[Python-Dev] Const-correctness in C-API Object Protocol

["Martin v. Löwis"]

>> Though I do not get that warning -- which compiler and version issues
>> it? Is it a C or a C++ compiler?
> 
> Well, which warning are you talking about?

I think Guido assumed that the OP was getting actual complaints from
some actual compiler - else he wouldn't have asked the question.
However, he didn't actually say he got compile issues.

If you compile

#include <Python.h>

int main()
{
    const char* s = "stdin";
    PyObject_CallMethod(0, s, s);
}

with a g++, you get

a.cc: In function ‘int main()’:
a.cc:6: error: invalid conversion from ‘const char*’ to ‘char*’
a.cc:6: error:   initializing argument 2 of ‘PyObject*
PyObject_CallMethod(PyObject*, char*, char*, ...)’
a.cc:6: error: invalid conversion from ‘const char*’ to ‘char*’
a.cc:6: error:   initializing argument 3 of ‘PyObject*
PyObject_CallMethod(PyObject*, char*, char*, ...)’

If you compile

#include <Python.h>

int main()
{
    PyObject_CallMethod(0, "stdin", "stdin");
}

you get

a.cc: In function ‘int main()’:
a.cc:5: warning: deprecated conversion from string constant to ‘char*’
a.cc:5: warning: deprecated conversion from string constant to ‘char*’

Since most people likely use string literals, and since g++ only started
warning about the deprecated conversion only recently, most people
probably haven't run into the issue.

Regards,
Martin