Remove unused #![feature(custom_attribute)]s

Author: petrochenkov

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_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/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/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/run-pass/check-static-recursion-foreign.rs

@@ -6,7 +6,7 @@
 
 // pretty-expanded FIXME #23616
 
-#![feature(custom_attribute, rustc_private)]
+#![feature(rustc_private)]
 
 extern crate check_static_recursion_foreign_helper;
 extern crate libc;

src/test/run-pass/macros/macro-attributes.rs

@@ -1,5 +1,4 @@
 // run-pass
-#![feature(custom_attribute)]
 
 macro_rules! compiles_fine {
     (#[$at:meta]) => {