warning: attribute should be applied to a free function, impl method or static
  --> $DIR/extern-no-mangle.rs:24:5
   |
LL |     #[no_mangle]
   |     ^^^^^^^^^^^^
...
LL |     let x = 0_u8;
   |     ------------- not a free function, impl method or static
   |
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
note: the lint level is defined here
  --> $DIR/extern-no-mangle.rs:1:9
   |
LL | #![warn(unused_attributes)]
   |         ^^^^^^^^^^^^^^^^^

warning: `#[no_mangle]` has no effect on a foreign static
  --> $DIR/extern-no-mangle.rs:11:5
   |
LL |     #[no_mangle]
   |     ^^^^^^^^^^^^ help: remove this attribute
...
LL |     pub static FOO: u8;
   |     ------------------- foreign static
   |
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: symbol names in extern blocks are not mangled

warning: `#[no_mangle]` has no effect on a foreign function
  --> $DIR/extern-no-mangle.rs:16:5
   |
LL |     #[no_mangle]
   |     ^^^^^^^^^^^^ help: remove this attribute
...
LL |     pub fn bar();
   |     ------------- foreign function
   |
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: symbol names in extern blocks are not mangled

warning: 3 warnings emitted