Make RValue::Discriminant a normal Shallow read #56790
Merged
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
Enum layout optimizations mean that the discriminant of an enum may not be stored in a tag disjoint from the rest of the fields of the enum. Stop borrow checking as though they are.
matthewjasper
added
beta-nominated
rust-highfive
added
the
S-waiting-on-review
|
Egads! Good catch. Fascinating. |
|
@bors r+ |
|
📌 Commit cdd5373 has been approved by |
bors
added
S-waiting-on-bors
|
@bors r- |
bors
added
S-waiting-on-author
|
so I think we should merge this but I'd like to hold off just a second until we get everything setup. e.g., @matthewjasper, perhaps we should file an issue? |
|
@bors r+ |
|
📌 Commit cdd5373 has been approved by |
bors
added
S-waiting-on-bors
Centril
added a commit
to Centril/rust
that referenced
this pull request
Dec 16, 2018
…nts, r=nikomatsakis Make RValue::Discriminant a normal Shallow read Enum layout optimizations mean that the discriminant of an enum may not be stored in a tag disjoint from the rest of the fields of the enum. Stop borrow checking as though they are. Run with MIRI to see why this is needed: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=09a3236685a06b6096e2e2e3968b852c. This issue exists with the lexical borrow checker as well (see rust-lang#45045) so migrate mode should prevent this from being immediately breaking. r? @nikomatsakis Fixes rust-lang#56797
bors
added a commit
that referenced
this pull request
Dec 16, 2018
Rollup of 20 pull requests Successful merges: - #53506 (Documentation for impl From for AtomicBool and other Atomic types) - #56343 (Remove not used mod) - #56439 (Clearer error message for dead assign) - #56640 (Add FreeBSD unsigned char platforms to std::os::raw) - #56648 (Fix BTreeMap UB) - #56672 (Document time of back operations of a Linked List) - #56706 (Make `const unsafe fn` bodies `unsafe`) - #56742 (infer: remove Box from a returned Iterator) - #56761 (Suggest using `.display()` when trying to print a `Path`) - #56781 (Update LLVM submodule) - #56789 (rustc: Add an unstable `simd_select_bitmask` intrinsic) - #56790 (Make RValue::Discriminant a normal Shallow read) - #56793 (rustdoc: look for comments when scraping attributes/crates from doctests) - #56826 (rustc: Add the `cmpxchg16b` target feature on x86/x86_64) - #56832 (std: Use `rustc_demangle` from crates.io) - #56844 (Improve CSS rule) - #56850 (Fixed issue with using `Self` ctor in typedefs) - #56855 (Remove u8 cttz hack) - #56857 (Fix a small mistake regarding NaNs in a deprecation message) - #56858 (Fix doc of `std::fs::canonicalize`) Failed merges: - #56741 (treat ref-to-raw cast like a reborrow: do a special kind of retag) r? @ghost
Mark-Simulacrum
added
the
T-compiler
|
discussed at T-compiler meeting. Not approved for beta backport, mainly since, as @nikomatsakis put it:
|
pnkfelix
removed
the
beta-nominated
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.
Enum layout optimizations mean that the discriminant of an enum may not be stored in a tag disjoint from the rest of the fields of the enum. Stop borrow checking as though they are.
Run with MIRI to see why this is needed: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=4ea0e31adbb3fe1893be528277060248.
This issue exists with the lexical borrow checker as well (see #45045) so migrate mode should prevent this from being immediately breaking.
r? @nikomatsakis
Fixes #56797