Deduplicate errors that come from places like normalization, sized

compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

@@ -15,6 +15,7 @@ use crate::check::{
 use crate::structured_errors::StructuredDiagnostic;
 
 use rustc_ast as ast;
+use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{pluralize, Applicability, Diagnostic, DiagnosticId, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
@@ -1612,24 +1613,52 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         errors: &mut Vec<traits::FulfillmentError<'tcx>>,
     ) {
+        let mut remap_cause = FxHashSet::default();
+        let mut not_adjusted = vec![];
+
         for error in errors {
-            self.adjust_fulfillment_error_for_expr_obligation(error);
+            let before_span = error.obligation.cause.span;
+            if self.adjust_fulfillment_error_for_expr_obligation(error) {
+                remap_cause.insert((
+                    before_span,
+                    error.obligation.predicate,
+                    error.obligation.cause.clone(),
+                ));
+                remap_cause.insert((
+                    before_span,
+                    error.obligation.predicate.without_const(self.tcx),
+                    error.obligation.cause.clone(),
+                ));
+            } else {
+                not_adjusted.push(error);
+            }
+        }
+
+        for error in not_adjusted {
+            for (span, predicate, cause) in &remap_cause {
+                if *predicate == error.obligation.predicate
+                    && span.contains(error.obligation.cause.span)
+                {
+                    error.obligation.cause = cause.clone();
+                    continue;
+                }
+            }
         }
     }
 
     fn adjust_fulfillment_error_for_expr_obligation(
         &self,
         error: &mut traits::FulfillmentError<'tcx>,
-    ) {
+    ) -> bool {
         let (traits::ExprItemObligation(def_id, hir_id, idx) | traits::ExprBindingObligation(def_id, _, hir_id, idx))
-            = *error.obligation.cause.code().peel_derives() else { return; };
+            = *error.obligation.cause.code().peel_derives() else { return false; };
 
         // Skip over mentioning async lang item
         if Some(def_id) == self.tcx.lang_items().from_generator_fn()
             && error.obligation.cause.span.desugaring_kind()
                 == Some(rustc_span::DesugaringKind::Async)
         {
-            return;
+            return false;
         }
         // Skip over closure arg mismatch, which has a better heuristic
         // to determine what span to point at.
@@ -1638,11 +1667,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ) = error.code
             && let ty::Closure(..) | ty::Generator(..) = expected.skip_binder().self_ty().kind()
         {
-            return;
+            return false;
         }
 
         let Some(unsubstituted_pred) =
-            self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx) else { return; };
+            self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx)
+            else { return false; };
 
         let generics = self.tcx.generics_of(def_id);
         let predicate_substs = match unsubstituted_pred.kind().skip_binder() {
@@ -1709,19 +1739,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 {
                     if let Some(param_to_point_at) = param_to_point_at
                         && self.point_at_args_if_possible(error, def_id, param_to_point_at, *call_hir_id, callee.span, args) {
-                        return;
+                        return true;
                     }
 
                     if let Some(fallback_param_to_point_at) = fallback_param_to_point_at
                         && self.point_at_args_if_possible(error, def_id, fallback_param_to_point_at, *call_hir_id, callee.span, args)
                     {
-                        return;
+                        return true;
                     }
 
                     if let Some(self_param_to_point_at) = self_param_to_point_at
                         && self.point_at_args_if_possible(error, def_id, self_param_to_point_at, *call_hir_id, callee.span, args)
                     {
-                        return;
+                        return true;
                     }
 
                     if let hir::QPath::Resolved(_, path) = qpath
@@ -1729,14 +1759,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         && let Some(segment) = path.segments.last()
                         && self.point_at_generics_if_possible(error, def_id, param_to_point_at, segment)
                     {
-                        return;
+                        return true;
                     }
 
                     if let hir::QPath::TypeRelative(_, segment) = qpath
                         && let Some(param_to_point_at) = param_to_point_at
                         && self.point_at_generics_if_possible(error, def_id, param_to_point_at, segment)
                     {
-                        return;
+                        return true;
                     }
                 }
             }
@@ -1744,25 +1774,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 if let Some(param_to_point_at) = param_to_point_at
                     && self.point_at_args_if_possible(error, def_id, param_to_point_at, hir_id, segment.ident.span, args)
                 {
-                    return;
+                    return true;
                 }
 
                 if let Some(fallback_param_to_point_at) = fallback_param_to_point_at
                     && self.point_at_args_if_possible(error, def_id, fallback_param_to_point_at, hir_id, segment.ident.span, args)
                 {
-                    return;
+                    return true;
                 }
 
                 if let Some(self_param_to_point_at) = self_param_to_point_at
                     && self.point_at_args_if_possible(error, def_id, self_param_to_point_at, hir_id, segment.ident.span, args)
                 {
-                    return;
+                    return true;
                 }
 
                 if let Some(param_to_point_at) = param_to_point_at
                     && self.point_at_generics_if_possible(error, def_id, param_to_point_at, segment)
                 {
-                    return;
+                    return true;
                 }
             }
             hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Struct(..), .. }) => {
@@ -1770,6 +1800,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             _ => {}
         }
+
+        false
     }
 
     fn find_ambiguous_parameter_in<T: TypeVisitable<'tcx>>(

src/test/ui/iterators/issue-28098.stderr

@@ -8,14 +8,6 @@ LL |     let _ = Iterator::next(&mut ());
    |
    = help: the trait `Iterator` is not implemented for `()`
 
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:2:13
-   |
-LL |     let _ = Iterator::next(&mut ());
-   |             ^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
 error[E0277]: `bool` is not an iterator
   --> $DIR/issue-28098.rs:5:14
    |
@@ -35,14 +27,6 @@ LL |     let _ = Iterator::next(&mut ());
    |
    = help: the trait `Iterator` is not implemented for `()`
 
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:8:13
-   |
-LL |     let _ = Iterator::next(&mut ());
-   |             ^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
 error[E0277]: `()` is not an iterator
   --> $DIR/issue-28098.rs:17:28
    |
@@ -53,14 +37,6 @@ LL |     let _ = Iterator::next(&mut ());
    |
    = help: the trait `Iterator` is not implemented for `()`
 
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:17:13
-   |
-LL |     let _ = Iterator::next(&mut ());
-   |             ^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
 error[E0277]: `()` is not an iterator
   --> $DIR/issue-28098.rs:20:28
    |
@@ -71,14 +47,6 @@ LL |     let _ = Iterator::next(&mut ());
    |
    = help: the trait `Iterator` is not implemented for `()`
 
-error[E0277]: `()` is not an iterator
-  --> $DIR/issue-28098.rs:20:13
-   |
-LL |     let _ = Iterator::next(&mut ());
-   |             ^^^^^^^^^^^^^^ `()` is not an iterator
-   |
-   = help: the trait `Iterator` is not implemented for `()`
-
 error[E0277]: `bool` is not an iterator
   --> $DIR/issue-28098.rs:23:14
    |
@@ -88,6 +56,6 @@ LL |     for _ in false {}
    = help: the trait `Iterator` is not implemented for `bool`
    = note: required for `bool` to implement `IntoIterator`
 
-error: aborting due to 10 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

src/test/ui/on-unimplemented/multiple-impls.stderr

@@ -11,17 +11,6 @@ LL |     Index::index(&[] as &[i32], 2u32);
              <[i32] as Index<Bar<usize>>>
              <[i32] as Index<Foo<usize>>>
 
-error[E0277]: the trait bound `[i32]: Index<u32>` is not satisfied
-  --> $DIR/multiple-impls.rs:33:5
-   |
-LL |     Index::index(&[] as &[i32], 2u32);
-   |     ^^^^^^^^^^^^ trait message
-   |
-   = help: the trait `Index<u32>` is not implemented for `[i32]`
-   = help: the following other types implement trait `Index<Idx>`:
-             <[i32] as Index<Bar<usize>>>
-             <[i32] as Index<Foo<usize>>>
-
 error[E0277]: the trait bound `[i32]: Index<Foo<u32>>` is not satisfied
   --> $DIR/multiple-impls.rs:35:33
    |
@@ -35,17 +24,6 @@ LL |     Index::index(&[] as &[i32], Foo(2u32));
              <[i32] as Index<Bar<usize>>>
              <[i32] as Index<Foo<usize>>>
 
-error[E0277]: the trait bound `[i32]: Index<Foo<u32>>` is not satisfied
-  --> $DIR/multiple-impls.rs:35:5
-   |
-LL |     Index::index(&[] as &[i32], Foo(2u32));
-   |     ^^^^^^^^^^^^ on impl for Foo
-   |
-   = help: the trait `Index<Foo<u32>>` is not implemented for `[i32]`
-   = help: the following other types implement trait `Index<Idx>`:
-             <[i32] as Index<Bar<usize>>>
-             <[i32] as Index<Foo<usize>>>
-
 error[E0277]: the trait bound `[i32]: Index<Bar<u32>>` is not satisfied
   --> $DIR/multiple-impls.rs:37:33
    |
@@ -59,17 +37,6 @@ LL |     Index::index(&[] as &[i32], Bar(2u32));
              <[i32] as Index<Bar<usize>>>
              <[i32] as Index<Foo<usize>>>
 
-error[E0277]: the trait bound `[i32]: Index<Bar<u32>>` is not satisfied
+error: aborting due to 3 previous errors
-  --> $DIR/multiple-impls.rs:37:5
-   |
-LL |     Index::index(&[] as &[i32], Bar(2u32));
-   |     ^^^^^^^^^^^^ on impl for Bar
-   |
-   = help: the trait `Index<Bar<u32>>` is not implemented for `[i32]`
-   = help: the following other types implement trait `Index<Idx>`:
-             <[i32] as Index<Bar<usize>>>
-             <[i32] as Index<Foo<usize>>>
-
-error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

src/test/ui/on-unimplemented/on-impl.stderr

@@ -9,15 +9,6 @@ LL |     Index::<u32>::index(&[1, 2, 3] as &[i32], 2u32);
    = help: the trait `Index<u32>` is not implemented for `[i32]`
    = help: the trait `Index<usize>` is implemented for `[i32]`
 
-error[E0277]: the trait bound `[i32]: Index<u32>` is not satisfied
+error: aborting due to previous error
-  --> $DIR/on-impl.rs:22:5
-   |
-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<usize>` is implemented for `[i32]`
-
-error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

src/test/ui/str/str-idx.stderr

@@ -28,17 +28,6 @@ note: required by a bound in `core::str::<impl str>::get`
 LL |     pub const fn get<I: ~const SliceIndex<str>>(&self, i: I) -> Option<&I::Output> {
    |                         ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `core::str::<impl str>::get`
 
-error[E0277]: the type `str` cannot be indexed by `{integer}`
-  --> $DIR/str-idx.rs:4:15
-   |
-LL |     let _ = s.get(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<[T]>` is implemented for `usize`
-
 error[E0277]: the type `str` cannot be indexed by `{integer}`
   --> $DIR/str-idx.rs:5:29
    |
@@ -57,17 +46,6 @@ note: required by a bound in `core::str::<impl str>::get_unchecked`
 LL |     pub const unsafe fn get_unchecked<I: ~const SliceIndex<str>>(&self, i: I) -> &I::Output {
    |                                          ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `core::str::<impl str>::get_unchecked`
 
-error[E0277]: the type `str` cannot be indexed by `{integer}`
-  --> $DIR/str-idx.rs:5:15
-   |
-LL |     let _ = s.get_unchecked(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<[T]>` is implemented for `usize`
-
 error[E0277]: the type `str` cannot be indexed by `char`
   --> $DIR/str-idx.rs:6:19
    |
@@ -77,6 +55,6 @@ LL |     let _: u8 = s['c'];
    = help: the trait `SliceIndex<str>` is not implemented for `char`
    = note: required for `str` to implement `Index<char>`
 
-error: aborting due to 6 previous errors
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

src/test/ui/str/str-mut-idx.stderr

@@ -52,17 +52,6 @@ note: required by a bound in `core::str::<impl str>::get_mut`
 LL |     pub const fn get_mut<I: ~const SliceIndex<str>>(&mut self, i: I) -> Option<&mut I::Output> {
    |                             ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `core::str::<impl str>::get_mut`
 
-error[E0277]: the type `str` cannot be indexed by `{integer}`
-  --> $DIR/str-mut-idx.rs:9:7
-   |
-LL |     s.get_mut(1);
-   |       ^^^^^^^ 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<[T]>` is implemented for `usize`
-
 error[E0277]: the type `str` cannot be indexed by `{integer}`
   --> $DIR/str-mut-idx.rs:11:25
    |
@@ -81,17 +70,6 @@ note: required by a bound in `core::str::<impl str>::get_unchecked_mut`
 LL |     pub const unsafe fn get_unchecked_mut<I: ~const SliceIndex<str>>(
    |                                              ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `core::str::<impl str>::get_unchecked_mut`
 
-error[E0277]: the type `str` cannot be indexed by `{integer}`
-  --> $DIR/str-mut-idx.rs:11:7
-   |
-LL |     s.get_unchecked_mut(1);
-   |       ^^^^^^^^^^^^^^^^^ 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<[T]>` is implemented for `usize`
-
 error[E0277]: the type `str` cannot be indexed by `char`
   --> $DIR/str-mut-idx.rs:13:7
    |
@@ -101,6 +79,6 @@ LL |     s['c'];
    = help: the trait `SliceIndex<str>` is not implemented for `char`
    = note: required for `str` to implement `Index<char>`
 
-error: aborting due to 8 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

src/test/ui/suggestions/mut-borrow-needed-by-trait.stderr

@@ -13,19 +13,6 @@ note: required by a bound in `BufWriter::<W>::new`
 LL | impl<W: Write> BufWriter<W> {
    |         ^^^^^ required by this bound in `BufWriter::<W>::new`
 
-error[E0277]: the trait bound `&dyn std::io::Write: std::io::Write` is not satisfied
-  --> $DIR/mut-borrow-needed-by-trait.rs:17:14
-   |
-LL |     let fp = BufWriter::new(fp);
-   |              ^^^^^^^^^ the trait `std::io::Write` is not implemented for `&dyn std::io::Write`
-   |
-   = note: `std::io::Write` is implemented for `&mut dyn std::io::Write`, but not for `&dyn std::io::Write`
-note: required by a bound in `BufWriter`
-  --> $SRC_DIR/std/src/io/buffered/bufwriter.rs:LL:COL
-   |
-LL | pub struct BufWriter<W: Write> {
-   |                         ^^^^^ required by this bound in `BufWriter`
-
 error[E0277]: the trait bound `&dyn std::io::Write: std::io::Write` is not satisfied
   --> $DIR/mut-borrow-needed-by-trait.rs:17:14
    |
@@ -55,7 +42,7 @@ LL | pub struct BufWriter<W: Write> {
            which is required by `BufWriter<&dyn std::io::Write>: std::io::Write`
    = note: this error originates in the macro `writeln` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0277, E0599.
 For more information about an error, try `rustc --explain E0277`.