Constant promotion doesn't work in certain situations

This code:

const C: *const *const i32 = [
    &{
        let x: i32 = 0;
        x
    } as *const i32,
]
.as_ptr();

fails to build with an error: error: encountered dangling pointer in final value of constant.

My belief is that the subexpression { let x: i32 = 0; x } should be promoted to a constant. It works if the final .as_ptr() is removed:

const C: [*const i32; 1] = [
    &{
        let x: i32 = 0;
        x
    } as *const i32,
];

If the inner subexpression is replaced with zero, it works as well:

const C: *const *const i32 = [
    &{
        0
    } as *const i32,
]
.as_ptr();

Tested in Rust 1.95.0-nightly (2026-02-24 859951e3c7c9d0322c39).

No repository file or test is named. Reproduce the reported snippets on the stated nightly, then trace Rust's constant-promotion handling and the dangling-pointer final-value diagnostic. Done means the first example is accepted consistently with the working variants, with regression coverage for the reported case.