SocketFamily::Ipv6 definition is wrong because it's OS dependent

[xanathar]

This issue involves many repos (sys, gio, and gir-files), so I'm not 100% sure this is the correct one to open the issue to. I've tried to solve the issue, but could not find a similar case to copy so, in case, guidance is needed.

TL;DR: The value of the constant gio_sys::G_SOCKET_FAMILY_IPV6 is operating system dependent, and so code using it (directly or indirectly) fails on non-Linux OSs (Linux is safe because gir files are generated from Ubuntu's .debs).

Repro/Symptom

Running a simple code like:

    if let Err(e) = Socket::new(SocketFamily::Ipv6, SocketType::Datagram, SocketProtocol::Udp) {
        println!("ERROR: {:?}", e);
    }

fails on MacOS (and Windows) with the following output:

(process:7858): GLib-GObject-WARNING **: 20:12:12.881: value "((GSocketFamily) 10)" of type 'GSocketFamily' is invalid or out of range for property 'family' of type 'GSocketFamily'
ERROR: Error { domain: g-io-error-quark, code: 13, message: "Unable to create socket: Unknown family was specified" }

on the other hand the following works (on MacOS):

    if let Err(e) = Socket::new(SocketFamily::__Unknown(30), SocketType::Datagram, SocketProtocol::Udp) {
        println!("ERROR: {:?}", e);
    }

Root cause

• SocketFamily::Ipv6 is defined to be the same value (via the to_glib method) of gio_sys::G_SOCKET_FAMILY_IPV6
• gio_sys::G_SOCKET_FAMILY_IPV6 has a fixed value of 10 in https://github.com/gtk-rs/gir-files/blob/master/Gio-2.0.gir
• The value in Gio-2.0.gir comes from a libgirepository1.0.*.deb package of Ubuntu and the original glib sources.
• Checking the original glib sources, the constant is defined in glib/glibconfig.h.in as a constant coming from meson
• Checking meson.build it seems that it takes the value from the AF_INET6 constant from system includes
• AF_INET6 is defined as 10 on Linux (at least, Ubuntu), as 30 on MacOS and as 23 on Windows (found by inspecting system SDK header files)

[sdroege]

This means that we should ignore these constants from the .gir file and instead point at libc::AF_INET etc. manually.

We already do similar things in https://github.com/gtk-rs/sys/blob/master/glib-sys/src/manual.rs for example.

Do you want to provide a PR for this?

[xanathar]

Sure! I just needed this pointer :)

[sdroege]

Ignoring can be done via the Gir.toml file btw :)