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android / platform / external / rust / crates / remain / f5f2a70de750a937d170099c62dce843a1a142bc
commitf5f2a70de750a937d170099c62dce843a1a142bc[log] [tgz]
authorJeff Vander Stoep <[email protected]>Tue Jan 31 21:35:37 2023 +0000
committerAutomerger Merge Worker <[email protected]>Tue Jan 31 21:35:37 2023 +0000
tree5b478dc53aa58194261e04ddcf8fb52a45a02df7
parent805a99a9ca6f7f6ed869f6230f1433a28e2ff737 [diff]
parent5575d0f525637d9d61e435c8844a745142994a5e [diff]
Update TEST_MAPPING am: 2ace9eb7e0 am: b9e8b629bb am: 5575d0f525

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/remain/+/2411780

Change-Id: I4a2a9a3d9f8520d5ca2c5a6488e8296cab560cd4
Signed-off-by: Automerger Merge Worker <[email protected]>
tree: 5b478dc53aa58194261e04ddcf8fb52a45a02df7
  1. .github/
  2. src/
  3. tests/
  4. LICENSE ⇨ LICENSE-APACHE
  5. .cargo_vcs_info.json
  6. .gitignore
  7. Android.bp
  8. Cargo.toml
  9. Cargo.toml.orig
  10. cargo2android.json
  11. LICENSE-APACHE
  12. LICENSE-MIT
  13. METADATA
  14. MODULE_LICENSE_APACHE2
  15. OWNERS
  16. README.md
  17. TEST_MAPPING
README.md

Remain sorted

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