Could libm be removed ?

[yjhmelody]

It seems that no_std could works well without libm. I want to know ther reason about import it? For performance?

[Robbepop]

My gut feeling is "no" but I forgot why. 🙃
In the past we used libm because the Rust standard library did not support the required floating point instructions under certain circumstances such as compilation to WebAssembly in no_std mode.
I don't know if this is still the case ...

Importants links:

• https://github.com/rust-lang/libm
• Update libm to fix floating point panics for debug no_std builds #240
• Upgrade libm and make no-std config testable #241

I would certainly love if we were able to safely remove libm.

[Robbepop]

We indeed need libm since some f32 and f64 methods such as fract and trunc are not available in Rust's core library unfortunately. This may change in the future though since some people are working on that.

Compare the following docs for f32:

• std: https://doc.rust-lang.org/std/primitive.f32.html
• core: https://doc.rust-lang.org/core/primitive.f32.html