fn trait_has_sized_self<'tcx>(tcx: &ty::ctxt<'tcx>,
trait_def_id: ast::DefId)
-> bool
+{
+ let trait_def = ty::lookup_trait_def(tcx, trait_def_id);
+ let trait_predicates = ty::lookup_predicates(tcx, trait_def_id);
+ generics_require_sized_self(tcx, &trait_def.generics, &trait_predicates)
+}
+
+fn generics_require_sized_self<'tcx>(tcx: &ty::ctxt<'tcx>,
+ generics: &ty::Generics<'tcx>,
+ predicates: &ty::GenericPredicates<'tcx>)
+ -> bool
{
let sized_def_id = match tcx.lang_items.sized_trait() {
Some(def_id) => def_id,
};
// Search for a predicate like `Self : Sized` amongst the trait bounds.
- let trait_def = ty::lookup_trait_def(tcx, trait_def_id);
- let free_substs = ty::construct_free_substs(tcx, &trait_def.generics, ast::DUMMY_NODE_ID);
-
- let trait_predicates = ty::lookup_predicates(tcx, trait_def_id);
- let predicates = trait_predicates.instantiate(tcx, &free_substs).predicates.into_vec();
-
+ let free_substs = ty::construct_free_substs(tcx, generics, ast::DUMMY_NODE_ID);
+ let predicates = predicates.instantiate(tcx, &free_substs).predicates.into_vec();
elaborate_predicates(tcx, predicates)
.any(|predicate| {
match predicate {
method: &ty::Method<'tcx>)
-> Option<MethodViolationCode>
{
+ // Any method that has a `Self : Sized` requisite is otherwise
+ // exempt from the regulations.
+ if generics_require_sized_self(tcx, &method.generics, &method.predicates) {
+ return None;
+ }
+
// The method's first parameter must be something that derefs to
// `&self`. For now, we only accept `&self` and `Box<Self>`.
match method.explicit_self {
param_substs,
substs.clone()).val;
- // currently, at least, by-value self is not object safe
- assert!(m.explicit_self != ty::ByValueExplicitSelfCategory);
-
Some(fn_ref).into_iter()
}
}
// except according to those terms.
// Check that we correctly prevent users from making trait objects
-// from traits with a `fn(self)` method.
+// from traits with a `fn(self)` method, unless `where Self : Sized`
+// is present on the method.
trait Bar {
fn bar(self);
fn baz(self: Self);
}
+trait Quux {
+ // Legal because of the where clause:
+ fn baz(self: Self) where Self : Sized;
+}
+
fn make_bar<T:Bar>(t: &T) -> &Bar {
t
//~^ ERROR `Bar` is not object-safe
//~| NOTE method `baz` has a receiver type of `Self`
}
+fn make_quux<T:Quux>(t: &T) -> &Quux {
+ t
+}
+
+fn make_quux_explicit<T:Quux>(t: &T) -> &Quux {
+ t as &Quux
+}
+
fn main() {
}
// except according to those terms.
// Check that we correctly prevent users from making trait objects
-// from traits with generic methods.
+// from traits with generic methods, unless `where Self : Sized` is
+// present.
trait Bar {
fn bar<T>(&self, t: T);
}
+trait Quux {
+ fn bar<T>(&self, t: T)
+ where Self : Sized;
+}
+
fn make_bar<T:Bar>(t: &T) -> &Bar {
t
//~^ ERROR `Bar` is not object-safe
//~| NOTE method `bar` has generic type parameters
}
+fn make_quux<T:Quux>(t: &T) -> &Quux {
+ t
+}
+
+fn make_quux_explicit<T:Quux>(t: &T) -> &Quux {
+ t as &Quux
+}
+
fn main() {
}
// except according to those terms.
// Check that we correctly prevent users from making trait objects
-// form traits that make use of `Self` in an argument or return position.
+// form traits that make use of `Self` in an argument or return
+// position, unless `where Self : Sized` is present..
trait Bar {
fn bar(&self, x: &Self);
fn bar(&self) -> Self;
}
+trait Quux {
+ fn get(&self, s: &Self) -> Self where Self : Sized;
+}
+
fn make_bar<T:Bar>(t: &T) -> &Bar {
t
//~^ ERROR `Bar` is not object-safe
//~| NOTE method `bar` references the `Self` type in its arguments or return type
}
+fn make_quux<T:Quux>(t: &T) -> &Quux {
+ t
+}
+
+fn make_quux_explicit<T:Quux>(t: &T) -> &Quux {
+ t as &Quux
+}
+
fn main() {
}
--- /dev/null
+// 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 <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.
+
+// Check that a trait is still object-safe (and usable) if it has
+// methods with by-value self so long as they require `Self : Sized`.
+
+trait Counter {
+ fn tick(&mut self) -> u32;
+ fn get(self) -> u32 where Self : Sized;
+}
+
+struct CCounter {
+ c: u32
+}
+
+impl Counter for CCounter {
+ fn tick(&mut self) -> u32 { self.c += 1; self.c }
+ fn get(self) -> u32 where Self : Sized { self.c }
+}
+
+fn tick1<C:Counter>(mut c: C) -> u32 {
+ tick2(&mut c);
+ c.get()
+}
+
+fn tick2(c: &mut Counter) {
+ tick3(c);
+}
+
+fn tick3<C:?Sized+Counter>(c: &mut C) {
+ c.tick();
+ c.tick();
+}
+
+fn main() {
+ let mut c = CCounter { c: 0 };
+ let value = tick1(c);
+ assert_eq!(value, 2);
+}
--- /dev/null
+// 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 <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.
+
+// Check that a trait is still object-safe (and usable) if it has
+// generic methods so long as they require `Self : Sized`.
+
+trait Counter {
+ fn tick(&mut self) -> u32;
+ fn with<F:FnOnce(u32)>(&self, f: F) where Self : Sized;
+}
+
+struct CCounter {
+ c: u32
+}
+
+impl Counter for CCounter {
+ fn tick(&mut self) -> u32 { self.c += 1; self.c }
+ fn with<F:FnOnce(u32)>(&self, f: F) { f(self.c); }
+}
+
+fn tick1<C:Counter>(c: &mut C) {
+ tick2(c);
+ c.with(|i| ());
+}
+
+fn tick2(c: &mut Counter) {
+ tick3(c);
+}
+
+fn tick3<C:?Sized+Counter>(c: &mut C) {
+ c.tick();
+ c.tick();
+}
+
+fn main() {
+ let mut c = CCounter { c: 0 };
+ tick1(&mut c);
+ assert_eq!(c.tick(), 3);
+}
--- /dev/null
+// 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 <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.
+
+// Check that a trait is still object-safe (and usable) if it has
+// methods that return `Self` so long as they require `Self : Sized`.
+
+trait Counter {
+ fn new() -> Self where Self : Sized;
+ fn tick(&mut self) -> u32;
+}
+
+struct CCounter {
+ c: u32
+}
+
+impl Counter for CCounter {
+ fn new() -> CCounter { CCounter { c: 0 } }
+ fn tick(&mut self) -> u32 { self.c += 1; self.c }
+}
+
+fn preticked<C:Counter>() -> C {
+ let mut c: C = Counter::new();
+ tick(&mut c);
+ c
+}
+
+fn tick(c: &mut Counter) {
+ tick_generic(c);
+}
+
+fn tick_generic<C:?Sized+Counter>(c: &mut C) {
+ c.tick();
+ c.tick();
+}
+
+fn main() {
+ let mut c = preticked::<CCounter>();
+ tick(&mut c);
+ assert_eq!(c.tick(), 5);
+}
projects / rust.git / commitdiff