Add Little Endian variants for Read/WriteExt

[leshow]

Motivation

There are functions to read in big endian format but not little endian, as mentioned on reddit.

Solution

Add read/write methods to AsyncReadExt and AsyncWriteExt that allow reading/writing in little endian.

Looks like these methods are all generated with macros, I'll add *Le variants of all the read/write types and then implement them in AsyncReadExt and AsyncWriteExt respectively.

I'm submitting a WIP MR to make sure I'm on the right track, I'll complete the docs and AsyncWriteExt shortly.

Tests are now fixed and everything appears to work correctly. I kept the test input the same between le and be variants.

[Kobzol]

Could this be parametrized with a type argument, same as in https://docs.rs/byteorder/1.1.0/byteorder/trait.ReadBytesExt.html?

[leshow]

The underlying crate tokio uses is the bytes crate, from which I copied the naming convention https://docs.rs/bytes/0.5.2/bytes/buf/trait.Buf.html#method.get_u16_le

This is the same naming that is used in std as well with methods like from_le

If you decide to move in a different direction, I can change this PR, but I think following the familiar naming convention is probably a good idea.

[Kobzol]

Ok, you're right, byteorder does it differently, but std and bytes use this convention, so it's a better idea for tokio as well I guess. Thanks for the PR btw! I need it in my use case.

[leshow]

Any update on this?

[zebp]

Can this get a review? This seems super handy.

[leshow]

If you need me to rebase and update it, give me a heads up.

[Darksonn]

This seems reasonable to me.

[Darksonn]

It is preferred that you simply make a merge commit instead of rebasing.

[leshow]

Fair enough. Merged with master, everything builds fine, but I ran into some very odd errors during cargo test

[hawkw]

Fair enough. Merged with master, everything builds fine, but I ran into some very odd errors during cargo test

@leshow what errors are you seeing? It looks like the tests passed for your branch on CI...

[leshow]

This is running from the git root dir. If I run from tokio subdir, all the tests pass

❯ cargo test --all-features            
   Compiling smallvec v1.2.0
   Compiling scopeguard v1.0.0
   Compiling lock_api v0.3.3
   Compiling parking_lot_core v0.7.0
   Compiling parking_lot v0.10.0
   Compiling tokio v0.2.21 (/home/leshow/dev/rust/tokio/tokio)
   Compiling tokio-test v0.2.1 (/home/leshow/dev/rust/tokio/tokio-test)
   Compiling tokio-util v0.3.1 (/home/leshow/dev/rust/tokio/tokio-util)
   Compiling tests-build v0.1.0 (/home/leshow/dev/rust/tokio/tests-build)
   Compiling tests-integration v0.1.0 (/home/leshow/dev/rust/tokio/tests-integration)
   Compiling examples v0.0.0 (/home/leshow/dev/rust/tokio/examples)
   Compiling tokio-macros v0.2.5 (/home/leshow/dev/rust/tokio/tokio-macros)
    Finished test [unoptimized + debuginfo] target(s) in 55.82s
     Running target/debug/deps/tests_build-d99f5f3e0262922b

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

     Running target/debug/deps/macros-6f38e01ab371efcf

running 1 test
    Updating crates.io index
error: failed to select a version for `proc-macro2`.
    ... required by package `tokio-macros v0.2.5 (/home/leshow/dev/rust/tokio/tokio-macros)`
    ... which is depended on by `tokio v0.2.21 (/home/leshow/dev/rust/tokio/tokio)`
    ... which is depended on by `tests-build v0.1.0 (/home/leshow/dev/rust/tokio/tests-build)`
    ... which is depended on by `tests-build-tests v0.0.0 (/home/leshow/dev/rust/tokio/target/tests/tests-build)`
versions that meet the requirements `^1.0.7` are: 1.0.18, 1.0.17, 1.0.16, 1.0.15, 1.0.14, 1.0.13, 1.0.12, 1.0.10, 1.0.9, 1.0.8, 1.0.7

all possible versions conflict with previously selected packages.

  previously selected package `proc-macro2 v1.0.6`
    ... which is depended on by `quote v1.0.2`
    ... which is depended on by `syn v1.0.11`
    ... which is depended on by `tokio-macros v0.2.5 (/home/leshow/dev/rust/tokio/tokio-macros)`
    ... which is depended on by `tokio v0.2.21 (/home/leshow/dev/rust/tokio/tokio)`
    ... which is depended on by `tests-build v0.1.0 (/home/leshow/dev/rust/tokio/tests-build)`
    ... which is depended on by `tests-build-tests v0.0.0 (/home/leshow/dev/rust/tokio/target/tests/tests-build)`

failed to select a version for `proc-macro2` which could resolve this conflict
test compile_fail ... FAILED

failures:

---- compile_fail stdout ----
thread 'compile_fail' panicked at 'tests failed', /home/leshow/.cargo/registry/src/github.com-1ecc6299db9ec823/trybuild-1.0.18/src/run.rs:38:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    compile_fail

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out

error: test failed, to rerun pass '-p tests-build --test macros'

This is the local failure I'm seeing