Add flag to configure noalias on Box<T> #99436
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| r? @fee1-dead (rust-highfive has picked a reviewer for you, use r? to override) |
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Noratrieb force-pushed the toggle-box-noalias branch from 26aaa45 to 09ac838 Compare 
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| Wait, (Checking the code) ah, |
| How about |
Noratrieb force-pushed the toggle-box-noalias branch from 09ac838 to 200f3b8 Compare Noratrieb changed the title noalias on Box<T>noalias on Box<T> 
| The changes look good to me, but to make sure that it works, can you please add a test? (see this for info) |
Noratrieb force-pushed the toggle-box-noalias branch from 200f3b8 to a8253c4 Compare | I added a test to ensure that noalias doesn't get passed when the flag is set to no. Now that I think about it, I should add another test for the default case. |
To aid making an informed decision about the aliasing rules of box, give users an option to remove `noalias` from box.
| So, I hope it works now. |
Noratrieb force-pushed the toggle-box-noalias branch from a8253c4 to 7c900c9 Compare 
fee1-dead approved these changes Jul 19, 2022
| @fee1-dead and it's green now 🎉 |
| @bors r+ |
bors added S-waiting-on-bors 
bors added a commit to rust-lang-ci/rust that referenced this pull request Jul 20, 2022
Rollup of 7 pull requests Successful merges: - rust-lang#98101 (stdlib support for Apple WatchOS) - rust-lang#99345 (Do not allow typeck children items to constrain outer RPITs) - rust-lang#99383 (Formalize defining_use_anchor) - rust-lang#99436 (Add flag to configure `noalias` on `Box<T>`) - rust-lang#99483 (Fix a numerical underflow in tuple wrap suggestion) - rust-lang#99485 (Stop injecting `#[allow(unused_qualifications)]` in generated `derive` implementations) - rust-lang#99486 (Refactor: remove a string comparison between types in `check_str_addition`) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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The aliasing rules of
Box<T>are still not decided, but currently,Box<T>is unique and getsnoalias. To aid making an informed decision about the future ofBox<T>, this PR adds a flag-Zbox-noaliasto configurenoaliasforBox<T>(for example, for benchmarking). The same flag already exists for&mut Tnoalias, where it was added because it was the problem of various miscompilations in LLVM.For more information, see rust-lang/unsafe-code-guidelines#326