struct RGB { red: f64, green: f64, blue: f64 }

/*
fn main() {
    let (red, green, blue): (f32, f32, f32) = (0., 0., 0.);
    let _ = RGB { red, green, blue };
}
*/

// This gives a bad/misleading error message

/*

error[E0308]: mismatched types
 --> src/main.rs:6:19
  |
6 |     let _ = RGB { red, green, blue };
  |                   ^^^ expected f64, found f32
help: you can cast an `f32` to `f64` in a lossless way
  |
6 |     let _ = RGB { red.into(), green, blue };
  |                   ^^^^^^^^^^

// But, if I do try with that .into(), the error message is even worse!

error: expected one of `,` or `}`, found `.`
 --> src/main.rs:6:22
  |
6 |     let _ = RGB { red.into(), green, blue };
  |                      ^ expected one of `,` or `}` here

error[E0308]: mismatched types
 --> src/main.rs:6:19
  |
6 |     let _ = RGB { red.into(), green, blue };
  |                   ^^^ expected f64, found f32
help: you can cast an `f32` to `f64` in a lossless way
  |
6 |     let _ = RGB { red.into().into(), green, blue };
  |                   ^^^^^^^^^^

error[E0063]: missing fields `blue`, `green` in initializer of `RGB`
 --> src/main.rs:6:13
  |
6 |     let _ = RGB { red.into(), green, blue };
  |             ^^^ missing `blue`, `green`

error: aborting due to 3 previous errors

*/

// The expected way to fix this issue is:

fn main() {
    let (red, green, blue): (f32, f32, f32) = (0., 0., 0.);
    let _ = RGB { red: red.into(), green: green.into(), blue: blue.into() };
}

// Which is EXTREMELY, unnecesarily verbose...
// I wish there was a better way, but the best so far is to
// have an explicit conversion function.
// (And you can't write a From impl if you don't own the RGB type)