`MethodCallee` now has no information about the method, other than its `DefId`.
The previous bits of information can be recovered as follows:
```rust
let method_item = tcx.impl_or_trait_item(callee.def_id);
let container = method_item.container();
```
The method is inherent if `container` is a `ty::ImplContainer`:
* the `impl` the method comes from is `container.id()`
The method is a trait method if `container` is a `ty::TraitContainer:
* the `trait` the method is part of is `container.id()`
* a `ty::TraitRef` can be constructed by putting together:
* `container.id()` as the `trait` ID
* `callee.substs.clone().method_to_trait()` as the `trait` substs (including `Self`)
* the above `trait_ref` is a valid `T: Trait<A, B, C>` predicate
* selecting `trait_ref` could result in one of the following:
* `traits::VtableImpl(data)`: static dispatch to `data.impl_def_id`
* `traits::VtableObject(data)`: dynamic dispatch, with the vtable index:
`traits::get_vtable_index_of_object_method(tcx, data, callee.def_id)`
* other variants of `traits::Vtable`: various other `impl` sources
core: Use memcmp in is_prefix_of / is_suffix_of
The basic str equality in core::str calls memcmp, re-use the same
function in StrSearcher's is_prefix_of, is_suffix_of.
Documentation claims it panics on out of bounds -- it regards out of
bounds as just not a char boundary.
core::str module is aware of how it works and uses it appropriately.
Maybe we should rename it to `is_valid_index`, `is_slicable_index`, or
something similar.
This is an implementation of RFC rust-lang/rfcs#1156. It includes the code to implement the new rules, but that code is currently disabled. It also includes code to issue warnings when the change will cause breakage. These warnings try hard to be targeted but are also somewhat approximate. They could, with some effort, be made *more* targeted by adjusting the code in ty_relate that propagates the "will change" flag to consider the specific operation. Might be worth doing.
r? @pnkfelix (I think you understand region inference best)
bound that is likely to change. In that case, it will change to 'static,
so then scan down the graph to see whether there are any hard
constraints that would prevent 'static from being a valid value
here. Report a warning.
region-bound is expected to change in Rust 1.3, but don't use it for
anything in this commit. Note that this is not a "significant" part of
the type (it's not part of the formal model) so we have to normalize
this away or trans starts to get confused because two equal types wind
up with distinct LLVM types.
This commit resolves the race condition in the `get_mut` and
`make_unique` functions, which arose through interaction with weak
pointers. The basic strategy is to "lock" the weak pointer count when
trying to establish uniqueness, by reusing the field as a simple
spinlock. The overhead for normal use of `Arc` is expected to be minimal
-- it will be *none* when only strong pointers are used, and only
requires a move from atomic increment to CAS for usage of weak pointers.
The commit also removes the `unsafe` and deprecated status of these functions.
Closes#24880
r? @alexcrichton
cc @metajack @SimonSapin @Ms2ger
