Auto merge of #11872 - eddyb:back-to-roots, r=Ms2ger

Replace return_address usage for rooting with stack guards and convenience macros.

The existing `Rooted` and `RootedVec` users were migrated the the following two macros:
```rust
let x = Rooted::new(cx, value);
// Was changed to:
rooted!(in(cx) let x = value);
// Which expands to:
let mut __root = Rooted::new_unrooted(value);
let x = RootedGuard::new(cx, &mut __root);
```
```rust
let mut v = RootedVec::new();
v.extend(iterator);
// Was changed to:
rooted_vec!(let v <- iterator);
// Which expands to:
let mut __root = RootableVec::new();
let v = RootedVec::new(&mut __root, iterator);
```

The `rooted!` macro depends on servo/rust-mozjs#272.
These APIs based on two types, a container to be rooted and a rooting guard, allow implementing both `Rooted`-style rooting and `Traceable`-based rooting in stable Rust, without abusing `return_address`.

Such macros may have been tried before, but in 1.9 their hygiene is broken, they work only since 1.10.

Sadly, `Rooted` is a FFI type and completely exposed, so I cannot prevent anyone from creating their own, although all fields but the value get overwritten by `RootedGuard::new` anyway.
`RootableVec` OTOH is *guaranteed* to be empty when not rooted, which makes it harmless AFAICT.

By fixing rust-lang/rust#34227, this PR enables Servo to build with `-Zorbit`.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix rust-lang/rust#34227
- [x] These changes do not require tests because they are not functional changes

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This commit is contained in:
bors-servo 2016-07-04 11:03:35 -07:00 committed by GitHub
commit 80cb0cf821
33 changed files with 315 additions and 308 deletions

View file

@ -28,7 +28,6 @@ use dom::bindings::num::Finite;
use dom::bindings::refcounted::Trusted;
use dom::bindings::reflector::{Reflectable, reflect_dom_object};
use dom::bindings::str::{DOMString, USVString};
use dom::bindings::trace::RootedVec;
use dom::bindings::xmlname::XMLName::InvalidXMLName;
use dom::bindings::xmlname::{validate_and_extract, namespace_from_domstring, xml_name_type};
use dom::browsingcontext::BrowsingContext;
@ -115,6 +114,7 @@ use std::cell::{Cell, Ref, RefMut};
use std::collections::HashMap;
use std::collections::hash_map::Entry::{Occupied, Vacant};
use std::default::Default;
use std::iter::once;
use std::mem;
use std::ptr;
use std::rc::Rc;
@ -1009,18 +1009,15 @@ impl Document {
}
}
let mut touches = RootedVec::new();
rooted_vec!(let mut touches);
touches.extend(self.active_touch_points.borrow().iter().cloned());
let mut changed_touches = RootedVec::new();
changed_touches.push(JS::from_ref(&*touch));
let mut target_touches = RootedVec::new();
rooted_vec!(let mut target_touches);
target_touches.extend(self.active_touch_points
.borrow()
.iter()
.filter(|t| t.Target() == target)
.cloned());
rooted_vec!(let changed_touches <- once(touch));
let event = TouchEvent::new(window,
DOMString::from(event_name),