Easier error handling by using automatic code generation [Perl interpreter]

Perl interpreter has an interesting mechanism to checks if function arguments have correct values. Below is its example from util.c:

char *
Perl_delimcpy(register char *to, 
      register const char *toend, 
      register const char *from, 
      register const char *fromend, 
      register int delim, I32 *retlen)
    register I32 tolen;


    /* ... */

Body of PERL_ARGS_ASSERT_DELIMCPY is in proto.h:

    assert(to); assert(toend); assert(from); assert(fromend); assert(retlen)

What makes those macros interesting, is that they are automatically generated by a perl script (regen.pl). They are created from a data stored in embed.fnc, a sample entry of this file is presented below:

: Used in util.cp
op  |void   |example_function   |NN const char *name|STRLEN len|

The script needs to be executed after any change in embed.fnc.

Interesting and weird.