erase types in the move-path abstract domain
Leaving types unerased would lead to 2 types with a different "name"
getting different move-paths, which would cause major brokenness (see
e.g. #42903).
This does not fix any *known* issue, but is required if we want to use
abs_domain with non-erased regions (because the same can easily
have different names). cc @RalfJung.
r? @eddyb
Provide positional information when visiting ty, substs and closure_substs in MIR
This will enable the region renumbering portion of #43234 (non-lexical lifetimes). @nikomatsakis's current plan [here](https://gist.github.com/nikomatsakis/dfc27b28cd024eb25054b52bb11082f2) shows that we need spans of the original code to create new region variables, e.g. `self.infcx.next_region_var(infer::MiscVariable(span))`. The current visitor impls did not pass positional information (`Location` in some, `Span` and `SourceInfo` for others) for all types. I did not expand this to all visits, just the ones necessary for the above-mentioned plan.
Leaving types unerased would lead to 2 types with a different "name"
getting different move-paths, which would cause major brokenness (see
e.g. #42903).
This does not fix any *known* issue, but is required if we want to use
abs_domain with non-erased regions (because the same can easily
have different names). cc @RalfJung.
Make the "main" constructors of NonZero/Shared/Unique return Option
Per discussion in https://github.com/rust-lang/rust/issues/27730#issuecomment-303939441.
This is a breaking change to unstable APIs.
The old behavior is still available under the name `new_unchecked`. Note that only that one can be `const fn`, since `if` is currently not allowed in constant contexts.
In the case of `NonZero` this requires adding a new `is_zero` method to the `Zeroable` trait. I mildly dislike this, but it’s not much worse than having a `Zeroable` trait in the first place. `Zeroable` and `NonZero` are both unstable, this can be reworked later.
Shift mir-dataflow from `rustc_borrowck` to `rustc_mir` crate.
Shift mir-dataflow from `rustc_borrowck` to `rustc_mir` crate.
Turn `elaborate_drops` and `rustc_peek` implementations into MIR passes that also live in `rustc_mir` crate.
Rewire things so `rustc_driver` uses the `ElaborateDrops` from `rustc_mir` crate.
(This PR is another baby step for mir-borrowck; it is a piece of work that other people want to rebase their stuff on top of, namely developers who are doing other dataflow analyses on top of MIR.)
I have deliberately architected this PR in an attempt to minimize the number of actual code changes. The majority of the diff should be little more than changes to mod and use declarations, as well as a few visibility promotions to pub(crate) when a declaration was moved downward in the module hierarchy.
(I have no problem with other PR's that move declarations around to try to clean this up; my goal was to ensure that the diff here was as small as possible, to make the review nearly trivial.)
Turn `elaborate_drops` and `rustc_peek` implementations into MIR
passes that also live in `rustc_mir` crate.
Rewire things so `rustc_driver` uses the `ElaborateDrops` from
`rustc_mir` crate.
re-add the call to `super_statement` in EraseRegions
The move gathering code is sensitive to type-equality - that is rather
un-robust and I plan to fix it eventually, but that's a more invasive
change. And we want to fix the visitor anyway.
Fixes#42903.
r? @eddyb
The move gathering code is sensitive to type-equality - that is rather
un-robust and I plan to fix it eventually, but that's a more invasive
change. And we want to fix the visitor anyway.
Fixes#42903.
Replaced by adding extra imports, adding hidden code (`# ...`), modifying
examples to be runnable (sorry Homura), specifying non-Rust code, and
converting to should_panic, no_run, or compile_fail.
Remaining "```ignore"s received an explanation why they are being ignored.
MIR EndRegion Statements (was MIR dataflow for Borrows)
This PR adds an `EndRegion` statement to MIR (where the `EndRegion` statement is what terminates a borrow).
An earlier version of the PR implemented a dataflow analysis on borrow expressions, but I am now factoring that into a follow-up PR so that reviewing this one is easier. (And also because there are some revisions I want to make to that dataflow code, but I want this PR to get out of WIP status...)
This is a baby step towards MIR borrowck. I just want to get the review process going while I independently work on the remaining steps.
* Emit `EndRegion` for every code-extent for which we observe a
borrow. To do this, we needed to thread source info back through
to `fn in_scope`, which makes this commit a bit more painful than
one might have expected.
* There is `end_region` emission in `Builder::pop_scope` and in
`Builder::exit_scope`; the first handles falling out of a scope
normally, the second handles e.g. `break`.
* Remove `EndRegion` statements during the erase_regions mir
transformation.
* Preallocate the terminator block, and throw an `Unreachable` marker
on it from the outset. Then overwrite that Terminator as necessary
on demand.
* Instead of marking the scope as needs_cleanup after seeing a
borrow, just treat every scope in the chain as being part of the
diverge_block (after any *one* of them has separately signalled
that it needs cleanup, e.g. due to having a destructor to run).
* Allow for resume terminators to be patched when looking up drop flags.
(In particular, `MirPatch::new` has an explicit code path,
presumably previously unreachable, that patches up such resume
terminators.)
* Make `Scope` implement `Debug` trait.
* Expanded a stray comment: we do not emit StorageDead on diverging
paths, but that end behavior might not be desirable.
Create directory for dump-mir-dir automatically
Fixes#35543 r? @Mark-Simulacrum
@Mark-Simulacrum I know someone else said that they'll work on this, but it has been 3+ weeks and I had nothing to do and wanted to contribute a bit.
I now added the call to automatically create the directory as discussed, but was wondering how you feel about the suggestion to set a default directory, i.e. `target/mir`?
array drop glue: avoid using out-of-bounds index lvalues
Avoid using out-of-bounds index lvalues. Miri doesn't like them, and they seem fishy in general.
Instead, use a pointer cast to compute the address of the beginning, and Offset to compute the end.
Cc @arielb1 @nagisa
