This increases regionck performance greatly - type-checking on
librustc decreased from 9.1s to 8.1s. Because of Amdahl's law,
total performance is improved only by about 1.5% (LLVM wizards,
this is your opportunity to shine!).
before:
576.91user 4.26system 7:42.36elapsed 125%CPU (0avgtext+0avgdata 1142192maxresident)k
after:
566.50user 4.84system 7:36.84elapsed 125%CPU (0avgtext+0avgdata 1124304maxresident)k
I am somewhat worried really need to find out why we have this Red Queen's
Race going on here. Originally I suspected it may be a problem from RFC1214's
warnings, but it seems to be an effect from other changes.
However, the increase seems to be mostly in LLVM's time, so I guess
it's the LLVM wizards' problem.
The algorithm was not correctly detecting conflicts after moving
defaults into TypeVariableValue. The updated algorithm
correctly detects and reports conflicts with information about
where the conflict occured and which items the defaults were
introduced by. The span's for said items are not being correctly
attached and still need to be patched.
This patch allows type parameter defaults to influence type inference. This is a possible breaking change since it effects the way type inference works and will have different behavior when mixing defaults and literal fallback.
Correct regression in type-inference caused by failing to reconfirm that
the object trait matches the required trait during trait selection. The
existing code was checking that the object trait WOULD match (in a
probe), but never executing the match outside of a probe.
This corrects various regressions observed in the wild, including
issue #26952. Fixes#26952.
r? @eddyb
cc @frankmcsherry
the object trait matches the required trait during trait selection. The
existing code was checking that the object trait WOULD match (in a
probe), but never executing the match outside of a probe.
This corrects various regressions observed in the wild, including
issue #26952. Fixes#26952.
is being used now before the final regionck stage and in some cases SOME
amount of unresolved inference is OK. In fact, we could probably just
allow inference variables as well with only minimal pain.
TyClosure variant; thread this through wherever closure substitutions
are expected, which leads to a net simplification. Simplify trans
treatment of closures in particular.
Transition to the new object lifetime defaults, replacing the old defaults completely.
r? @pnkfelix
This is a [breaking-change] as specified by [RFC 1156][1156] (though all cases that would break should have been receiving warnings starting in Rust 1.2). Types like `&'a Box<Trait>` (or `&'a Rc<Trait>`, etc) will change from being interpreted as `&'a Box<Trait+'a>` to `&'a Box<Trait+'static>`. To restore the old behavior, write the `+'a` explicitly. For example, the function:
```rust
trait Trait { }
fn foo(x: &Box<Trait>) { ... }
```
would be rewritten as:
```rust
trait Trait { }
fn foo(x: &'a Box<Trait+'a>) { ... }
```
if one wanted to preserve the current typing.
[1156]: https://github.com/rust-lang/rfcs/blob/master/text/1156-adjust-default-object-bounds.md
This PR modernizes some names in the type checker. The only remaining snake_case name in ty.rs is `ctxt` which should be resolved by @eddyb's pending refactor. We can bike shed over the names, it would just be nice to bring the type checker inline with modern Rust.
r? @eddyb
cc @nikomatsakis
The common pattern `iter::repeat(elt).take(n).collect::<Vec<_>>()` is
exactly equivalent to `vec![elt; n]`, do this replacement in the whole
tree.
(Actually, vec![] is smart enough to only call clone n - 1 times, while
the former solution would call clone n times, and this fact is
virtually irrelevant in practice.)
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.
