Auto merge of #34077 - durka:patch-23, r=alexcrichton
upgrade thread_local! invocation syntax Allows declaring multiple statics in one macro invocation, and supports attaching attributes to the generated items. In particular, `#![forbid(missing_docs, unused)]` is now tenable on a crate/module containing thread locals. For an example see [here](https://is.gd/aVFZZF). This change is fully backwards compatible as far as I can tell. cc @frankmcsherry
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4d9faf3632
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@ -100,18 +100,52 @@ pub struct LocalKey<T: 'static> {
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/// Declare a new thread local storage key of type `std::thread::LocalKey`.
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///
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/// # Syntax
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///
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/// The macro wraps any number of static declarations and makes them thread local.
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/// Each static may be public or private, and attributes are allowed. Example:
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///
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/// ```
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/// use std::cell::RefCell;
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/// thread_local! {
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/// pub static FOO: RefCell<u32> = RefCell::new(1);
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///
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/// #[allow(unused)]
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/// static BAR: RefCell<f32> = RefCell::new(1.0);
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/// }
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/// # fn main() {}
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/// ```
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///
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/// See [LocalKey documentation](thread/struct.LocalKey.html) for more
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/// information.
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#[macro_export]
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#[stable(feature = "rust1", since = "1.0.0")]
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#[allow_internal_unstable]
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macro_rules! thread_local {
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(static $name:ident: $t:ty = $init:expr) => (
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static $name: $crate::thread::LocalKey<$t> =
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// rule 0: empty (base case for the recursion)
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() => {};
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// rule 1: process multiple declarations where the first one is private
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($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
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thread_local!($(#[$attr])* static $name: $t = $init); // go to rule 2
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thread_local!($($rest)*);
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);
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// rule 2: handle a single private declaration
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($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr) => (
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$(#[$attr])* static $name: $crate::thread::LocalKey<$t> =
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__thread_local_inner!($t, $init);
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);
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(pub static $name:ident: $t:ty = $init:expr) => (
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pub static $name: $crate::thread::LocalKey<$t> =
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// rule 3: handle multiple declarations where the first one is public
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($(#[$attr:meta])* pub static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
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thread_local!($(#[$attr])* pub static $name: $t = $init); // go to rule 4
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thread_local!($($rest)*);
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);
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// rule 4: handle a single public declaration
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($(#[$attr:meta])* pub static $name:ident: $t:ty = $init:expr) => (
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$(#[$attr])* pub static $name: $crate::thread::LocalKey<$t> =
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__thread_local_inner!($t, $init);
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);
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}
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@ -0,0 +1,23 @@
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// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![deny(missing_docs)]
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//! this tests the syntax of `thread_local!`
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thread_local! {
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// no docs
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#[allow(unused)]
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static FOO: i32 = 42;
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/// docs
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pub static BAR: String = String::from("bar");
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}
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thread_local!(static BAZ: u32 = 0);
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fn main() {}
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