The main goal here is to make the function pointers comptime, so that we
don't have to do the crazy stuff with async function frames.
Since InStream, OutStream, and SeekableStream are already generic
across error sets, it's not really worse to make them generic across the
vtable as well.
See #764 for the open issue acknowledging that using generics for these
abstractions is a design flaw.
See #130 for the efforts to make these abstractions non-generic.
This commit also changes the OutStream API so that `write` returns
number of bytes written, and `writeAll` is the one that loops until the
whole buffer is written.
* delete the std/event/net directory
* `std.event.Loop.waitUntilFdReadable` and related functions
no longer have possibility of failure. On Linux, they fall
back to poll() and then fall back to sleep().
* add some missing `noasync` decorations in `std.event.Loop`
* redo the `std.net.Server` API. it's quite nice now, but
shutdown does not work cleanly. There is a race condition with
close() that I am actively working on.
* move `std.io.OutStream` to its own file to match `std.io.InStream`.
I started working on making `write` integrated with evented I/O,
but it got tricky so I backed off and filed #3557. However
I did integrate `std.os.writev` and `std.os.pwritev` with evented I/O.
* add `std.Target.stack_align`
* move networking tests to `lib/std/net/test.zig`
* add `std.net.tcpConnectToHost` and `std.net.tcpConnectToAddress`.
* rename `error.UnknownName` to `error.UnknownHostName` within the
context of DNS resolution.
* add `std.os.readv`, which is integrated with evented I/O.
* `std.os.preadv`, is now integrated with evented I/O.
* `std.os.accept4` now asserts that ENOTSOCK and EOPNOTSUPP never
occur (misuse of API), instead of returning errors.
* `std.os.connect` is now integrated with evented I/O.
`std.os.connect_async` is gone. Just use `std.os.connect`.
* fix false positive dependency loop regarding async function frames
* add more compile notes to help when dependency loops occur
in determining whether a function is async.
* ir: change an assert to ir_assert to make it easier to find
workarounds for when such an assert is triggered. In this case
it was trying to parse an IPv4 address at comptime.
