diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index e4aabbdb7ede7..727285e4927a0 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -1361,7 +1361,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { ) => false, (ParamCandidate(other), ParamCandidate(victim)) => { - if other.value == victim.value && victim.constness == Constness::NotConst { + let value_same_except_bound_vars = other.value.skip_binder() + == victim.value.skip_binder() + && !other.value.skip_binder().has_escaping_bound_vars(); + if value_same_except_bound_vars { + // See issue #84398. In short, we can generate multiple ParamCandidates which are + // the same except for unused bound vars. Just pick the one with the fewest bound vars + // or the current one if tied (they should both evaluate to the same answer). This is + // probably best characterized as a "hack", since we might prefer to just do our + // best to *not* create essentially duplicate candidates in the first place. + other.value.bound_vars().len() <= victim.value.bound_vars().len() + } else if other.value == victim.value && victim.constness == Constness::NotConst { // Drop otherwise equivalent non-const candidates in favor of const candidates. true } else { diff --git a/compiler/rustc_typeck/src/check/method/suggest.rs b/compiler/rustc_typeck/src/check/method/suggest.rs index 73e35f0171aa7..b2e4e7a981d20 100644 --- a/compiler/rustc_typeck/src/check/method/suggest.rs +++ b/compiler/rustc_typeck/src/check/method/suggest.rs @@ -579,6 +579,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } let mut restrict_type_params = false; + let mut unsatisfied_bounds = false; if !unsatisfied_predicates.is_empty() { let def_span = |def_id| { self.tcx.sess.source_map().guess_head_span(self.tcx.def_span(def_id)) @@ -739,6 +740,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { err.note(&format!( "the following trait bounds were not satisfied:\n{bound_list}" )); + unsatisfied_bounds = true; } } @@ -752,6 +754,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { source, out_of_scope_traits, &unsatisfied_predicates, + unsatisfied_bounds, ); } @@ -984,9 +987,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { source: SelfSource<'tcx>, valid_out_of_scope_traits: Vec, unsatisfied_predicates: &[(ty::Predicate<'tcx>, Option>)], + unsatisfied_bounds: bool, ) { let mut alt_rcvr_sugg = false; - if let SelfSource::MethodCall(rcvr) = source { + if let (SelfSource::MethodCall(rcvr), false) = (source, unsatisfied_bounds) { debug!(?span, ?item_name, ?rcvr_ty, ?rcvr); let skippable = [ self.tcx.lang_items().clone_trait(), diff --git a/src/stage0.txt b/src/stage0.txt index 3a76177474908..231e66719d00a 100644 --- a/src/stage0.txt +++ b/src/stage0.txt @@ -12,7 +12,7 @@ # stable release's version number. `date` is the date where the release we're # bootstrapping off was released. -date: 2021-05-04 +date: 2021-05-06 rustc: 1.52.0 # We use a nightly rustfmt to format the source because it solves some @@ -39,4 +39,4 @@ rustc: 1.52.0 # looking at a beta source tarball and it's uncommented we'll shortly comment it # out. -dev: 1 +#dev: 1 diff --git a/src/test/ui/lifetimes/issue-84398.rs b/src/test/ui/lifetimes/issue-84398.rs new file mode 100644 index 0000000000000..1912fa59b7990 --- /dev/null +++ b/src/test/ui/lifetimes/issue-84398.rs @@ -0,0 +1,20 @@ +// check-pass + +pub trait Deserialize<'de>: Sized {} +pub trait DeserializeOwned: for<'de> Deserialize<'de> {} + +pub trait Extensible { + type Config; +} + +// The `C` here generates a `C: Sized` candidate +pub trait Installer { + fn init>(&mut self) -> () + where + // This clause generates a `for<'de> C: Sized` candidate + B::Config: DeserializeOwned, + { + } +} + +fn main() {} diff --git a/src/test/ui/suggestions/import-trait-for-method-call.rs b/src/test/ui/suggestions/import-trait-for-method-call.rs index 646f68dea14e8..4dbadbdf98206 100644 --- a/src/test/ui/suggestions/import-trait-for-method-call.rs +++ b/src/test/ui/suggestions/import-trait-for-method-call.rs @@ -6,4 +6,11 @@ fn next_u64() -> u64 { h.finish() //~ ERROR no method named `finish` found for struct `DefaultHasher` } -fn main() {} +trait Bar {} +impl Bar for String {} + +fn main() { + let s = String::from("hey"); + let x: &dyn Bar = &s; + x.as_ref(); //~ ERROR the method `as_ref` exists for reference `&dyn Bar`, but its trait bounds +} diff --git a/src/test/ui/suggestions/import-trait-for-method-call.stderr b/src/test/ui/suggestions/import-trait-for-method-call.stderr index f3ae20552f3d5..a2b9b9d14ab09 100644 --- a/src/test/ui/suggestions/import-trait-for-method-call.stderr +++ b/src/test/ui/suggestions/import-trait-for-method-call.stderr @@ -15,6 +15,22 @@ help: the following trait is implemented but not in scope; perhaps add a `use` f LL | use std::hash::Hasher; | -error: aborting due to previous error +error[E0599]: the method `as_ref` exists for reference `&dyn Bar`, but its trait bounds were not satisfied + --> $DIR/import-trait-for-method-call.rs:15:7 + | +LL | trait Bar {} + | --------- doesn't satisfy `dyn Bar: AsRef<_>` +... +LL | x.as_ref(); + | ^^^^^^ method cannot be called on `&dyn Bar` due to unsatisfied trait bounds + | + = note: the following trait bounds were not satisfied: + `dyn Bar: AsRef<_>` + which is required by `&dyn Bar: AsRef<_>` + = help: items from traits can only be used if the trait is implemented and in scope + = note: the following trait defines an item `as_ref`, perhaps you need to implement it: + candidate #1: `AsRef` + +error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0599`.