Minimize use of #![feature(custom_attribute)]

src/doc/rustc/src/lints/listing/warn-by-default.md

@@ -728,19 +728,17 @@ This lint detects attributes that were not used by the compiler. Some
 example code that triggers this lint:
 
 ```rust
-#![feature(custom_attribute)]
-
-#![mutable_doc]
+#![macro_export]
 ```
 
 This will produce:
 
 ```text
 warning: unused attribute
- --> src/main.rs:4:1
+ --> src/main.rs:1:1
   |
-4 | #![mutable_doc]
-  | ^^^^^^^^^^^^^^^
+1 | #![macro_export]
+  | ^^^^^^^^^^^^^^^^
   |
 ```
 

src/liballoc/alloc.rs

@@ -15,7 +15,8 @@ extern "Rust" {
     // them from the `#[global_allocator]` attribute if there is one, or uses the
     // default implementations in libstd (`__rdl_alloc` etc in `src/libstd/alloc.rs`)
     // otherwise.
-    #[allocator]
+    #[cfg_attr(bootstrap, allocator)]
+    #[cfg_attr(not(bootstrap), rustc_allocator)]
     #[rustc_allocator_nounwind]
     fn __rust_alloc(size: usize, align: usize) -> *mut u8;
     #[rustc_allocator_nounwind]

src/liballoc/lib.rs

@@ -79,7 +79,7 @@
 #![feature(coerce_unsized)]
 #![feature(dispatch_from_dyn)]
 #![feature(core_intrinsics)]
-#![feature(custom_attribute)]
+#![cfg_attr(bootstrap, feature(custom_attribute))]
 #![feature(dropck_eyepatch)]
 #![feature(exact_size_is_empty)]
 #![feature(fmt_internals)]

src/libcore/lib.rs

@@ -75,7 +75,6 @@
 #![feature(concat_idents)]
 #![feature(const_fn)]
 #![feature(const_fn_union)]
-#![feature(custom_attribute)]
 #![feature(doc_cfg)]
 #![feature(doc_spotlight)]
 #![feature(extern_types)]

src/librustc/hir/mod.rs

@@ -2574,7 +2574,7 @@ bitflags! {
         /// `#[cold]`: a hint to LLVM that this function, when called, is never on
         /// the hot path.
         const COLD                      = 1 << 0;
-        /// `#[allocator]`: a hint to LLVM that the pointer returned from this
+        /// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this
         /// function is never null.
         const ALLOCATOR                 = 1 << 1;
         /// `#[unwind]`: an indicator that this function may unwind despite what

src/librustc_codegen_llvm/lib.rs

@@ -10,7 +10,6 @@
 #![feature(box_syntax)]
 #![feature(const_cstr_unchecked)]
 #![feature(crate_visibility_modifier)]
-#![feature(custom_attribute)]
 #![feature(extern_types)]
 #![feature(in_band_lifetimes)]
 #![allow(unused_attributes)]

src/librustc_codegen_ssa/lib.rs

@@ -3,7 +3,6 @@
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(core_intrinsics)]
-#![feature(custom_attribute)]
 #![feature(libc)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(stmt_expr_attributes)]

src/librustc_codegen_utils/lib.rs

@@ -8,7 +8,6 @@
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(core_intrinsics)]
-#![feature(custom_attribute)]
 #![feature(never_type)]
 #![feature(nll)]
 #![allow(unused_attributes)]

src/librustc_errors/lib.rs

@@ -1,6 +1,5 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 
-#![feature(custom_attribute)]
 #![allow(unused_attributes)]
 #![cfg_attr(unix, feature(libc))]
 #![feature(nll)]

src/librustc_save_analysis/lib.rs

@@ -1,5 +1,4 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
-#![feature(custom_attribute)]
 #![feature(nll)]
 #![deny(rust_2018_idioms)]
 #![deny(internal)]

src/librustc_typeck/collect.rs

@@ -2445,7 +2445,7 @@ fn codegen_fn_attrs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: DefId) -> Codegen
     for attr in attrs.iter() {
         if attr.check_name(sym::cold) {
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
-        } else if attr.check_name(sym::allocator) {
+        } else if attr.check_name(sym::rustc_allocator) {
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
         } else if attr.check_name(sym::unwind) {
             codegen_fn_attrs.flags |= CodegenFnAttrFlags::UNWIND;

src/libsyntax/feature_gate.rs

@@ -1331,6 +1331,16 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
                                                 "internal implementation detail",
                                                 cfg_fn!(rustc_attrs))),
 
+    (sym::rustc_allocator, Whitelisted, template!(Word), Gated(Stability::Unstable,
+                                                sym::rustc_attrs,
+                                                "internal implementation detail",
+                                                cfg_fn!(rustc_attrs))),
+
+    (sym::rustc_dummy, Normal, template!(Word /* doesn't matter*/), Gated(Stability::Unstable,
+                                         sym::rustc_attrs,
+                                         "used by the test suite",
+                                         cfg_fn!(rustc_attrs))),
+
     // FIXME: #14408 whitelist docs since rustdoc looks at them
     (
         sym::doc,
@@ -1957,12 +1967,10 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         }
 
         match attr_info {
-            Some(&(name, _, template, _)) => self.check_builtin_attribute(
-                attr,
-                name,
-                template
-            ),
-            None => if let Some(TokenTree::Token(token)) = attr.tokens.trees().next() {
+            // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
+            Some(&(name, _, template, _)) if name != sym::rustc_dummy =>
+                self.check_builtin_attribute(attr, name, template),
+            _ => if let Some(TokenTree::Token(token)) = attr.tokens.trees().next() {
                 if token == token::Eq {
                     // All key-value attributes are restricted to meta-item syntax.
                     attr.parse_meta(self.context.parse_sess).map_err(|mut err| err.emit()).ok();

src/libsyntax_pos/lib.rs

@@ -11,7 +11,6 @@
 
 #![feature(const_fn)]
 #![feature(crate_visibility_modifier)]
-#![feature(custom_attribute)]
 #![feature(nll)]
 #![feature(non_exhaustive)]
 #![feature(optin_builtin_traits)]

src/libsyntax_pos/symbol.rs

@@ -513,6 +513,7 @@ symbols! {
         rust_2018_preview,
         rust_begin_unwind,
         rustc,
+        rustc_allocator,
         rustc_allocator_nounwind,
         rustc_allow_const_fn_ptr,
         rustc_args_required_const,
@@ -526,6 +527,7 @@ symbols! {
         rustc_diagnostic_macros,
         rustc_dirty,
         rustc_doc_only_macro,
+        rustc_dummy,
         rustc_dump_env_program_clauses,
         rustc_dump_program_clauses,
         rustc_dump_user_substs,

src/libterm/lib.rs

@@ -38,9 +38,6 @@
 #![deny(rust_2018_idioms)]
 
 #![cfg_attr(windows, feature(libc))]
-// Handle rustfmt skips
-#![feature(custom_attribute)]
-#![allow(unused_attributes)]
 
 use std::io::prelude::*;
 use std::io::{self, Stdout, Stderr};

src/test/codegen/function-arguments.rs

@@ -2,7 +2,7 @@
 // ignore-tidy-linelength
 
 #![crate_type = "lib"]
-#![feature(custom_attribute)]
+#![feature(rustc_attrs)]
 
 pub struct S {
   _field: [i32; 8],
@@ -146,7 +146,7 @@ pub fn enum_id_2(x: Option<u8>) -> Option<u8> {
 
 // CHECK: noalias i8* @allocator()
 #[no_mangle]
-#[allocator]
+#[rustc_allocator]
 pub fn allocator() -> *const i8 {
   std::ptr::null()
 }

src/test/pretty/attr-fn-inner.rs

@@ -1,15 +1,16 @@
-// pp-exact
 // Testing that both the inner item and next outer item are
 // preserved, and that the first outer item parsed in main is not
 // accidentally carried over to each inner function
 
-#![feature(custom_attribute)]
+// pp-exact
+
+#![feature(rustc_attrs)]
 
 fn main() {
-    #![inner_attr]
-    #[outer_attr]
+    #![rustc_dummy]
+    #[rustc_dummy]
     fn f() { }
 
-    #[outer_attr]
+    #[rustc_dummy]
     fn g() { }
 }

src/test/pretty/attr-literals.rs

@@ -1,13 +1,14 @@
-// pp-exact
 // Tests literals in attributes.
 
-#![feature(custom_attribute)]
+// pp-exact
+
+#![feature(rustc_attrs)]
 
 fn main() {
-    #![hello("hi", 1, 2, 1.012, pi = 3.14, bye, name("John"))]
-    #[align = 8]
+    #![rustc_dummy("hi", 1, 2, 1.012, pi = 3.14, bye, name("John"))]
+    #[rustc_dummy = 8]
     fn f() { }
 
-    #[vector(1, 2, 3)]
+    #[rustc_dummy(1, 2, 3)]
     fn g() { }
 }