Do not suggest internal crates in error messages

[IvanUkhov]

The following code:

fn main() {
    let _ = 42.0.ln();
}

produces the following error:

error: no method named `ln` found for type `_` in the current scope
 --> <anon>:2:18
2 |>     let _ = 42.0.ln();
  |>                  ^^
help: items from traits can only be used if the trait is in scope; the following trait is implemented but not in scope, perhaps add a `use` for it:
help: candidate #1: `use rand::FloatMath`

error: aborting due to previous error

The fact that unsuffixed floating-point numbers don’t currently default to f64 has already been discussed in #24124. The point of this issue is the error message: it suggests using rand::FloatMath, which is confusing as it’s an internal crate.

Regards,
Ivan

[Michael-F-Bryan]

I just got bitten by this one too. The fix is easy (just throw in an as f64), but the fact that you are told you don't have the trait in scope and are told to use an internal crate which is named the same as an external one is super confusing.

Luckily after doing some digging through rand's docs a bit of googling led me to this issue, but it would be really nice if this issue was fixed so others don't have to deal with it.

[Mark-Simulacrum]

This appears to no longer happen, so I'm going to close. I don't think a test is needed here (we basically test this with other UI tests).