`memcpy()` usage without `#include <string.h>` in `pwdmodule.c`
Bug report
Bug description:
For a non-gcc/clang compiler, _Py_TYPEOF is not defined.
| // The macro is only defined if GCC or clang compiler is used. | |
| #if defined(__GNUC__) || defined(__clang__) | |
| # define _Py_TYPEOF(expr) __typeof__(expr) | |
| #endif |
Which leads to Py_CLEAR() fallback to an implementation with memcpy() call.
| #else | |
| #define Py_CLEAR(op) \ | |
| do { \ | |
| PyObject **_tmp_op_ptr = _Py_CAST(PyObject**, &(op)); \ | |
| PyObject *_tmp_old_op = (*_tmp_op_ptr); \ | |
| if (_tmp_old_op != NULL) { \ | |
| PyObject *_null_ptr = _Py_NULL; \ | |
| memcpy(_tmp_op_ptr, &_null_ptr, sizeof(PyObject*)); \ | |
| Py_DECREF(_tmp_old_op); \ | |
| } \ | |
| } while (0) | |
| #endif |
Py_CLEAR() is used in ./Modules/pwdmodule.c
| static int pwdmodule_clear(PyObject *m) { | |
| Py_CLEAR(get_pwd_state(m)->StructPwdType); | |
| return 0; | |
| } |
without including string.h
| #include <errno.h> // ERANGE | |
| #include <pwd.h> // getpwuid() | |
| #include <unistd.h> // sysconf() | |
For a non-gcc/clang compiler, this may fail due to missing memcpy() declaration.
./Include/object.h:1017: #define Py_CLEAR(op) do { PyObject **_tmp_op_ptr = _Py_CAST(PyObject**, &(op)); PyObject *_tmp_old_op = (*_tmp_op_ptr); if (_tmp_old_op != NULL) { PyObject *_null_ptr = _Py_NULL; memcpy(_tmp_op_ptr, &_null_ptr, sizeof(PyObject*)); Py_DECREF(_tmp_old_op); } } while (0)
^ implicit declaration of a function
./Modules/pwdmodule.c:356: Py_CLEAR(get_pwd_state(m)->StructPwdType);
^ in expansion of macro
On a side note, typeof is widely implemented among alternative C compilers like TinyCC and cproc, kefir, chibicc, and is standardized in C23. It could be beneficial to enable typeof usage through configure option or probing, instead of hard-coded off on non-gcc/clang compilers.
CPython versions tested on:
3.13
Operating systems tested on:
Linux