Invoke the specified visitor functor on the value contained by the specified arg, providing that functor non-modifiable access to that value. visitor must be a variant-style functor that is able to visit all supported types listed in the {DESCRIPTION}.
Declared in <bslfmt_format_arg.h>
template<
class t_VISITOR,
class t_CONTEXT>
decltype(auto)
visit_format_arg(
t_VISITOR&& visitor,
basic_format_arg<t_CONTEXT> arg);