error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
  --> $DIR/issue-43106-gating-of-derive.rs:4:1
   |
LL |   #[derive(Debug)]
   |   ^^^^^^^^^^^^^^^^ not applicable here
LL |
LL | / mod derive {
LL | |     mod inner { #![derive(Debug)] }
LL | |
LL | |
...  |
LL | |     impl S { }
LL | | }
   | |_- not a `struct`, `enum` or `union`

error[E0658]: inner macro attributes are unstable
  --> $DIR/issue-43106-gating-of-derive.rs:7:20
   |
LL |     mod inner { #![derive(Debug)] }
   |                    ^^^^^^
   |
   = note: see issue #54726 <https://github.com/rust-lang/rust/issues/54726> for more information
   = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
  --> $DIR/issue-43106-gating-of-derive.rs:7:17
   |
LL |     mod inner { #![derive(Debug)] }
   |     ------------^^^^^^^^^^^^^^^^^--
   |     |           |
   |     |           not applicable here
   |     not a `struct`, `enum` or `union`

error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
  --> $DIR/issue-43106-gating-of-derive.rs:11:5
   |
LL |     #[derive(Debug)]
   |     ^^^^^^^^^^^^^^^^ not applicable here
LL |
LL |     fn derive() { }
   |     --------------- not a `struct`, `enum` or `union`

error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
  --> $DIR/issue-43106-gating-of-derive.rs:24:5
   |
LL |     #[derive(Debug)]
   |     ^^^^^^^^^^^^^^^^ not applicable here
LL |
LL |     type T = S;
   |     ----------- not a `struct`, `enum` or `union`

error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
  --> $DIR/issue-43106-gating-of-derive.rs:28:5
   |
LL |     #[derive(Debug)]
   |     ^^^^^^^^^^^^^^^^ not applicable here
LL |
LL |     impl S { }
   |     ---------- not a `struct`, `enum` or `union`

error: aborting due to 6 previous errors

Some errors have detailed explanations: E0658, E0774.
For more information about an error, try `rustc --explain E0658`.