rustc refuses to compile const function due to potential drops even when nothing is being dropped

[TheNeikos]

I tried this code:

use core::marker::PhantomData;
use std::sync::Arc;
struct Foo<T> {
    drop_value: Arc<u32>,
    pd: PhantomData<fn(T)>,
}

impl<T> Foo<T> {
    const fn convert<R>(self) -> Foo<R> {
        let Foo { drop_value, pd: _ } = self;

        Foo {
            drop_value,
            pd: PhantomData,
        }
    }
    
    const fn convert2<R>(self) -> Foo<R> {
        Foo {
            drop_value: self.drop_value,
            pd: PhantomData,
        }
    }
}

I expected to see this happen: It compiles

Instead, this happened:

Compiling playground v0.0.1 (/playground)
error[[E0493]](https://doc.rust-lang.org/nightly/error_codes/E0493.html): destructor of `Foo<T>` cannot be evaluated at compile-time
  --> src/lib.rs:9:25
   |
9  |     const fn convert<R>(self) -> Foo<R> {
   |                         ^^^^ the destructor for this type cannot be evaluated in constant functions
...
16 |     }
   |     - value is dropped here

For more information about this error, try `rustc --explain E0493`.
error: could not compile `playground` (lib) due to previous error

Meta

This errors on stable 1.72 as well as on nightly-2023-08-30.

This is maybe the same as #109427, but since that is about patterns, and this is not, I thought the independent report is justified.

[TheNeikos]

This will be fixed by: #73255

Adding #![feature(const_precise_live_drops)] makes it compile as expected.

[itsxaos]

I have a similar issue. My crate construe compiles on stable 1.72 but fails with this error on beta & nightly.

I've removed everything not needed to reproduce the error and put it in a playground here:
https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6d368dce7e0476b4243d8295ae24e5b2