my mistake or regex error? (recyclate)

[MatejMagat305]

can I ask I have made regex:

fn find_fn_name(row string) string {
	mut re := regex.regex_opt('fn C\.[\w_]+') or { panic(err) }
	start, end := re.match_string(row)
	return row[(start + 5)..end]
}

fn find_fn_args(row string) string {
	mut re := regex.regex_opt('\([\w_ ,&*]+\)') or { panic(err) }
	start, end := re.match_string(row)
	return row[start..end]
}

I was expected the find_fn_args from fn C.clCreateBuffer(context ClContext, flags ClMemFlags, size usize, host_ptr voidptr, errcode_ret &int) ClMem return (context ClContext, flags ClMemFlags, size usize, host_ptr voidptr, errcode_ret &int), but it panicwith:

V panic: substr(-1, 0) out of bounds (len=110)
v hash: cf95d77
/tmp/v_1000/add_dynamic.4824720304848064593.tmp.c:7971: at _v_panic: Backtrace
/tmp/v_1000/add_dynamic.4824720304848064593.tmp.c:11317: by string_substr
/tmp/v_1000/add_dynamic.4824720304848064593.tmp.c:19974: by main__find_fn_args
...

[MatejMagat305]

And yes I m trying to create openCL to shared library (mainly due to android (it have 15 posible path) and I have wanted to create tool to automatic conversion from static to dynamic ...
add_dynamic.zip

unzip add_dynamic.zip
cd add_dynamic/add_dynamic
v .
 ./add_dynamic ../_ctypes.c.v
and see ...

Yes, maybe it is crazy or silly, but it is error of regex ? I was try to use No "\", one, double, triple at "(" and it was wrong too