Extra semicolon with `define`

Given this code:

#[repr(C)]
struct Foobar {
    a: u32,
    #[cfg(feature="xyz")]
    b: u32,
    c: u32,
}

#[no_mangle]
pub extern "C" fn xx(_f: &Foobar) {}

and this configuration:

[defines]
"feature = xyz" = "XYZ"

cbindgen generates the following for the struct

struct Foobar {
  uint32_t a;
#if defined(XYZ)
  uint32_t b
#endif
  ;
  uint32_t c;
};

As you can see, the ; is not in the #if, for some reason.

When compiling the code with with -Wextra-semi, gcc generates the following warning:

<source>:8:3: warning: extra ';' inside a struct [-Wextra-semi]
    8 |   ;
      |   ^
      |   -

Reproduce the issue with the Rust Foobar snippet and the [defines] configuration shown in the report, then inspect the generated C++ around the cfg-controlled field. The generated semicolon should remain inside the conditional block so GCC does not report an extra semicolon with -Wextra-semi.