Auto merge of #47006 - bitshifter:stabilize-repr-align, r=eddyb

Stabilized `#[repr(align(x))]` attribute (RFC 1358)

Stabilzed `#[repr(align(x))]` with attr_literal syntax as proposed by @eddyb #33626 (comment)

Author: bors

src/liballoc/tests/lib.rs

@@ -23,7 +23,6 @@
 #![feature(pattern)]
 #![feature(placement_in_syntax)]
 #![feature(rand)]
-#![feature(repr_align)]
 #![feature(slice_rotate)]
 #![feature(splice)]
 #![feature(str_escape)]

src/libstd/lib.rs

@@ -296,7 +296,6 @@
 #![feature(ptr_internals)]
 #![feature(rand)]
 #![feature(raw)]
-#![feature(repr_align)]
 #![feature(rustc_attrs)]
 #![feature(sip_hash_13)]
 #![feature(slice_bytes)]
@@ -323,6 +322,7 @@
 #![feature(doc_spotlight)]
 #![cfg_attr(test, feature(update_panic_count))]
 #![cfg_attr(windows, feature(used))]
+#![cfg_attr(stage0, feature(repr_align))]
 
 #![default_lib_allocator]
 

src/libsyntax/feature_gate.rs

@@ -343,9 +343,6 @@ declare_features! (
     // Allows the `catch {...}` expression
     (active, catch_expr, "1.17.0", Some(31436)),
 
-    // Allows `repr(align(u16))` struct attribute (RFC 1358)
-    (active, repr_align, "1.17.0", Some(33626)),
-
     // Used to preserve symbols (see llvm.used)
     (active, used, "1.18.0", Some(40289)),
 
@@ -546,6 +543,8 @@ declare_features! (
     // Allows the sysV64 ABI to be specified on all platforms
     // instead of just the platforms on which it is the C ABI
     (accepted, abi_sysv64, "1.24.0", Some(36167)),
+    // Allows `repr(align(16))` struct attribute (RFC 1358)
+    (accepted, repr_align, "1.24.0", Some(33626)),
 );
 
 // If you change this, please modify src/doc/unstable-book as well. You must
@@ -1456,15 +1455,25 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             }
         }
 
+        // allow attr_literals in #[repr(align(x))]
+        let mut is_repr_align = false;
+        if attr.path == "repr" {
+            if let Some(content) = attr.meta_item_list() {
+                is_repr_align = content.iter().any(|c| c.check_name("align"));
+            }
+        }
+
         if self.context.features.proc_macro && attr::is_known(attr) {
             return
         }
 
-        let meta = panictry!(attr.parse_meta(self.context.parse_sess));
-        if contains_novel_literal(&meta) {
-            gate_feature_post!(&self, attr_literals, attr.span,
-                               "non-string literals in attributes, or string \
-                               literals in top-level positions, are experimental");
+        if !is_repr_align {
+            let meta = panictry!(attr.parse_meta(self.context.parse_sess));
+            if contains_novel_literal(&meta) {
+                gate_feature_post!(&self, attr_literals, attr.span,
+                                   "non-string literals in attributes, or string \
+                                   literals in top-level positions, are experimental");
+            }
         }
     }
 
@@ -1522,11 +1531,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                             gate_feature_post!(&self, repr_simd, attr.span,
                                                "SIMD types are experimental and possibly buggy");
                         }
-                        if item.check_name("align") {
-                            gate_feature_post!(&self, repr_align, attr.span,
-                                               "the struct `#[repr(align(u16))]` attribute \
-                                                is experimental");
-                        }
                         if item.check_name("transparent") {
                             gate_feature_post!(&self, repr_transparent, attr.span,
                                                "the `#[repr(transparent)]` attribute \

src/test/codegen/align-struct.rs

@@ -13,9 +13,6 @@
 
 #![crate_type = "lib"]
 
-#![feature(attr_literals)]
-#![feature(repr_align)]
-
 #[repr(align(64))]
 pub struct Align64(i32);
 // CHECK: %Align64 = type { [0 x i32], i32, [15 x i32] }

src/test/compile-fail/conflicting-repr-hints.rs

@@ -9,8 +9,6 @@
 // except according to those terms.
 
 #![allow(dead_code)]
-#![feature(attr_literals)]
-#![feature(repr_align)]
 
 #[repr(C)]
 enum A { A }

src/test/compile-fail/repr-align.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 #![allow(dead_code)]
-#![feature(attr_literals)]
-#![feature(repr_align)]
 
 #[repr(align(16.0))] //~ ERROR: invalid `repr(align)` attribute: not an unsuffixed integer
 struct A(i32);

src/test/compile-fail/repr-packed-contains-align.rs

@@ -7,8 +7,6 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
-#![feature(attr_literals)]
-#![feature(repr_align)]
 #![feature(untagged_unions)]
 #![allow(dead_code)]
 

src/test/run-pass/align-struct.rs

@@ -7,8 +7,6 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
-#![feature(attr_literals)]
-#![feature(repr_align)]
 #![feature(box_syntax)]
 
 use std::mem;

src/test/run-pass/union/union-align.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(attr_literals)]
-#![feature(repr_align)]
 #![feature(untagged_unions)]
 
 use std::mem::{size_of, size_of_val, align_of, align_of_val};