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upgrade thread_local! invocation syntax #34077

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Jun 24, 2016
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42 changes: 38 additions & 4 deletions src/libstd/thread/local.rs
Original file line number Diff line number Diff line change
Expand Up @@ -100,18 +100,52 @@ pub struct LocalKey<T: 'static> {

/// Declare a new thread local storage key of type `std::thread::LocalKey`.
///
/// # Syntax
///
/// The macro wraps any number of static declarations and makes them thread local.
/// Each static may be public or private, and attributes are allowed. Example:
///
/// ```
/// use std::cell::RefCell;
/// thread_local! {
/// pub static FOO: RefCell<u32> = RefCell::new(1);
///
/// #[allow(unused)]
/// static BAR: RefCell<f32> = RefCell::new(1.0);
/// }
/// # fn main() {}
/// ```
///
/// See [LocalKey documentation](thread/struct.LocalKey.html) for more
/// information.
#[macro_export]
#[stable(feature = "rust1", since = "1.0.0")]
#[allow_internal_unstable]
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this attribute must be redundant since I was able to simply copy the macro into a playpen, right?

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OK, it shouldn't be redundant because __thread_local_inner! is marked unstable, but something is failing to check that!

macro_rules! thread_local {
(static $name:ident: $t:ty = $init:expr) => (
static $name: $crate::thread::LocalKey<$t> =
// rule 0: empty (base case for the recursion)
() => {};

// rule 1: process multiple declarations where the first one is private
($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
thread_local!($(#[$attr])* static $name: $t = $init); // go to rule 2
thread_local!($($rest)*);
);

// rule 2: handle a single private declaration
($(#[$attr:meta])* static $name:ident: $t:ty = $init:expr) => (
$(#[$attr])* static $name: $crate::thread::LocalKey<$t> =
__thread_local_inner!($t, $init);
);
(pub static $name:ident: $t:ty = $init:expr) => (
pub static $name: $crate::thread::LocalKey<$t> =

// rule 3: handle multiple declarations where the first one is public
($(#[$attr:meta])* pub static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
thread_local!($(#[$attr])* pub static $name: $t = $init); // go to rule 4
thread_local!($($rest)*);
);

// rule 4: handle a single public declaration
($(#[$attr:meta])* pub static $name:ident: $t:ty = $init:expr) => (
$(#[$attr])* pub static $name: $crate::thread::LocalKey<$t> =
__thread_local_inner!($t, $init);
);
}
Expand Down
23 changes: 23 additions & 0 deletions src/test/run-pass/thread-local-syntax.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![deny(missing_docs)]
//! this tests the syntax of `thread_local!`

thread_local! {
// no docs
#[allow(unused)]
static FOO: i32 = 42;
/// docs
pub static BAR: String = String::from("bar");
}
thread_local!(static BAZ: u32 = 0);

fn main() {}