2016-12-18 9:31 GMT+01:00 Serhiy Storchaka
Originally C API didn't use the const qualifier. Over few last years the const qualifier was added to C API if that preserved backward compatibility. For example input "char *" parameters were changed to "const char *". This makes C API compatible with C++, eliminates C compiler warnings, and helps to found possible errors.
Since the "const" keyword does not impact the stable *ABI*, I think that it's fine to add use it in more places. In the worst case, if an extension chose to be compiled with -Werror (convert warnings into errors), the maintainer will have to fix conversion warnings in the code. But it's easy to write C code which works with and without const (old and new Python *API*), using explicit cast (to const char* for example). In the common case, it will just be a warning and nobody will notice it since more and more people use pip which compiles C extensions in the background and doesn't show GCC output anymore. I agree that it can help to find real bugs. Victor