Handle constant arguments to attributed function argument types.
Parameter attr
Attribute that arg_type had.
Parameter value
Constant value sent as parameter.
Parameter arg_type
Declared type of the function argument.
Parameter cont_type
Continuation function type after the current argument.
This function is called when a function is called
with the constant value value and it has been
successfully matched against arg_type ,
and arg_type had the type attribute attr .
This function is typically used to perform specialized
argument checking and to allow for a strengthening
of the function type based on value .
The default implementation implements the "sprintf_format",
"sscanf_format" and "sscanf_76_format" attributes.
Returns
Returns a continuation type if it succeeded in strengthening the type.
Returns UNDEFINED otherwise (this is not an error indication).