dbg! put spaces around ::

[pickfire]

While trying out Ipv4Addr for #81202

I tried this code:

https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=d4e00191c64a2608f3306178bff743c8

use std::net::Ipv4Addr;

fn main() {
    dbg!(format!("{:#?}", Ipv4Addr::new(127, 0, 0, 1)));
}

I expected to see this happen:

[src/main.rs:4] format!("{:#?}", Ipv4Addr::new(127, 0, 0, 1)) = "127.0.0.1"

Instead, this happened:

[src/main.rs:4] format!("{:#?}", Ipv4Addr :: new(127, 0, 0, 1)) = "127.0.0.1"

Meta

rustc --version --verbose: Same happens for nightly

rustc 1.49.0 (e1884a8e3 2020-12-29)
binary: rustc
commit-hash: e1884a8e3c3e813aada8254edfa120e85bf5ffca
commit-date: 2020-12-29
host: x86_64-unknown-linux-gnu
release: 1.49.0

[jonas-schievink]

This is just what stringify! does, I believe

[clarfonthey]

The result is based upon tokens, not the actual code. It will be normalised like this no matter what.

[pickfire]

But why shouldn't it be normalized without spaces around :: like (?

[clarfonthey]

I didn't realise that, and it's a good point.

It could potentially be worthwhile to make stringify! format the code in a reasonably nice way if it's valid Rust syntax, but that could induce a lot of overhead. Really depends on what people think is best and makes the most sense.

[GrigorenkoPV]

Pretty sure it got fixed in 1.76

https://godbolt.org/z/3bnrvE5M7

[clarfonthey]

Seems like this should be closed, then.