Methods of floating point types are not available for #![no_std]

[upsuper]

The following code

#![no_std]

fn main() {
    let a = 1.0f32;
    let _ = a.is_finite();
}

doesn't compile. It reports:

error[E0599]: no method named `is_finite` found for type `f32` in the current scope
 --> src/main.rs:5:15
  |
5 |     let _ = a.is_finite();
  |               ^^^^^^^^^
  |
  = help: items from traits can only be used if the trait is in scope
  = note: the following trait is implemented but not in scope, perhaps add a `use` for it:
          candidate #1: `use core::num::Float;`

but core::num::Float is not yet stable.

The implementations of the methods should probably be moved to core rather than staying in std.

[upsuper]

Looking at #27823, it seems they are intentionally moved out from libcore, so this issue is probably invalid.