Hm, I wonder if there's a typo here in pythonrun.c:

/* For use in Py_LIMITED_API */
#undef Py_CompileString
PyObject *
PyCompileString(const char *str, const char *filename, int start)
{
    return Py_CompileStringFlags(str, filename, start, NULL);
}

Shouldn't that function be named Py_CompileString (i.e. Py_ instead of Py)?

This seems to be old code, but there's normally a macro Py_CompileString() that translates to Py_CompileStringFlags() in pythonrun.h:

#ifdef Py_LIMITED_API
PyAPI_FUNC(PyObject *) Py_CompileString(const char *, const char *, int);
#else
#define Py_CompileString(str, p, s) Py_CompileStringExFlags(str, p, s, NULL, -1)
#define Py_CompileStringFlags(str, p, s, f) Py_CompileStringExFlags(str, p, s, f, -1)
.
.
.