error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:11:21
   |
LL | extern "C" { fn ffi(#[id] arg1: i32, #[id] ...); }
   |                     ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:11:38
   |
LL | extern "C" { fn ffi(#[id] arg1: i32, #[id] ...); }
   |                                      ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:15:38
   |
LL | unsafe extern "C" fn cvar(arg1: i32, #[id] mut args: ...) {}
   |                                      ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:18:28
   |
LL | type Alias = extern "C" fn(#[id] u8, #[id] ...);
   |                            ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:18:38
   |
LL | type Alias = extern "C" fn(#[id] u8, #[id] ...);
   |                                      ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:22:9
   |
LL | fn free(#[id] arg1: u8) {
   |         ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:24:16
   |
LL |     let lam = |#[id] W(x), #[id] y| ();
   |                ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:24:28
   |
LL |     let lam = |#[id] W(x), #[id] y| ();
   |                            ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:30:18
   |
LL |     fn inherent1(#[id] self, #[id] arg1: u8) {}
   |                  ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:30:30
   |
LL |     fn inherent1(#[id] self, #[id] arg1: u8) {}
   |                              ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:33:18
   |
LL |     fn inherent2(#[id] &self, #[id] arg1: u8) {}
   |                  ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:33:31
   |
LL |     fn inherent2(#[id] &self, #[id] arg1: u8) {}
   |                               ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:36:22
   |
LL |     fn inherent3<'a>(#[id] &'a mut self, #[id] arg1: u8) {}
   |                      ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:36:42
   |
LL |     fn inherent3<'a>(#[id] &'a mut self, #[id] arg1: u8) {}
   |                                          ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:39:22
   |
LL |     fn inherent4<'a>(#[id] self: Box<Self>, #[id] arg1: u8) {}
   |                      ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:39:45
   |
LL |     fn inherent4<'a>(#[id] self: Box<Self>, #[id] arg1: u8) {}
   |                                             ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:45:15
   |
LL |     fn trait1(#[id] self, #[id] arg1: u8);
   |               ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:45:27
   |
LL |     fn trait1(#[id] self, #[id] arg1: u8);
   |                           ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:48:15
   |
LL |     fn trait2(#[id] &self, #[id] arg1: u8);
   |               ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:48:28
   |
LL |     fn trait2(#[id] &self, #[id] arg1: u8);
   |                            ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:51:19
   |
LL |     fn trait3<'a>(#[id] &'a mut self, #[id] arg1: u8);
   |                   ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:51:39
   |
LL |     fn trait3<'a>(#[id] &'a mut self, #[id] arg1: u8);
   |                                       ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:54:19
   |
LL |     fn trait4<'a>(#[id] self: Box<Self>, #[id] arg1: u8, #[id] Vec<u8>);
   |                   ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:54:42
   |
LL |     fn trait4<'a>(#[id] self: Box<Self>, #[id] arg1: u8, #[id] Vec<u8>);
   |                                          ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: the attribute `id` is currently unknown to the compiler and may have meaning added to it in the future
  --> $DIR/proc-macro-cannot-be-used.rs:54:58
   |
LL |     fn trait4<'a>(#[id] self: Box<Self>, #[id] arg1: u8, #[id] Vec<u8>);
   |                                                          ^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29642
   = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error: aborting due to 25 previous errors

For more information about this error, try `rustc --explain E0658`.