Deduplicate information in E0599

rust-lang · Dylan-DPC-zz · Feb 9, 2020 · Feb 9, 2020 · Feb 10, 2020 · Feb 10, 2020
commit 2e8399de22a10463bde964595bbad1b2d75cb40f
diff --git a/src/librustc_typeck/check/method/suggest.rs b/src/librustc_typeck/check/method/suggest.rs
@@ -538,16 +538,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     let mut bound_spans = vec![];
                     let mut bound_list = unsatisfied_predicates
                         .iter()
-                        .map(|p| {
+                        .filter_map(|p| {
                             let self_ty = p.self_ty();
                             match &self_ty.kind {
-                                ty::Adt(def, _) => bound_spans.push((
-                                    self.tcx.sess.source_map().def_span(self.tcx.def_span(def.did)),
-                                    format!(
-                                        "this type doesn't satisfy the bound `{}`",
-                                        p.print_only_trait_path()
-                                    ),
-                                )),
+                                ty::Adt(def, _) => {
+                                    bound_spans.push((
+                                        self.tcx
+                                            .sess
+                                            .source_map()
+                                            .def_span(self.tcx.def_span(def.did)),
+                                        format!(
+                                            "the method `{}` exists but this type doesn't satisfy \
+                                             the bound `{}: {}`",
+                                            item_name,
+                                            p.self_ty(),
+                                            p.print_only_trait_path()
+                                        ),
+                                    ));
+                                    None
+                                }
                                 ty::Dynamic(preds, _) => {
                                     for pred in *preds.skip_binder() {
                                         match pred {
@@ -558,18 +567,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                                         .source_map()
                                                         .def_span(self.tcx.def_span(tr.def_id)),
                                                     format!(
-                                                        "this trait doesn't satisfy the bound `{}`",
+                                                        "the method `{}` exists but this trait \
+                                                         doesn't satisfy the bound `{}: {}`",
+                                                        item_name,
+                                                        p.self_ty(),
                                                         p.print_only_trait_path()
                                                     ),
                                                 )),
                                             ty::ExistentialPredicate::Projection(_)
                                             | ty::ExistentialPredicate::AutoTrait(_) => {}
                                         }
                                     }
+                                    None
                                 }
-                                _ => {}
-                            };
-                            format!("`{}: {}`", p.self_ty(), p.print_only_trait_path())
+                                _ => Some(format!(
+                                    "`{}: {}`",
+                                    p.self_ty(),
+                                    p.print_only_trait_path()
+                                )),
+                            }
                         })
                         .collect::<Vec<_>>();
                     bound_list.sort();
@@ -579,12 +595,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     for (span, msg) in bound_spans.into_iter() {
                         err.span_label(span, &msg);
                     }
-                    let bound_list = bound_list.join("\n");
-                    err.note(&format!(
-                        "the method `{}` exists but the following trait bounds were not \
-                         satisfied:\n{}",
-                        item_name, bound_list
-                    ));
+                    if !bound_list.is_empty() {
+                        let bound_list = bound_list.join("\n");
+                        err.note(&format!(
+                            "the method `{}` exists but the following trait bounds were not \
+                             satisfied:\n{}",
+                            item_name, bound_list
+                        ));
+                    }
                 }
 
                 if actual.is_numeric() && actual.is_fresh() {

diff --git a/src/test/ui/derives/derive-assoc-type-not-impl.stderr b/src/test/ui/derives/derive-assoc-type-not-impl.stderr
@@ -5,13 +5,11 @@ LL | struct Bar<T: Foo> {
    | ------------------ method `clone` not found for this
 ...
 LL | struct NotClone;
-   | ---------------- this type doesn't satisfy the bound `std::clone::Clone`
+   | ---------------- the method `clone` exists but this type doesn't satisfy the bound `NotClone: std::clone::Clone`
 ...
 LL |     Bar::<NotClone> { x: 1 }.clone();
    |                              ^^^^^ method not found in `Bar<NotClone>`
    |
-   = note: the method `clone` exists but the following trait bounds were not satisfied:
-           `NotClone: std::clone::Clone`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following trait defines an item `clone`, perhaps you need to implement it:
            candidate #1: `std::clone::Clone`

diff --git a/src/test/ui/issues/issue-31173.stderr b/src/test/ui/issues/issue-31173.stderr
@@ -16,10 +16,7 @@ LL |         .collect();
   ::: $SRC_DIR/libcore/iter/adapters/mod.rs:LL:COL
    |
 LL | pub struct Cloned<I> {
-   | -------------------- this type doesn't satisfy the bound `std::iter::Iterator`
-   |
-   = note: the method `collect` exists but the following trait bounds were not satisfied:
-           `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:10:39: 13:6 found_e:_]>>: std::iter::Iterator`
+   | -------------------- the method `collect` exists but this type doesn't satisfy the bound `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:10:39: 13:6 found_e:_]>>: std::iter::Iterator`
 
 error: aborting due to 2 previous errors
 

diff --git a/src/test/ui/methods/method-call-err-msg.stderr b/src/test/ui/methods/method-call-err-msg.stderr
@@ -38,13 +38,11 @@ LL | pub struct Foo;
    | ---------------
    | |
    | method `take` not found for this
-   | this type doesn't satisfy the bound `std::iter::Iterator`
+   | the method `take` exists but this type doesn't satisfy the bound `Foo: std::iter::Iterator`
 ...
 LL |      .take()
    |       ^^^^ method not found in `Foo`
    |
-   = note: the method `take` exists but the following trait bounds were not satisfied:
-           `Foo: std::iter::Iterator`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following traits define an item `take`, perhaps you need to implement one of them:
            candidate #1: `std::io::Read`

diff --git a/src/test/ui/mismatched_types/issue-36053-2.stderr b/src/test/ui/mismatched_types/issue-36053-2.stderr
@@ -7,11 +7,10 @@ LL |     once::<&str>("str").fuse().filter(|a: &str| true).count();
   ::: $SRC_DIR/libcore/iter/adapters/mod.rs:LL:COL
    |
 LL | pub struct Filter<I, P> {
-   | ----------------------- this type doesn't satisfy the bound `std::iter::Iterator`
+   | ----------------------- the method `count` exists but this type doesn't satisfy the bound `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:11:39: 11:53]>: std::iter::Iterator`
    |
    = note: the method `count` exists but the following trait bounds were not satisfied:
            `[closure@$DIR/issue-36053-2.rs:11:39: 11:53]: std::ops::FnMut<(&_,)>`
-           `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:11:39: 11:53]>: std::iter::Iterator`
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/issue-36053-2.rs:11:32

diff --git a/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr b/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr
@@ -2,13 +2,10 @@ error[E0599]: no method named `unwrap` found for enum `std::result::Result<(), F
   --> $DIR/method-help-unsatisfied-bound.rs:5:7
    |
 LL | struct Foo;
-   | ----------- this type doesn't satisfy the bound `std::fmt::Debug`
+   | ----------- the method `unwrap` exists but this type doesn't satisfy the bound `Foo: std::fmt::Debug`
 ...
 LL |     a.unwrap();
    |       ^^^^^^ method not found in `std::result::Result<(), Foo>`
-   |
-   = note: the method `unwrap` exists but the following trait bounds were not satisfied:
-           `Foo: std::fmt::Debug`
 
 error: aborting due to previous error
 

diff --git a/src/test/ui/specialization/defaultimpl/specialization-trait-not-implemented.stderr b/src/test/ui/specialization/defaultimpl/specialization-trait-not-implemented.stderr
@@ -8,13 +8,11 @@ LL | struct MyStruct;
    | ----------------
    | |
    | method `foo_one` not found for this
-   | this type doesn't satisfy the bound `Foo`
+   | the method `foo_one` exists but this type doesn't satisfy the bound `MyStruct: Foo`
 ...
 LL |     println!("{}", MyStruct.foo_one());
    |                             ^^^^^^^ method not found in `MyStruct`
    |
-   = note: the method `foo_one` exists but the following trait bounds were not satisfied:
-           `MyStruct: Foo`
    = help: items from traits can only be used if the trait is implemented and in scope
 
 error: aborting due to previous error

diff --git a/src/test/ui/union/union-derive-clone.stderr b/src/test/ui/union/union-derive-clone.stderr
@@ -14,13 +14,11 @@ LL | union U5<T> {
    | ----------- method `clone` not found for this
 ...
 LL | struct CloneNoCopy;
-   | ------------------- this type doesn't satisfy the bound `std::marker::Copy`
+   | ------------------- the method `clone` exists but this type doesn't satisfy the bound `CloneNoCopy: std::marker::Copy`
 ...
 LL |     let w = u.clone();
    |               ^^^^^ method not found in `U5<CloneNoCopy>`
    |
-   = note: the method `clone` exists but the following trait bounds were not satisfied:
-           `CloneNoCopy: std::marker::Copy`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following trait defines an item `clone`, perhaps you need to implement it:
            candidate #1: `std::clone::Clone`

diff --git a/src/test/ui/unique-object-noncopyable.stderr b/src/test/ui/unique-object-noncopyable.stderr
@@ -4,15 +4,12 @@ error[E0599]: no method named `clone` found for struct `std::boxed::Box<dyn Foo>
 LL | trait Foo {
    | ---------
    | |
-   | this trait doesn't satisfy the bound `std::clone::Clone`
-   | this trait doesn't satisfy the bound `std::marker::Sized`
+   | the method `clone` exists but this trait doesn't satisfy the bound `dyn Foo: std::clone::Clone`
+   | the method `clone` exists but this trait doesn't satisfy the bound `dyn Foo: std::marker::Sized`
 ...
 LL |     let _z = y.clone();
    |                ^^^^^ method not found in `std::boxed::Box<dyn Foo>`
    |
-   = note: the method `clone` exists but the following trait bounds were not satisfied:
-           `dyn Foo: std::clone::Clone`
-           `dyn Foo: std::marker::Sized`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following trait defines an item `clone`, perhaps you need to implement it:
            candidate #1: `std::clone::Clone`

diff --git a/src/test/ui/unique-pinned-nocopy.stderr b/src/test/ui/unique-pinned-nocopy.stderr
@@ -2,13 +2,11 @@ error[E0599]: no method named `clone` found for struct `std::boxed::Box<R>` in t
   --> $DIR/unique-pinned-nocopy.rs:12:16
    |
 LL | struct R {
-   | -------- this type doesn't satisfy the bound `std::clone::Clone`
+   | -------- the method `clone` exists but this type doesn't satisfy the bound `R: std::clone::Clone`
 ...
 LL |     let _j = i.clone();
    |                ^^^^^ method not found in `std::boxed::Box<R>`
    |
-   = note: the method `clone` exists but the following trait bounds were not satisfied:
-           `R: std::clone::Clone`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following trait defines an item `clone`, perhaps you need to implement it:
            candidate #1: `std::clone::Clone`