Extend invalid floating point literal suffix suggestion

[Rageking8]

Given the following code: link

fn main() {
    let a = 12.f;
    let b = 34.F;
    let c = 56.l;
    let d = 78.L;
}

The current output is:

Compiling playground v0.0.1 (/playground)
error[[E0610]](https://doc.rust-lang.org/nightly/error-index.html#E0610): `{integer}` is a primitive type and therefore doesn't have fields
 --> src/main.rs:2:16
  |
2 |     let a = 12.f;
  |                ^

error[[E0610]](https://doc.rust-lang.org/nightly/error-index.html#E0610): `{integer}` is a primitive type and therefore doesn't have fields
 --> src/main.rs:3:16
  |
3 |     let b = 34.F;
  |                ^

error[[E0610]](https://doc.rust-lang.org/nightly/error-index.html#E0610): `{integer}` is a primitive type and therefore doesn't have fields
 --> src/main.rs:4:16
  |
4 |     let c = 56.l;
  |                ^

error[[E0610]](https://doc.rust-lang.org/nightly/error-index.html#E0610): `{integer}` is a primitive type and therefore doesn't have fields
 --> src/main.rs:5:16
  |
5 |     let d = 78.L;
  |                ^

For more information about this error, try `rustc --explain E0610`.
error: could not compile `playground` due to 4 previous errors

Ideally for all the above invalid ways to writing a floating point literal, the complier should highlight that there are only 2 valid floating point literal suffix "f32" and "f64". Additionally, it may also include a note informing the user that a trailing '0' must be present in floating point literals.

[chenyukang]

why would

 let c = 56.l;
 let d = 78.L;

suggest to write float?

I think l or L maybe means to write integer.

[Rageking8]

@chenyukang It's because that's the "long double" floating point literal suffix for C++.

[chenyukang]

@rustbot claim