[BUG] `llvm-cov` warning `mismatched data` when impl const fn

bug

llvm-cov warning mismatched data when impl const fn

reproduce

https://github.com/loynoir/reproduce-rust-130139

pub use bar::Bar;

mod bar {
    pub struct Bar<T>(T);

    impl Bar<i32> {
        pub const unsafe fn from_unchecked(value: i32) -> Self {
            Bar(value)
        }

        pub const fn get(&self) -> i32 {
            self.0
        }
    }
}

workaround

pub use bar::{Bar, bar_get_i32};

mod bar {
    pub struct Bar<T>(T);

    impl Bar<i32> {
        pub const unsafe fn from_unchecked(value: i32) -> Self {
            Bar(value)
        }

        pub fn get(&self) -> i32 {
            self.0
        }
    }

    pub fn bar_get_i32(bar: &Bar<i32>) -> i32 {
        bar.0
    }
}

related

llvm-cov warning mismatched data when double slash comment above use

https://github.com/rust-lang/rust/issues/130065

llvm-cov warning mismatched data when triple slash safety comment above unsafe fn

https://github.com/rust-lang/rust/issues/130097

Start with the linked reproduction repository and run its llvm-cov example to confirm the mismatched data warning. Compare the const and non-const get cases, then read the related issues #130065 and #130097 for coverage of similar warnings. Done means the reported case no longer produces mismatched coverage data and has a regression test.