diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs index 0144d51a9693f..f8efa0b9de204 100644 --- a/src/librustc/traits/error_reporting.rs +++ b/src/librustc/traits/error_reporting.rs @@ -38,6 +38,7 @@ use std::fmt; use syntax::ast; use syntax::symbol::{sym, kw}; use syntax_pos::{DUMMY_SP, Span, ExpnKind, MultiSpan}; +use rustc::hir::def_id::LOCAL_CRATE; use rustc_error_codes::*; @@ -799,6 +800,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { self.suggest_fn_call(&obligation, &mut err, &trait_ref, points_at_arg); self.suggest_remove_reference(&obligation, &mut err, &trait_ref); self.suggest_semicolon_removal(&obligation, &mut err, span, &trait_ref); + self.note_version_mismatch(&mut err, &trait_ref); // Try to report a help message if !trait_ref.has_infer_types() && @@ -1050,6 +1052,43 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { err.emit(); } + /// If the `Self` type of the unsatisfied trait `trait_ref` implements a trait + /// with the same path as `trait_ref`, a help message about + /// a probable version mismatch is added to `err` + fn note_version_mismatch( + &self, + err: &mut DiagnosticBuilder<'_>, + trait_ref: &ty::PolyTraitRef<'tcx>, + ) { + let get_trait_impl = |trait_def_id| { + let mut trait_impl = None; + self.tcx.for_each_relevant_impl(trait_def_id, trait_ref.self_ty(), |impl_def_id| { + if trait_impl.is_none() { + trait_impl = Some(impl_def_id); + } + }); + trait_impl + }; + let required_trait_path = self.tcx.def_path_str(trait_ref.def_id()); + let all_traits = self.tcx.all_traits(LOCAL_CRATE); + let traits_with_same_path: std::collections::BTreeSet<_> = all_traits + .iter() + .filter(|trait_def_id| **trait_def_id != trait_ref.def_id()) + .filter(|trait_def_id| self.tcx.def_path_str(**trait_def_id) == required_trait_path) + .collect(); + for trait_with_same_path in traits_with_same_path { + if let Some(impl_def_id) = get_trait_impl(*trait_with_same_path) { + let impl_span = self.tcx.def_span(impl_def_id); + err.span_help(impl_span, "trait impl with same name found"); + let trait_crate = self.tcx.crate_name(trait_with_same_path.krate); + let crate_msg = format!( + "Perhaps two different versions of crate `{}` are being used?", + trait_crate + ); + err.note(&crate_msg); + } + } + } fn suggest_restricting_param_bound( &self, err: &mut DiagnosticBuilder<'_>, diff --git a/src/test/ui/traits/auxiliary/crate_a1.rs b/src/test/ui/traits/auxiliary/crate_a1.rs index e2e18500541ef..6aa010258ebd5 100644 --- a/src/test/ui/traits/auxiliary/crate_a1.rs +++ b/src/test/ui/traits/auxiliary/crate_a1.rs @@ -1,11 +1,9 @@ -pub struct Foo; +pub trait Bar {} -pub trait Bar{} +pub fn try_foo(x: impl Bar) {} -pub fn bar() -> Box { - unimplemented!() +pub struct ImplementsTraitForUsize { + _marker: std::marker::PhantomData, } - -pub fn try_foo(x: Foo){} -pub fn try_bar(x: Box){} +impl Bar for ImplementsTraitForUsize {} diff --git a/src/test/ui/traits/auxiliary/crate_a2.rs b/src/test/ui/traits/auxiliary/crate_a2.rs new file mode 100644 index 0000000000000..d6057db5e63f1 --- /dev/null +++ b/src/test/ui/traits/auxiliary/crate_a2.rs @@ -0,0 +1,13 @@ +pub struct Foo; + +pub trait Bar {} + +impl Bar for Foo {} + +pub struct DoesNotImplementTrait; + +pub struct ImplementsWrongTraitConditionally { + _marker: std::marker::PhantomData, +} + +impl Bar for ImplementsWrongTraitConditionally {} diff --git a/src/test/ui/traits/trait-bounds-same-crate-name.rs b/src/test/ui/traits/trait-bounds-same-crate-name.rs new file mode 100644 index 0000000000000..af720ecfdc063 --- /dev/null +++ b/src/test/ui/traits/trait-bounds-same-crate-name.rs @@ -0,0 +1,55 @@ +// aux-build:crate_a1.rs +// aux-build:crate_a2.rs + +// Issue 22750 +// This tests the extra help message reported when a trait bound +// is not met but the struct implements a trait with the same path. + +fn main() { + let foo = { + extern crate crate_a2 as a; + a::Foo + }; + + let implements_no_traits = { + extern crate crate_a2 as a; + a::DoesNotImplementTrait + }; + + let other_variant_implements_mismatched_trait = { + extern crate crate_a2 as a; + a::ImplementsWrongTraitConditionally { _marker: std::marker::PhantomData:: } + }; + + let other_variant_implements_correct_trait = { + extern crate crate_a1 as a; + a::ImplementsTraitForUsize { _marker: std::marker::PhantomData:: } + }; + + { + extern crate crate_a1 as a; + a::try_foo(foo); + //~^ ERROR E0277 + //~| trait impl with same name found + //~| Perhaps two different versions of crate `crate_a2` + + // We don't want to see the "version mismatch" help message here + // because `implements_no_traits` has no impl for `Foo` + a::try_foo(implements_no_traits); + //~^ ERROR E0277 + + // We don't want to see the "version mismatch" help message here + // because `other_variant_implements_mismatched_trait` + // does not have an impl for its `` variant, + // only for its `` variant. + a::try_foo(other_variant_implements_mismatched_trait); + //~^ ERROR E0277 + + // We don't want to see the "version mismatch" help message here + // because `ImplementsTraitForUsize` only has + // impls for the correct trait where the path is not misleading. + a::try_foo(other_variant_implements_correct_trait); + //~^ ERROR E0277 + //~| the following implementations were found: + } +} diff --git a/src/test/ui/traits/trait-bounds-same-crate-name.stderr b/src/test/ui/traits/trait-bounds-same-crate-name.stderr new file mode 100644 index 0000000000000..8fd0bd13e54b3 --- /dev/null +++ b/src/test/ui/traits/trait-bounds-same-crate-name.stderr @@ -0,0 +1,64 @@ +error[E0277]: the trait bound `main::a::Foo: main::a::Bar` is not satisfied + --> $DIR/trait-bounds-same-crate-name.rs:31:20 + | +LL | a::try_foo(foo); + | ^^^ the trait `main::a::Bar` is not implemented for `main::a::Foo` + | + ::: $DIR/auxiliary/crate_a1.rs:3:24 + | +LL | pub fn try_foo(x: impl Bar) {} + | --- required by this bound in `main::a::try_foo` + | +help: trait impl with same name found + --> $DIR/auxiliary/crate_a2.rs:5:1 + | +LL | impl Bar for Foo {} + | ^^^^^^^^^^^^^^^^^^^ + = note: Perhaps two different versions of crate `crate_a2` are being used? + +error[E0277]: the trait bound `main::a::DoesNotImplementTrait: main::a::Bar` is not satisfied + --> $DIR/trait-bounds-same-crate-name.rs:38:20 + | +LL | a::try_foo(implements_no_traits); + | ^^^^^^^^^^^^^^^^^^^^ the trait `main::a::Bar` is not implemented for `main::a::DoesNotImplementTrait` + | + ::: $DIR/auxiliary/crate_a1.rs:3:24 + | +LL | pub fn try_foo(x: impl Bar) {} + | --- required by this bound in `main::a::try_foo` + +error[E0277]: the trait bound `main::a::ImplementsWrongTraitConditionally: main::a::Bar` is not satisfied + --> $DIR/trait-bounds-same-crate-name.rs:45:20 + | +LL | a::try_foo(other_variant_implements_mismatched_trait); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `main::a::Bar` is not implemented for `main::a::ImplementsWrongTraitConditionally` + | + ::: $DIR/auxiliary/crate_a1.rs:3:24 + | +LL | pub fn try_foo(x: impl Bar) {} + | --- required by this bound in `main::a::try_foo` + | +help: trait impl with same name found + --> $DIR/auxiliary/crate_a2.rs:13:1 + | +LL | impl Bar for ImplementsWrongTraitConditionally {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + = note: Perhaps two different versions of crate `crate_a2` are being used? + +error[E0277]: the trait bound `main::a::ImplementsTraitForUsize: main::a::Bar` is not satisfied + --> $DIR/trait-bounds-same-crate-name.rs:51:20 + | +LL | a::try_foo(other_variant_implements_correct_trait); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `main::a::Bar` is not implemented for `main::a::ImplementsTraitForUsize` + | + ::: $DIR/auxiliary/crate_a1.rs:3:24 + | +LL | pub fn try_foo(x: impl Bar) {} + | --- required by this bound in `main::a::try_foo` + | + = help: the following implementations were found: + as main::a::Bar> + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0277`.