mirror of
https://github.com/rust-lang/rust.git
synced 2024-12-01 03:03:40 +00:00
102 lines
3.2 KiB
Rust
102 lines
3.2 KiB
Rust
// edition:2021
|
|
|
|
#![feature(rustc_attrs)]
|
|
|
|
// `u8` aligned at a byte and are unaffected by repr(packed).
|
|
// Therefore we can precisely (and safely) capture references to both the fields.
|
|
fn test_alignment_not_affected() {
|
|
#[repr(packed)]
|
|
struct Foo { x: u8, y: u8 }
|
|
|
|
let mut foo = Foo { x: 0, y: 0 };
|
|
|
|
let mut c = #[rustc_capture_analysis]
|
|
//~^ ERROR: attributes on expressions are experimental
|
|
//~| NOTE: see issue #15701 <https://github.com/rust-lang/rust/issues/15701>
|
|
|| {
|
|
//~^ ERROR: First Pass analysis includes:
|
|
//~| ERROR: Min Capture analysis includes:
|
|
let z1: &u8 = &foo.x;
|
|
//~^ NOTE: Capturing foo[(0, 0)] -> ImmBorrow
|
|
//~| NOTE: Min Capture foo[(0, 0)] -> ImmBorrow
|
|
let z2: &mut u8 = &mut foo.y;
|
|
//~^ NOTE: Capturing foo[(1, 0)] -> MutBorrow
|
|
//~| NOTE: Min Capture foo[(1, 0)] -> MutBorrow
|
|
|
|
*z2 = 42;
|
|
|
|
println!("({}, {})", z1, z2);
|
|
};
|
|
|
|
c();
|
|
}
|
|
|
|
// `String`, `u16` are not aligned at a one byte boundary and are thus affected by repr(packed).
|
|
//
|
|
// Here we test that the closure doesn't capture a reference point to `foo.x` but
|
|
// rather capture `foo` entirely.
|
|
fn test_alignment_affected() {
|
|
#[repr(packed)]
|
|
struct Foo { x: String, y: u16 }
|
|
|
|
let mut foo = Foo { x: String::new(), y: 0 };
|
|
|
|
let mut c = #[rustc_capture_analysis]
|
|
//~^ ERROR: attributes on expressions are experimental
|
|
//~| NOTE: see issue #15701 <https://github.com/rust-lang/rust/issues/15701>
|
|
|| {
|
|
//~^ ERROR: First Pass analysis includes:
|
|
//~| ERROR: Min Capture analysis includes:
|
|
let z1: &String = &foo.x;
|
|
//~^ NOTE: Capturing foo[] -> ImmBorrow
|
|
let z2: &mut u16 = &mut foo.y;
|
|
//~^ NOTE: Capturing foo[] -> MutBorrow
|
|
//~| NOTE: Min Capture foo[] -> MutBorrow
|
|
|
|
|
|
*z2 = 42;
|
|
|
|
println!("({}, {})", z1, z2);
|
|
};
|
|
|
|
c();
|
|
}
|
|
|
|
// Given how the closure desugaring is implemented (at least at the time of writing this test),
|
|
// we don't need to truncate the captured path to a reference into a packed-struct if the field
|
|
// being referenced will be moved into the closure, since it's safe to move out a field from a
|
|
// packed-struct.
|
|
//
|
|
// However to avoid surprises for the user, or issues when the closure is
|
|
// inlined we will truncate the capture to access just the struct regardless of if the field
|
|
// might get moved into the closure.
|
|
fn test_truncation_when_ref_and_move() {
|
|
#[repr(packed)]
|
|
struct Foo { x: String }
|
|
|
|
let mut foo = Foo { x: String::new() };
|
|
|
|
let c = #[rustc_capture_analysis]
|
|
//~^ ERROR: attributes on expressions are experimental
|
|
//~| NOTE: see issue #15701 <https://github.com/rust-lang/rust/issues/15701>
|
|
|| {
|
|
//~^ ERROR: First Pass analysis includes:
|
|
//~| ERROR: Min Capture analysis includes:
|
|
println!("{}", foo.x);
|
|
//~^ NOTE: Capturing foo[] -> ImmBorrow
|
|
//~| NOTE: Min Capture foo[] -> ByValue
|
|
//~| NOTE: foo[] used here
|
|
let _z = foo.x;
|
|
//~^ NOTE: Capturing foo[(0, 0)] -> ByValue
|
|
//~| NOTE: foo[] captured as ByValue here
|
|
};
|
|
|
|
c();
|
|
}
|
|
|
|
fn main() {
|
|
test_truncation_when_ref_and_move();
|
|
test_alignment_affected();
|
|
test_alignment_not_affected();
|
|
}
|