macro_rules! tt_is_lifetime {
{
$caller:tt
input = [{ $lifetime:lifetime }]
} => { ... };
{
$caller:tt
input = [{ $other:tt }]
} => { ... };
}
Predicate that accepts a single token and determines whether it is a
lifetime token.
[tt-call]
input = [{
a single token tree }]
is_lifetime = [{
either true or false }]