class X::Syntax::Signature::InvocantMarker

Compilation error due to a misplaced invocant marker in a signature

class X::Syntax::Signature::InvocantMarker does X::Syntax { }

Syntax error when the invocant in a signature is anywhere else than after the first parameter.

For example

:($a, $b: $c);

dies with

===SORRY!===
Can only use : as invocant marker in a signature after the first parameter