Adjust messages, address some nits

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

@@ -973,6 +973,23 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     || ref_inner_ty_satisfies_pred
                 {
                     if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
+                        // We don't want a borrowing suggestion on the fields in structs,
+                        // ```
+                        // struct Foo {
+                        //  the_foos: Vec<Foo>
+                        // }
+                        // ```
+                        if !matches!(
+                            span.ctxt().outer_expn_data().kind,
+                            ExpnKind::Root | ExpnKind::Desugaring(DesugaringKind::ForLoop)
+                        ) {
+                            return false;
+                        }
+                        if snippet.starts_with('&') {
+                            // This is already a literal borrow and the obligation is failing
+                            // somewhere else in the obligation chain. Do not suggest non-sense.
+                            return false;
+                        }
                         // We have a very specific type of error, where just borrowing this argument
                         // might solve the problem. In cases like this, the important part is the
                         // original type obligation, not the last one that failed, which is arbitrary.
@@ -986,50 +1003,33 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                             err.message =
                                 vec![(rustc_errors::DiagnosticMessage::Str(msg), Style::NoStyle)];
                         }
-                        if snippet.starts_with('&') {
-                            // This is already a literal borrow and the obligation is failing
-                            // somewhere else in the obligation chain. Do not suggest non-sense.
-                            return false;
-                        }
                         err.span_label(
                             span,
-                            &format!(
+                            format!(
-                                "expected an implementor of trait `{}`",
+                                "the trait `{}` is not implemented for `{}`",
                                 old_pred.print_modifiers_and_trait_path(),
+                                old_pred.self_ty().skip_binder(),
                             ),
                         );
 
-                        // This if is to prevent a special edge-case
+                        if imm_ref_self_ty_satisfies_pred && mut_ref_self_ty_satisfies_pred {
-                        if matches!(
+                            err.span_suggestions(
-                            span.ctxt().outer_expn_data().kind,
+                                span.shrink_to_lo(),
-                            ExpnKind::Root | ExpnKind::Desugaring(DesugaringKind::ForLoop)
+                                "consider borrowing here",
-                        ) {
+                                ["&".to_string(), "&mut ".to_string()].into_iter(),
-                            // We don't want a borrowing suggestion on the fields in structs,
+                                Applicability::MaybeIncorrect,
-                            // ```
+                            );
-                            // struct Foo {
+                        } else {
-                            //  the_foos: Vec<Foo>
+                            let is_mut = mut_ref_self_ty_satisfies_pred || ref_inner_ty_mut;
-                            // }
+                            err.span_suggestion_verbose(
-                            // ```
+                                span.shrink_to_lo(),
-
+                                &format!(
-                            if imm_ref_self_ty_satisfies_pred && mut_ref_self_ty_satisfies_pred {
+                                    "consider{} borrowing here",
-                                err.span_suggestions(
+                                    if is_mut { " mutably" } else { "" }
-                                    span.shrink_to_lo(),
+                                ),
-                                    "consider borrowing here",
+                                format!("&{}", if is_mut { "mut " } else { "" }),
-                                    ["&".to_string(), "&mut ".to_string()].into_iter(),
+                                Applicability::MaybeIncorrect,
-                                    Applicability::MaybeIncorrect,
+                            );
-                                );
-                            } else {
-                                let is_mut = mut_ref_self_ty_satisfies_pred || ref_inner_ty_mut;
-                                err.span_suggestion_verbose(
-                                    span.shrink_to_lo(),
-                                    &format!(
-                                        "consider{} borrowing here",
-                                        if is_mut { " mutably" } else { "" }
-                                    ),
-                                    format!("&{}", if is_mut { "mut " } else { "" }),
-                                    Applicability::MaybeIncorrect,
-                                );
-                            }
                         }
                         return true;
                     }

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

@@ -1753,9 +1753,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 {
                     for param in
                         [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
+                        .into_iter()
+                        .flatten()
                     {
-                        if let Some(param) = param
+                        if self.point_at_arg_if_possible(
-                            && self.point_at_arg_if_possible(
                                 error,
                                 def_id,
                                 param,
@@ -1784,17 +1785,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 ..
             }) => {
                 for param in [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
+                    .into_iter()
+                    .flatten()
                 {
-                    if let Some(param) = param
+                    if self.point_at_arg_if_possible(
-                        && self.point_at_arg_if_possible(
+                        error,
-                            error,
+                        def_id,
-                            def_id,
+                        param,
-                            param,
+                        hir_id,
-                            hir_id,
+                        segment.ident.span,
-                            segment.ident.span,
+                        args,
-                            args,
+                    ) {
-                        )
-                    {
                         return true;
                     }
                 }
@@ -1903,6 +1904,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 if self.tcx.adjust_ident(expr_field.ident, variant_def_id) == field.ident(self.tcx)
                 {
                     error.obligation.cause.span = expr_field
+                        .expr
                         .span
                         .find_ancestor_in_same_ctxt(error.obligation.cause.span)
                         .unwrap_or(expr_field.span);

src/test/ui/chalkify/type_wf.stderr

@@ -1,8 +1,8 @@
 error[E0277]: the trait bound `{float}: Foo` is not satisfied
-  --> $DIR/type_wf.rs:19:9
+  --> $DIR/type_wf.rs:19:12
    |
 LL |         x: 5.0,
-   |         ^^^^^^ the trait `Foo` is not implemented for `{float}`
+   |            ^^^ the trait `Foo` is not implemented for `{float}`
    |
    = help: the trait `Foo` is implemented for `i32`
 note: required by a bound in `S`

src/test/ui/consts/const-block-const-bound.stderr

@@ -2,7 +2,7 @@ error[E0277]: can't drop `UnconstDrop` in const contexts
   --> $DIR/const-block-const-bound.rs:20:11
    |
 LL |         f(UnconstDrop);
-   |         - ^^^^^^^^^^^ expected an implementor of trait `~const Destruct`
+   |         - ^^^^^^^^^^^ the trait `~const Destruct` is not implemented for `UnconstDrop`
    |         |
    |         required by a bound introduced by this call
    |
@@ -23,7 +23,7 @@ error[E0277]: can't drop `NonDrop` in const contexts
   --> $DIR/const-block-const-bound.rs:22:11
    |
 LL |         f(NonDrop);
-   |         - ^^^^^^^ expected an implementor of trait `~const Destruct`
+   |         - ^^^^^^^ the trait `~const Destruct` is not implemented for `NonDrop`
    |         |
    |         required by a bound introduced by this call
    |

src/test/ui/derives/deriving-copyclone.stderr

@@ -2,7 +2,7 @@ error[E0277]: the trait bound `B<C>: Copy` is not satisfied
   --> $DIR/deriving-copyclone.rs:31:13
    |
 LL |     is_copy(B { a: 1, b: C });
-   |     ------- ^^^^^^^^^^^^^^^^ expected an implementor of trait `Copy`
+   |     ------- ^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `B<C>`
    |     |
    |     required by a bound introduced by this call
    |
@@ -26,7 +26,7 @@ error[E0277]: the trait bound `B<C>: Clone` is not satisfied
   --> $DIR/deriving-copyclone.rs:32:14
    |
 LL |     is_clone(B { a: 1, b: C });
-   |     -------- ^^^^^^^^^^^^^^^^ expected an implementor of trait `Clone`
+   |     -------- ^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `B<C>`
    |     |
    |     required by a bound introduced by this call
    |
@@ -50,7 +50,7 @@ error[E0277]: the trait bound `B<D>: Copy` is not satisfied
   --> $DIR/deriving-copyclone.rs:35:13
    |
 LL |     is_copy(B { a: 1, b: D });
-   |     ------- ^^^^^^^^^^^^^^^^ expected an implementor of trait `Copy`
+   |     ------- ^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `B<D>`
    |     |
    |     required by a bound introduced by this call
    |

src/test/ui/issues/issue-20605.stderr

@@ -2,7 +2,7 @@ error[E0277]: the size for values of type `dyn Iterator<Item = &'a mut u8>` cann
   --> $DIR/issue-20605.rs:2:17
    |
 LL |     for item in *things { *item = 0 }
-   |                 ^^^^^^^ expected an implementor of trait `IntoIterator`
+   |                 ^^^^^^^ the trait `IntoIterator` is not implemented for `dyn Iterator<Item = &'a mut u8>`
    |
    = note: the trait bound `dyn Iterator<Item = &'a mut u8>: IntoIterator` is not satisfied
    = note: required for `dyn Iterator<Item = &'a mut u8>` to implement `IntoIterator`

src/test/ui/kindck/kindck-impl-type-params-2.rs

@@ -11,5 +11,5 @@ fn take_param<T:Foo>(foo: &T) { }
 fn main() {
     let x: Box<_> = Box::new(3);
     take_param(&x);
-    //~^ ERROR the trait bound `Box<{integer}>: Foo` is not satisfied
+    //~^ ERROR the trait bound `Box<{integer}>: Copy` is not satisfied
 }

src/test/ui/kindck/kindck-impl-type-params-2.stderr

@@ -1,4 +1,4 @@
-error[E0277]: the trait bound `Box<{integer}>: Foo` is not satisfied
+error[E0277]: the trait bound `Box<{integer}>: Copy` is not satisfied
   --> $DIR/kindck-impl-type-params-2.rs:13:16
    |
 LL |     take_param(&x);

src/test/ui/kindck/kindck-inherited-copy-bound.curr.stderr

@@ -1,4 +1,4 @@
-error[E0277]: the trait bound `Box<{integer}>: Foo` is not satisfied
+error[E0277]: the trait bound `Box<{integer}>: Copy` is not satisfied
   --> $DIR/kindck-inherited-copy-bound.rs:21:16
    |
 LL |     take_param(&x);

src/test/ui/kindck/kindck-inherited-copy-bound.object_safe_for_dispatch.stderr

@@ -1,4 +1,4 @@
-error[E0277]: the trait bound `Box<{integer}>: Foo` is not satisfied
+error[E0277]: the trait bound `Box<{integer}>: Copy` is not satisfied
   --> $DIR/kindck-inherited-copy-bound.rs:21:16
    |
 LL |     take_param(&x);

src/test/ui/rfc-2632-const-trait-impl/const-drop-fail.precise.stderr

@@ -5,7 +5,7 @@ LL |         const _: () = check($exp);
    |                       ----- required by a bound introduced by this call
 ...
 LL |     NonTrivialDrop,
-   |     ^^^^^^^^^^^^^^ expected an implementor of trait `~const Destruct`
+   |     ^^^^^^^^^^^^^^ the trait `~const Destruct` is not implemented for `NonTrivialDrop`
    |
    = note: the trait bound `NonTrivialDrop: ~const Destruct` is not satisfied
 note: required by a bound in `check`
@@ -52,7 +52,7 @@ LL |         const _: () = check($exp);
    |                       ----- required by a bound introduced by this call
 ...
 LL |     ConstDropImplWithBounds::<NonTrivialDrop>(PhantomData),
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected an implementor of trait `~const Destruct`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `~const Destruct` is not implemented for `ConstDropImplWithBounds<NonTrivialDrop>`
    |
 note: required for `ConstDropImplWithBounds<NonTrivialDrop>` to implement `~const Destruct`
   --> $DIR/const-drop-fail.rs:28:25

src/test/ui/rfc-2632-const-trait-impl/const-drop-fail.stock.stderr

@@ -5,7 +5,7 @@ LL |         const _: () = check($exp);
    |                       ----- required by a bound introduced by this call
 ...
 LL |     NonTrivialDrop,
-   |     ^^^^^^^^^^^^^^ expected an implementor of trait `~const Destruct`
+   |     ^^^^^^^^^^^^^^ the trait `~const Destruct` is not implemented for `NonTrivialDrop`
    |
    = note: the trait bound `NonTrivialDrop: ~const Destruct` is not satisfied
 note: required by a bound in `check`
@@ -52,7 +52,7 @@ LL |         const _: () = check($exp);
    |                       ----- required by a bound introduced by this call
 ...
 LL |     ConstDropImplWithBounds::<NonTrivialDrop>(PhantomData),
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected an implementor of trait `~const Destruct`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `~const Destruct` is not implemented for `ConstDropImplWithBounds<NonTrivialDrop>`
    |
 note: required for `ConstDropImplWithBounds<NonTrivialDrop>` to implement `~const Destruct`
   --> $DIR/const-drop-fail.rs:28:25

src/test/ui/suggestions/imm-ref-trait-object-literal.stderr

@@ -21,7 +21,7 @@ error[E0277]: the trait bound `S: Trait` is not satisfied
   --> $DIR/imm-ref-trait-object-literal.rs:13:7
    |
 LL |   foo(s);
-   |   --- ^ expected an implementor of trait `Trait`
+   |   --- ^ the trait `Trait` is not implemented for `S`
    |   |
    |   required by a bound introduced by this call
    |

src/test/ui/suggestions/issue-62843.stderr

@@ -2,7 +2,7 @@ error[E0277]: expected a `FnMut<(char,)>` closure, found `String`
   --> $DIR/issue-62843.rs:4:32
    |
 LL |     println!("{:?}", line.find(pattern));
-   |                           ---- ^^^^^^^ expected an implementor of trait `Pattern<'_>`
+   |                           ---- ^^^^^^^ the trait `Pattern<'_>` is not implemented for `String`
    |                           |
    |                           required by a bound introduced by this call
    |

src/test/ui/suggestions/issue-84973-2.stderr

@@ -2,7 +2,7 @@ error[E0277]: the trait bound `i32: Tr` is not satisfied
   --> $DIR/issue-84973-2.rs:11:9
    |
 LL |     foo(a);
-   |     --- ^ expected an implementor of trait `Tr`
+   |     --- ^ the trait `Tr` is not implemented for `i32`
    |     |
    |     required by a bound introduced by this call
    |

src/test/ui/suggestions/issue-84973-negative.stderr

@@ -17,7 +17,7 @@ error[E0277]: the trait bound `f32: Tr` is not satisfied
   --> $DIR/issue-84973-negative.rs:11:9
    |
 LL |     bar(b);
-   |     --- ^ expected an implementor of trait `Tr`
+   |     --- ^ the trait `Tr` is not implemented for `f32`
    |     |
    |     required by a bound introduced by this call
    |

src/test/ui/suggestions/issue-84973.stderr

@@ -2,7 +2,7 @@ error[E0277]: the trait bound `Fancy: SomeTrait` is not satisfied
   --> $DIR/issue-84973.rs:6:24
    |
 LL |     let o = Other::new(f);
-   |             ---------- ^ expected an implementor of trait `SomeTrait`
+   |             ---------- ^ the trait `SomeTrait` is not implemented for `Fancy`
    |             |
    |             required by a bound introduced by this call
    |

src/test/ui/suggestions/slice-issue-87994.stderr

@@ -2,7 +2,7 @@ error[E0277]: the size for values of type `[i32]` cannot be known at compilation
   --> $DIR/slice-issue-87994.rs:3:12
    |
 LL |   for _ in v[1..] {
-   |            ^^^^^^ expected an implementor of trait `IntoIterator`
+   |            ^^^^^^ the trait `IntoIterator` is not implemented for `[i32]`
    |
    = note: the trait bound `[i32]: IntoIterator` is not satisfied
    = note: required for `[i32]` to implement `IntoIterator`
@@ -17,7 +17,7 @@ error[E0277]: `[i32]` is not an iterator
   --> $DIR/slice-issue-87994.rs:3:12
    |
 LL |   for _ in v[1..] {
-   |            ^^^^^^ expected an implementor of trait `IntoIterator`
+   |            ^^^^^^ the trait `IntoIterator` is not implemented for `[i32]`
    |
    = note: the trait bound `[i32]: IntoIterator` is not satisfied
    = note: required for `[i32]` to implement `IntoIterator`
@@ -32,7 +32,7 @@ error[E0277]: the size for values of type `[K]` cannot be known at compilation t
   --> $DIR/slice-issue-87994.rs:11:13
    |
 LL |   for i2 in v2[1..] {
-   |             ^^^^^^^ expected an implementor of trait `IntoIterator`
+   |             ^^^^^^^ the trait `IntoIterator` is not implemented for `[K]`
    |
    = note: the trait bound `[K]: IntoIterator` is not satisfied
    = note: required for `[K]` to implement `IntoIterator`
@@ -47,7 +47,7 @@ error[E0277]: `[K]` is not an iterator
   --> $DIR/slice-issue-87994.rs:11:13
    |
 LL |   for i2 in v2[1..] {
-   |             ^^^^^^^ expected an implementor of trait `IntoIterator`
+   |             ^^^^^^^ the trait `IntoIterator` is not implemented for `[K]`
    |
    = note: the trait bound `[K]: IntoIterator` is not satisfied
    = note: required for `[K]` to implement `IntoIterator`

src/test/ui/suggestions/suggest-imm-mut-trait-implementations.stderr

@@ -2,7 +2,7 @@ error[E0277]: the trait bound `A: Trait` is not satisfied
   --> $DIR/suggest-imm-mut-trait-implementations.rs:20:9
    |
 LL |     foo(a);
-   |     --- ^ expected an implementor of trait `Trait`
+   |     --- ^ the trait `Trait` is not implemented for `A`
    |     |
    |     required by a bound introduced by this call
    |
@@ -22,7 +22,7 @@ error[E0277]: the trait bound `B: Trait` is not satisfied
   --> $DIR/suggest-imm-mut-trait-implementations.rs:21:9
    |
 LL |     foo(b);
-   |     --- ^ expected an implementor of trait `Trait`
+   |     --- ^ the trait `Trait` is not implemented for `B`
    |     |
    |     required by a bound introduced by this call
    |
@@ -40,7 +40,7 @@ error[E0277]: the trait bound `C: Trait` is not satisfied
   --> $DIR/suggest-imm-mut-trait-implementations.rs:22:9
    |
 LL |     foo(c);
-   |     --- ^ expected an implementor of trait `Trait`
+   |     --- ^ the trait `Trait` is not implemented for `C`
    |     |
    |     required by a bound introduced by this call
    |

src/test/ui/traits/bound/on-structs-and-enums-locals.stderr

@@ -11,10 +11,10 @@ LL | struct Foo<T:Trait> {
    |              ^^^^^ required by this bound in `Foo`
 
 error[E0277]: the trait bound `{integer}: Trait` is not satisfied
-  --> $DIR/on-structs-and-enums-locals.rs:11:9
+  --> $DIR/on-structs-and-enums-locals.rs:11:12
    |
 LL |         x: 3
-   |         ^^^^ the trait `Trait` is not implemented for `{integer}`
+   |            ^ the trait `Trait` is not implemented for `{integer}`
    |
 note: required by a bound in `Foo`
   --> $DIR/on-structs-and-enums-locals.rs:5:14

src/test/ui/traits/bound/on-structs-and-enums-xc1.stderr

@@ -11,10 +11,10 @@ LL | pub enum Bar<T:Trait> {
    |                ^^^^^ required by this bound in `Bar`
 
 error[E0277]: the trait bound `{integer}: Trait` is not satisfied
-  --> $DIR/on-structs-and-enums-xc1.rs:9:9
+  --> $DIR/on-structs-and-enums-xc1.rs:9:12
    |
 LL |         x: 3
-   |         ^^^^ the trait `Trait` is not implemented for `{integer}`
+   |            ^ the trait `Trait` is not implemented for `{integer}`
    |
 note: required by a bound in `Foo`
   --> $DIR/auxiliary/on_structs_and_enums_xc.rs:5:18

src/test/ui/traits/issue-71136.stderr

@@ -1,14 +1,18 @@
-error[E0277]: the trait bound `Vec<Foo>: Clone` is not satisfied
+error[E0277]: the trait bound `Foo: Clone` is not satisfied
   --> $DIR/issue-71136.rs:5:5
    |
 LL | #[derive(Clone)]
    |          ----- in this derive macro expansion
 LL | struct FooHolster {
 LL |     the_foos: Vec<Foo>,
-   |     ^^^^^^^^^^^^^^^^^^ expected an implementor of trait `~const Clone`
+   |     ^^^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `Foo`
    |
    = note: required for `Vec<Foo>` to implement `Clone`
    = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider annotating `Foo` with `#[derive(Clone)]`
+   |
+LL | #[derive(Clone)]
+   |
 
 error: aborting due to previous error
 

src/test/ui/traits/negative-impls/negated-auto-traits-error.stderr

@@ -61,7 +61,7 @@ error[E0277]: `dummy2::TestType` cannot be sent between threads safely
   --> $DIR/negated-auto-traits-error.rs:48:13
    |
 LL |     is_send(Box::new(TestType));
-   |     ------- ^^^^^^^^^^^^^^^^^^ expected an implementor of trait `Send`
+   |     ------- ^^^^^^^^^^^^^^^^^^ the trait `Send` is not implemented for `Unique<dummy2::TestType>`
    |     |
    |     required by a bound introduced by this call
    |