blob: a5f6ae198f61182176c376375d219b91ea9c8eec (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
// Ensure that we don't consider `const Trait` to
// match the macro fragment specifier `ty` as that would be a breaking
// change theoretically speaking. Syntactically trait object types can
// be "bare", i.e., lack the prefix `dyn`.
// By contrast, `?Trait` *does* match `ty` and therefore an arm like
// `?$Trait:path` would never be reached.
// See `parser/macro/mbe-bare-trait-object-maybe-trait-bound.rs`.
// `[const] Trait` is already an error for a `ty` fragment,
// so we do not need to prevent that.
macro_rules! check {
($Type:ty) => {
compile_error!("ty");
};
(const $Trait:path) => {};
([const] $Trait:path) => {};
}
check! { const Trait }
check! { [const] Trait }
//~^ ERROR: expected identifier, found `]`
//~| ERROR: const trait impls are experimental
fn main() {}
|
