Re-implement leak check in terms of universes
This PR temporarily restores the leak-check, but implemented in terms of universes. This is not because the leak check behavior was necessarily **correct**, but because (a) we may want to have a transition period and because (b) we want to have more breathing room to work through the full implications of handling higher-ranked types correctly. Note that this PR builds atop https://github.com/rust-lang/rust/pull/58056.
Fixes#58451Fixes#46989Fixes#57639
r? @aturon
cc @arielb1, @lqd
~~Temporary note: I've not finished running `./x.py test` locally -- I'm confident a lot of error messages in tests will need updating. I sort of expect them to revert to the older, (imo) less good error messages, which is mildly unfortunate. There might be a way to preserve the new error messages, not sure.~~
* Adjust fake borrows to only be live over guards.
* Remove unused `slice_len_checked` field.
* Split the methods on builder into those for matches and those for all
kinds of pattern bindings.
Update cargo
9 commits in 865cb70106a6b1171a500ff68f93ab52eea56e72..b33ce7fc9092962b0657b4c25354984b5e5c47e4
2019-02-10 15:49:37 +0000 to 2019-02-19 18:42:50 +0000
- Don't retry invalid credentials from git credential helpers (rust-lang/cargo#6681)
- Fix some typos in resolver tests (rust-lang/cargo#6682)
- Add an unstable option to build proc macros for both the host and the target (rust-lang/cargo#6547)
- Test cases proving RUSTC_WRAPPER can be a relative path (rust-lang/cargo#6638)
- Add support for Azure DevOps (rust-lang/cargo#6264)
- Update docs for removed `patch` restriction. (rust-lang/cargo#6663)
- Fix incorrect help message (rust-lang/cargo#6555)
- Stabilize Alternative Registries (rust-lang/cargo#6654)
- Having a [patch] section when publishing is not an error (rust-lang/cargo#6535)
The solution which uses braces to release the borrow
before it is moved is only required to satisfy the 2015
edition borrow checker.
All other examples give the expected results for both
2015 and 2018 editions.
`codegen_allocator` and `write_metadata` mutate the underlying LLVM module. As
such, it makes sense for these two functions to receive a mutable reference to
the module (as opposed to an immutable one).
make generalization code create new variables in correct universe
In our type inference system, when we "generalize" a type T to become
a suitable value for a type variable V, we sometimes wind up creating
new inference variables. So, for example, if we are making V be some
subtype of `&'X u32`, then we might instantiate V with `&'Y u32`.
This generalized type is then related `&'Y u32 <: &'X u32`, resulting
in a region constriant `'Y: 'X`. Previously, however, we were making
these fresh variables like `'Y` in the "current universe", but they
should be created in the universe of V. Moreover, we sometimes cheat
in an invariant context and avoid creating fresh variables if we know
the result must be equal -- we can only do that when the universes
work out.
Fixes#57843
r? @pnkfelix
