stabilize align(N) on function items

folkertdev · folkertdev · commit d01b56e849d5 · 2025-06-19T12:24:20.000+02:00
diff --git a/compiler/rustc_attr_parsing/src/attributes/repr.rs b/compiler/rustc_attr_parsing/src/attributes/repr.rs
@@ -273,7 +273,7 @@ pub(crate) struct AlignParser(Option<(Align, Span)>);
 
 impl AlignParser {
     const PATH: &'static [Symbol] = &[sym::align];
-    const TEMPLATE: AttributeTemplate = template!(Word, List: "<alignment in bytes>");
+    const TEMPLATE: AttributeTemplate = template!(List: "<alignment in bytes>");
 
     fn parse<'c, S: Stage>(
         &mut self,
diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
@@ -216,6 +216,8 @@ declare_features! (
     (accepted, f16c_target_feature, "1.68.0", Some(44839)),
     /// Allows field shorthands (`x` meaning `x: x`) in struct literal expressions.
     (accepted, field_init_shorthand, "1.17.0", Some(37340)),
+    /// Allows using `#[align(...)]` on function items
+    (accepted, fn_align, "CURRENT_RUSTC_VERSION", Some(82232)),
     /// Allows `#[must_use]` on functions, and introduces must-use operators (RFC 1940).
     (accepted, fn_must_use, "1.27.0", Some(43302)),
     /// Allows capturing variables in scope using format_args!
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -495,7 +495,7 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ),
     ungated!(no_link, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
     ungated!(repr, Normal, template!(List: "C"), DuplicatesOk, EncodeCrossCrate::No),
-    gated!(align, Normal, template!(List: "alignment"), DuplicatesOk, EncodeCrossCrate::No, fn_align, experimental!(align)),
+    ungated!(align, Normal, template!(List: "alignment"), DuplicatesOk, EncodeCrossCrate::No),
     ungated!(unsafe(Edition2024) export_name, Normal, template!(NameValueStr: "name"), FutureWarnPreceding, EncodeCrossCrate::No),
     ungated!(unsafe(Edition2024) link_section, Normal, template!(NameValueStr: "name"), FutureWarnPreceding, EncodeCrossCrate::No),
     ungated!(unsafe(Edition2024) no_mangle, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
@@ -510,8 +510,6 @@ declare_features! (
     (unstable, ffi_pure, "1.45.0", Some(58329)),
     /// Controlling the behavior of fmt::Debug
     (unstable, fmt_debug, "1.82.0", Some(129709)),
-    /// Allows using `#[repr(align(...))]` on function items
-    (unstable, fn_align, "1.53.0", Some(82232)),
     /// Support delegating implementation of functions to other already implemented functions.
     (incomplete, fn_delegation, "1.76.0", Some(118212)),
     /// Allows impls for the Freeze trait.
diff --git a/src/tools/miri/tests/pass/fn_align.rs b/src/tools/miri/tests/pass/fn_align.rs
@@ -1,5 +1,4 @@
 //@compile-flags: -Zmin-function-alignment=8
-#![feature(fn_align)]
 
 // When a function uses `align(N)`, the function address should be a multiple of `N`.
 
diff --git a/tests/assembly/naked-functions/aix.rs b/tests/assembly/naked-functions/aix.rs
@@ -9,7 +9,7 @@
 //@[aix] needs-llvm-components: powerpc
 
 #![crate_type = "lib"]
-#![feature(no_core, asm_experimental_arch, f128, linkage, fn_align)]
+#![feature(no_core, asm_experimental_arch, f128, linkage)]
 #![no_core]
 
 // tests that naked functions work for the `powerpc64-ibm-aix` target.
diff --git a/tests/assembly/naked-functions/wasm32.rs b/tests/assembly/naked-functions/wasm32.rs
@@ -9,7 +9,7 @@
 //@ [wasm32-wasip1] needs-llvm-components: webassembly
 
 #![crate_type = "lib"]
-#![feature(no_core, asm_experimental_arch, f128, linkage, fn_align)]
+#![feature(no_core, asm_experimental_arch, f128, linkage)]
 #![no_core]
 
 extern crate minicore;
diff --git a/tests/codegen/align-fn.rs b/tests/codegen/align-fn.rs
@@ -1,7 +1,6 @@
 //@ compile-flags: -C no-prepopulate-passes -Z mir-opt-level=0
 
 #![crate_type = "lib"]
-#![feature(fn_align)]
 
 // CHECK: align 16
 #[no_mangle]
diff --git a/tests/codegen/min-function-alignment.rs b/tests/codegen/min-function-alignment.rs
@@ -4,7 +4,6 @@
 //@ [align1024] compile-flags: -Zmin-function-alignment=1024
 
 #![crate_type = "lib"]
-#![feature(fn_align)]
 
 // functions without explicit alignment use the global minimum
 //
diff --git a/tests/codegen/naked-fn/aligned.rs b/tests/codegen/naked-fn/aligned.rs
@@ -3,7 +3,6 @@
 //@ ignore-arm no "ret" mnemonic
 
 #![crate_type = "lib"]
-#![feature(fn_align)]
 use std::arch::naked_asm;
 
 // CHECK: .balign 16
diff --git a/tests/codegen/naked-fn/min-function-alignment.rs b/tests/codegen/naked-fn/min-function-alignment.rs
@@ -2,7 +2,6 @@
 //@ needs-asm-support
 //@ ignore-arm no "ret" mnemonic
 
-#![feature(fn_align)]
 #![crate_type = "lib"]
 
 // functions without explicit alignment use the global minimum
diff --git a/tests/ui/asm/naked-with-invalid-repr-attr.rs b/tests/ui/asm/naked-with-invalid-repr-attr.rs
@@ -1,5 +1,4 @@
 //@ needs-asm-support
-#![feature(fn_align)]
 #![crate_type = "lib"]
 use std::arch::naked_asm;
 
diff --git a/tests/ui/asm/naked-with-invalid-repr-attr.stderr b/tests/ui/asm/naked-with-invalid-repr-attr.stderr
@@ -1,5 +1,5 @@
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/naked-with-invalid-repr-attr.rs:6:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:5:8
    |
 LL |   #[repr(C)]
    |          ^
@@ -11,7 +11,7 @@ LL | | }
    | |_- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/naked-with-invalid-repr-attr.rs:14:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:13:8
    |
 LL |   #[repr(transparent)]
    |          ^^^^^^^^^^^
@@ -23,7 +23,7 @@ LL | | }
    | |_- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/naked-with-invalid-repr-attr.rs:22:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:21:8
    |
 LL |   #[repr(C)]
    |          ^
@@ -35,7 +35,7 @@ LL | | }
    | |_- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct, enum, or union
-  --> $DIR/naked-with-invalid-repr-attr.rs:32:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:31:8
    |
 LL |   #[repr(C, packed)]
    |          ^
@@ -48,7 +48,7 @@ LL | | }
    | |_- not a struct, enum, or union
 
 error[E0517]: attribute should be applied to a struct or union
-  --> $DIR/naked-with-invalid-repr-attr.rs:32:11
+  --> $DIR/naked-with-invalid-repr-attr.rs:31:11
    |
 LL |   #[repr(C, packed)]
    |             ^^^^^^
@@ -61,7 +61,7 @@ LL | | }
    | |_- not a struct or union
 
 error[E0517]: attribute should be applied to an enum
-  --> $DIR/naked-with-invalid-repr-attr.rs:42:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:41:8
    |
 LL |   #[repr(u8)]
    |          ^^
diff --git a/tests/ui/attributes/malformed-fn-align.rs b/tests/ui/attributes/malformed-fn-align.rs
@@ -1,9 +1,11 @@
-#![feature(fn_align)]
 #![crate_type = "lib"]
 
 trait MyTrait {
     #[align] //~ ERROR malformed `align` attribute input
-    fn myfun();
+    fn myfun1();
+
+    #[align(1, 2)] //~ ERROR malformed `align` attribute input
+    fn myfun2();
 }
 
 #[align = 16] //~ ERROR malformed `align` attribute input
diff --git a/tests/ui/attributes/malformed-fn-align.stderr b/tests/ui/attributes/malformed-fn-align.stderr
@@ -1,55 +1,56 @@
 error[E0539]: malformed `align` attribute input
-  --> $DIR/malformed-fn-align.rs:5:5
+  --> $DIR/malformed-fn-align.rs:4:5
    |
 LL |     #[align]
-   |     ^^^^^^^^ expected this to be a list
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL |     #[align(<alignment in bytes>)]
-   |            ++++++++++++++++++++++
+   |     ^^^^^^^^
+   |     |
+   |     expected this to be a list
+   |     help: must be of the form: `#[align(<alignment in bytes>)]`
+
+error[E0805]: malformed `align` attribute input
+  --> $DIR/malformed-fn-align.rs:7:5
+   |
+LL |     #[align(1, 2)]
+   |     ^^^^^^^------^
+   |     |      |
+   |     |      expected a single argument here
+   |     help: must be of the form: `#[align(<alignment in bytes>)]`
 
 error[E0539]: malformed `align` attribute input
-  --> $DIR/malformed-fn-align.rs:9:1
+  --> $DIR/malformed-fn-align.rs:11:1
    |
 LL | #[align = 16]
-   | ^^^^^^^^^^^^^ expected this to be a list
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #[align = 16]
-LL + #[align(<alignment in bytes>)]
-   |
-LL - #[align = 16]
-LL + #[align]
-   |
+   | ^^^^^^^^^^^^^
+   | |
+   | expected this to be a list
+   | help: must be of the form: `#[align(<alignment in bytes>)]`
 
 error[E0589]: invalid alignment value: not an unsuffixed integer
-  --> $DIR/malformed-fn-align.rs:12:9
+  --> $DIR/malformed-fn-align.rs:14:9
    |
 LL | #[align("hello")]
    |         ^^^^^^^
 
 error[E0589]: invalid alignment value: not a power of two
-  --> $DIR/malformed-fn-align.rs:15:9
+  --> $DIR/malformed-fn-align.rs:17:9
    |
 LL | #[align(0)]
    |         ^
 
 error: `#[repr(align(...))]` is not supported on function items
-  --> $DIR/malformed-fn-align.rs:18:8
+  --> $DIR/malformed-fn-align.rs:20:8
    |
 LL | #[repr(align(16))]
    |        ^^^^^^^^^
    |
 help: use `#[align(...)]` instead
-  --> $DIR/malformed-fn-align.rs:18:8
+  --> $DIR/malformed-fn-align.rs:20:8
    |
 LL | #[repr(align(16))]
    |        ^^^^^^^^^
 
 error: `#[align(...)]` is not supported on struct items
-  --> $DIR/malformed-fn-align.rs:21:1
+  --> $DIR/malformed-fn-align.rs:23:1
    |
 LL | #[align(16)]
    | ^^^^^^^^^^^^
@@ -60,7 +61,7 @@ LL - #[align(16)]
 LL + #[repr(align(16))]
    |
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0539, E0589.
+Some errors have detailed explanations: E0539, E0589, E0805.
 For more information about an error, try `rustc --explain E0539`.
diff --git a/tests/ui/feature-gates/feature-gate-fn_align.rs b/tests/ui/feature-gates/feature-gate-fn_align.rs
diff --git a/tests/ui/feature-gates/feature-gate-fn_align.stderr b/tests/ui/feature-gates/feature-gate-fn_align.stderr

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,4 @@`
`1`	`1`	`//@compile-flags: -Zmin-function-alignment=8`
`2`		`-#![feature(fn_align)]`
`3`	`2`
`4`	`3`	// When a function uses `align(N)`, the function address should be a multiple of `N`.
`5`	`4`