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.

(cherry picked from commit 69b71e44107b4905ec7ad84ccb3edf4f14b3df69)

1 files changed, 14 insertions, 12 deletions

diff --git a/tests/codegen/align-fn.rs b/tests/codegen/align-fn.rs
index 267da060240..f30b63f96d5 100644
--- a/tests/codegen/align-fn.rs
+++ b/tests/codegen/align-fn.rs
@@ -1,11 +1,13 @@
 //@ compile-flags: -C no-prepopulate-passes -Z mir-opt-level=0
 
 #![crate_type = "lib"]
+// FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
+#![feature(rustc_attrs)]
 #![feature(fn_align)]
 
 // CHECK: align 16
 #[no_mangle]
-#[align(16)]
+#[rustc_align(16)]
 pub fn fn_align() {}
 
 pub struct A;
@@ -13,12 +15,12 @@ pub struct A;
 impl A {
     // CHECK: align 16
     #[no_mangle]
-    #[align(16)]
+    #[rustc_align(16)]
     pub fn method_align(self) {}
 
     // CHECK: align 16
     #[no_mangle]
-    #[align(16)]
+    #[rustc_align(16)]
     pub fn associated_fn() {}
 }
 
@@ -26,19 +28,19 @@ trait T: Sized {
     fn trait_fn() {}
 
     // CHECK: align 32
-    #[align(32)]
+    #[rustc_align(32)]
     fn trait_method(self) {}
 }
 
 impl T for A {
     // CHECK: align 16
     #[no_mangle]
-    #[align(16)]
+    #[rustc_align(16)]
     fn trait_fn() {}
 
     // CHECK: align 16
     #[no_mangle]
-    #[align(16)]
+    #[rustc_align(16)]
     fn trait_method(self) {}
 }
 
@@ -51,20 +53,20 @@ pub fn foo() {
 // CHECK-LABEL: align_specified_twice_1
 // CHECK-SAME: align 64
 #[no_mangle]
-#[align(32)]
-#[align(64)]
+#[rustc_align(32)]
+#[rustc_align(64)]
 pub fn align_specified_twice_1() {}
 
 // CHECK-LABEL: align_specified_twice_2
 // CHECK-SAME: align 128
 #[no_mangle]
-#[align(128)]
-#[align(32)]
+#[rustc_align(128)]
+#[rustc_align(32)]
 pub fn align_specified_twice_2() {}
 
 // CHECK-LABEL: align_specified_twice_3
 // CHECK-SAME: align 256
 #[no_mangle]
-#[align(32)]
-#[align(256)]
+#[rustc_align(32)]
+#[rustc_align(256)]
 pub fn align_specified_twice_3() {}