Previously, the --keep-stage argument would only function for compilers
that were depended on by future stages. For example, if trying to build
a stage 1 compiler you could --keep-stage 0 to avoid re-building the
stage 0 compiler. However, this is often not what users want in
practice.
The new implementation essentially skips builds all higher stages of the
compiler, so an argument of 1 to keep-stage will skip rebuilds of the
libraries, just linking them into the sysroot. This is unlikely to work
well in cases where metadata or similar changes have been made, but is
likely fine otherwise.
This change is somewhat untested, but since it shouldn't have any effect
except with --keep-stage, I don't see that as a large problem.
Make custom trait object for `Future` generic
- `TaskObj` -> `FutureObj<'static, ()>`
- The `impl From<...> for FutureObj<'a, T>` impls are impossible because of the type parameter `T`. The impl has to live in libstd, but `FutureObj<'a, T>` is from libcore. Therefore `Into<FutureObj<'a, T>>` was implemented instead. Edit: This didn‘t compile without warnings. I am now using non-generic Form impls.
See https://github.com/rust-lang-nursery/futures-rs/issues/1058
r? @cramertj
Edit: Added lifetime
introduce dirty list to liveness, eliminate `ins` vector
At least in my measurements, this seems to knock much of the liveness computation off the profile.
r? @Zoxc
cc @nnethercote
This new query returns only the predicates *directly defined* on an
item (in contrast to the more common `predicates_of`, which returns
the predicates that must be proven to reference an item). These two
sets are almost always identical except for traits, where
`predicates_of` includes an artificial `Self: Trait<...>` predicate
(basically saying that you cannot use a trait item without proving
that the trait is implemented for the type parameters).
This new query is only used in chalk lowering, where this artificial
`Self: Trait` predicate is problematic. We encode it in metadata but
only where needed since it is kind of repetitive with existing
information.
Co-authored-by: Tyler Mandry <tmandry@gmail.com>
If we have
```rust
struct Foo<T: Copy = String> { .. }
```
the old code would have proven that `String: Copy` was WF -- this,
incidentally, also proved that `String: Copy`. The new code just
proves `String: Copy` directly.
Co-authored-by: Tyler Mandry <tmandry@gmail.com>
