Omit suffixes (e. g. `1_i32`) in const generic compilation errors

[Logarithmus]

I'm working on a library for compile time dimensional analysis. It uses const generics. On unit mismatch I get errors like this:

error[E0308]: mismatched types
   --> src/isq.rs:346:23
    |
346 |         let l3 = l1 + l2;
    |                       ^^ expected `1_i32`, found `2_i32`
    |
    = note: expected struct `Quantity<isq::Unit<(meter, Const<1_i32>)>, _>`
               found struct `Quantity<isq::Unit<(meter, Const<2_i32>)>, _>`

As you can see, rustc includes this _i32 type suffix into each const generic parameter. I think it's redundant & only makes compilation errors longer (which is important especially if you have complex combinations of units), because if you really want to learn the type of const generic parameter, you can just look at struct definition in source code.

I'd like error message to look like this:

error[E0308]: mismatched types
   --> src/isq.rs:346:23
    |
346 |         let l3 = l1 + l2;
    |                       ^^ expected `1`, found `2`
    |
    = note: expected struct `Quantity<isq::Unit<(meter, Const<1>)>, _>`
               found struct `Quantity<isq::Unit<(meter, Const<2>)>, _>`

[mqudsi]

I would say this is fairly minor, but if they should be omitted then they should only be omitted if they match (i32 and i32).

[compiler-errors]

but if they should be omitted then they should only be omitted if they match (i32 and i32).

So const generics always have a type, so they should always match, I think. Or else we'd have hit en error earlier along the lines of "expected i32, found u32".