Files
rust/tests/ui/attributes/fn-align-dyn.rs
Jieyou Xu 69b71e4410 Mitigate #[align] name resolution ambiguity regression with a rename
From `#[align]` -> `#[rustc_align]`. Attributes starting with `rustc`
are always perma-unstable and feature-gated by `feature(rustc_attrs)`.

See regression RUST-143834.

For the underlying problem where even introducing new feature-gated
unstable built-in attributes can break user code such as

```rs
macro_rules! align {
    () => {
        /* .. */
    };
}

pub(crate) use align; // `use` here becomes ambiguous
```

refer to RUST-134963.

Since the `#[align]` attribute is still feature-gated by
`feature(fn_align)`, we can rename it as a mitigation. Note that
`#[rustc_align]` will obviously mean that current unstable user code
using `feature(fn_aling)` will need additionally `feature(rustc_attrs)`,
but this is a short-term mitigation to buy time, and is expected to be
changed to a better name with less collision potential.

See
<https://rust-lang.zulipchat.com/#narrow/channel/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202025-07-17/near/529290371>
where mitigation options were considered.
2025-07-19 01:42:30 +08:00

20 lines
489 B
Rust

//@ run-pass
//@ ignore-wasm32 aligning functions is not currently supported on wasm (#143368)
// FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
#![feature(rustc_attrs)]
#![feature(fn_align)]
trait Test {
#[rustc_align(4096)]
fn foo(&self);
#[rustc_align(4096)]
fn foo1(&self);
}
fn main() {
assert_eq!((<dyn Test>::foo as fn(_) as usize & !1) % 4096, 0);
assert_eq!((<dyn Test>::foo1 as fn(_) as usize & !1) % 4096, 0);
}