Trim output of E0277 in some cases

estebank · estebank · commit 7b9105dd8865 · 2024-11-02T03:08:04.000Z
Remove default note for "trait is not implemented" in favor of the
more colorful diff output from the previous commit. Removes
duplicated output.
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
@@ -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
@@ -4,7 +4,6 @@ error[E0277]: the type `[{integer}]` cannot be indexed by `i32`
 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`
diff --git a/tests/ui/indexing/indexing-requires-a-uint.stderr b/tests/ui/indexing/indexing-requires-a-uint.stderr
@@ -4,7 +4,6 @@ error[E0277]: the type `[{integer}]` cannot be indexed by `u8`
 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`
diff --git a/tests/ui/integral-indexing.stderr b/tests/ui/integral-indexing.stderr
@@ -4,7 +4,6 @@ error[E0277]: the type `[isize]` cannot be indexed by `u8`
 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`
@@ -16,7 +15,6 @@ error[E0277]: the type `[isize]` cannot be indexed by `i8`
 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`
@@ -28,7 +26,6 @@ error[E0277]: the type `[isize]` cannot be indexed by `u32`
 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`
@@ -40,7 +37,6 @@ error[E0277]: the type `[isize]` cannot be indexed by `i32`
 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`
@@ -52,7 +48,6 @@ error[E0277]: the type `[u8]` cannot be indexed by `u8`
 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`
@@ -64,7 +59,6 @@ error[E0277]: the type `[u8]` cannot be indexed by `i8`
 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`
@@ -76,7 +70,6 @@ error[E0277]: the type `[u8]` cannot be indexed by `u32`
 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`
@@ -88,7 +81,6 @@ error[E0277]: the type `[u8]` cannot be indexed by `i32`
 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`
diff --git a/tests/ui/issues/issue-34334.stderr b/tests/ui/issues/issue-34334.stderr
@@ -17,7 +17,6 @@ error[E0277]: a value of type `Vec<(u32, _, _)>` cannot be built from an iterato
 LL |     let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();
    |                                                                                       ^^^^^^^ 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 `()`
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
@@ -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
@@ -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`
@@ -124,7 +123,6 @@ error[E0277]: a value of type `Vec<i32>` cannot be built from an iterator over e
 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 `()`
diff --git 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`
@@ -181,7 +180,6 @@ error[E0277]: a value of type `Vec<i32>` cannot be built from an iterator over e
 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 `()`
diff --git a/tests/ui/on-unimplemented/impl-substs.stderr b/tests/ui/on-unimplemented/impl-substs.stderr
@@ -6,7 +6,6 @@ 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
@@ -6,7 +6,6 @@ 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`
@@ -17,7 +16,6 @@ error[E0277]: the trait bound `[i32]: Index<u32>` is not satisfied
 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
@@ -4,7 +4,6 @@ error[E0277]: the type `[i32]` cannot be indexed by `i32`
 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`
diff --git 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
@@ -30,7 +30,6 @@ error[E0277]: the type `str` cannot be indexed by `usize`
 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`
@@ -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
@@ -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
@@ -66,7 +66,6 @@ LL | fn result_to_control_flow() -> ControlFlow<String> {
 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>`
@@ -79,7 +78,6 @@ LL | fn option_to_control_flow() -> ControlFlow<u64> {
 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
@@ -6,7 +6,6 @@ LL | fn bar() -> Bar {
 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
 

Original file line number	Diff line number	Diff line change
@@ -4,7 +4,6 @@ error[E0277]: the type `[{integer}]` cannot be indexed by `i32`
`4`	`4`	`LL \| x[0i32];`
`5`	`5`	\| ^^^^ slice indices are of type `usize` or ranges of `usize`
`6`	`6`	`\|`
`7`		- = help: the trait `SliceIndex<[{integer}]>` is not implemented for `i32`
`8`	`7`	= help: the trait `SliceIndex<[{integer}]>` is not implemented for `i32`
`9`	`8`	but it is implemented for `usize`
`10`	`9`	= help: for that trait implementation, expected `usize`, found `i32`
Original file line number	Diff line number	Diff line change
@@ -4,7 +4,6 @@ error[E0277]: the type `[{integer}]` cannot be indexed by `u8`
`4`	`4`	`LL \| [0][0u8];`
`5`	`5`	\| ^^^ slice indices are of type `usize` or ranges of `usize`
`6`	`6`	`\|`
`7`		- = help: the trait `SliceIndex<[{integer}]>` is not implemented for `u8`
`8`	`7`	= help: the trait `SliceIndex<[{integer}]>` is not implemented for `u8`
`9`	`8`	but it is implemented for `usize`
`10`	`9`	= help: for that trait implementation, expected `usize`, found `u8`
Original file line number	Diff line number	Diff line change
@@ -17,7 +17,6 @@ error[E0277]: a value of type `Vec<(u32, _, _)>` cannot be built from an iterato
`17`	`17`	`LL \| let sr2: Vec<(u32, _, _)> = sr.iter().map(\|(faction, th_sender, th_receiver)\| {}).collect();`
`18`	`18`	\| ^^^^^^^ value of type `Vec<(u32, _, _)>` cannot be built from `std::iter::Iterator<Item=()>`
`19`	`19`	`\|`
`20`		- = help: the trait `FromIterator<()>` is not implemented for `Vec<(u32, _, _)>`
`21`	`20`	= help: the trait `FromIterator<()>` is not implemented for `Vec<(u32, _, _)>`
`22`	`21`	but trait `FromIterator<(u32, _, _)>` is implemented for it
`23`	`22`	= help: for that trait implementation, expected `(u32, _, _)`, found `()`
Original file line number	Diff line number	Diff line change
`@@ -6,7 +6,6 @@ LL \| Foo::<usize>::foo((1i32, 1i32, 1i32));`
`6`	`6`	`\| \|`
`7`	`7`	`\| required by a bound introduced by this call`
`8`	`8`	`\|`
`9`		- = help: the trait `Foo<usize>` is not implemented for `(i32, i32, i32)`
`10`	`9`	= help: the trait `Foo<usize>` is not implemented for `(i32, i32, i32)`
`11`	`10`	but trait `Foo<i32>` is implemented for it
`12`	`11`	= help: for that trait implementation, expected `i32`, found `usize`