Suggest adding zero to errornous floating point number with dot and exponent but no post-dot digit

[Havvy]

When writing floating point numbers, some people try to include the dot and and exponent notation. Rust sees this as a field access on an integral value. It should suggest adding a 0 after the dot.

Given the following code: Playpen

fn main() {
    let n = 2.e1;
}

The current output is:

Compiling playground v0.0.1 (/playground)
error[[E0610]](https://doc.rust-lang.org/stable/error-index.html#E0610): `{integer}` is a primitive type and therefore doesn't have fields
 --> src/main.rs:2:15
  |
2 |     let n = 2.e1;
  |               ^^

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

Ideally the output should suggest adding a zero, like as follows:

Compiling playground v0.0.1 (/playground)
error[[E0610]](https://doc.rust-lang.org/stable/error-index.html#E0610): `{integer}` is a primitive type and therefore doesn't have fields
 --> src/main.rs:2:15
  |
2 |     let n = 2.e1;
  |               ^^

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

help: If the number is meant to be a floating point number, add a `0` after the period.
 --> src/main.rs:2:15
  |
2 |     let n = 2.0e1;
  |                 ^

It might also be good to squelch the E0610 message altogether too.

[leonardo-m]

I think not requiring a zero (or other digit) before and after the dot for floating point numbers was a small Rust design mistake, that causes troubles later.

[mcobzarenco]

I think not requiring a zero (or other digit) before and after the dot for floating point numbers was a small Rust design mistake, that causes troubles later.

Even so, the problem would remain, no? Rust interprets 2 as an integer and . as field acces. Requiring a 0 after the dot for floats would not change how this gets parsed.

Rereading, do you mean that if a digit after the dot were required, then people would be used to always include it and not to run into this? Agreed