Inline const blocks default integers to i32

[DutchGhost]

Inline const blocks default to the i32 type on integer literals, see the following:

#![feature(inline_const)]

fn main() {
    let _: usize = const { 0 };
}

fails compilation with:

error[E0308]: mismatched types
 --> src/main.rs:4:20
  |
4 |     let _: usize = const { 0 };
  |            -----   ^^^^^ expected `usize`, found `i32`
  |            |
  |            expected due to this
  |
help: you can convert an `i32` to `usize` and panic if the converted value wouldn't fit
  |
4 |     let _: usize = const.try_into().unwrap() { 0 };

Regular integer literals, and in unsafe blocks just get the type right: let _: usize = 0 and let _: usize = unsafe { 0 };

Another minor thing is the error message, const.try_into().unwrap() { 0 }; is an invalid suggestion ^^.

[camelid]

Originally posted by @lcnr in #78330 (comment):

we probably have to treat inline consts similar to closures during typeck. That might be somewhat complicated and I don't have the time to look into this myself.

If someone wants to work on this feel free to open a topic on zulip and ping me there though

[nbdd0121]

I'll take a lot at this.

@rustbot claim

[lcnr]

@nbdd0121 the reason this happens is because of #78132 (comment).

@spastorino already intends to work on this, so it might make sense to talk about this with them to prevent any duplicate work.
The relevant zulip thread is https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck