Execute codon callback function from C issue.

[learnforpractice]

I have encountered a strange problem:

#include <stdint.h>
#include <stdio.h>

typedef int64_t (*fn_foo)(int64_t);

void call_fn(fn_foo fn) {
	printf("call_fn: %p\n", fn);
	fn(123);
}

gcc -shared -o libfoo.so foo.c

LIBRARY = "libfoo.so"
from C import LIBRARY.call_fn(cobj)

@export
def foo(n: int) -> int:
    for i in range(n):
        print(i * i)
    return n * n

print("+++++++type(foo):", type(foo))
call_fn(foo)

codon build main.py
./main

output:

+++++++type(foo): (item1: (), item2: ())
call_fn: 0x7ff85f10dba8
Bus error: 10

if I comment out print("+++++++type(foo):", type(foo)), the output is:

call_fn: 0x0
Segmentation fault: 11

Sounds like really weird.

[arshajii]

Hi @learnforpractice -- plain functions in Codon can actually have some extra data associated with them so they're not directly ABI compatible with C functions. You can use the __raw__ method to get a plain function pointer, which fixes your example:

call_fn(foo.__raw__())

However I'm not sure why call_fn(foo) doesn't cause a type error, since foo is not a cobj; @inumanag any ideas?

[learnforpractice]

Awesome!