Enable contracts for const functions #138374
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I am still trying to understand why the new logic triggers the new warning, when the old one didn't.
So, if you look at the following example from one of the tests: #![feature(contracts)]
pub struct Baz { baz: i32 }
#[core::contracts::requires(x.baz > 0)]
#[core::contracts::ensures(|ret| *ret > 100)]
pub fn nest(x: Baz) -> i32
{
loop {
return x.baz + 50;
}
}with the existing changes, you will get a warning: which in a way it makes sense, since we do add a call to check the post-condition after the loop statement. What I don't get is why it wasn't being triggered before, and whether I can mark the new code as If I compile with fn nest(x: Baz) -> i32 {
#[lang = "contract_check_requires"](|| x.baz > 0);
let __ensures_checker = #[lang = "contract_build_check_ensures"](|ret| *ret > 100);
#[lang = "contract_check_ensures"]({
loop { return #[lang = "contract_check_ensures"](x.baz + 50, __ensures_checker); }
}, __ensures_checker)
}before the changes, we had: fn nest(x: Baz) -> i32 {
#[lang = "contract_check_requires"](|| x.baz > 0);
let __ensures_checker = #[lang = "contract_build_check_ensures"](|ret| *ret > 100);
__ensures_checker({ loop { return __ensures_checker(x.baz + 50); } })
} |
Use `const_eval_select!()` macro to enable contract checking only at runtime. The existing contract logic relies on closures, which are not supported in constant functions. This commit also removes one level of indirection for ensures clauses, however, it currently has a spurious warning message when the bottom of the function is unreachable.
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The job Click to see the possible cause of the failure (guessed by this bot) |
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@compiler-errors any thoughts? |
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No, I didn't look at it yet |
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Use
const_eval_select!()macro to enable contract checking only at runtime. The existing contract logic relies on closures, which are not supported in constant functions.This commit also removes one level of indirection for ensures clauses since we no longer build a closure around the ensures predicate.
Call-out: This is still a draft PR since CI is broken due to a new warning message for unreachable code when the bottom of the function is indeed unreachable. It's not clear to me why the warning wasn't triggered before.
r? @compiler-errors