The forbiding for "return NULL;" in function declared returned int

Ideas
1

Sometimes in C extern module, in some function that returned an int (0 means successful and -1 means failed), people may mistaken write return NULL; in error branch (for example: in tp_setattro slot). Usually the IDE won’t warn it in c++ because it will be change to return 0; and 0 is a valid value to return, and then compiler will pass, but then problem will occurred in runtime because python find the return value is 0 means all right but error occurred.

However, in musllinux python version 3.10, the compiling will failed. The message is usually:

In file included from /usr/include/c++/14.2.0/clocale:42,
                   from /usr/include/c++/14.2.0/x86_64-alpine-linux-musl/bits/c++locale.h:41,
                   from /usr/include/c++/14.2.0/bits/localefwd.h:40,
                   from /usr/include/c++/14.2.0/string:45,
                   from xxx.cpp:8:
 xxx.cpp: In function 'int XXX_delattr(PyObject*, PyObject*)':
  xxx.cpp:a:b: error: cannot convert 'std::nullptr_t' to 'int' in return
    a   |                 return NULL;
        |                        ^~~~
  xxx.cpp:c:d: error: cannot convert 'std::nullptr_t' to 'int' in return
    c   |                 return NULL;
        |                        ^~~~
  error: command '/usr/bin/g++' failed with exit code 1

This can note programmer to change the wrong return value. So can we use that way in all of the systems to ensure programmer can find the problem in advance?

2

This is how C works. Python has nothing to do with this. You can use other programming languages to write extensions. For example, nullptr_t is a thing in C++.

Interesting, gcc emits a warning or an error, depending on the choosen C standard version.

$ cat test.c
#include <stddef.h>

int f(void)
{
    return NULL;
}
$ gcc -std=c89 -c test.c
test.c: In function ‘f’:
test.c:5:12: warning: returning ‘void *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Wint-conversion]
    5 |     return NULL;
      |            ^~~~
$ gcc -std=c99 -c test.c
test.c: In function ‘f’:
test.c:5:12: error: returning ‘void *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Wint-conversion]
    5 |     return NULL;
      |            ^~~~

This is why such error never survived compilation.