diff --git a/src/librustc/traits/object_safety.rs b/src/librustc/traits/object_safety.rs index d190635bec3..e5393288802 100644 --- a/src/librustc/traits/object_safety.rs +++ b/src/librustc/traits/object_safety.rs @@ -37,6 +37,9 @@ pub enum ObjectSafetyViolation { /// Method has something illegal Method(ast::Name, MethodViolationCode), + + /// Associated const + AssociatedConst(ast::Name), } impl ObjectSafetyViolation { @@ -54,6 +57,8 @@ impl ObjectSafetyViolation { in its arguments or return type", name).into(), ObjectSafetyViolation::Method(name, MethodViolationCode::Generic) => format!("method `{}` has generic type parameters", name).into(), + ObjectSafetyViolation::AssociatedConst(name) => + format!("the trait cannot contain associated consts like `{}`", name).into(), } } } @@ -141,6 +146,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { violations.push(ObjectSafetyViolation::SupertraitSelf); } + violations.extend(self.associated_items(trait_def_id) + .filter(|item| item.kind == ty::AssociatedKind::Const) + .map(|item| ObjectSafetyViolation::AssociatedConst(item.name))); + debug!("object_safety_violations_for_trait(trait_def_id={:?}) = {:?}", trait_def_id, violations); diff --git a/src/test/compile-fail/object-safety-associated-consts.rs b/src/test/compile-fail/object-safety-associated-consts.rs new file mode 100644 index 00000000000..c442cd40836 --- /dev/null +++ b/src/test/compile-fail/object-safety-associated-consts.rs @@ -0,0 +1,28 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// Check that we correctly prevent users from making trait objects +// from traits with associated consts. + +#![feature(associated_consts)] + +trait Bar { + const X: usize; +} + +fn make_bar(t: &T) -> &Bar { + //~^ ERROR E0038 + //~| NOTE the trait cannot contain associated consts like `X` + //~| NOTE the trait `Bar` cannot be made into an object + t +} + +fn main() { +}