue-91614.stderr
index 293ca6232b1..13ea4a295af 100644
--- a/src/test/ui/const-generics/generic_arg_infer/issue-91614.stderr
+++ b/src/test/ui/const-generics/generic_arg_infer/issue-91614.stderr
@@ -5,6 +5,12 @@ LL |     let y = Mask::<_, _>::splat(false);
    |         ^   ------------------- type must be known at this point
    |
    = note: cannot satisfy `_: MaskElement`
+   = help: the following types implement trait `MaskElement`:
+             i16
+             i32
+             i64
+             i8
+             isize
 note: required by a bound in `Mask::<T, LANES>::splat`
   --> $SRC_DIR/core/src/../../portable-simd/crates/core_simd/src/masks.rs:LL:COL
 help: consider giving `y` an explicit type, where the type for type parameter `T` is specified
diff --git a/src/test/ui/const-generics/generic_const_exprs/issue-105608.rs b/src/test/ui/const-generics/generic_const_exprs/issue-105608.rs
new file mode 100644
index 00000000000..e28ba3b1ada
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/issue-105608.rs
@@ -0,0 +1,15 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+struct Combination<const STRATEGIES: usize>;
+
+impl<const STRATEGIES: usize> Combination<STRATEGIES> {
+    fn and<M>(self) -> Combination<{ STRATEGIES + 1 }> {
+        Combination
+    }
+}
+
+pub fn main() {
+    Combination::<0>.and::<_>().and::<_>();
+    //~^ ERROR: type annotations needed
+}
diff --git a/src/test/ui/const-generics/generic_const_exprs/issue-105608.stderr b/src/test/ui/const-generics/generic_const_exprs/issue-105608.stderr
new file mode 100644
index 00000000000..0be4c43daac
--- /dev/null
+++ b/src/test/ui/const-generics/generic_const_exprs/issue-105608.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed
+  --> $DIR/issue-105608.rs:13:22
+   |
+LL |     Combination::<0>.and::<_>().and::<_>();
+   |                      ^^^ cannot infer type of the type parameter `M` declared on the associated function `and`
+   |
+help: consider specifying the generic argument
+   |
+LL |     Combination::<0>.and::<_>().and::<_>();
+   |                         ~~~~~
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/const-generics/generic_const_exprs/issue-72787.min.stderr b/src/test/ui/const-generics/generic_const_exprs/issue-72787.min.stderr
index 4d0d0253f1b..e0444042614 100644
--- a/src/test/ui/const-generics/generic_const_exprs/issue-72787.min.stderr
+++ b/src/test/ui/const-generics/generic_const_exprs/issue-72787.min.stderr
@@ -41,6 +41,7 @@ LL |     IsLessOrEqual<I, 8>: True,
    |                          ^^^^
    |
    = note: cannot satisfy `IsLessOrEqual<I, 8>: True`
+   = help: the trait `True` is implemented for `IsLessOrEqual<LHS, RHS>`
 
 error[E0283]: type annotations needed: cannot satisfy `IsLessOrEqual<I, 8>: True`
   --> $DIR/issue-72787.rs:21:26
@@ -49,6 +50,7 @@ LL |     IsLessOrEqual<I, 8>: True,
    |                          ^^^^
    |
    = note: cannot satisfy `IsLessOrEqual<I, 8>: True`
+   = help: the trait `True` is implemented for `IsLessOrEqual<LHS, RHS>`
 
 error: aborting due to 6 previous errors
 
diff --git a/src/test/ui/const-generics/issues/issue-83249.stderr b/src/test/ui/const-generics/issues/issue-83249.stderr
index 362b8554b2f..7491fdc8a69 100644
--- a/src/test/ui/const-generics/issues/issue-83249.stderr
+++ b/src/test/ui/const-generics/issues/issue-83249.stderr
@@ -6,8 +6,8 @@ LL |     let _ = foo([0; 1]);
    |
 help: consider giving this pattern a type
    |
-LL |     let _: _ = foo([0; 1]);
-   |          +++
+LL |     let _: /* Type */ = foo([0; 1]);
+   |          ++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0282.stderr b/src/test/ui/error-codes/E0282.stderr
index d01aa3617c7..892d3a81f27 100644
--- a/src/test/ui/error-codes/E0282.stderr
+++ b/src/test/ui/error-codes/E0282.stderr
@@ -6,8 +6,8 @@ LL |     let x = "hello".chars().rev().collect();
    |
 help: consider giving `x` an explicit type
    |
-LL |     let x: _ = "hello".chars().rev().collect();
-   |          +++
+LL |     let x: Vec<_> = "hello".chars().rev().collect();
+   |          ++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0401.stderr b/src/test/ui/error-codes/E0401.stderr
index 9687eca61fa..fa4b91cacef 100644
--- a/src/test/ui/error-codes/E0401.stderr
+++ b/src/test/ui/error-codes/E0401.stderr
@@ -59,7 +59,7 @@ note: required by a bound in `bfnr`
    |
 LL |     fn bfnr<U, V: Baz<U>, W: Fn()>(y: T) {
    |                              ^^^^ required by this bound in `bfnr`
-help: consider specifying the type arguments in the function call
+help: consider specifying the generic arguments
    |
 LL |     bfnr::<U, V, W>(x);
    |         +++++++++++
diff --git a/src/test/ui/illegal-sized-bound/mutability-mismatch.rs b/src/test/ui/illegal-sized-bound/mutability-mismatch.rs
new file mode 100644
index 00000000000..deb84f6fe97
--- /dev/null
+++ b/src/test/ui/illegal-sized-bound/mutability-mismatch.rs
@@ -0,0 +1,34 @@
+struct MutType;
+
+pub trait MutTrait {
+    fn function(&mut self)
+    where
+        Self: Sized;
+    //~^ this has a `Sized` requirement
+}
+
+impl MutTrait for MutType {
+    fn function(&mut self) {}
+}
+
+struct Type;
+
+pub trait Trait {
+    fn function(&self)
+    where
+        Self: Sized;
+    //~^ this has a `Sized` requirement
+}
+
+impl Trait for Type {
+    fn function(&self) {}
+}
+
+fn main() {
+    (&MutType as &dyn MutTrait).function();
+    //~^ ERROR the `function` method cannot be invoked on a trait object
+    //~| NOTE you need `&mut dyn MutTrait` instead of `&dyn MutTrait`
+    (&mut Type as &mut dyn Trait).function();
+    //~^ ERROR the `function` method cannot be invoked on a trait object
+    //~| NOTE you need `&dyn Trait` instead of `&mut dyn Trait`
+}
diff --git a/src/test/ui/illegal-sized-bound/mutability-mismatch.stderr b/src/test/ui/illegal-sized-bound/mutability-mismatch.stderr
new file mode 100644
index 00000000000..dbbf79a4f1a
--- /dev/null
+++ b/src/test/ui/illegal-sized-bound/mutability-mismatch.stderr
@@ -0,0 +1,24 @@
+error: the `function` method cannot be invoked on a trait object
+  --> $DIR/mutability-mismatch.rs:28:33
+   |
+LL |         Self: Sized;
+   |               ----- this has a `Sized` requirement
+...
+LL |     (&MutType as &dyn MutTrait).function();
+   |                                 ^^^^^^^^
+   |
+   = note: you need `&mut dyn MutTrait` instead of `&dyn MutTrait`
+
+error: the `function` method cannot be invoked on a trait object
+  --> $DIR/mutability-mismatch.rs:31:35
+   |
+LL |         Self: Sized;
+   |               ----- this has a `Sized` requirement
+...
+LL |     (&mut Type as &mut dyn Trait).function();
+   |                                   ^^^^^^^^
+   |
+   = note: you need `&dyn Trait` instead of `&mut dyn Trait`
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/illegal-sized-bound/regular.rs b/src/test/ui/illegal-sized-bound/regular.rs
new file mode 100644
index 00000000000..7abd27ef983
--- /dev/null
+++ b/src/test/ui/illegal-sized-bound/regular.rs
@@ -0,0 +1,32 @@
+struct MutType;
+
+pub trait MutTrait {
+    fn function(&mut self)
+    where
+        Self: Sized;
+    //~^ this has a `Sized` requirement
+}
+
+impl MutTrait for MutType {
+    fn function(&mut self) {}
+}
+
+struct Type;
+
+pub trait Trait {
+    fn function(&self)
+    where
+        Self: Sized;
+    //~^ this has a `Sized` requirement
+}
+
+impl Trait for Type {
+    fn function(&self) {}
+}
+
+fn main() {
+    (&mut MutType as &mut dyn MutTrait).function();
+    //~^ ERROR the `function` method cannot be invoked on a trait object
+    (&Type as &dyn Trait).function();
+    //~^ ERROR the `function` method cannot be invoked on a trait object
+}
diff --git a/src/test/ui/illegal-sized-bound/regular.stderr b/src/test/ui/illegal-sized-bound/regular.stderr
new file mode 100644
index 00000000000..7f3744145d9
--- /dev/null
+++ b/src/test/ui/illegal-sized-bound/regular.stderr
@@ -0,0 +1,20 @@
+error: the `function` method cannot be invoked on a trait object
+  --> $DIR/regular.rs:28:41
+   |
+LL |         Self: Sized;
+   |               ----- this has a `Sized` requirement
+...
+LL |     (&mut MutType as &mut dyn MutTrait).function();
+   |                                         ^^^^^^^^
+
+error: the `function` method cannot be invoked on a trait object
+  --> $DIR/regular.rs:30:27
+   |
+LL |         Self: Sized;
+   |               ----- this has a `Sized` requirement
+...
+LL |     (&Type as &dyn Trait).function();
+   |                           ^^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/impl-trait/issues/issue-86719.stderr b/src/test/ui/impl-trait/issues/issue-86719.stderr
index 09047cdcbe1..7592418fdfd 100644
--- a/src/test/ui/impl-trait/issues/issue-86719.stderr
+++ b/src/test/ui/impl-trait/issues/issue-86719.stderr
@@ -20,8 +20,8 @@ LL |         |_| true
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |_: _| true
-   |           +++
+LL |         |_: /* Type */| true
+   |           ++++++++++++
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/inference/erase-type-params-in-label.stderr b/src/test/ui/inference/erase-type-params-in-label.stderr
index 5c52e7bcfab..9be18286480 100644
--- a/src/test/ui/inference/erase-type-params-in-label.stderr
+++ b/src/test/ui/inference/erase-type-params-in-label.stderr
@@ -10,10 +10,10 @@ note: required by a bound in `foo`
    |
 LL | fn foo<T, K, W: Default, Z: Default>(t: T, k: K) -> Foo<T, K, W, Z> {
    |                 ^^^^^^^ required by this bound in `foo`
-help: consider specifying the type arguments in the function call
+help: consider giving `foo` an explicit type, where the type for type parameter `W` is specified
    |
-LL |     let foo = foo::<T, K, W, Z>(1, "");
-   |                  ++++++++++++++
+LL |     let foo: Foo<i32, &str, W, Z> = foo(1, "");
+   |            ++++++++++++++++++++++
 
 error[E0283]: type annotations needed for `Bar<i32, &str, Z>`
   --> $DIR/erase-type-params-in-label.rs:5:9
@@ -27,10 +27,10 @@ note: required by a bound in `bar`
    |
 LL | fn bar<T, K, Z: Default>(t: T, k: K) -> Bar<T, K, Z> {
    |                 ^^^^^^^ required by this bound in `bar`
-help: consider specifying the type arguments in the function call
+help: consider giving `bar` an explicit type, where the type for type parameter `Z` is specified
    |
-LL |     let bar = bar::<T, K, Z>(1, "");
-   |                  +++++++++++
+LL |     let bar: Bar<i32, &str, Z> = bar(1, "");
+   |            +++++++++++++++++++
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/inference/issue-72690.stderr b/src/test/ui/inference/issue-72690.stderr
index d4eeda07366..8eda71ec09b 100644
--- a/src/test/ui/inference/issue-72690.stderr
+++ b/src/test/ui/inference/issue-72690.stderr
@@ -32,8 +32,8 @@ LL |     |x| String::from("x".as_ref());
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |     |x: _| String::from("x".as_ref());
-   |       +++
+LL |     |x: /* Type */| String::from("x".as_ref());
+   |       ++++++++++++
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:12:26
diff --git a/src/test/ui/issues/issue-18159.stderr b/src/test/ui/issues/issue-18159.stderr
index 605ff3829d1..5e0589eed43 100644
--- a/src/test/ui/issues/issue-18159.stderr
+++ b/src/test/ui/issues/issue-18159.stderr
@@ -6,8 +6,8 @@ LL |     let x;
    |
 help: consider giving `x` an explicit type
    |
-LL |     let x: _;
-   |          +++
+LL |     let x: /* Type */;
+   |          ++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-2151.stderr b/src/test/ui/issues/issue-2151.stderr
index 31a8ca5fbfa..c75038b6169 100644
--- a/src/test/ui/issues/issue-2151.stderr
+++ b/src/test/ui/issues/issue-2151.stderr
@@ -8,8 +8,8 @@ LL |     x.clone();
    |
 help: consider giving `x` an explicit type
    |
-LL |     let x: _ = panic!();
-   |          +++
+LL |     let x: /* Type */ = panic!();
+   |          ++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-24036.stderr b/src/test/ui/issues/issue-24036.stderr
index a42e35c4cad..0e73a51faed 100644
--- a/src/test/ui/issues/issue-24036.stderr
+++ b/src/test/ui/issues/issue-24036.stderr
@@ -19,8 +19,8 @@ LL |         1 => |c| c + 1,
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         1 => |c: _| c + 1,
-   |                +++
+LL |         1 => |c: /* Type */| c + 1,
+   |                ++++++++++++
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/lazy-type-alias-impl-trait/branches3.stderr b/src/test/ui/lazy-type-alias-impl-trait/branches3.stderr
index 420104e526d..fe2631f9474 100644
--- a/src/test/ui/lazy-type-alias-impl-trait/branches3.stderr
+++ b/src/test/ui/lazy-type-alias-impl-trait/branches3.stderr
@@ -6,8 +6,8 @@ LL |         |s| s.len()
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |s: _| s.len()
-   |           +++
+LL |         |s: /* Type */| s.len()
+   |           ++++++++++++
 
 error[E0282]: type annotations needed
   --> $DIR/branches3.rs:15:10
@@ -17,8 +17,8 @@ LL |         |s| s.len()
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |s: _| s.len()
-   |           +++
+LL |         |s: /* Type */| s.len()
+   |           ++++++++++++
 
 error[E0282]: type annotations needed
   --> $DIR/branches3.rs:23:10
@@ -28,8 +28,8 @@ LL |         |s| s.len()
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |s: _| s.len()
-   |           +++
+LL |         |s: /* Type */| s.len()
+   |           ++++++++++++
 
 error[E0282]: type annotations needed
   --> $DIR/branches3.rs:30:10
@@ -39,8 +39,8 @@ LL |         |s| s.len()
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |s: _| s.len()
-   |           +++
+LL |         |s: /* Type */| s.len()
+   |           ++++++++++++
 
 error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/lifetimes/issue-34979.stderr b/src/test/ui/lifetimes/issue-34979.stderr
index 5832c4d173c..a332c6547b8 100644
--- a/src/test/ui/lifetimes/issue-34979.stderr
+++ b/src/test/ui/lifetimes/issue-34979.stderr
@@ -5,6 +5,7 @@ LL |     &'a (): Foo,
    |             ^^^
    |
    = note: cannot satisfy `&'a (): Foo`
+   = help: the trait `Foo` is implemented for `&'a T`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/match/match-unresolved-one-arm.stderr b/src/test/ui/match/match-unresolved-one-arm.stderr
index 9eadb88a8ba..e3b501b2fd5 100644
--- a/src/test/ui/match/match-unresolved-one-arm.stderr
+++ b/src/test/ui/match/match-unresolved-one-arm.stderr
@@ -6,8 +6,8 @@ LL |     let x = match () {
    |
 help: consider giving `x` an explicit type
    |
-LL |     let x: _ = match () {
-   |          +++
+LL |     let x: /* Type */ = match () {
+   |          ++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/numeric/uppercase-base-prefix-invalid-no-fix.rs b/src/test/ui/numeric/uppercase-base-prefix-invalid-no-fix.rs
new file mode 100644
index 00000000000..f00cde4a74c
--- /dev/null
+++ b/src/test/ui/numeric/uppercase-base-prefix-invalid-no-fix.rs
@@ -0,0 +1,34 @@
+// Checks that integers with seeming uppercase base prefixes do not get bogus capitalization
+// suggestions.
+
+fn main() {
+    _ = 123X1a3;
+    //~^ ERROR invalid suffix `X1a3` for number literal
+    //~| NOTE invalid suffix `X1a3`
+    //~| HELP the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+    _ = 456O123;
+    //~^ ERROR invalid suffix `O123` for number literal
+    //~| NOTE invalid suffix `O123`
+    //~| HELP the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+    _ = 789B101;
+    //~^ ERROR invalid suffix `B101` for number literal
+    //~| NOTE invalid suffix `B101`
+    //~| HELP the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+    _ = 0XYZ;
+    //~^ ERROR invalid suffix `XYZ` for number literal
+    //~| NOTE invalid suffix `XYZ`
+    //~| HELP the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+    _ = 0OPQ;
+    //~^ ERROR invalid suffix `OPQ` for number literal
+    //~| NOTE invalid suffix `OPQ`
+    //~| HELP the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+    _ = 0BCD;
+    //~^ ERROR invalid suffix `BCD` for number literal
+    //~| NOTE invalid suffix `BCD`
+    //~| HELP the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+}
diff --git a/src/test/ui/numeric/uppercase-base-prefix-invalid-no-fix.stderr b/src/test/ui/numeric/uppercase-base-prefix-invalid-no-fix.stderr
new file mode 100644
index 00000000000..380c16ca789
--- /dev/null
+++ b/src/test/ui/numeric/uppercase-base-prefix-invalid-no-fix.stderr
@@ -0,0 +1,50 @@
+error: invalid suffix `X1a3` for number literal
+  --> $DIR/uppercase-base-prefix-invalid-no-fix.rs:5:9
+   |
+LL |     _ = 123X1a3;
+   |         ^^^^^^^ invalid suffix `X1a3`
+   |
+   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+error: invalid suffix `O123` for number literal
+  --> $DIR/uppercase-base-prefix-invalid-no-fix.rs:10:9
+   |
+LL |     _ = 456O123;
+   |         ^^^^^^^ invalid suffix `O123`
+   |
+   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+error: invalid suffix `B101` for number literal
+  --> $DIR/uppercase-base-prefix-invalid-no-fix.rs:15:9
+   |
+LL |     _ = 789B101;
+   |         ^^^^^^^ invalid suffix `B101`
+   |
+   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+error: invalid suffix `XYZ` for number literal
+  --> $DIR/uppercase-base-prefix-invalid-no-fix.rs:20:9
+   |
+LL |     _ = 0XYZ;
+   |         ^^^^ invalid suffix `XYZ`
+   |
+   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+error: invalid suffix `OPQ` for number literal
+  --> $DIR/uppercase-base-prefix-invalid-no-fix.rs:25:9
+   |
+LL |     _ = 0OPQ;
+   |         ^^^^ invalid suffix `OPQ`
+   |
+   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+error: invalid suffix `BCD` for number literal
+  --> $DIR/uppercase-base-prefix-invalid-no-fix.rs:30:9
+   |
+LL |     _ = 0BCD;
+   |         ^^^^ invalid suffix `BCD`
+   |
+   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
+
+error: aborting due to 6 previous errors
+
diff --git a/src/test/ui/parser/issue-105366.fixed b/src/test/ui/parser/issue-105366.fixed
new file mode 100644
index 00000000000..ad26643c327
--- /dev/null
+++ b/src/test/ui/parser/issue-105366.fixed
@@ -0,0 +1,12 @@
+// run-rustfix
+
+struct Foo;
+
+impl From<i32> for Foo {
+    //~^ ERROR you might have meant to write `impl` instead of `fn`
+    fn from(_a: i32) -> Self {
+        Foo
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/parser/issue-105366.rs b/src/test/ui/parser/issue-105366.rs
new file mode 100644
index 00000000000..311b6a60f1a
--- /dev/null
+++ b/src/test/ui/parser/issue-105366.rs
@@ -0,0 +1,12 @@
+// run-rustfix
+
+struct Foo;
+
+fn From<i32> for Foo {
+    //~^ ERROR you might have meant to write `impl` instead of `fn`
+    fn from(_a: i32) -> Self {
+        Foo
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/parser/issue-105366.stderr b/src/test/ui/parser/issue-105366.stderr
new file mode 100644
index 00000000000..0a7408e2c17
--- /dev/null
+++ b/src/test/ui/parser/issue-105366.stderr
@@ -0,0 +1,13 @@
+error: you might have meant to write `impl` instead of `fn`
+  --> $DIR/issue-105366.rs:5:1
+   |
+LL | fn From<i32> for Foo {
+   | ^^
+   |
+help: replace `fn` with `impl` here
+   |
+LL | impl From<i32> for Foo {
+   | ~~~~
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/pattern/pat-tuple-bad-type.stderr b/src/test/ui/pattern/pat-tuple-bad-type.stderr
index 3342b8e4002..da369d33397 100644
--- a/src/test/ui/pattern/pat-tuple-bad-type.stderr
+++ b/src/test/ui/pattern/pat-tuple-bad-type.stderr
@@ -9,8 +9,8 @@ LL |         (..) => {}
    |
 help: consider giving `x` an explicit type
    |
-LL |     let x: _;
-   |          +++
+LL |     let x: /* Type */;
+   |          ++++++++++++
 
 error[E0308]: mismatched types
   --> $DIR/pat-tuple-bad-type.rs:10:9
diff --git a/src/test/ui/pattern/rest-pat-semantic-disallowed.stderr b/src/test/ui/pattern/rest-pat-semantic-disallowed.stderr
index e6a4e5f19b7..beba7def96f 100644
--- a/src/test/ui/pattern/rest-pat-semantic-disallowed.stderr
+++ b/src/test/ui/pattern/rest-pat-semantic-disallowed.stderr
@@ -193,8 +193,8 @@ LL |     let x @ ..;
    |
 help: consider giving this pattern a type
    |
-LL |     let x @ ..: _;
-   |               +++
+LL |     let x @ ..: /* Type */;
+   |               ++++++++++++
 
 error: aborting due to 23 previous errors
 
diff --git a/src/test/ui/resolve/issue-85348.stderr b/src/test/ui/resolve/issue-85348.stderr
index f839dd927db..42b43f825d1 100644
--- a/src/test/ui/resolve/issue-85348.stderr
+++ b/src/test/ui/resolve/issue-85348.stderr
@@ -21,8 +21,8 @@ LL |         let mut N;
    |
 help: consider giving `N` an explicit type
    |
-LL |         let mut N: _;
-   |                  +++
+LL |         let mut N: /* Type */;
+   |                  ++++++++++++
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/span/method-and-field-eager-resolution.stderr b/src/test/ui/span/method-and-field-eager-resolution.stderr
index 7d240589a3f..f6efbe40bc2 100644
--- a/src/test/ui/span/method-and-field-eager-resolution.stderr
+++ b/src/test/ui/span/method-and-field-eager-resolution.stderr
@@ -9,8 +9,8 @@ LL |     x.0;
    |
 help: consider giving `x` an explicit type
    |
-LL |     let mut x: _ = Default::default();
-   |              +++
+LL |     let mut x: /* Type */ = Default::default();
+   |              ++++++++++++
 
 error[E0282]: type annotations needed
   --> $DIR/method-and-field-eager-resolution.rs:11:9
@@ -23,8 +23,8 @@ LL |     x[0];
    |
 help: consider giving `x` an explicit type
    |
-LL |     let mut x: _ = Default::default();
-   |              +++
+LL |     let mut x: /* Type */ = Default::default();
+   |              ++++++++++++
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/traits/issue-77982.stderr b/src/test/ui/traits/issue-77982.stderr
index 8ab6414d4d8..0b57a8212bd 100644
--- a/src/test/ui/traits/issue-77982.stderr
+++ b/src/test/ui/traits/issue-77982.stderr
@@ -43,7 +43,15 @@ LL |     let ips: Vec<_> = (0..100_000).map(|_| u32::from(0u32.into())).collect(
    |                                            |
    |                                            required by a bound introduced by this call
    |
-   = note: cannot satisfy `u32: From<_>`
+   = note: multiple `impl`s satisfying `u32: From<_>` found in the following crates: `core`, `std`:
+           - impl From<Ipv4Addr> for u32;
+           - impl From<NonZeroU32> for u32;
+           - impl From<bool> for u32;
+           - impl From<char> for u32;
+           - impl From<u16> for u32;
+           - impl From<u8> for u32;
+           - impl<T> From<!> for T;
+           - impl<T> From<T> for T;
 help: try using a fully qualified path to specify the expected types
    |
 LL |     let ips: Vec<_> = (0..100_000).map(|_| u32::from(<u32 as Into<T>>::into(0u32))).collect();
diff --git a/src/test/ui/traits/issue-85735.stderr b/src/test/ui/traits/issue-85735.stderr
index fa280135beb..930708f9ad8 100644
--- a/src/test/ui/traits/issue-85735.stderr
+++ b/src/test/ui/traits/issue-85735.stderr
@@ -5,6 +5,9 @@ LL |     T: FnMut(&'a ()),
    |        ^^^^^^^^^^^^^
    |
    = note: cannot satisfy `T: FnMut<(&'a (),)>`
+   = help: the following types implement trait `FnMut<Args>`:
+             &F
+             &mut F
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.fixed b/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.fixed
new file mode 100644
index 00000000000..ea3d1bf853a
--- /dev/null
+++ b/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.fixed
@@ -0,0 +1,14 @@
+// run-rustfix
+
+struct TargetStruct;
+
+impl From<usize> for TargetStruct {
+    fn from(_unchecked: usize) -> Self {
+        TargetStruct
+    }
+}
+
+fn main() {
+    let a = &3;
+    let _b: TargetStruct = (*a).into(); //~ ERROR the trait bound `TargetStruct: From<&{integer}>` is not satisfied
+}
diff --git a/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.rs b/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.rs
new file mode 100644
index 00000000000..9eda68027b2
--- /dev/null
+++ b/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.rs
@@ -0,0 +1,14 @@
+// run-rustfix
+
+struct TargetStruct;
+
+impl From<usize> for TargetStruct {
+    fn from(_unchecked: usize) -> Self {
+        TargetStruct
+    }
+}
+
+fn main() {
+    let a = &3;
+    let _b: TargetStruct = a.into(); //~ ERROR the trait bound `TargetStruct: From<&{integer}>` is not satisfied
+}
diff --git a/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.stderr b/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.stderr
new file mode 100644
index 00000000000..ede31a2c7bc
--- /dev/null
+++ b/src/test/ui/traits/suggest-deferences/suggest-dereferencing-receiver-argument.stderr
@@ -0,0 +1,15 @@
+error[E0277]: the trait bound `TargetStruct: From<&{integer}>` is not satisfied
+  --> $DIR/suggest-dereferencing-receiver-argument.rs:13:30
+   |
+LL |     let _b: TargetStruct = a.into();
+   |                              ^^^^ the trait `From<&{integer}>` is not implemented for `TargetStruct`
+   |
+   = note: required for `&{integer}` to implement `Into<TargetStruct>`
+help: consider dereferencing here
+   |
+LL |     let _b: TargetStruct = (*a).into();
+   |                            ++ +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr b/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr
index 48b7946ea82..9cc15f14a99 100644
--- a/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr
+++ b/src/test/ui/type-alias-impl-trait/closures_in_branches.stderr
@@ -6,8 +6,8 @@ LL |         |x| x.len()
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |x: _| x.len()
-   |           +++
+LL |         |x: /* Type */| x.len()
+   |           ++++++++++++
 
 error[E0282]: type annotations needed
   --> $DIR/closures_in_branches.rs:21:10
@@ -17,8 +17,8 @@ LL |         |x| x.len()
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |         |x: _| x.len()
-   |           +++
+LL |         |x: /* Type */| x.len()
+   |           ++++++++++++
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/type/type-annotation-needed.stderr b/src/test/ui/type/type-annotation-needed.stderr
index 4af4c22f751..87bba3166be 100644
--- a/src/test/ui/type/type-annotation-needed.stderr
+++ b/src/test/ui/type/type-annotation-needed.stderr
@@ -10,7 +10,7 @@ note: required by a bound in `foo`
    |
 LL | fn foo<T: Into<String>>(x: i32) {}
    |           ^^^^^^^^^^^^ required by this bound in `foo`
-help: consider specifying the type argument in the function call
+help: consider specifying the generic argument
    |
 LL |     foo::<T>(42);
    |        +++++
diff --git a/src/test/ui/type/type-check/unknown_type_for_closure.stderr b/src/test/ui/type/type-check/unknown_type_for_closure.stderr
index 9ae97f390d3..e5e29aabf37 100644
--- a/src/test/ui/type/type-check/unknown_type_for_closure.stderr
+++ b/src/test/ui/type/type-check/unknown_type_for_closure.stderr
@@ -12,8 +12,8 @@ LL |     let x = |_| {};
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |     let x = |_: _| {};
-   |               +++
+LL |     let x = |_: /* Type */| {};
+   |               ++++++++++++
 
 error[E0282]: type annotations needed
   --> $DIR/unknown_type_for_closure.rs:10:14
diff --git a/src/test/ui/type/type-path-err-node-types.stderr b/src/test/ui/type/type-path-err-node-types.stderr
index c1ae10efac4..1aed1dbe4ba 100644
--- a/src/test/ui/type/type-path-err-node-types.stderr
+++ b/src/test/ui/type/type-path-err-node-types.stderr
@@ -30,8 +30,8 @@ LL |     let _ = |a, b: _| -> _ { 0 };
    |
 help: consider giving this closure parameter an explicit type
    |
-LL |     let _ = |a: _, b: _| -> _ { 0 };
-   |               +++
+LL |     let _ = |a: /* Type */, b: _| -> _ { 0 };
+   |               ++++++++++++
 
 error: aborting due to 5 previous errors