error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
  --> $DIR/trace_macros-gate.rs:4:5
   |
LL |     trace_macros!();
   |     ^^^^^^^^^^^^
   |
   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
   = help: add `#![feature(trace_macros)]` to the crate attributes to enable

error: trace_macros! accepts only `true` or `false`
  --> $DIR/trace_macros-gate.rs:4:5
   |
LL |     trace_macros!();
   |     ^^^^^^^^^^^^^^^

error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
  --> $DIR/trace_macros-gate.rs:6:5
   |
LL |     trace_macros!(true);
   |     ^^^^^^^^^^^^
   |
   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
   = help: add `#![feature(trace_macros)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
  --> $DIR/trace_macros-gate.rs:7:5
   |
LL |     trace_macros!(false);
   |     ^^^^^^^^^^^^
   |
   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
   = help: add `#![feature(trace_macros)]` to the crate attributes to enable

error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
  --> $DIR/trace_macros-gate.rs:10:26
   |
LL |         ($x: ident) => { trace_macros!($x) }
   |                          ^^^^^^^^^^^^
...
LL |     expando!(true);
   |     -------------- in this macro invocation
   |
   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
   = help: add `#![feature(trace_macros)]` to the crate attributes to enable
   = note: this error originates in the macro `expando` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 5 previous errors

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