commit | 2a16a4d81dad337a53cb094ae927a239fbd730b3 | [log] [tgz] |
---|---|---|
author | Chih-Hung Hsieh <chh@google.com> | Thu Mar 19 21:09:09 2020 +0000 |
committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Thu Mar 19 21:09:09 2020 +0000 |
tree | 1b9f1909282fc1970ffd41958cc0188f03db2636 | |
parent | 86b3860c15bb06a53d42332807be1ad48b1bebea [diff] | |
parent | 1665ba2b0c13d7c75e9e237b26211af5781c2cd6 [diff] |
Remove old 0.1.3; used only by old crosvm. am: 5846f731f4 am: cbf485ae47 am: ed54bdd494 am: 1665ba2b0c Change-Id: Ieceb4ad3d020700aa66916b2ad0b178fcce8fec1
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"
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>), | ^^^^^^^
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 { /* ... */ } } }