pub const REFUSED: &str = "<refused>";Expand description
What an expansion that failed leaves where the call was.
The alternative is leaving the call, and then the checker cannot find the macro’s name and says so — a second, contradictory error about a name that was found and refused. The checker gives this a fresh type variable, so nothing downstream cascades either.
Spelled so that no program can write it. A head the checker matches on and a name a
program may use are the same namespace, which is what RESERVED_FORMS exists to police;
a marker only the compiler ever builds should not cost a word, and < cannot begin an
identifier.