src/test/ui/proc-macro/cfg-eval.rs

   1 // check-pass
   2 // compile-flags: -Z span-debug
   3 // aux-build:test-macros.rs
   4
   5 #![feature(cfg_eval)]
   6 #![feature(proc_macro_hygiene)]
   7 #![feature(stmt_expr_attributes)]
   8 #![feature(rustc_attrs)]
   9 #![no_std] // Don't load unnecessary hygiene information from std
  10 extern crate std;
  11
  12 #[macro_use]
  13 extern crate test_macros;
  14
  15 #[cfg_eval]
  16 #[print_attr]
  17 struct S1 {
  18     #[cfg(FALSE)]
  19     field_false: u8,
  20     #[cfg(all(/*true*/))]
  21     #[cfg_attr(FALSE, unknown_attr)]
  22     #[cfg_attr(all(/*true*/), allow())]
  23     field_true: u8,
  24 }
  25
  26 #[cfg_eval]
  27 #[cfg(FALSE)]
  28 struct S2 {}
  29
  30 fn main() {
  31     // Subtle - we need a trailing comma after the '1' - otherwise, `#[cfg_eval]` will
  32     // turn this into `(#[cfg(all())] 1)`, which is a parenthesized expression, not a tuple
  33     // expression. `#[cfg]` is not supported inside parenthesized expressions, so this will
  34     // produce an error when attribute collection runs.
  35     let _ = #[cfg_eval] #[print_attr] #[cfg_attr(not(FALSE), rustc_dummy)]
  36     (#[cfg(FALSE)] 0, #[cfg(all(/*true*/))] 1,);
  37 }