Refer to the TraitRef::identity in the message to be clearer

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1763,13 +1763,12 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
             if candidates.len() == 0 {
                 return false;
             }
-            let trait_ref = candidates[0];
             if candidates.len() == 1 {
                 err.highlighted_help(vec![
                     (
                         format!(
                             "the trait `{}` is implemented for `",
-                            trait_ref.print_only_trait_path()
+                            candidates[0].print_only_trait_path()
                         ),
                         Style::NoStyle,
                     ),
@@ -1778,6 +1777,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                 ]);
                 return true;
             }
+            let trait_ref = TraitRef::identity(self.tcx, candidates[0].def_id);
             // Check if the trait is the same in all cases. If so, we'll only show the type.
             // FIXME: there *has* to be a better way!
             let mut traits: Vec<_> = candidates

src/test/ui/binop/binop-mul-i32-f32.stderr

@@ -5,7 +5,7 @@ LL |     x * y
    |       ^ no implementation for `i32 * f32`
    |
    = help: the trait `Mul<f32>` is not implemented for `i32`
-   = help: the following other types implement trait `Mul`:
+   = help: the following other types implement trait `Mul<Rhs>`:
              <&'a f32 as Mul<f32>>
              <&'a f64 as Mul<f64>>
              <&'a i128 as Mul<i128>>

src/test/ui/binop/shift-various-bad-types.stderr

@@ -5,7 +5,7 @@ LL |     22 >> p.char;
    |        ^^ no implementation for `{integer} >> char`
    |
    = help: the trait `Shr<char>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Shr`:
+   = help: the following other types implement trait `Shr<Rhs>`:
              <&'a i128 as Shr<i128>>
              <&'a i128 as Shr<i16>>
              <&'a i128 as Shr<i32>>
@@ -23,7 +23,7 @@ LL |     22 >> p.str;
    |        ^^ no implementation for `{integer} >> &str`
    |
    = help: the trait `Shr<&str>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Shr`:
+   = help: the following other types implement trait `Shr<Rhs>`:
              <&'a i128 as Shr<i128>>
              <&'a i128 as Shr<i16>>
              <&'a i128 as Shr<i32>>
@@ -41,7 +41,7 @@ LL |     22 >> p;
    |        ^^ no implementation for `{integer} >> &Panolpy`
    |
    = help: the trait `Shr<&Panolpy>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Shr`:
+   = help: the following other types implement trait `Shr<Rhs>`:
              <&'a i128 as Shr<i128>>
              <&'a i128 as Shr<i16>>
              <&'a i128 as Shr<i32>>

src/test/ui/const-generics/defaults/rp_impl_trait_fail.stderr

@@ -25,7 +25,7 @@ error[E0277]: the trait bound `u32: Traitor<N, N>` is not satisfied
 LL | fn uwu<const N: u8>() -> impl Traitor<N> {
    |                          ^^^^^^^^^^^^^^^ the trait `Traitor<N, N>` is not implemented for `u32`
    |
-   = help: the following other types implement trait `Traitor<N, 2_u8>`:
+   = help: the following other types implement trait `Traitor<N, M>`:
              <u32 as Traitor<N, 2_u8>>
              <u64 as Traitor<1_u8, 2_u8>>
 
@@ -50,7 +50,7 @@ error[E0277]: the trait bound `u64: Traitor<1_u8, 1_u8>` is not satisfied
 LL | fn owo() -> impl Traitor {
    |             ^^^^^^^^^^^^ the trait `Traitor<1_u8, 1_u8>` is not implemented for `u64`
    |
-   = help: the following other types implement trait `Traitor<N, 2_u8>`:
+   = help: the following other types implement trait `Traitor<N, M>`:
              <u32 as Traitor<N, 2_u8>>
              <u64 as Traitor<1_u8, 2_u8>>
 

src/test/ui/const-generics/exhaustive-value.stderr

@@ -4,7 +4,7 @@ error[E0277]: the trait bound `(): Foo<N>` is not satisfied
 LL |     <() as Foo<N>>::test()
    |     ^^^^^^^^^^^^^^^^^^^^ the trait `Foo<N>` is not implemented for `()`
    |
-   = help: the following other types implement trait `Foo<0_u8>`:
+   = help: the following other types implement trait `Foo<N>`:
              <() as Foo<0_u8>>
              <() as Foo<100_u8>>
              <() as Foo<101_u8>>

src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr

@@ -11,7 +11,7 @@ LL |     = [0; (i8::MAX + 1u8) as usize];
    |                    ^ no implementation for `i8 + u8`
    |
    = help: the trait `Add<u8>` is not implemented for `i8`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>

src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr

@@ -11,7 +11,7 @@ LL |     : [u32; (i8::MAX as i8 + 1u8) as usize]
    |                            ^ no implementation for `i8 + u8`
    |
    = help: the trait `Add<u8>` is not implemented for `i8`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>

src/test/ui/consts/too_generic_eval_ice.stderr

@@ -21,7 +21,7 @@ LL |         [5; Self::HOST_SIZE] == [6; 0]
    |                              ^^ no implementation for `[{integer}; _] == [{integer}; 0]`
    |
    = help: the trait `PartialEq<[{integer}; 0]>` is not implemented for `[{integer}; _]`
-   = help: the following other types implement trait `PartialEq<[B; N]>`:
+   = help: the following other types implement trait `PartialEq<Rhs>`:
              <&[B] as PartialEq<[A; N]>>
              <&[T] as PartialEq<Vec<U, A>>>
              <&mut [B] as PartialEq<[A; N]>>

src/test/ui/did_you_mean/issue-21659-show-relevant-trait-impls-1.stderr

@@ -4,7 +4,7 @@ error[E0277]: the trait bound `Bar: Foo<usize>` is not satisfied
 LL |     f1.foo(1usize);
    |        ^^^ the trait `Foo<usize>` is not implemented for `Bar`
    |
-   = help: the following other types implement trait `Foo<i32>`:
+   = help: the following other types implement trait `Foo<A>`:
              <Bar as Foo<i32>>
              <Bar as Foo<u8>>
 

src/test/ui/did_you_mean/issue-21659-show-relevant-trait-impls-2.stderr

@@ -4,7 +4,7 @@ error[E0277]: the trait bound `Bar: Foo<usize>` is not satisfied
 LL |     f1.foo(1usize);
    |        ^^^ the trait `Foo<usize>` is not implemented for `Bar`
    |
-   = help: the following other types implement trait `Foo<i8>`:
+   = help: the following other types implement trait `Foo<A>`:
              <Bar as Foo<i16>>
              <Bar as Foo<i32>>
              <Bar as Foo<i8>>

src/test/ui/did_you_mean/issue-39802-show-5-trait-impls.stderr

@@ -6,7 +6,7 @@ LL |     Foo::<i32>::bar(&1i8);
    |     |
    |     required by a bound introduced by this call
    |
-   = help: the following other types implement trait `Foo<bool>`:
+   = help: the following other types implement trait `Foo<B>`:
              <i8 as Foo<bool>>
              <i8 as Foo<u16>>
              <i8 as Foo<u32>>
@@ -25,7 +25,7 @@ LL |     Foo::<i32>::bar(&1u8);
    |     |
    |     required by a bound introduced by this call
    |
-   = help: the following other types implement trait `Foo<bool>`:
+   = help: the following other types implement trait `Foo<B>`:
              <i8 as Foo<bool>>
              <i8 as Foo<u16>>
              <i8 as Foo<u32>>
@@ -44,7 +44,7 @@ LL |     Foo::<i32>::bar(&true);
    |     |
    |     required by a bound introduced by this call
    |
-   = help: the following other types implement trait `Foo<bool>`:
+   = help: the following other types implement trait `Foo<B>`:
              <bool as Foo<bool>>
              <bool as Foo<i8>>
              <bool as Foo<u16>>

src/test/ui/did_you_mean/issue-49746-unicode-confusable-in-float-literal-expt.stderr

@@ -22,7 +22,7 @@ LL | const UNIVERSAL_GRAVITATIONAL_CONSTANT: f64 = 6.674e−11; // m³⋅kg⁻¹
    |                                                     ^ no implementation for `{float} - {integer}`
    |
    = help: the trait `Sub<{integer}>` is not implemented for `{float}`
-   = help: the following other types implement trait `Sub`:
+   = help: the following other types implement trait `Sub<Rhs>`:
              <&'a f32 as Sub<f32>>
              <&'a f64 as Sub<f64>>
              <&'a i128 as Sub<i128>>

src/test/ui/impl-trait/equality.stderr

@@ -24,7 +24,7 @@ LL |         n + sum_to(n - 1)
    |           ^ no implementation for `u32 + impl Foo`
    |
    = help: the trait `Add<impl Foo>` is not implemented for `u32`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>

src/test/ui/issues/issue-11771.stderr

@@ -5,7 +5,7 @@ LL |     1 +
    |       ^ no implementation for `{integer} + ()`
    |
    = help: the trait `Add<()>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>
@@ -23,7 +23,7 @@ LL |     1 +
    |       ^ no implementation for `{integer} + ()`
    |
    = help: the trait `Add<()>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>

src/test/ui/issues/issue-24352.stderr

@@ -5,7 +5,7 @@ LL |     1.0f64 - 1
    |            ^ no implementation for `f64 - {integer}`
    |
    = help: the trait `Sub<{integer}>` is not implemented for `f64`
-   = help: the following other types implement trait `Sub`:
+   = help: the following other types implement trait `Sub<Rhs>`:
              <&'a f32 as Sub<f32>>
              <&'a f64 as Sub<f64>>
              <&'a i128 as Sub<i128>>

src/test/ui/issues/issue-50582.stderr

@@ -14,7 +14,7 @@ LL |     Vec::<[(); 1 + for x in 0..1 {}]>::new();
    |                  ^ no implementation for `{integer} + ()`
    |
    = help: the trait `Add<()>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>

src/test/ui/lexer/lex-bad-char-literals-6.stderr

@@ -38,7 +38,7 @@ LL |     if x == y {}
    |          ^^ no implementation for `&str == char`
    |
    = help: the trait `PartialEq<char>` is not implemented for `&str`
-   = help: the following other types implement trait `PartialEq<Cow<'a, str>>`:
+   = help: the following other types implement trait `PartialEq<Rhs>`:
              <&'a str as PartialEq<OsString>>
              <&'a str as PartialEq<String>>
              <&'b str as PartialEq<Cow<'a, str>>>
@@ -64,7 +64,7 @@ LL |     if x == z {}
    |          ^^ no implementation for `&str == char`
    |
    = help: the trait `PartialEq<char>` is not implemented for `&str`
-   = help: the following other types implement trait `PartialEq<Cow<'a, str>>`:
+   = help: the following other types implement trait `PartialEq<Rhs>`:
              <&'a str as PartialEq<OsString>>
              <&'a str as PartialEq<String>>
              <&'b str as PartialEq<Cow<'a, str>>>

src/test/ui/mismatched_types/binops.stderr

@@ -5,7 +5,7 @@ LL |     1 + Some(1);
    |       ^ no implementation for `{integer} + Option<{integer}>`
    |
    = help: the trait `Add<Option<{integer}>>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>
@@ -23,7 +23,7 @@ LL |     2 as usize - Some(1);
    |                ^ no implementation for `usize - Option<{integer}>`
    |
    = help: the trait `Sub<Option<{integer}>>` is not implemented for `usize`
-   = help: the following other types implement trait `Sub`:
+   = help: the following other types implement trait `Sub<Rhs>`:
              <&'a f32 as Sub<f32>>
              <&'a f64 as Sub<f64>>
              <&'a i128 as Sub<i128>>
@@ -41,7 +41,7 @@ LL |     3 * ();
    |       ^ no implementation for `{integer} * ()`
    |
    = help: the trait `Mul<()>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Mul`:
+   = help: the following other types implement trait `Mul<Rhs>`:
              <&'a f32 as Mul<f32>>
              <&'a f64 as Mul<f64>>
              <&'a i128 as Mul<i128>>
@@ -59,7 +59,7 @@ LL |     4 / "";
    |       ^ no implementation for `{integer} / &str`
    |
    = help: the trait `Div<&str>` is not implemented for `{integer}`
-   = help: the following other types implement trait `Div`:
+   = help: the following other types implement trait `Div<Rhs>`:
              <&'a f32 as Div<f32>>
              <&'a f64 as Div<f64>>
              <&'a i128 as Div<i128>>
@@ -77,7 +77,7 @@ LL |     5 < String::new();
    |       ^ no implementation for `{integer} < String` and `{integer} > String`
    |
    = help: the trait `PartialOrd<String>` is not implemented for `{integer}`
-   = help: the following other types implement trait `PartialOrd`:
+   = help: the following other types implement trait `PartialOrd<Rhs>`:
              f32
              f64
              i128
@@ -95,7 +95,7 @@ LL |     6 == Ok(1);
    |       ^^ no implementation for `{integer} == Result<{integer}, _>`
    |
    = help: the trait `PartialEq<Result<{integer}, _>>` is not implemented for `{integer}`
-   = help: the following other types implement trait `PartialEq`:
+   = help: the following other types implement trait `PartialEq<Rhs>`:
              f32
              f64
              i128

src/test/ui/never_type/issue-13352.stderr

@@ -5,7 +5,7 @@ LL |     2_usize + (loop {});
    |             ^ no implementation for `usize + ()`
    |
    = help: the trait `Add<()>` is not implemented for `usize`
-   = help: the following other types implement trait `Add`:
+   = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
              <&'a i128 as Add<i128>>