| // run-pass |
| // Test that we don't duplicate storage for a variable that is moved to another |
| // binding. This used to happen in the presence of unwind and drop edges (see |
| // `complex` below.) |
| // |
| // The exact sizes here can change (we'd like to know when they do). What we |
| // don't want to see is the `complex` generator size being upwards of 2048 bytes |
| // (which would indicate it is reserving space for two copies of Foo.) |
| // |
| // See issue #59123 for a full explanation. |
| |
| // edition:2018 |
| // ignore-wasm32 issue #62807 |
| |
| #![feature(generators, generator_trait)] |
| |
| use std::ops::Generator; |
| |
| const FOO_SIZE: usize = 1024; |
| struct Foo([u8; FOO_SIZE]); |
| |
| impl Drop for Foo { |
| fn drop(&mut self) {} |
| } |
| |
| fn move_before_yield() -> impl Generator<Yield = (), Return = ()> { |
| static || { |
| let first = Foo([0; FOO_SIZE]); |
| let _second = first; |
| yield; |
| // _second dropped here |
| } |
| } |
| |
| fn noop() {} |
| |
| fn move_before_yield_with_noop() -> impl Generator<Yield = (), Return = ()> { |
| static || { |
| let first = Foo([0; FOO_SIZE]); |
| noop(); |
| let _second = first; |
| yield; |
| // _second dropped here |
| } |
| } |
| |
| // Today we don't have NRVO (we allocate space for both `first` and `second`,) |
| // but we can overlap `first` with `_third`. |
| fn overlap_move_points() -> impl Generator<Yield = (), Return = ()> { |
| static || { |
| let first = Foo([0; FOO_SIZE]); |
| yield; |
| let second = first; |
| yield; |
| let _third = second; |
| yield; |
| } |
| } |
| |
| fn overlap_x_and_y() -> impl Generator<Yield = (), Return = ()>{ |
| static || { |
| let x = Foo([0; FOO_SIZE]); |
| yield; |
| drop(x); |
| let y = Foo([0; FOO_SIZE]); |
| yield; |
| drop(y); |
| } |
| } |
| |
| fn main() { |
| assert_eq!(1028, std::mem::size_of_val(&move_before_yield())); |
| assert_eq!(1032, std::mem::size_of_val(&move_before_yield_with_noop())); |
| assert_eq!(2056, std::mem::size_of_val(&overlap_move_points())); |
| assert_eq!(1032, std::mem::size_of_val(&overlap_x_and_y())); |
| } |