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android / platform / external / rust / crates / remain / refs/heads/android10-mainline-resolv-release
commit3d5e5850baf2bc2f9314acd29e90efac3ba451fa[log] [tgz]
authorandroid-build-team Robot <android-build-team-robot@google.com>Mon Nov 11 21:11:51 2019 +0000
committerandroid-build-team Robot <android-build-team-robot@google.com>Mon Nov 11 21:11:51 2019 +0000
tree383c3e355db0910ba3a513b1f837375c5656106b
parent353d7d10ca6acceba596ae90716c0d53845cb2c8 [diff]
parent8ed7a370bef4647c82fe5b22b0696ddc715b706b [diff]
Snap for 6001391 from 8ed7a370bef4647c82fe5b22b0696ddc715b706b to qt-aml-resolv-release

Change-Id: Id148334291bdbd5f92407840bbc62cf048bf37bc
tree: 383c3e355db0910ba3a513b1f837375c5656106b
  1. src/
  2. tests/
  3. .cargo_vcs_info.json
  4. .gitignore
  5. .travis.yml
  6. Android.bp
  7. Cargo.toml
  8. Cargo.toml.orig
  9. LICENSE-APACHE
  10. LICENSE-MIT
  11. README.md
README.md

Remain sorted

Build Status Latest Version Rust Documentation

This crate provides an attribute macro to check at compile time that the variants of an enum or the arms of a match expression are written in sorted order.

[dependencies]
remain = "0.1"

Syntax

Place a #[remain::sorted] attribute on enums, structs, match-expressions, or let-statements whose value is a match-expression.

Alternatively, import as use remain::sorted; and use #[sorted] as the attribute.

#[remain::sorted]
#[derive(Debug)]
pub enum Error {
    BlockSignal(signal::Error),
    CreateCrasClient(libcras::Error),
    CreateEventFd(sys_util::Error),
    CreateSignalFd(sys_util::SignalFdError),
    CreateSocket(io::Error),
    DetectImageType(qcow::Error),
    DeviceJail(io_jail::Error),
    NetDeviceNew(virtio::NetError),
    SpawnVcpu(io::Error),
}

#[remain::sorted]
#[derive(Debug)]
pub enum Registers {
    ax: u16,
    cx: u16,
    di: u16,
    si: u16,
    sp: u16,
}

impl Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        use self::Error::*;

        #[remain::sorted]
        match self {
            BlockSignal(e) => write!(f, "failed to block signal: {}", e),
            CreateCrasClient(e) => write!(f, "failed to create cras client: {}", e),
            CreateEventFd(e) => write!(f, "failed to create eventfd: {}", e),
            CreateSignalFd(e) => write!(f, "failed to create signalfd: {}", e),
            CreateSocket(e) => write!(f, "failed to create socket: {}", e),
            DetectImageType(e) => write!(f, "failed to detect disk image type: {}", e),
            DeviceJail(e) => write!(f, "failed to jail device: {}", e),
            NetDeviceNew(e) => write!(f, "failed to set up virtio networking: {}", e),
            SpawnVcpu(e) => write!(f, "failed to spawn VCPU thread: {}", e),
        }
    }
}

If an enum variant, struct field, or match arm is inserted out of order,

      NetDeviceNew(virtio::NetError),
      SpawnVcpu(io::Error),
+     AaaUhOh(Box<dyn StdError>),
  }

then the macro produces a compile error.

error: AaaUhOh should sort before BlockSignal
  --> tests/stable.rs:49:5
   |
49 |     AaaUhOh(Box<dyn StdError>),
   |     ^^^^^^^

Compiler support

The attribute on enums and structs is supported on any rustc version 1.31+.

Rust does not yet have stable support for user-defined attributes within a function body, so the attribute on match-expressions and let-statements requires a nightly compiler and the following two features enabled:

#![feature(proc_macro_hygiene, stmt_expr_attributes)]

As a stable alternative, this crate provides a function-level attribute called #[remain::check] which makes match-expression and let-statement attributes work on any rustc version 1.31+. Place this attribute on any function containing #[sorted] to make them work on a stable compiler.

impl Display for Error {
    #[remain::check]
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        use self::Error::*;

        #[sorted]
        match self {
            /* ... */
        }
    }
}

License