Trim output of E0277 in some cases

Remove default note for "trait is not implemented" in favor of the
more colorful diff output from the previous commit. Removes
duplicated output.

16 files changed, 18 insertions, 34 deletions

diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index 358c244eca9..dd2f0ec2096 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -6,8 +6,8 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
 use rustc_errors::{
-    Applicability, Diag, ErrorGuaranteed, MultiSpan, StashKey, StringPart, Suggestions, pluralize,
-    struct_span_code_err,
+    Applicability, Diag, ErrorGuaranteed, Level, MultiSpan, StashKey, StringPart, Suggestions,
+    pluralize, struct_span_code_err,
 };
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
@@ -1833,6 +1833,22 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         return false;
                     }
 
+                    if let [child, ..] = &err.children[..]
+                        && child.level == Level::Help
+                        && let Some(line) = child.messages.get(0)
+                        && let Some(line) = line.0.as_str()
+                        && line.starts_with("the trait")
+                        && line.contains("is not implemented for")
+                    {
+                        // HACK(estebank): we remove the pre-existing
+                        // "the trait `X` is not implemented for" note, which only happens if there
+                        // was a custom label. We do this because we want that note to always be the
+                        // first, and making this logic run earlier will get tricky. For now, we
+                        // instead keep the logic the same and modify the already constructed error
+                        // to avoid the wording duplication.
+                        err.children.remove(0);
+                    }
+
                     let traits = self.cmp_traits(
                         obligation_trait_ref.def_id,
                         &obligation_trait_ref.args[1..],
diff --git a/tests/ui/indexing/index-help.stderr b/tests/ui/indexing/index-help.stderr
index d4637da1426..1974e13eabc 100644
--- a/tests/ui/indexing/index-help.stderr
+++ b/tests/ui/indexing/index-help.stderr
@@ -5,7 +5,6 @@ LL |     x[0i32];
    |       ^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[{integer}]>` is not implemented for `i32`
-   = help: the trait `SliceIndex<[{integer}]>` is not implemented for `i32`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `i32`
    = note: required for `Vec<{integer}>` to implement `Index<i32>`
diff --git a/tests/ui/indexing/indexing-requires-a-uint.stderr b/tests/ui/indexing/indexing-requires-a-uint.stderr
index fdcf9b030a5..5c60a30946d 100644
--- a/tests/ui/indexing/indexing-requires-a-uint.stderr
+++ b/tests/ui/indexing/indexing-requires-a-uint.stderr
@@ -5,7 +5,6 @@ LL |     [0][0u8];
    |         ^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[{integer}]>` is not implemented for `u8`
-   = help: the trait `SliceIndex<[{integer}]>` is not implemented for `u8`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `u8`
    = note: required for `[{integer}]` to implement `Index<u8>`
diff --git a/tests/ui/integral-indexing.stderr b/tests/ui/integral-indexing.stderr
index f731d303774..e7a45c2c88d 100644
--- a/tests/ui/integral-indexing.stderr
+++ b/tests/ui/integral-indexing.stderr
@@ -5,7 +5,6 @@ LL |     v[3u8];
    |       ^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[isize]>` is not implemented for `u8`
-   = help: the trait `SliceIndex<[isize]>` is not implemented for `u8`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `u8`
    = note: required for `Vec<isize>` to implement `Index<u8>`
@@ -17,7 +16,6 @@ LL |     v[3i8];
    |       ^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[isize]>` is not implemented for `i8`
-   = help: the trait `SliceIndex<[isize]>` is not implemented for `i8`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `i8`
    = note: required for `Vec<isize>` to implement `Index<i8>`
@@ -29,7 +27,6 @@ LL |     v[3u32];
    |       ^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[isize]>` is not implemented for `u32`
-   = help: the trait `SliceIndex<[isize]>` is not implemented for `u32`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `u32`
    = note: required for `Vec<isize>` to implement `Index<u32>`
@@ -41,7 +38,6 @@ LL |     v[3i32];
    |       ^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[isize]>` is not implemented for `i32`
-   = help: the trait `SliceIndex<[isize]>` is not implemented for `i32`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `i32`
    = note: required for `Vec<isize>` to implement `Index<i32>`
@@ -53,7 +49,6 @@ LL |     s.as_bytes()[3u8];
    |                  ^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[u8]>` is not implemented for `u8`
-   = help: the trait `SliceIndex<[u8]>` is not implemented for `u8`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `u8`
    = note: required for `[u8]` to implement `Index<u8>`
@@ -65,7 +60,6 @@ LL |     s.as_bytes()[3i8];
    |                  ^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[u8]>` is not implemented for `i8`
-   = help: the trait `SliceIndex<[u8]>` is not implemented for `i8`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `i8`
    = note: required for `[u8]` to implement `Index<i8>`
@@ -77,7 +71,6 @@ LL |     s.as_bytes()[3u32];
    |                  ^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[u8]>` is not implemented for `u32`
-   = help: the trait `SliceIndex<[u8]>` is not implemented for `u32`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `u32`
    = note: required for `[u8]` to implement `Index<u32>`
@@ -89,7 +82,6 @@ LL |     s.as_bytes()[3i32];
    |                  ^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[u8]>` is not implemented for `i32`
-   = help: the trait `SliceIndex<[u8]>` is not implemented for `i32`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `i32`
    = note: required for `[u8]` to implement `Index<i32>`
diff --git a/tests/ui/issues/issue-34334.stderr b/tests/ui/issues/issue-34334.stderr
index 8213136faa1..6562ccfdcd2 100644
--- a/tests/ui/issues/issue-34334.stderr
+++ b/tests/ui/issues/issue-34334.stderr
@@ -18,7 +18,6 @@ LL |     let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_rece
    |                                                                                       ^^^^^^^ value of type `Vec<(u32, _, _)>` cannot be built from `std::iter::Iterator<Item=()>`
    |
    = help: the trait `FromIterator<()>` is not implemented for `Vec<(u32, _, _)>`
-   = help: the trait `FromIterator<()>` is not implemented for `Vec<(u32, _, _)>`
            but trait `FromIterator<(u32, _, _)>` is implemented for it
    = help: for that trait implementation, expected `(u32, _, _)`, found `()`
 note: the method call chain might not have had the expected associated types
diff --git a/tests/ui/issues/issue-66923-show-error-for-correct-call.stderr b/tests/ui/issues/issue-66923-show-error-for-correct-call.stderr
index e62be48edf6..d2852093725 100644
--- a/tests/ui/issues/issue-66923-show-error-for-correct-call.stderr
+++ b/tests/ui/issues/issue-66923-show-error-for-correct-call.stderr
@@ -4,7 +4,6 @@ error[E0277]: a value of type `Vec<f64>` cannot be built from an iterator over e
 LL |     let x2: Vec<f64> = x1.into_iter().collect();
    |                                       ^^^^^^^ value of type `Vec<f64>` cannot be built from `std::iter::Iterator<Item=&f64>`
    |
-   = help: the trait `FromIterator<&f64>` is not implemented for `Vec<f64>`
    = help: the trait `FromIterator<&_>` is not implemented for `Vec<f64>`
            but trait `FromIterator<_>` is implemented for it
    = help: for that trait implementation, expected `f64`, found `&f64`
@@ -26,7 +25,6 @@ LL |     let x3 = x1.into_iter().collect::<Vec<f64>>();
    |                             |
    |                             required by a bound introduced by this call
    |
-   = help: the trait `FromIterator<&f64>` is not implemented for `Vec<f64>`
    = help: the trait `FromIterator<&_>` is not implemented for `Vec<f64>`
            but trait `FromIterator<_>` is implemented for it
    = help: for that trait implementation, expected `f64`, found `&f64`
diff --git a/tests/ui/iterators/invalid-iterator-chain-fixable.stderr b/tests/ui/iterators/invalid-iterator-chain-fixable.stderr
index d6f82741c4c..09439fe8fbd 100644
--- a/tests/ui/iterators/invalid-iterator-chain-fixable.stderr
+++ b/tests/ui/iterators/invalid-iterator-chain-fixable.stderr
@@ -6,7 +6,6 @@ LL |     let i = i.map(|x| x.clone());
 LL |     i.collect()
    |       ^^^^^^^ value of type `Vec<X>` cannot be built from `std::iter::Iterator<Item=&X>`
    |
-   = help: the trait `FromIterator<&X>` is not implemented for `Vec<X>`
    = help: the trait `FromIterator<&_>` is not implemented for `Vec<X>`
            but trait `FromIterator<_>` is implemented for it
    = help: for that trait implementation, expected `X`, found `&X`
@@ -125,7 +124,6 @@ LL |     let g: Vec<i32> = f.collect();
    |                         ^^^^^^^ value of type `Vec<i32>` cannot be built from `std::iter::Iterator<Item=()>`
    |
    = help: the trait `FromIterator<()>` is not implemented for `Vec<i32>`
-   = help: the trait `FromIterator<()>` is not implemented for `Vec<i32>`
            but trait `FromIterator<i32>` is implemented for it
    = help: for that trait implementation, expected `i32`, found `()`
 note: the method call chain might not have had the expected associated types
diff --git a/tests/ui/iterators/invalid-iterator-chain.stderr b/tests/ui/iterators/invalid-iterator-chain.stderr
index 2522471b3b5..b810e06d0f7 100644
--- a/tests/ui/iterators/invalid-iterator-chain.stderr
+++ b/tests/ui/iterators/invalid-iterator-chain.stderr
@@ -6,7 +6,6 @@ LL |     let i = i.map(|x| x.clone());
 LL |     i.collect()
    |       ^^^^^^^ value of type `Vec<X>` cannot be built from `std::iter::Iterator<Item=&X>`
    |
-   = help: the trait `FromIterator<&X>` is not implemented for `Vec<X>`
    = help: the trait `FromIterator<&_>` is not implemented for `Vec<X>`
            but trait `FromIterator<_>` is implemented for it
    = help: for that trait implementation, expected `X`, found `&X`
@@ -182,7 +181,6 @@ LL |     let g: Vec<i32> = f.collect();
    |                         ^^^^^^^ value of type `Vec<i32>` cannot be built from `std::iter::Iterator<Item=()>`
    |
    = help: the trait `FromIterator<()>` is not implemented for `Vec<i32>`
-   = help: the trait `FromIterator<()>` is not implemented for `Vec<i32>`
            but trait `FromIterator<i32>` is implemented for it
    = help: for that trait implementation, expected `i32`, found `()`
 note: the method call chain might not have had the expected associated types
diff --git a/tests/ui/on-unimplemented/impl-substs.stderr b/tests/ui/on-unimplemented/impl-substs.stderr
index cdb9172ef0f..b85d45eba5b 100644
--- a/tests/ui/on-unimplemented/impl-substs.stderr
+++ b/tests/ui/on-unimplemented/impl-substs.stderr
@@ -7,7 +7,6 @@ LL |     Foo::<usize>::foo((1i32, 1i32, 1i32));
    |     required by a bound introduced by this call
    |
    = help: the trait `Foo<usize>` is not implemented for `(i32, i32, i32)`
-   = help: the trait `Foo<usize>` is not implemented for `(i32, i32, i32)`
            but trait `Foo<i32>` is implemented for it
    = help: for that trait implementation, expected `i32`, found `usize`
 
diff --git a/tests/ui/on-unimplemented/on-impl.stderr b/tests/ui/on-unimplemented/on-impl.stderr
index d20b559def7..5e7e2c4ea77 100644
--- a/tests/ui/on-unimplemented/on-impl.stderr
+++ b/tests/ui/on-unimplemented/on-impl.stderr
@@ -7,7 +7,6 @@ LL |     Index::<u32>::index(&[1, 2, 3] as &[i32], 2u32);
    |     required by a bound introduced by this call
    |
    = help: the trait `Index<u32>` is not implemented for `[i32]`
-   = help: the trait `Index<u32>` is not implemented for `[i32]`
            but trait `Index<usize>` is implemented for it
    = help: for that trait implementation, expected `usize`, found `u32`
 
@@ -18,7 +17,6 @@ LL |     Index::<u32>::index(&[1, 2, 3] as &[i32], 2u32);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ a usize is required to index into a slice
    |
    = help: the trait `Index<u32>` is not implemented for `[i32]`
-   = help: the trait `Index<u32>` is not implemented for `[i32]`
            but trait `Index<usize>` is implemented for it
    = help: for that trait implementation, expected `usize`, found `u32`
 
diff --git a/tests/ui/on-unimplemented/slice-index.stderr b/tests/ui/on-unimplemented/slice-index.stderr
index 8f7169b30d4..0a9ebe3f088 100644
--- a/tests/ui/on-unimplemented/slice-index.stderr
+++ b/tests/ui/on-unimplemented/slice-index.stderr
@@ -5,7 +5,6 @@ LL |     x[1i32];
    |       ^^^^ slice indices are of type `usize` or ranges of `usize`
    |
    = help: the trait `SliceIndex<[i32]>` is not implemented for `i32`
-   = help: the trait `SliceIndex<[i32]>` is not implemented for `i32`
            but it is implemented for `usize`
    = help: for that trait implementation, expected `usize`, found `i32`
    = note: required for `[i32]` to implement `Index<i32>`
diff --git a/tests/ui/str/str-idx.stderr b/tests/ui/str/str-idx.stderr
index 0ce0c207561..bedbbd9cb50 100644
--- a/tests/ui/str/str-idx.stderr
+++ b/tests/ui/str/str-idx.stderr
@@ -4,7 +4,6 @@ error[E0277]: the type `str` cannot be indexed by `{integer}`
 LL |     let _: u8 = s[4];
    |                   ^ string indices are ranges of `usize`
    |
-   = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
    = note: you can use `.chars().nth()` or `.bytes().nth()`
            for more information, see chapter 8 in The Book: <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>
    = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
@@ -20,7 +19,6 @@ LL |     let _ = s.get(4);
    |               |
    |               required by a bound introduced by this call
    |
-   = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
    = note: you can use `.chars().nth()` or `.bytes().nth()`
            for more information, see chapter 8 in The Book: <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>
    = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
@@ -37,7 +35,6 @@ LL |     let _ = s.get_unchecked(4);
    |               |
    |               required by a bound introduced by this call
    |
-   = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
    = note: you can use `.chars().nth()` or `.bytes().nth()`
            for more information, see chapter 8 in The Book: <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>
    = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
diff --git a/tests/ui/str/str-mut-idx.stderr b/tests/ui/str/str-mut-idx.stderr
index 7bc46ff33b3..f09a4c329e5 100644
--- a/tests/ui/str/str-mut-idx.stderr
+++ b/tests/ui/str/str-mut-idx.stderr
@@ -31,7 +31,6 @@ LL |     s[1usize] = bot();
    |       ^^^^^^ string indices are ranges of `usize`
    |
    = help: the trait `SliceIndex<str>` is not implemented for `usize`
-   = help: the trait `SliceIndex<str>` is not implemented for `usize`
            but trait `SliceIndex<[_]>` is implemented for it
    = help: for that trait implementation, expected `[_]`, found `str`
    = note: required for `str` to implement `Index<usize>`
@@ -44,7 +43,6 @@ LL |     s.get_mut(1);
    |       |
    |       required by a bound introduced by this call
    |
-   = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
    = note: you can use `.chars().nth()` or `.bytes().nth()`
            for more information, see chapter 8 in The Book: <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>
    = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
@@ -61,7 +59,6 @@ LL |     s.get_unchecked_mut(1);
    |       |
    |       required by a bound introduced by this call
    |
-   = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
    = note: you can use `.chars().nth()` or `.bytes().nth()`
            for more information, see chapter 8 in The Book: <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>
    = help: the trait `SliceIndex<str>` is not implemented for `{integer}`
diff --git a/tests/ui/suggestions/suggest-dereferencing-index.stderr b/tests/ui/suggestions/suggest-dereferencing-index.stderr
index cd5364fcffb..0335d8eafde 100644
--- a/tests/ui/suggestions/suggest-dereferencing-index.stderr
+++ b/tests/ui/suggestions/suggest-dereferencing-index.stderr
@@ -4,7 +4,6 @@ error[E0277]: the type `[{integer}]` cannot be indexed by `&usize`
 LL |     let one_item_please: i32 = [1, 2, 3][i];
    |                                          ^ slice indices are of type `usize` or ranges of `usize`
    |
-   = help: the trait `SliceIndex<[{integer}]>` is not implemented for `&usize`
    = help: the trait `SliceIndex<[{integer}]>` is not implemented for `&_`
            but it is implemented for `_`
    = help: for that trait implementation, expected `usize`, found `&usize`
diff --git a/tests/ui/try-trait/bad-interconversion.stderr b/tests/ui/try-trait/bad-interconversion.stderr
index 20fe2d721bc..bb5e5646ad2 100644
--- a/tests/ui/try-trait/bad-interconversion.stderr
+++ b/tests/ui/try-trait/bad-interconversion.stderr
@@ -67,7 +67,6 @@ LL |     ControlFlow::Continue(Err("hello")?)
    |                                       ^ this `?` produces `Result<Infallible, &str>`, which is incompatible with `ControlFlow<String>`
    |
    = help: the trait `FromResidual<Result<Infallible, &str>>` is not implemented for `ControlFlow<String>`
-   = help: the trait `FromResidual<Result<Infallible, &str>>` is not implemented for `ControlFlow<String>`
            but trait `FromResidual<ControlFlow<String, Infallible>>` is implemented for it
    = help: for that trait implementation, expected `ControlFlow<String, Infallible>`, found `Result<Infallible, &str>`
 
@@ -80,7 +79,6 @@ LL |     Some(3)?;
    |            ^ this `?` produces `Option<Infallible>`, which is incompatible with `ControlFlow<u64>`
    |
    = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `ControlFlow<u64>`
-   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `ControlFlow<u64>`
            but trait `FromResidual<ControlFlow<u64, Infallible>>` is implemented for it
    = help: for that trait implementation, expected `ControlFlow<u64, Infallible>`, found `Option<Infallible>`
 
@@ -92,7 +90,6 @@ LL | fn control_flow_to_control_flow() -> ControlFlow<i64> {
 LL |     ControlFlow::Break(4_u8)?;
    |                             ^ this `?` produces `ControlFlow<u8, Infallible>`, which is incompatible with `ControlFlow<i64>`
    |
-   = help: the trait `FromResidual<ControlFlow<u8, Infallible>>` is not implemented for `ControlFlow<i64>`
    = note: unlike `Result`, there's no `From`-conversion performed for `ControlFlow`
    = help: the trait `FromResidual<ControlFlow<u8, _>>` is not implemented for `ControlFlow<i64>`
            but trait `FromResidual<ControlFlow<i64, _>>` is implemented for it
diff --git a/tests/ui/type-alias-impl-trait/self-referential-2.current.stderr b/tests/ui/type-alias-impl-trait/self-referential-2.current.stderr
index 1e799f15635..e4399f2d8f4 100644
--- a/tests/ui/type-alias-impl-trait/self-referential-2.current.stderr
+++ b/tests/ui/type-alias-impl-trait/self-referential-2.current.stderr
@@ -7,7 +7,6 @@ LL |     42_i32
    |     ------ return type was inferred to be `i32` here
    |
    = help: the trait `PartialEq<Foo>` is not implemented for `i32`
-   = help: the trait `PartialEq<Foo>` is not implemented for `i32`
            but trait `PartialEq<i32>` is implemented for it
 
 error: aborting due to 1 previous error