[NLL] Allow conflicting borrows of promoted length zero arrays #52834
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rust-highfive
added
the
S-waiting-on-review
oli-obk
reviewed
Jul 30, 2018
| // different promoteds - base case, disjoint | ||
| debug!("place_element_conflict: DISJOINT-PROMOTED"); | ||
| Overlap::Disjoint | ||
| } else if mir.promoted[p1.0].ignore_borrow_conflicts { |
There was a problem hiding this comment.
couldn't we just check for zero length array type here instead of infecting everything with that info?
There was a problem hiding this comment.
i'm with @oli-obk here: Lets see if that (presumably simpler) fix does the job here?
There was a problem hiding this comment.
I think I was concerned about performance thinking that it would need to be check way more than it actually is (which is once per promoted).
pnkfelix
added
S-waiting-on-author
matthewjasper
force-pushed
the
allow-zst-conflicts
branch
from
045cb80
to
84dc485
Compare
|
@bors r+ |
|
📌 Commit 84dc485 has been approved by |
bors
added
S-waiting-on-bors
pietroalbini
added a commit
to pietroalbini/rust
that referenced
this pull request
Aug 1, 2018
…r=pnkfelix [NLL] Allow conflicting borrows of promoted length zero arrays This is currently overkill as there's no way to create two conflicting borrows of any promoted. It is possible that the following code might not fail due to const eval in the future (@oli-obk?). In which case either the array marked needs to not be promoted, or to be checked for conflicts ```rust static mut A: () = { let mut y = None; let z; let mut done_y = false; loop { let x = &mut [1]; // < this array if done_y { z = x; break; } y = Some(x); done_y = true; } some_const_fn(y, z); // some_const_fn expects that y to not alias z. }; ``` r? @pnkfelix @nikomatsakis closes rust-lang#52671 cc rust-lang#51823
bors
added a commit
that referenced
this pull request
Aug 1, 2018
Rollup of 15 pull requests Successful merges: - #52793 (Add test for NLL: unexpected "free region `` does not outlive" error ) - #52799 (Use BitVector for global sets of AttrId) - #52809 (Add test for unexpected region for local data ReStatic) - #52834 ([NLL] Allow conflicting borrows of promoted length zero arrays) - #52835 (Fix Alias intra doc ICE) - #52854 (fix memrchr in miri) - #52899 (tests/ui: Add missing mips{64} ignores) - #52908 (Use SetLenOnDrop in Vec::truncate()) - #52915 (Don't count MIR locals as borrowed after StorageDead when finding locals live across a yield terminator) - #52926 (rustc: Trim down the `rust_2018_idioms` lint group) - #52930 (rustc_resolve: record single-segment extern crate import resolutions.) - #52939 (Make io::Read::read_to_end consider io::Take::limit) - #52942 (Another SmallVec.extend optimization) - #52947 (1.27 actually added the `armv5te-unknown-linux-musleabi` target) - #52954 (async can begin expressions) Failed merges: r? @ghost
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This is currently overkill as there's no way to create two conflicting borrows of any promoted.
It is possible that the following code might not fail due to const eval in the future (@oli-obk?). In which case either the array marked needs to not be promoted, or to be checked for conflicts
r? @pnkfelix @nikomatsakis
closes #52671
cc #51823