Point at impl and type defs introducing requirements on E0277

compiler/rustc_middle/src/ty/mod.rs

@@ -1598,7 +1598,7 @@ impl<'tcx> TyCtxt<'tcx> {
             .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
     }
 
-    fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
+    pub fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
         self.hir().get_if_local(def_id).and_then(|node| node.ident())
     }
 

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

@@ -2070,7 +2070,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 
                 // Don't print the tuple of capture types
                 if !is_upvar_tys_infer_tuple {
-                    err.note(&format!("required because it appears within the type `{}`", ty));
+                    let msg = format!("required because it appears within the type `{}`", ty);
+                    match ty.kind() {
+                        ty::Adt(def, _) => match self.tcx.item_name_from_hir(def.did) {
+                            Some(ident) => err.span_note(ident.span, &msg),
+                            None => err.note(&msg),
+                        },
+                        _ => err.note(&msg),
+                    };
                 }
 
                 obligated_types.push(ty);
@@ -2092,11 +2099,36 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             ObligationCauseCode::ImplDerivedObligation(ref data) => {
                 let mut parent_trait_ref = self.resolve_vars_if_possible(data.parent_trait_ref);
                 let parent_def_id = parent_trait_ref.def_id();
-                err.note(&format!(
+                let msg = format!(
                     "required because of the requirements on the impl of `{}` for `{}`",
                     parent_trait_ref.print_only_trait_path(),
                     parent_trait_ref.skip_binder().self_ty()
-                ));
+                );
+                let mut candidates = vec![];
+                self.tcx.for_each_relevant_impl(
+                    parent_def_id,
+                    parent_trait_ref.self_ty().skip_binder(),
+                    |impl_def_id| {
+                        candidates.push(impl_def_id);
+                    },
+                );
+                match &candidates[..] {
+                    [def_id] => match self.tcx.hir().get_if_local(*def_id) {
+                        Some(Node::Item(hir::Item {
+                            kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }),
+                            ..
+                        })) => {
+                            let mut spans = Vec::with_capacity(2);
+                            if let Some(trait_ref) = of_trait {
+                                spans.push(trait_ref.path.span);
+                            }
+                            spans.push(self_ty.span);
+                            err.span_note(spans, &msg)
+                        }
+                        _ => err.note(&msg),
+                    },
+                    _ => err.note(&msg),
+                };
 
                 let mut parent_predicate = parent_trait_ref.without_const().to_predicate(tcx);
                 let mut data = data;

src/test/ui/associated-types/impl-wf-cycle-1.stderr

@@ -10,7 +10,11 @@ LL | |
 LL | | }
    | |_^
    |
-   = note: required because of the requirements on the impl of `Grault` for `(T,)`
+note: required because of the requirements on the impl of `Grault` for `(T,)`
+  --> $DIR/impl-wf-cycle-1.rs:15:17
+   |
+LL | impl<T: Grault> Grault for (T,)
+   |                 ^^^^^^     ^^^^
    = note: 1 redundant requirements hidden
    = note: required because of the requirements on the impl of `Grault` for `(T,)`
 
@@ -20,7 +24,11 @@ error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
 LL |     type A = ();
    |     ^^^^^^^^^^^^
    |
-   = note: required because of the requirements on the impl of `Grault` for `(T,)`
+note: required because of the requirements on the impl of `Grault` for `(T,)`
+  --> $DIR/impl-wf-cycle-1.rs:15:17
+   |
+LL | impl<T: Grault> Grault for (T,)
+   |                 ^^^^^^     ^^^^
    = note: 1 redundant requirements hidden
    = note: required because of the requirements on the impl of `Grault` for `(T,)`
 
@@ -30,7 +38,11 @@ error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
 LL |     type B = bool;
    |     ^^^^^^^^^^^^^^
    |
-   = note: required because of the requirements on the impl of `Grault` for `(T,)`
+note: required because of the requirements on the impl of `Grault` for `(T,)`
+  --> $DIR/impl-wf-cycle-1.rs:15:17
+   |
+LL | impl<T: Grault> Grault for (T,)
+   |                 ^^^^^^     ^^^^
    = note: 1 redundant requirements hidden
    = note: required because of the requirements on the impl of `Grault` for `(T,)`
 

src/test/ui/associated-types/impl-wf-cycle-2.stderr

@@ -10,15 +10,23 @@ LL | |
 LL | | }
    | |_^
    |
-   = note: required because of the requirements on the impl of `Grault` for `(T,)`
+note: required because of the requirements on the impl of `Grault` for `(T,)`
+  --> $DIR/impl-wf-cycle-2.rs:7:17
+   |
+LL | impl<T: Grault> Grault for (T,)
+   |                 ^^^^^^     ^^^^
 
 error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
   --> $DIR/impl-wf-cycle-2.rs:11:5
    |
 LL |     type A = ();
    |     ^^^^^^^^^^^^
    |
-   = note: required because of the requirements on the impl of `Grault` for `(T,)`
+note: required because of the requirements on the impl of `Grault` for `(T,)`
+  --> $DIR/impl-wf-cycle-2.rs:7:17
+   |
+LL | impl<T: Grault> Grault for (T,)
+   |                 ^^^^^^     ^^^^
 
 error: aborting due to 2 previous errors
 

src/test/ui/associated-types/issue-44153.stderr

@@ -7,7 +7,11 @@ LL |     fn visit() {}
 LL |     <() as Visit>::visit();
    |     ^^^^^^^^^^^^^^^^^^^^ expected `&()`, found `()`
    |
-   = note: required because of the requirements on the impl of `Visit` for `()`
+note: required because of the requirements on the impl of `Visit` for `()`
+  --> $DIR/issue-44153.rs:13:10
+   |
+LL | impl<'a> Visit for () where
+   |          ^^^^^     ^^
 
 error: aborting due to previous error
 

src/test/ui/associated-types/issue-65774-1.stderr

@@ -13,7 +13,11 @@ error[E0277]: the trait bound `T: MyDisplay` is not satisfied
 LL |         let closure = |config: &mut <S as MPU>::MpuConfig| writer.my_write(&config);
    |                                                                            ^^^^^^^ the trait `MyDisplay` is not implemented for `T`
    |
-   = note: required because of the requirements on the impl of `MyDisplay` for `&mut T`
+note: required because of the requirements on the impl of `MyDisplay` for `&mut T`
+  --> $DIR/issue-65774-1.rs:5:24
+   |
+LL | impl<'a, T: MyDisplay> MyDisplay for &'a mut T { }
+   |                        ^^^^^^^^^     ^^^^^^^^^
    = note: required for the cast to the object type `dyn MyDisplay`
 
 error: aborting due to 2 previous errors

src/test/ui/async-await/issue-72590-type-error-sized.stderr

@@ -17,7 +17,11 @@ LL |     async fn frob(self) {}
    |                   ^^^^ doesn't have a size known at compile-time
    |
    = help: within `Foo`, the trait `Sized` is not implemented for `str`
-   = note: required because it appears within the type `Foo`
+note: required because it appears within the type `Foo`
+  --> $DIR/issue-72590-type-error-sized.rs:5:8
+   |
+LL | struct Foo {
+   |        ^^^
    = help: unsized fn params are gated as an unstable feature
 help: function arguments must have a statically known size, borrowed types always have a known size
    |

src/test/ui/async-await/pin-needed-to-poll-2.rs

@@ -0,0 +1,48 @@
+use std::{
+    future::Future,
+    pin::Pin,
+    marker::Unpin,
+    task::{Context, Poll},
+};
+
+struct Sleep(std::marker::PhantomPinned);
+
+impl Future for Sleep {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        Poll::Ready(())
+    }
+}
+
+impl Drop for Sleep {
+    fn drop(&mut self) {}
+}
+
+fn sleep() -> Sleep {
+    Sleep(std::marker::PhantomPinned)
+}
+
+
+struct MyFuture {
+    sleep: Sleep,
+}
+
+impl MyFuture {
+    fn new() -> Self {
+        Self {
+            sleep: sleep(),
+        }
+    }
+}
+
+impl Future for MyFuture {
+    type Output = ();
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        Pin::new(&mut self.sleep).poll(cx)
+        //~^ ERROR `PhantomPinned` cannot be unpinned
+    }
+}
+
+fn main() {}

src/test/ui/async-await/pin-needed-to-poll-2.stderr

@@ -0,0 +1,16 @@
+error[E0277]: `PhantomPinned` cannot be unpinned
+  --> $DIR/pin-needed-to-poll-2.rs:43:9
+   |
+LL |         Pin::new(&mut self.sleep).poll(cx)
+   |         ^^^^^^^^ within `Sleep`, the trait `Unpin` is not implemented for `PhantomPinned`
+   |
+note: required because it appears within the type `Sleep`
+  --> $DIR/pin-needed-to-poll-2.rs:8:8
+   |
+LL | struct Sleep(std::marker::PhantomPinned);
+   |        ^^^^^
+   = note: required by `Pin::<P>::new`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

src/test/ui/block-result/issue-22645.stderr

@@ -6,7 +6,11 @@ LL |   b + 3
    |
    = help: the following implementations were found:
              <f64 as Scalar>
-   = note: required because of the requirements on the impl of `Add<{integer}>` for `Bob`
+note: required because of the requirements on the impl of `Add<{integer}>` for `Bob`
+  --> $DIR/issue-22645.rs:8:19
+   |
+LL | impl<RHS: Scalar> Add <RHS> for Bob {
+   |                   ^^^^^^^^^     ^^^
 
 error[E0308]: mismatched types
   --> $DIR/issue-22645.rs:15:3

src/test/ui/builtin-superkinds/builtin-superkinds-in-metadata.stderr

@@ -9,7 +9,11 @@ LL | impl <T:Sync+'static> RequiresRequiresShareAndSend for X<T> { }
 LL | pub trait RequiresRequiresShareAndSend : RequiresShare + Send { }
    |                                                          ---- required by this bound in `RequiresRequiresShareAndSend`
    |
-   = note: required because it appears within the type `X<T>`
+note: required because it appears within the type `X<T>`
+  --> $DIR/builtin-superkinds-in-metadata.rs:9:8
+   |
+LL | struct X<T>(T);
+   |        ^
 help: consider further restricting this bound
    |
 LL | impl <T:Sync+'static + std::marker::Send> RequiresRequiresShareAndSend for X<T> { }

src/test/ui/did_you_mean/recursion_limit.stderr

@@ -8,16 +8,56 @@ LL |     is_send::<A>();
    |     ^^^^^^^^^^^^
    |
    = help: consider adding a `#![recursion_limit="20"]` attribute to your crate (`recursion_limit`)
-   = note: required because it appears within the type `J`
-   = note: required because it appears within the type `I`
-   = note: required because it appears within the type `H`
-   = note: required because it appears within the type `G`
-   = note: required because it appears within the type `F`
-   = note: required because it appears within the type `E`
-   = note: required because it appears within the type `D`
-   = note: required because it appears within the type `C`
-   = note: required because it appears within the type `B`
-   = note: required because it appears within the type `A`
+note: required because it appears within the type `J`
+  --> $DIR/recursion_limit.rs:24:9
+   |
+LL | link! { J, K }
+   |         ^
+note: required because it appears within the type `I`
+  --> $DIR/recursion_limit.rs:23:9
+   |
+LL | link! { I, J }
+   |         ^
+note: required because it appears within the type `H`
+  --> $DIR/recursion_limit.rs:22:9
+   |
+LL | link! { H, I }
+   |         ^
+note: required because it appears within the type `G`
+  --> $DIR/recursion_limit.rs:21:9
+   |
+LL | link! { G, H }
+   |         ^
+note: required because it appears within the type `F`
+  --> $DIR/recursion_limit.rs:20:9
+   |
+LL | link! { F, G }
+   |         ^
+note: required because it appears within the type `E`
+  --> $DIR/recursion_limit.rs:19:9
+   |
+LL | link! { E, F }
+   |         ^
+note: required because it appears within the type `D`
+  --> $DIR/recursion_limit.rs:18:9
+   |
+LL | link! { D, E }
+   |         ^
+note: required because it appears within the type `C`
+  --> $DIR/recursion_limit.rs:17:9
+   |
+LL | link! { C, D }
+   |         ^
+note: required because it appears within the type `B`
+  --> $DIR/recursion_limit.rs:16:9
+   |
+LL | link! { B, C }
+   |         ^
+note: required because it appears within the type `A`
+  --> $DIR/recursion_limit.rs:15:9
+   |
+LL | link! { A, B }
+   |         ^
 
 error: aborting due to previous error
 

src/test/ui/dst/dst-bad-deep.stderr

@@ -5,8 +5,16 @@ LL |     let h: &Fat<Fat<[isize]>> = &Fat { ptr: *g };
    |                                  ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: within `Fat<Fat<[isize]>>`, the trait `Sized` is not implemented for `[isize]`
-   = note: required because it appears within the type `Fat<[isize]>`
-   = note: required because it appears within the type `Fat<Fat<[isize]>>`
+note: required because it appears within the type `Fat<[isize]>`
+  --> $DIR/dst-bad-deep.rs:6:8
+   |
+LL | struct Fat<T: ?Sized> {
+   |        ^^^
+note: required because it appears within the type `Fat<Fat<[isize]>>`
+  --> $DIR/dst-bad-deep.rs:6:8
+   |
+LL | struct Fat<T: ?Sized> {
+   |        ^^^
    = note: structs must have a statically known size to be initialized
 
 error: aborting due to previous error

src/test/ui/error-codes/E0275.stderr

@@ -8,7 +8,11 @@ LL | impl<T> Foo for T where Bar<T>: Foo {}
    |                                 ^^^
    |
    = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`E0275`)
-   = note: required because of the requirements on the impl of `Foo` for `Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
+note: required because of the requirements on the impl of `Foo` for `Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
+  --> $DIR/E0275.rs:5:9
+   |
+LL | impl<T> Foo for T where Bar<T>: Foo {}
+   |         ^^^     ^
    = note: 127 redundant requirements hidden
    = note: required because of the requirements on the impl of `Foo` for `Bar<T>`
 

src/test/ui/error-codes/E0277-2.stderr

@@ -8,9 +8,21 @@ LL |     is_send::<Foo>();
    |     ^^^^^^^^^^^^^^ `*const u8` cannot be sent between threads safely
    |
    = help: within `Foo`, the trait `Send` is not implemented for `*const u8`
-   = note: required because it appears within the type `Baz`
-   = note: required because it appears within the type `Bar`
-   = note: required because it appears within the type `Foo`
+note: required because it appears within the type `Baz`
+  --> $DIR/E0277-2.rs:9:8
+   |
+LL | struct Baz {
+   |        ^^^
+note: required because it appears within the type `Bar`
+  --> $DIR/E0277-2.rs:5:8
+   |
+LL | struct Bar {
+   |        ^^^
+note: required because it appears within the type `Foo`
+  --> $DIR/E0277-2.rs:1:8
+   |
+LL | struct Foo {
+   |        ^^^
 
 error: aborting due to previous error