This is virtually certain to cause regressions, needs crater.
In #50781 it was discovered that our object safety rules are not sound because we allow `Self` in where clauses without restrain. This PR is a direct fix to the rules so that we disallow methods with unsound where clauses.
This currently uses hard error to measure impact, but we will want to downgrade it to a future compat error.
Fixes #50781.
r? @nikomatsakis
return Some(MethodViolationCode::Generic);
}
+ if self.predicates_of(method.def_id).predicates.into_iter()
+ // A trait object can't claim to live more than the concrete type,
+ // so outlives predicates will always hold.
+ .filter(|p| p.to_opt_type_outlives().is_none())
+ .collect::<Vec<_>>()
+ // Do a shallow visit so that `contains_illegal_self_type_reference`
+ // may apply it's custom visiting.
+ .visit_tys_shallow(|t| self.contains_illegal_self_type_reference(trait_def_id, t)) {
+ return Some(MethodViolationCode::ReferencesSelf);
+ }
+
None
}
fn has_late_bound_regions(&self) -> bool {
self.has_type_flags(TypeFlags::HAS_RE_LATE_BOUND)
}
+
+ /// A visitor that does not recurse into types, works like `fn walk_shallow` in `Ty`.
+ fn visit_tys_shallow(&self, visit: impl FnMut(Ty<'tcx>) -> bool) -> bool {
+
+ pub struct Visitor<F>(F);
+
+ impl<'tcx, F: FnMut(Ty<'tcx>) -> bool> TypeVisitor<'tcx> for Visitor<F> {
+ fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
+ self.0(ty)
+ }
+ }
+
+ self.visit_with(&mut Visitor(visit))
+ }
}
/// The TypeFolder trait defines the actual *folding*. There is a
+++ /dev/null
-// Copyright 2015 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 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// Test that we do not ICE when a default method implementation has
-// requirements (in this case, `Self : Baz`) that do not hold for some
-// specific impl (in this case, `Foo : Bar`). This causes problems
-// only when building a vtable, because that goes along and
-// instantiates all the methods, even those that could not otherwise
-// be called.
-
-// pretty-expanded FIXME #23616
-
-struct Foo {
- x: i32
-}
-
-trait Bar {
- fn bar(&self) where Self : Baz { self.baz(); }
-}
-
-trait Baz {
- fn baz(&self);
-}
-
-impl Bar for Foo {
-}
-
-fn main() {
- let x: &Bar = &Foo { x: 22 };
-}
--- /dev/null
+// Copyright 2018 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 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+trait Trait {}
+
+trait X {
+ fn foo(&self) where Self: Trait;
+}
+
+impl X for () {
+ fn foo(&self) {}
+}
+
+impl Trait for dyn X {}
+//~^ ERROR the trait `X` cannot be made into an object
+
+pub fn main() {
+ // Check that this does not segfault.
+ <X as X>::foo(&());
+}
--- /dev/null
+error[E0038]: the trait `X` cannot be made into an object
+ --> $DIR/issue-50781.rs:21:6
+ |
+LL | impl Trait for dyn X {}
+ | ^^^^^ the trait `X` cannot be made into an object
+ |
+ = note: method `foo` references the `Self` type in its arguments or return type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0038`.