diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/librustc/traits/error_reporting.rs | 30 | ||||
| -rw-r--r-- | src/test/compile-fail/E0277.rs | 9 |
2 files changed, 32 insertions, 7 deletions
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs index 2e8e45468dd..db375f2be73 100644 --- a/src/librustc/traits/error_reporting.rs +++ b/src/librustc/traits/error_reporting.rs @@ -487,13 +487,29 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { } else { let trait_ref = trait_predicate.to_poly_trait_ref(); - let mut err = struct_span_err!(self.tcx.sess, span, E0277, - "the trait bound `{}` is not satisfied", - trait_ref.to_predicate()); - err.span_label(span, &format!("the trait `{}` is not implemented \ - for `{}`", - trait_ref, - trait_ref.self_ty())); + let (post_message, pre_message) = + if let ObligationCauseCode::BuiltinDerivedObligation(ref data) + = obligation.cause.code { + let parent_trait_ref = self.resolve_type_vars_if_possible( + &data.parent_trait_ref); + (format!(" in `{}`", parent_trait_ref.0.self_ty()), + format!("within `{}`, ", parent_trait_ref.0.self_ty())) + } else { + (String::new(), String::new()) + }; + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0277, + "the trait bound `{}` is not satisfied{}", + trait_ref.to_predicate(), + post_message); + err.span_label(span, + &format!("{}the trait `{}` is not \ + implemented for `{}`", + pre_message, + trait_ref, + trait_ref.self_ty())); // Try to report a help message diff --git a/src/test/compile-fail/E0277.rs b/src/test/compile-fail/E0277.rs index e4cb50cd3f2..e31fea1e458 100644 --- a/src/test/compile-fail/E0277.rs +++ b/src/test/compile-fail/E0277.rs @@ -8,6 +8,8 @@ // option. This file may not be copied, modified, or distributed // except according to those terms. +use std::path::Path; + trait Foo { fn bar(&self); } @@ -16,6 +18,13 @@ fn some_func<T: Foo>(foo: T) { foo.bar(); } +fn f(p: Path) { } +//~^ ERROR the trait bound `[u8]: std::marker::Sized` is not satisfied in `std::path::Path` +//~| NOTE within `std::path::Path`, the trait `std::marker::Sized` is not implemented for `[u8]` +//~| NOTE `[u8]` does not have a constant size known at compile-time +//~| NOTE required because it appears within the type `std::path::Path` +//~| NOTE all local variables must have a statically known size + fn main() { some_func(5i32); //~^ ERROR the trait bound `i32: Foo` is not satisfied |