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android / platform / external / rust / crates / remain / ee79e1535e7cf320e3d65df262b9d1afb34f2687
commitee79e1535e7cf320e3d65df262b9d1afb34f2687[log] [tgz]
authorBob Badour <bbadour@google.com>Fri Apr 24 19:11:28 2020 +0000
committerAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>Fri Apr 24 19:11:28 2020 +0000
tree11935e7ac54d28de033d0b5a0e5c3a9146a38561
parentf09865fd87ce8ef26e186332b8fb7c96b5049c29 [diff]
parent70b19f0ded910906f4562ba402f9c7db2dac534a [diff]
Add license type: Apache2+MIT are NOTICE licenses am: dcb9746c9c am: 53d2f11df4 am: 1389c1f5a7 am: 7598d899f1 am: 70b19f0ded

Change-Id: Id93c5624c77ae05906a258ae79f97e085c7c71c2
tree: 11935e7ac54d28de033d0b5a0e5c3a9146a38561
  1. src/
  2. tests/
  3. LICENSE ⇨ LICENSE-APACHE
  4. .cargo_vcs_info.json
  5. .gitignore
  6. .travis.yml
  7. Android.bp
  8. Cargo.toml
  9. Cargo.toml.orig
  10. LICENSE-APACHE
  11. LICENSE-MIT
  12. METADATA
  13. MODULE_LICENSE_APACHE2
  14. OWNERS
  15. 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 = "0.2"

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 struct 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