Add more context to E0599 errors

estebank · estebank · commit 9fa8d87797f1 · 2020-02-21T12:04:36.000-08:00
Point at the intermediary unfullfilled trait bounds.
diff --git a/src/librustc_infer/infer/error_reporting/note.rs b/src/librustc_infer/infer/error_reporting/note.rs
@@ -645,8 +645,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     self.tcx.sess,
                     span,
                     E0491,
-                    "in type `{}`, reference has a longer lifetime \
-                                                than the data it references",
+                    "in type `{}`, reference has a longer lifetime than the data it references",
                     self.ty_to_string(ty)
                 );
                 note_and_explain_region(
diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs
@@ -1404,15 +1404,40 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                             // `potentially_unsatisfied_predicates`.
                             return ProbeResult::NoMatch;
                         } else {
-                            // Some nested subobligation of this predicate
-                            // failed.
-                            //
-                            // FIXME: try to find the exact nested subobligation
-                            // and point at it rather than reporting the entire
-                            // trait-ref?
-                            result = ProbeResult::NoMatch;
-                            let trait_ref = self.resolve_vars_if_possible(&trait_ref);
-                            possibly_unsatisfied_predicates.push(trait_ref);
+                            self.probe(|_| {
+                                match self.select_trait_candidate(trait_ref) {
+                                    Ok(Some(traits::VtableImpl(traits::VtableImplData {
+                                        nested,
+                                        ..
+                                    }))) if !nested.is_empty() => {
+                                        for obligation in nested {
+                                            // Determine exactly which obligation wasn't met, so
+                                            // that we can give more context in the error.
+                                            if !self.predicate_may_hold(&obligation) {
+                                                result = ProbeResult::NoMatch;
+                                                if let Some(poly_trait_ref) =
+                                                    obligation.predicate.to_opt_poly_trait_ref()
+                                                {
+                                                    let trait_ref = poly_trait_ref.clone();
+                                                    let trait_ref = trait_ref.skip_binder();
+                                                    possibly_unsatisfied_predicates
+                                                        .push(*trait_ref);
+                                                }
+                                            }
+                                        }
+                                    }
+                                    _ => {}
+                                }
+                                // Some nested subobligation of this predicate
+                                // failed.
+                                //
+                                // FIXME: try to find the exact nested subobligation
+                                // and point at it rather than reporting the entire
+                                // trait-ref?
+                                result = ProbeResult::NoMatch;
+                                let trait_ref = self.resolve_vars_if_possible(&trait_ref);
+                                possibly_unsatisfied_predicates.push(trait_ref);
+                            });
                         }
                     }
                     vec![]
diff --git a/src/librustc_typeck/check/method/suggest.rs b/src/librustc_typeck/check/method/suggest.rs
@@ -394,6 +394,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     tcx.sess.diagnostic().struct_dummy()
                 };
 
+                // FIXME: Unify with unmet bound label.
                 if let Some(def) = actual.ty_adt_def() {
                     if let Some(full_sp) = tcx.hir().span_if_local(def.did) {
                         let def_sp = tcx.sess.source_map().def_span(full_sp);
@@ -535,16 +536,54 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
 
                 if !unsatisfied_predicates.is_empty() {
+                    let mut bound_spans = vec![];
                     let mut bound_list = unsatisfied_predicates
                         .iter()
-                        .map(|p| format!("`{} : {}`", p.self_ty(), p.print_only_trait_path()))
+                        .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::Dynamic(preds, _) => {
+                                    for pred in *preds.skip_binder() {
+                                        match pred {
+                                            ty::ExistentialPredicate::Trait(tr) => bound_spans
+                                                .push((
+                                                    self.tcx
+                                                        .sess
+                                                        .source_map()
+                                                        .def_span(self.tcx.def_span(tr.def_id)),
+                                                    format!(
+                                                        "this trait doesn't satisfy the bound `{}`",
+                                                        p.print_only_trait_path()
+                                                    ),
+                                                )),
+                                            ty::ExistentialPredicate::Projection(_)
+                                            | ty::ExistentialPredicate::AutoTrait(_) => {}
+                                        }
+                                    }
+                                }
+                                _ => {}
+                            };
+                            format!("`{}: {}`", p.self_ty(), p.print_only_trait_path())
+                        })
                         .collect::<Vec<_>>();
                     bound_list.sort();
                     bound_list.dedup(); // #35677
+                    bound_spans.sort();
+                    bound_spans.dedup(); // #35677
+                    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{}",
+                        "the method `{}` exists but the following trait bounds were not \
+                         satisfied:\n{}",
                         item_name, bound_list
                     ));
                 }
diff --git a/src/test/ui/consts/too_generic_eval_ice.stderr b/src/test/ui/consts/too_generic_eval_ice.stderr
@@ -8,8 +8,8 @@ LL |         [5; Self::HOST_SIZE] == [6; 0]
    |                   ^^^^^^^^^ associated item not found in `Foo<A, B>`
    |
    = note: the method `HOST_SIZE` exists but the following trait bounds were not satisfied:
-           `A : std::marker::Sized`
-           `B : std::marker::Sized`
+           `A: std::marker::Sized`
+           `B: std::marker::Sized`
 
 error[E0277]: the size for values of type `A` cannot be known at compilation time
   --> $DIR/too_generic_eval_ice.rs:7:13
diff --git a/src/test/ui/derives/derive-assoc-type-not-impl.stderr b/src/test/ui/derives/derive-assoc-type-not-impl.stderr
@@ -2,13 +2,20 @@ error[E0599]: no method named `clone` found for struct `Bar<NotClone>` in the cu
   --> $DIR/derive-assoc-type-not-impl.rs:18:30
    |
 LL | struct Bar<T: Foo> {
-   | ------------------ method `clone` not found for this
+   | ------------------
+   | |
+   | method `clone` not found for this
+   | this type doesn't satisfy the bound `std::clone::Clone`
+...
+LL | struct NotClone;
+   | ---------------- this type doesn't satisfy the bound `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:
-           `Bar<NotClone> : std::clone::Clone`
+           `Bar<NotClone>: std::clone::Clone`
+           `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-21596.stderr b/src/test/ui/issues/issue-21596.stderr
@@ -7,7 +7,8 @@ LL |     println!("{}", z.to_string());
    = note: try using `<*const T>::as_ref()` to get a reference to the type behind the pointer: https://doc.rust-lang.org/std/primitive.pointer.html#method.as_ref
    = note: using `<*const T>::as_ref()` on a pointer which is unaligned or points to invalid or uninitialized memory is undefined behavior
    = note: the method `to_string` exists but the following trait bounds were not satisfied:
-           `*const u8 : std::string::ToString`
+           `*const u8: std::fmt::Display`
+           `*const u8: std::string::ToString`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-31173.rs b/src/test/ui/issues/issue-31173.rs
@@ -1,3 +1,7 @@
+// FIXME: missing sysroot spans (#53081)
+// ignore-i586-unknown-linux-gnu
+// ignore-i586-unknown-linux-musl
+// ignore-i686-unknown-linux-musl
 use std::vec::IntoIter;
 
 pub fn get_tok(it: &mut IntoIter<u8>) {
diff --git a/src/test/ui/issues/issue-31173.stderr b/src/test/ui/issues/issue-31173.stderr
@@ -1,21 +1,26 @@
-error[E0271]: type mismatch resolving `<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:6:39: 9:6 found_e:_]> as std::iter::Iterator>::Item == &_`
-  --> $DIR/issue-31173.rs:10:10
+error[E0271]: type mismatch resolving `<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:10:39: 13:6 found_e:_]> as std::iter::Iterator>::Item == &_`
+  --> $DIR/issue-31173.rs:14:10
    |
 LL |         .cloned()
    |          ^^^^^^ expected `u8`, found reference
    |
    = note:   expected type `u8`
            found reference `&_`
 
-error[E0599]: no method named `collect` found for struct `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:6:39: 9:6 found_e:_]>>` in the current scope
-  --> $DIR/issue-31173.rs:14:10
+error[E0599]: no method named `collect` found for struct `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:10:39: 13:6 found_e:_]>>` in the current scope
+  --> $DIR/issue-31173.rs:18:10
    |
 LL |         .collect();
-   |          ^^^^^^^ method not found in `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:6:39: 9:6 found_e:_]>>`
+   |          ^^^^^^^ method not found in `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:10:39: 13:6 found_e:_]>>`
+   | 
+  ::: $SRC_DIR/libcore/iter/adapters/mod.rs:LL:COL
+   |
+LL | pub struct Cloned<I> {
+   | -------------------- this type doesn't satisfy the bound `std::iter::Iterator`
    |
    = note: the method `collect` exists but the following trait bounds were not satisfied:
-           `&mut std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:6:39: 9:6 found_e:_]>> : std::iter::Iterator`
-           `std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:6:39: 9:6 found_e:_]>> : std::iter::Iterator`
+           `&mut std::iter::Cloned<std::iter::TakeWhile<&mut std::vec::IntoIter<u8>, [closure@$DIR/issue-31173.rs:10:39: 13:6 found_e:_]>>: std::iter::Iterator`
+           `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/issues/issue-35677.stderr b/src/test/ui/issues/issue-35677.stderr
@@ -5,8 +5,8 @@ LL |     this.is_subset(other)
    |          ^^^^^^^^^ method not found in `&std::collections::HashSet<T>`
    |
    = note: the method `is_subset` exists but the following trait bounds were not satisfied:
-           `T : std::cmp::Eq`
-           `T : std::hash::Hash`
+           `T: std::cmp::Eq`
+           `T: std::hash::Hash`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref.stderr
@@ -5,7 +5,7 @@ LL |     let _result = &Some(42).as_deref();
    |                             ^^^^^^^^ help: there is a method with a similar name: `as_ref`
    |
    = note: the method `as_deref` exists but the following trait bounds were not satisfied:
-           `{integer} : std::ops::Deref`
+           `{integer}: std::ops::Deref`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref_mut.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/option-as_deref_mut.stderr
@@ -5,7 +5,7 @@ LL |     let _result = &mut Some(42).as_deref_mut();
    |                                 ^^^^^^^^^^^^ method not found in `std::option::Option<{integer}>`
    |
    = note: the method `as_deref_mut` exists but the following trait bounds were not satisfied:
-           `{integer} : std::ops::DerefMut`
+           `{integer}: std::ops::DerefMut`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref.stderr
@@ -5,7 +5,7 @@ LL |     let _result = &Ok(42).as_deref();
    |                           ^^^^^^^^ help: there is a method with a similar name: `as_ref`
    |
    = note: the method `as_deref` exists but the following trait bounds were not satisfied:
-           `{integer} : std::ops::Deref`
+           `{integer}: std::ops::Deref`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_err.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_err.stderr
@@ -5,7 +5,7 @@ LL |     let _result = &Err(41).as_deref_err();
    |                            ^^^^^^^^^^^^ help: there is a method with a similar name: `as_deref_mut`
    |
    = note: the method `as_deref_err` exists but the following trait bounds were not satisfied:
-           `{integer} : std::ops::Deref`
+           `{integer}: std::ops::Deref`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut.stderr
@@ -5,7 +5,7 @@ LL |     let _result = &mut Ok(42).as_deref_mut();
    |                               ^^^^^^^^^^^^ help: there is a method with a similar name: `as_deref_err`
    |
    = note: the method `as_deref_mut` exists but the following trait bounds were not satisfied:
-           `{integer} : std::ops::DerefMut`
+           `{integer}: std::ops::DerefMut`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut_err.stderr b/src/test/ui/issues/issue-50264-inner-deref-trait/result-as_deref_mut_err.stderr
@@ -5,7 +5,7 @@ LL |     let _result = &mut Err(41).as_deref_mut_err();
    |                                ^^^^^^^^^^^^^^^^ help: there is a method with a similar name: `as_deref_mut`
    |
    = note: the method `as_deref_mut_err` exists but the following trait bounds were not satisfied:
-           `{integer} : std::ops::DerefMut`
+           `{integer}: std::ops::DerefMut`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/methods/method-call-err-msg.stderr b/src/test/ui/methods/method-call-err-msg.stderr
@@ -35,13 +35,17 @@ error[E0599]: no method named `take` found for struct `Foo` in the current scope
   --> $DIR/method-call-err-msg.rs:19:7
    |
 LL | pub struct Foo;
-   | --------------- method `take` not found for this
+   | ---------------
+   | |
+   | method `take` not found for this
+   | this type doesn't satisfy the bound `std::iter::Iterator`
 ...
 LL |      .take()
    |       ^^^^ method not found in `Foo`
    |
    = note: the method `take` exists but the following trait bounds were not satisfied:
-           `&mut Foo : std::iter::Iterator`
+           `&mut Foo: std::iter::Iterator`
+           `Foo: std::iter::Iterator`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following traits define an item `take`, perhaps you need to implement one of them:
            candidate #1: `std::io::Read`
diff --git a/src/test/ui/mismatched_types/issue-36053-2.rs b/src/test/ui/mismatched_types/issue-36053-2.rs
@@ -1,3 +1,7 @@
+// FIXME: missing sysroot spans (#53081)
+// ignore-i586-unknown-linux-gnu
+// ignore-i586-unknown-linux-musl
+// ignore-i686-unknown-linux-musl
 // Regression test for #36053. ICE was caused due to obligations
 // being added to a special, dedicated fulfillment cx during
 // a probe.
diff --git a/src/test/ui/mismatched_types/issue-36053-2.stderr b/src/test/ui/mismatched_types/issue-36053-2.stderr
@@ -1,15 +1,21 @@
-error[E0599]: no method named `count` found for struct `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:7:39: 7:53]>` in the current scope
-  --> $DIR/issue-36053-2.rs:7:55
+error[E0599]: no method named `count` found for struct `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:11:39: 11:53]>` in the current scope
+  --> $DIR/issue-36053-2.rs:11:55
    |
 LL |     once::<&str>("str").fuse().filter(|a: &str| true).count();
-   |                                                       ^^^^^ method not found in `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:7:39: 7:53]>`
+   |                                                       ^^^^^ method not found in `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:11:39: 11:53]>`
+   | 
+  ::: $SRC_DIR/libcore/iter/adapters/mod.rs:LL:COL
+   |
+LL | pub struct Filter<I, P> {
+   | ----------------------- this type doesn't satisfy the bound `std::iter::Iterator`
    |
    = note: the method `count` exists but the following trait bounds were not satisfied:
-           `&mut std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:7:39: 7:53]> : std::iter::Iterator`
-           `std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:7:39: 7:53]> : std::iter::Iterator`
+           `&mut std::iter::Filter<std::iter::Fuse<std::iter::Once<&str>>, [closure@$DIR/issue-36053-2.rs:11:39: 11:53]>: std::iter::Iterator`
+           `[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:7:32
+  --> $DIR/issue-36053-2.rs:11:32
    |
 LL |     once::<&str>("str").fuse().filter(|a: &str| true).count();
    |                                ^^^^^^ -------------- found signature of `for<'r> fn(&'r str) -> _`
diff --git a/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr b/src/test/ui/mismatched_types/method-help-unsatisfied-bound.stderr
@@ -1,11 +1,14 @@
 error[E0599]: no method named `unwrap` found for enum `std::result::Result<(), Foo>` in the current scope
   --> $DIR/method-help-unsatisfied-bound.rs:5:7
    |
+LL | struct Foo;
+   | ----------- this type doesn't satisfy the bound `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`
+           `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
@@ -2,13 +2,16 @@ error[E0599]: no method named `foo_one` found for struct `MyStruct` in the curre
   --> $DIR/specialization-trait-not-implemented.rs:22:29
    |
 LL | struct MyStruct;
-   | ---------------- method `foo_one` not found for this
+   | ----------------
+   | |
+   | method `foo_one` not found for this
+   | this type doesn't satisfy the bound `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`
+           `MyStruct: Foo`
    = help: items from traits can only be used if the trait is implemented and in scope
    = note: the following trait defines an item `foo_one`, perhaps you need to implement it:
            candidate #1: `Foo`
diff --git a/src/test/ui/suggestions/mut-borrow-needed-by-trait.rs b/src/test/ui/suggestions/mut-borrow-needed-by-trait.rs
@@ -1,3 +1,7 @@
+// FIXME: missing sysroot spans (#53081)
+// ignore-i586-unknown-linux-gnu
+// ignore-i586-unknown-linux-musl
+// ignore-i686-unknown-linux-musl
 use std::env::args;
 use std::fs::File;
 use std::io::{stdout, Write, BufWriter};
diff --git a/src/test/ui/suggestions/mut-borrow-needed-by-trait.stderr b/src/test/ui/suggestions/mut-borrow-needed-by-trait.stderr
diff --git a/src/test/ui/union/union-derive-clone.stderr b/src/test/ui/union/union-derive-clone.stderr
diff --git a/src/test/ui/unique-object-noncopyable.rs b/src/test/ui/unique-object-noncopyable.rs
diff --git a/src/test/ui/unique-object-noncopyable.stderr b/src/test/ui/unique-object-noncopyable.stderr
diff --git a/src/test/ui/unique-pinned-nocopy.rs b/src/test/ui/unique-pinned-nocopy.rs
diff --git a/src/test/ui/unique-pinned-nocopy.stderr b/src/test/ui/unique-pinned-nocopy.stderr

Original file line number	Diff line number	Diff line change
`@@ -5,8 +5,8 @@ LL \| this.is_subset(other)`
`5`	`5`	\| ^^^^^^^^^ method not found in `&std::collections::HashSet<T>`
`6`	`6`	`\|`
`7`	`7`	= note: the method `is_subset` exists but the following trait bounds were not satisfied:
`8`		- `T : std::cmp::Eq`
`9`		- `T : std::hash::Hash`
	`8`	+ `T: std::cmp::Eq`
	`9`	+ `T: std::hash::Hash`
`10`	`10`
`11`	`11`	`error: aborting due to previous error`
`12`	`12`
Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@ LL \| let _result = &Some(42).as_deref();`
`5`	`5`	\| ^^^^^^^^ help: there is a method with a similar name: `as_ref`
`6`	`6`	`\|`
`7`	`7`	= note: the method `as_deref` exists but the following trait bounds were not satisfied:
`8`		- `{integer} : std::ops::Deref`
	`8`	+ `{integer}: std::ops::Deref`
`9`	`9`
`10`	`10`	`error: aborting due to previous error`
`11`	`11`