commit | 13b0aeb0881fe26b3805690a7d3b9d592859b241 | [log] [tgz] |
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author | Android Build Role Account android-build-prod <android-build-team-robot@google.com> | Thu Nov 14 23:03:06 2019 +0000 |
committer | Android Build Role Account android-build-prod <android-build-team-robot@google.com> | Thu Nov 14 23:03:06 2019 +0000 |
tree | 383c3e355db0910ba3a513b1f837375c5656106b | |
parent | 6e9247a1bc105c3d879a76a635970e530c2f9e42 [diff] | |
parent | 79f243fab0c3806c7dd98e7ec8d32494ef2b837d [diff] |
Snap for 6008936 from 79f243fab0c3806c7dd98e7ec8d32494ef2b837d to r-keystone-qcom-release Change-Id: Ie3eefefd336c5f8c744402f4529db56061edfcda
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"
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>), | ^^^^^^^
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 { /* ... */ } } }