stabilize repr(align(N)) on function items

folkertdev · folkertdev · commit ae9e03c7d655 · 2025-04-24T21:21:32.000+02:00
diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
@@ -214,6 +214,8 @@ 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 `#[repr(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/unstable.rs b/compiler/rustc_feature/src/unstable.rs
@@ -496,8 +496,6 @@ 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/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
@@ -629,9 +629,6 @@ passes_remove_fields =
      *[other] fields
     }
 
-passes_repr_align_function =
-    `repr(align)` attributes on functions are unstable
-
 passes_repr_align_greater_than_target_max =
     alignment must not be greater than `isize::MAX` bytes
     .note = `isize::MAX` is {$size} for the current target
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
@@ -1975,17 +1975,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 ReprAttr::ReprAlign(align) => {
                     match target {
                         Target::Struct | Target::Union | Target::Enum => {}
-                        Target::Fn | Target::Method(_) => {
-                            if !self.tcx.features().fn_align() {
-                                feature_err(
-                                    &self.tcx.sess,
-                                    sym::fn_align,
-                                    *repr_span,
-                                    fluent::passes_repr_align_function,
-                                )
-                                .emit();
-                            }
-                        }
+                        Target::Fn | Target::Method(_) => {}
                         _ => {
                             self.dcx().emit_err(
                                 errors::AttrApplication::StructEnumFunctionMethodUnion {
@@ -2049,15 +2039,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     if item.is_some() {
                         match target {
                             Target::Struct | Target::Union | Target::Enum => continue,
-                            Target::Fn | Target::Method(_) => {
-                                feature_err(
-                                    &self.tcx.sess,
-                                    sym::fn_align,
-                                    *repr_span,
-                                    fluent::passes_repr_align_function,
-                                )
-                                .emit();
-                            }
+                            Target::Fn | Target::Method(_) => continue,
                             _ => {
                                 self.dcx().emit_err(
                                     errors::AttrApplication::StructEnumFunctionMethodUnion {
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 `repr(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:22:19
+  --> $DIR/naked-with-invalid-repr-attr.rs:21:19
    |
 LL |   #[repr(align(16), 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:31:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:30:8
    |
 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:31:11
+  --> $DIR/naked-with-invalid-repr-attr.rs:30:11
    |
 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:41:8
+  --> $DIR/naked-with-invalid-repr-attr.rs:40:8
    |
 LL |   #[repr(u8)]
    |          ^^
diff --git a/tests/ui/attributes/malformed-fn-align.rs b/tests/ui/attributes/malformed-fn-align.rs
@@ -1,7 +1,9 @@
-#![feature(fn_align)]
 #![crate_type = "lib"]
 
 trait MyTrait {
     #[repr(align)] //~ ERROR invalid `repr(align)` attribute: `align` needs an argument
-    fn myfun();
+    fn myfun1();
+
+    #[repr(align(1, 2))] //~ ERROR incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
+    fn myfun2();
 }
diff --git a/tests/ui/attributes/malformed-fn-align.stderr b/tests/ui/attributes/malformed-fn-align.stderr
@@ -1,9 +1,16 @@
 error[E0589]: invalid `repr(align)` attribute: `align` needs an argument
-  --> $DIR/malformed-fn-align.rs:5:12
+  --> $DIR/malformed-fn-align.rs:4:12
    |
 LL |     #[repr(align)]
    |            ^^^^^ help: supply an argument here: `align(...)`
 
-error: aborting due to 1 previous error
+error[E0693]: incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
+  --> $DIR/malformed-fn-align.rs:7:12
+   |
+LL |     #[repr(align(1, 2))]
+   |            ^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0589`.
+Some errors have detailed explanations: E0589, E0693.
+For more information about an error, try `rustc --explain E0589`.
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
`@@ -629,9 +629,6 @@ passes_remove_fields =`
`629`	`629`	`*[other] fields`
`630`	`630`	`}`
`631`	`631`
`632`		`-passes_repr_align_function =`
`633`		- `repr(align)` attributes on functions are unstable
`634`		`-`
`635`	`632`	`passes_repr_align_greater_than_target_max =`
`636`	`633`	alignment must not be greater than `isize::MAX` bytes
`637`	`634`	.note = `isize::MAX` is {$size} for the current target
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 `repr(align(N))`, the function address should be a multiple of `N`.
`5`	`4`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,4 @@`
`1`	`1`	`//@ needs-asm-support`
`2`		`-#![feature(fn_align)]`
`3`	`2`	`#![crate_type = "lib"]`
`4`	`3`	`use std::arch::naked_asm;`
`5`	`4`