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rust/src/test/run-pass/log_syntax-trace_macros-macro-locations.rs

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syntax: allow `trace_macros!` and `log_syntax!` in item position. Previously trace_macros!(true) fn main() {} would complain about `trace_macros` being an expression macro in item position. This is a pointless limitation, because the macro is purely compile-time, with no runtime effect. (And similarly for log_syntax.) This also changes the behaviour of `trace_macros!` very slightly, it used to be equivalent to macro_rules! trace_macros { (true $($_x: tt)*) => { true }; (false $($_x: tt)*) => { false } } I.e. you could invoke it with arbitrary trailing arguments, which were ignored. It is changed to accept only exactly `true` or `false` (with no trailing arguments) and expands to `()`.
2014-03-18 23:14:08 +11:00
// Copyright 2014 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.
Remove ignore-fast that has cropped up
2014-04-03 13:02:50 -07:00
#![feature(trace_macros, log_syntax)]
syntax: allow `trace_macros!` and `log_syntax!` in item position. Previously trace_macros!(true) fn main() {} would complain about `trace_macros` being an expression macro in item position. This is a pointless limitation, because the macro is purely compile-time, with no runtime effect. (And similarly for log_syntax.) This also changes the behaviour of `trace_macros!` very slightly, it used to be equivalent to macro_rules! trace_macros { (true $($_x: tt)*) => { true }; (false $($_x: tt)*) => { false } } I.e. you could invoke it with arbitrary trailing arguments, which were ignored. It is changed to accept only exactly `true` or `false` (with no trailing arguments) and expands to `()`.
2014-03-18 23:14:08 +11:00
// make sure these macros can be used as in the various places that
// macros can occur.
// items
librustc: Always parse `macro!()`/`macro![]` as expressions if not followed by a semicolon. This allows code like `vec![1i, 2, 3].len();` to work. This breaks code that uses macros as statements without putting semicolons after them, such as: fn main() { ... assert!(a == b) assert!(c == d) println(...); } It also breaks code that uses macros as items without semicolons: local_data_key!(foo) fn main() { println("hello world") } Add semicolons to fix this code. Those two examples can be fixed as follows: fn main() { ... assert!(a == b); assert!(c == d); println(...); } local_data_key!(foo); fn main() { println("hello world") } RFC #378. Closes #18635. [breaking-change]
2014-11-14 09:18:10 -08:00
trace_macros!(false);
log_syntax!();
syntax: allow `trace_macros!` and `log_syntax!` in item position. Previously trace_macros!(true) fn main() {} would complain about `trace_macros` being an expression macro in item position. This is a pointless limitation, because the macro is purely compile-time, with no runtime effect. (And similarly for log_syntax.) This also changes the behaviour of `trace_macros!` very slightly, it used to be equivalent to macro_rules! trace_macros { (true $($_x: tt)*) => { true }; (false $($_x: tt)*) => { false } } I.e. you could invoke it with arbitrary trailing arguments, which were ignored. It is changed to accept only exactly `true` or `false` (with no trailing arguments) and expands to `()`.
2014-03-18 23:14:08 +11:00
fn main() {
// statements
trace_macros!(false);
log_syntax!();
// expressions
(trace_macros!(false),
log_syntax!());
}
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