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[ER] cfg(overflow_checks) #91130

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leonardo-m opened this issue Nov 22, 2021 · 4 comments · Fixed by #111096
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[ER] cfg(overflow_checks) #91130

leonardo-m opened this issue Nov 22, 2021 · 4 comments · Fixed by #111096
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A-attributes Area: Attributes (`#[…]`, `#![…]`) C-enhancement Category: An issue proposing an enhancement or a PR with one. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@leonardo-m
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An enhancement request discussed here:
https://users.rust-lang.org/t/detecting-overflow-checks/67698/

(That thread also contains a hacky solution by Yandros).

I propose to add a config like this:

#[cfg(overflow_checks)]

I would like to use it to enable/disable lines of code that perform safe unsafe "as" casts replacing them with casts when I compile with debug builds or with release builds compiled with "-C overflow-checks".
@leonardo-m
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@rustbot modify labels: C-enhancement

@rustbot rustbot added the C-enhancement Category: An issue proposing an enhancement or a PR with one. label Nov 22, 2021
@hkratz
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hkratz commented Nov 25, 2021

@rustbot label A-attributes T-compiler

@rustbot rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Nov 25, 2021
@schuelermine
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I’d also be interested in this.

@AngelicosPhosphoros AngelicosPhosphoros mentioned this issue May 2, 2023
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@AngelicosPhosphoros
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Tracking issue: #111466

Dylan-DPC added a commit to Dylan-DPC/rust that referenced this issue May 13, 2023
@Dylan-DPC
Rollup merge of rust-lang#111096 - AngelicosPhosphoros:overflow_check…
36125c4 
…s_issue_91130, r=petrochenkov

Add support for `cfg(overflow_checks)`

This PR adds support for detecting if overflow checks are enabled in similar fashion as `debug_assertions` are detected. Possible use-case of this, for example, if we want to use checked integer casts in builds with overflow checks, e.g.

```rust
pub fn cast(val: usize)->u16 {
    if cfg!(overflow_checks) {
        val.try_into().unwrap()
    }
    else{
        vas as _
    }
}
```

Resolves rust-lang#91130.
@bors bors closed this as completed in 7c263ad May 13, 2023
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A-attributes Area: Attributes (`#[…]`, `#![…]`) C-enhancement Category: An issue proposing an enhancement or a PR with one. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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Add support for cfg(overflow_checks) AngelicosPhosphoros/rust
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@hkratz @AngelicosPhosphoros @leonardo-m @rustbot @schuelermine