[fixed-hash] to_string() gives shortened version instead of full

[mo-rijndael]

How to reproduce

here is snippet

// fixed-hash is 0.7.0 (latest)
use fixed_hash::construct_fixed_hash;
construct_fixed_hash! {struct H160(20);}

fn main() {
    let hash = H160::zero();
    // Debug formatting
    println!("{:?}", hash); // 0x0000000000000000000000000000000000000000

    // Display formatting
    println!("{}", hash); // 0x0000…0000

    // ToString
    println!("{}", hash.to_string()); // 0x0000…0000
}

Expected results

to_string() returns string representation of H160

Real results

to_string() returns shortened version

Source of problem

This occurs due to default implementation of ToString in standard library: impl<T: Display + ?Sized> ToString for T

Proposed solution

swap realizations for Debug and Display

Advantages

• More suitable implementations of formatting traits (Shortened is useful for quick eye-checking, and when Display-ing to user we usually need full hash.)
• Generates same amount of code, do not increase load to compiler

Disadvantages

• It's a breaking change

Alternative solution

add codegen for ToString, which will return full version of hash

Advantages

• Non-breaking change

Disadvantage

• Generates more code, slowing compilation a bit
• Leaves unsuitable implementation of formatting traits

[hexcowboy]

Also came here to argue in favor of this.

additional context: gakonst/ethers-rs#2175

[Kuly14]

add codegen for ToString, which will return full version of hash

Wouldn't the alternate solution also be a breaking change? If somebody already is using to_string() and counts that it will only give him the shortened version? Just curious.

If we could get this changed it would be great IMO.