MIR borrow check (under debug flag)
Here is the current state of MIR borrow check.
It consists of (1.) some refactoring, (2.) a dataflow analysis to identify the borrows themselves, and (3.) a mir "transform" that does the borrow check itself based on the aforementioned dataflow results.
(There's also a drive-by fix to dataflow that I can factor into a separate PR if necessary. Interestingly I could not find a way to observe the bug outside of MIR borrowck.)
To be clear, this branch is not ready to be used as the default borrow check. Thus the code is guarded: To get mir-borrowck to run, you need to either supply an attribute `#[rustc_mir_borrowck]` or a debug flag `-Z borrowck-mir`.
Here are the main issues with the current MIR borrowck as it stands in this PR:
* No Notes emitted yet, just errors. (So the feedback is definitely inferior compared to AST borrowck today)
* Lvalue rendering differs between Ast and Mir. (Mostly minor, but replacement of field names with indices is very bad; big priority for me to fix ASAP.)
* Lots of ICEs (presumably because some MIR operations used here have well-formedness assumptions that are violated in borrowck-broken code)
* Conflates lots of cases that are distinguished by AST-borrowck
* Conflates "uninitialized" with "moved" (special case of previous bullet, one that I think should be fixed ASAP)
(I am hoping to fix as many of the above issues as I can in the near term, but I also would like to land this even if they are *not* all fixed, because the rebasing effort is getting to be a real drag.)
Added two fixmes: The `SimplifyBranches` pass cannot stay where it is,
and `BorrowckMir` should be a query, not a pass. But I am going to
leave those changes to a future PR.
One can either use `-Z borrowck-mir` or add the `#[rustc_mir_borrowck]` attribute
to opt into MIR based borrow checking.
Note that regardless of whether one opts in or not, AST-based borrow
check will still run as well. The errors emitted from AST-based
borrow check will include a "(Ast)" suffix in their error message,
while the errors emitted from MIR-based borrow check will include a
"(Mir)" suffix.
post-rebase: removed check for intra-statement mutual conflict;
replaced with assertion checking that at most one borrow is generated
per statement.
post-rebase: removed dead code: `IdxSet::pairs` and supporting stuff.
post-rebase: Do not put "(Ast)" suffix in error msg unless passed `-Z borrowck-mir`.
(But unconditionally include "(Mir)" suffix for mir-borrowck errors.)
rustc: Fix `unknown_lints` next to an unknown lint
The lint refactoring in #43522 didn't account for `#[allow(unknown_lints)]`
happening at the same node as an unknown lint itself, so this commit updates the
handling to ensure that the local set of lint configuration being built is
queried before looking at the chain of lint levels.
Closes#43809
Fix ICE with elided lifetimes in return type of foreign functions
cc https://github.com/rust-lang/rust/issues/43567
This is for a preliminary crater/cargobomb run.
Lifetime elision in foreign functions now works exactly like in other functions or function-like entities.
If the breakage is significant, I'll have to partially revert https://github.com/rust-lang/rust/pull/43543 (all the stuff that was required for dealing with late bound lifetimes in this position).
r? @eddyb
Add Vec::drain_filter
This implements the API proposed in #43244.
So I spent like half a day figuring out how to implement this in some awesome super-optimized unsafe way, which had me very confident this was worth putting into the stdlib.
Then I looked at the impl for `retain`, and was like "oh dang". I compared the two and they basically ended up being the same speed. And the `retain` impl probably translates to DoubleEndedIter a lot more cleanly if we ever want that.
So now I'm not totally confident this needs to go in the stdlib, but I've got two implementations and an amazingly robust test suite, so I figured I might as well toss it over the fence for discussion.
Make backtraces work on Redox, copying Unix implementation
The `backtrace/` directory here is the same as the Unix one, except for adding an implementation of `get_executable_filename`.
Add method `String::retain`
Behaves like `Vec::retain`, accepting a predicate `FnMut(char) -> bool`
and reducing the string to only characters for which the predicate
returns `true`.
emit StorageLive for box temporaries
We started emitting StorageDead, so we better emit the corrseponding
StorageLive to avoid problems.
cc #43772solson/miri#303
Behaves like `Vec::retain`, accepting a predicate `FnMut(char) -> bool`
and reducing the string to only characters for which the predicate
returns `true`.
Rewrite/reorganize docs for stack size/thread names for spawned threads.
* Moves docs about stack size and thread naming from `Builder` to the
`std::thread` module
* Adds more links to the new module-level documentation
* Mentions the 2 MiB stack size default, but indicate it's subject to
change
Fixes https://github.com/rust-lang/rust/issues/43805.
Instant is monotonically nondecreasing
We don't want to guarantee that `Instant::now() != Instant::now()` is
always true since that depends on the speed of the processor and the
resolution of the clock.
remove the "defaulted unit" type bit during writeback
The defaulted unit bit is only relevant for the surrounding inference
context, and can cause trouble, including spurious lints and ICEs,
outside of it.
Fixes#43853.
r? @eddyb
