rust-lang · bors · Dec 6, 2022 · Dec 5, 2022
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -1810,7 +1810,8 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         &self,
         trait_pred: ty::PolyTraitPredicate<'tcx>,
     ) -> Vec<ImplCandidate<'tcx>> {
-        self.tcx
+        let mut candidates: Vec<_> = self
+            .tcx
             .all_impls(trait_pred.def_id())
             .filter_map(|def_id| {
                 if self.tcx.impl_polarity(def_id) == ty::ImplPolarity::Negative
@@ -1826,7 +1827,14 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 self.fuzzy_match_tys(trait_pred.skip_binder().self_ty(), imp.self_ty(), false)
                     .map(|similarity| ImplCandidate { trait_ref: imp, similarity })
             })
-            .collect()
+            .collect();
+        if candidates.iter().any(|c| matches!(c.similarity, CandidateSimilarity::Exact { .. })) {
+            // If any of the candidates is a perfect match, we don't want to show all of them.
+            // This is particularly relevant for the case of numeric types (as they all have the
+            // same cathegory).
+            candidates.retain(|c| matches!(c.similarity, CandidateSimilarity::Exact { .. }));
+        }
+        candidates
     }
 
     fn report_similar_impl_candidates(

diff --git a/src/test/ui/binop/binop-mul-i32-f32.stderr b/src/test/ui/binop/binop-mul-i32-f32.stderr
@@ -6,15 +6,10 @@ LL |     x * y
    |
    = help: the trait `Mul<f32>` is not implemented for `i32`
    = help: the following other types implement trait `Mul<Rhs>`:
-             <&'a f32 as Mul<f32>>
-             <&'a f64 as Mul<f64>>
-             <&'a i128 as Mul<i128>>
-             <&'a i16 as Mul<i16>>
              <&'a i32 as Mul<i32>>
-             <&'a i64 as Mul<i64>>
-             <&'a i8 as Mul<i8>>
-             <&'a isize as Mul<isize>>
-           and 49 others
+             <&i32 as Mul<&i32>>
+             <i32 as Mul<&i32>>
+             <i32 as Mul>
 
 error: aborting due to previous error
 

diff --git a/src/test/ui/const-generics/defaults/rp_impl_trait_fail.stderr b/src/test/ui/const-generics/defaults/rp_impl_trait_fail.stderr
@@ -18,9 +18,7 @@ LL |
 LL |     1_u32
    |     ----- return type was inferred to be `u32` here
    |
-   = help: the following other types implement trait `Traitor<N, M>`:
-             <u32 as Traitor<N, 2>>
-             <u64 as Traitor<1, 2>>
+   = help: the trait `Traitor<N, 2>` is implemented for `u32`
 
 error[E0277]: the trait bound `u64: Traitor` is not satisfied
   --> $DIR/rp_impl_trait_fail.rs:21:13
@@ -31,9 +29,7 @@ LL |
 LL |     1_u64
    |     ----- return type was inferred to be `u64` here
    |
-   = help: the following other types implement trait `Traitor<N, M>`:
-             <u32 as Traitor<N, 2>>
-             <u64 as Traitor<1, 2>>
+   = help: the trait `Traitor<1, 2>` is implemented for `u64`
 
 error: aborting due to 3 previous errors
 

diff --git a/src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr b/src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr
@@ -12,15 +12,10 @@ LL |     = [0; (i8::MAX + 1u8) as usize];
    |
    = help: the trait `~const Add<u8>` is not implemented for `i8`
    = help: the following other types implement trait `Add<Rhs>`:
-             <&'a f32 as Add<f32>>
-             <&'a f64 as Add<f64>>
-             <&'a i128 as Add<i128>>
-             <&'a i16 as Add<i16>>
-             <&'a i32 as Add<i32>>
-             <&'a i64 as Add<i64>>
              <&'a i8 as Add<i8>>
-             <&'a isize as Add<isize>>
-           and 48 others
+             <&i8 as Add<&i8>>
+             <i8 as Add<&i8>>
+             <i8 as Add>
 
 error: aborting due to 2 previous errors
 

diff --git a/src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr b/src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr
@@ -12,15 +12,10 @@ LL |     : [u32; (i8::MAX as i8 + 1u8) as usize]
    |
    = help: the trait `~const Add<u8>` is not implemented for `i8`
    = help: the following other types implement trait `Add<Rhs>`:
-             <&'a f32 as Add<f32>>
-             <&'a f64 as Add<f64>>
-             <&'a i128 as Add<i128>>
-             <&'a i16 as Add<i16>>
-             <&'a i32 as Add<i32>>
-             <&'a i64 as Add<i64>>
              <&'a i8 as Add<i8>>
-             <&'a isize as Add<isize>>
-           and 48 others
+             <&i8 as Add<&i8>>
+             <i8 as Add<&i8>>
+             <i8 as Add>
 
 error[E0604]: only `u8` can be cast as `char`, not `i8`
   --> $DIR/const-eval-overflow-4b.rs:22:13

diff --git a/src/test/ui/did_you_mean/issue-39802-show-5-trait-impls.stderr b/src/test/ui/did_you_mean/issue-39802-show-5-trait-impls.stderr
@@ -12,10 +12,6 @@ LL |     Foo::<i32>::bar(&1i8);
              <i8 as Foo<u32>>
              <i8 as Foo<u64>>
              <i8 as Foo<u8>>
-             <u8 as Foo<bool>>
-             <u8 as Foo<u16>>
-             <u8 as Foo<u32>>
-             <u8 as Foo<u64>>
 
 error[E0277]: the trait bound `u8: Foo<i32>` is not satisfied
   --> $DIR/issue-39802-show-5-trait-impls.rs:25:21
@@ -26,11 +22,6 @@ LL |     Foo::<i32>::bar(&1u8);
    |     required by a bound introduced by this call
    |
    = help: the following other types implement trait `Foo<B>`:
-             <i8 as Foo<bool>>
-             <i8 as Foo<u16>>
-             <i8 as Foo<u32>>
-             <i8 as Foo<u64>>
-             <i8 as Foo<u8>>
              <u8 as Foo<bool>>
              <u8 as Foo<u16>>
              <u8 as Foo<u32>>

diff --git a/src/test/ui/impl-trait/equality.stderr b/src/test/ui/impl-trait/equality.stderr
@@ -30,15 +30,10 @@ LL |         n + sum_to(n - 1)
    |
    = help: the trait `Add<impl Foo>` is not implemented for `u32`
    = help: the following other types implement trait `Add<Rhs>`:
-             <&'a f32 as Add<f32>>
-             <&'a f64 as Add<f64>>
-             <&'a i128 as Add<i128>>
-             <&'a i16 as Add<i16>>
-             <&'a i32 as Add<i32>>
-             <&'a i64 as Add<i64>>
-             <&'a i8 as Add<i8>>
-             <&'a isize as Add<isize>>
-           and 48 others
+             <&'a u32 as Add<u32>>
+             <&u32 as Add<&u32>>
+             <u32 as Add<&u32>>
+             <u32 as Add>
 
 error: aborting due to 2 previous errors; 1 warning emitted
 

diff --git a/src/test/ui/issues/issue-24352.stderr b/src/test/ui/issues/issue-24352.stderr
@@ -6,15 +6,10 @@ LL |     1.0f64 - 1
    |
    = help: the trait `Sub<{integer}>` is not implemented for `f64`
    = help: the following other types implement trait `Sub<Rhs>`:
-             <&'a f32 as Sub<f32>>
              <&'a f64 as Sub<f64>>
-             <&'a i128 as Sub<i128>>
-             <&'a i16 as Sub<i16>>
-             <&'a i32 as Sub<i32>>
-             <&'a i64 as Sub<i64>>
-             <&'a i8 as Sub<i8>>
-             <&'a isize as Sub<isize>>
-           and 48 others
+             <&f64 as Sub<&f64>>
+             <f64 as Sub<&f64>>
+             <f64 as Sub>
 help: consider using a floating-point literal by writing it with `.0`
    |
 LL |     1.0f64 - 1.0

diff --git a/src/test/ui/kindck/kindck-copy.stderr b/src/test/ui/kindck/kindck-copy.stderr
@@ -4,16 +4,7 @@ error[E0277]: the trait bound `&'static mut isize: Copy` is not satisfied
 LL |     assert_copy::<&'static mut isize>();
    |                   ^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `&'static mut isize`
    |
-   = help: the following other types implement trait `Copy`:
-             f32
-             f64
-             i128
-             i16
-             i32
-             i64
-             i8
-             isize
-           and 6 others
+   = help: the trait `Copy` is implemented for `isize`
 note: required by a bound in `assert_copy`
   --> $DIR/kindck-copy.rs:5:18
    |
@@ -26,16 +17,7 @@ error[E0277]: the trait bound `&'a mut isize: Copy` is not satisfied
 LL |     assert_copy::<&'a mut isize>();
    |                   ^^^^^^^^^^^^^ the trait `Copy` is not implemented for `&'a mut isize`
    |
-   = help: the following other types implement trait `Copy`:
-             f32
-             f64
-             i128
-             i16
-             i32
-             i64
-             i8
-             isize
-           and 6 others
+   = help: the trait `Copy` is implemented for `isize`
 note: required by a bound in `assert_copy`
   --> $DIR/kindck-copy.rs:5:18
    |

diff --git a/src/test/ui/lexer/lex-bad-char-literals-6.stderr b/src/test/ui/lexer/lex-bad-char-literals-6.stderr
@@ -42,12 +42,11 @@ LL |     if x == y {}
              <&'a str as PartialEq<OsString>>
              <&'a str as PartialEq<String>>
              <&'b str as PartialEq<Cow<'a, str>>>
-             <String as PartialEq<&'a str>>
-             <String as PartialEq<Cow<'a, str>>>
-             <String as PartialEq<str>>
-             <String as PartialEq>
              <str as PartialEq<Cow<'a, str>>>
-           and 4 others
+             <str as PartialEq<OsStr>>
+             <str as PartialEq<OsString>>
+             <str as PartialEq<String>>
+             <str as PartialEq>
 
 error[E0308]: mismatched types
   --> $DIR/lex-bad-char-literals-6.rs:15:20
@@ -68,12 +67,11 @@ LL |     if x == z {}
              <&'a str as PartialEq<OsString>>
              <&'a str as PartialEq<String>>
              <&'b str as PartialEq<Cow<'a, str>>>
-             <String as PartialEq<&'a str>>
-             <String as PartialEq<Cow<'a, str>>>
-             <String as PartialEq<str>>
-             <String as PartialEq>
              <str as PartialEq<Cow<'a, str>>>
-           and 4 others
+             <str as PartialEq<OsStr>>
+             <str as PartialEq<OsString>>
+             <str as PartialEq<String>>
+             <str as PartialEq>
 
 error: aborting due to 6 previous errors
 

diff --git a/src/test/ui/mismatched_types/binops.stderr b/src/test/ui/mismatched_types/binops.stderr
@@ -24,15 +24,10 @@ LL |     2 as usize - Some(1);
    |
    = help: the trait `Sub<Option<{integer}>>` is not implemented for `usize`
    = help: the following other types implement trait `Sub<Rhs>`:
-             <&'a f32 as Sub<f32>>
-             <&'a f64 as Sub<f64>>
-             <&'a i128 as Sub<i128>>
-             <&'a i16 as Sub<i16>>
-             <&'a i32 as Sub<i32>>
-             <&'a i64 as Sub<i64>>
-             <&'a i8 as Sub<i8>>
-             <&'a isize as Sub<isize>>
-           and 48 others
+             <&'a usize as Sub<usize>>
+             <&usize as Sub<&usize>>
+             <usize as Sub<&usize>>
+             <usize as Sub>
 
 error[E0277]: cannot multiply `{integer}` by `()`
   --> $DIR/binops.rs:4:7

diff --git a/src/test/ui/never_type/issue-13352.stderr b/src/test/ui/never_type/issue-13352.stderr
@@ -6,15 +6,10 @@ LL |     2_usize + (loop {});
    |
    = help: the trait `Add<()>` is not implemented for `usize`
    = help: the following other types implement trait `Add<Rhs>`:
-             <&'a f32 as Add<f32>>
-             <&'a f64 as Add<f64>>
-             <&'a i128 as Add<i128>>
-             <&'a i16 as Add<i16>>
-             <&'a i32 as Add<i32>>
-             <&'a i64 as Add<i64>>
-             <&'a i8 as Add<i8>>
-             <&'a isize as Add<isize>>
-           and 48 others
+             <&'a usize as Add<usize>>
+             <&usize as Add<&usize>>
+             <usize as Add<&usize>>
+             <usize as Add>
 
 error: aborting due to previous error