A few ergonomic From impls for SocketAddr/IpAddr

[seanmonstar]

My main motivation is removing things like this: "127.0.0.1:3000".parse().unwrap(). Instead, this now works: SocketAddr::from(([127, 0, 0, 1], 3000)) or even ([127, 0, 0, 1], 3000).into()) when passing to a function.

[rust-highfive]

r? @alexcrichton

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[nagisa]

I wonder if something like

impl<T: Into<Ipv4Addr>> From<T> for IpAddr { ... }

would be at odds with the coherence.

[seanmonstar]

@nagisa I considered it, but also worried about the possibility of some type T that could conceivable have both Into<Ipv4Addr> and Into<Ipv6Addr>, and if that would cause problems. It does seem highly unlikely to do that, but was still a thought, so this seemed more conservative. I can switch to that if consensus is that it is the better route.

[clarfonthey]

For completion, can you add implementations for SocketAddrV[46]?

[seanmonstar]

@clarcharr implementations for From<SocketAddrV4> and From<SocketAddrV6> already exist, starting in 1.16.

[alexcrichton]

I worry slightly that this seems "too clever" but we've got precedent elsewhere in the standard library for working with (&str, u16) as a "socket address" with a ToSocketAddrs impl. In that case this seems reasonable to me, so:

@rfcbot fcp merge

[rfcbot]

Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged teams:

• @BurntSushi
• @Kimundi
• @alexcrichton
• @aturon
• @brson
• @sfackler

No concerns currently listed.

Once these reviewers reach consensus, this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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[aturon]

This is cool! 👍 from me.

[clarfonthey]

Tiny correction: this should say segments instead of octects.

[alexcrichton]

ping @BurntSushi, @brson (checkboxes)

[alexcrichton]

@bors: r+

[bors]

📌 Commit cd603e4 has been approved by alexcrichton