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.

1 files changed, 4 insertions, 2 deletions

diff --git a/tests/codegen/naked-fn/min-function-alignment.rs b/tests/codegen/naked-fn/min-function-alignment.rs
index 4ebaacd3eff..406e9334fa5 100644
--- a/tests/codegen/naked-fn/min-function-alignment.rs
+++ b/tests/codegen/naked-fn/min-function-alignment.rs
@@ -3,6 +3,8 @@
 //@ ignore-arm no "ret" mnemonic
 //@ 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)]
 #![crate_type = "lib"]
 
@@ -17,7 +19,7 @@ pub extern "C" fn naked_no_explicit_align() {
 
 // CHECK: .balign 16
 #[no_mangle]
-#[align(8)]
+#[rustc_align(8)]
 #[unsafe(naked)]
 pub extern "C" fn naked_lower_align() {
     core::arch::naked_asm!("ret")
@@ -25,7 +27,7 @@ pub extern "C" fn naked_lower_align() {
 
 // CHECK: .balign 32
 #[no_mangle]
-#[align(32)]
+#[rustc_align(32)]
 #[unsafe(naked)]
 pub extern "C" fn naked_higher_align() {
     core::arch::naked_asm!("ret")