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A comment on Why Cargo Check Is So Slow. Parent comment

Re:Why Cargo Check Is So Slow by LoganDark on Saturday August 09, 2025 @11:01AM (#44847047)
> Rust doesn't have an interpreter for the full language

Ever since a while ago, rustc uses Miri for const evaluation. So there are a lot of things it can do that it used to not be able to do. But, yes, const evaluation is limited to things that are part of the `const` subset.

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Re:Why Cargo Check Is So Slow by LegionMammal978 on Saturday August 09, 2025 @11:07AM (#44847107)
As far as I'm aware, it's always been the other way around: Miri adds some features on top of rustc's const-evaluation code. The limitations of the latter are mainly self-imposed, due to the issues of exposing the different runtime models to programs. (E.g., you don't want to create allocations in const code that get deallocated at runtime.) Indeed, since 2019, the full functionality can be exposed with the unstable -Zunleash-the-miri-inside-of-you flag [0].

[0] https://github.com/rust-lang/rust/pull/56123

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Re:Why Cargo Check Is So Slow by LoganDark on Saturday August 09, 2025 @03:50PM (#44849540)
I'm pretty sure we're in agreement? Miri is capable of a lot more but there are self-imposed limitations on what you're allowed to do in const.
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