tag | caf5333e1be6eae5c86dc18580b186db63f98357 | |
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tagger | The Android Open Source Project <initial-contribution@android.com> | Thu Feb 10 15:24:17 2022 -0800 |
object | 9226a713fe148124f90273f31f14b460f79fe947 |
Android T Preview 1
commit | 9226a713fe148124f90273f31f14b460f79fe947 | [log] [tgz] |
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author | Joel Galenson <jgalenson@google.com> | Wed Dec 15 15:28:00 2021 +0000 |
committer | Gerrit Code Review <noreply-gerritcodereview@google.com> | Wed Dec 15 15:28:00 2021 +0000 |
tree | a4ad33c12767c537e62c002f4b808f2535f25734 | |
parent | ceaf6f1923feb4e3ae1cc5a95a5e5f4bf2d31886 [diff] | |
parent | 48278686ef4182ad96c5c1c7e9d8e3979394ebde [diff] |
Merge "Refresh Android.bp, cargo2android.json, TEST_MAPPING."
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 { /* ... */ } } }