gh-157695: Rename HAVE_ICONV to _Py_HAVE_ICONV

[vstinner]

• Issue: The Python C API should only define macros with a name starting wit Py #157695

[vstinner]

cc @serhiy-storchaka

The HAVE_ICONV macro is new in Python 3.16.

[serhiy-storchaka]

I do not mind, but does it make difference if most of configure macros are HAVE_* and this is standard?

[encukou]

does it make difference if most of configure macros are HAVE_*

Before we fix things, we should stop making them worse.

and this is standard?

Which standard is that?

[serhiy-storchaka]

I do not know if this is a formal standard, but many projects use HAVE_*.

[vstinner]

I do not mind, but does it make difference if most of configure macros are HAVE_* and this is standard?
(...)
I do not know if this is a formal standard, but many projects use HAVE_*.

It's fine to use HAVE_xxx macros to build a project. What bothers me is that Python exposes these macros in its public C API.

It's rare that a project exposes its HAVE_xxx macros in public header files. Example of a search on my Fedora 44 which has 6,130 header files in /usr/include:

$ find -name "*.h"|wc -l
6130

$ grep -l 'define HAVE_' -R /usr/include/|grep -v /python3|grep -v /pypy3
/usr/include/ncurses/etip.h
/usr/include/ncursesw/etip.h
/usr/include/etip.h
/usr/include/expat_config.h
/usr/include/freetype2/freetype/config/ftconfig-64.h
/usr/include/tcl-private/unix/tclUnixPort.h

All macros:

Details

vstinner@vstinner-thinkpadp1gen3$ grep 'define HAVE_' -R /usr/include/|grep -v /python3|grep -v /pypy3
/usr/include/ncurses/etip.h:#define HAVE_BUILTIN_H 0
/usr/include/ncurses/etip.h:#define HAVE_EXCEPTION 1
/usr/include/ncurses/etip.h:#define HAVE_GXX_BUILTIN_H 0
/usr/include/ncurses/etip.h:#define HAVE_GPP_BUILTIN_H 0
/usr/include/ncurses/etip.h:#define HAVE_IOSTREAM 1
/usr/include/ncurses/etip.h:#define HAVE_NEW 1
/usr/include/ncurses/etip.h:#define HAVE_TYPEINFO 1
/usr/include/ncurses/etip.h:#define HAVE_VALUES_H 0
/usr/include/ncursesw/etip.h:#define HAVE_BUILTIN_H 0
/usr/include/ncursesw/etip.h:#define HAVE_EXCEPTION 1
/usr/include/ncursesw/etip.h:#define HAVE_GXX_BUILTIN_H 0
/usr/include/ncursesw/etip.h:#define HAVE_GPP_BUILTIN_H 0
/usr/include/ncursesw/etip.h:#define HAVE_IOSTREAM 1
/usr/include/ncursesw/etip.h:#define HAVE_NEW 1
/usr/include/ncursesw/etip.h:#define HAVE_TYPEINFO 1
/usr/include/ncursesw/etip.h:#define HAVE_VALUES_H 0
/usr/include/etip.h:#define HAVE_BUILTIN_H 0
/usr/include/etip.h:#define HAVE_EXCEPTION 1
/usr/include/etip.h:#define HAVE_GXX_BUILTIN_H 0
/usr/include/etip.h:#define HAVE_GPP_BUILTIN_H 0
/usr/include/etip.h:#define HAVE_IOSTREAM 1
/usr/include/etip.h:#define HAVE_NEW 1
/usr/include/etip.h:#define HAVE_TYPEINFO 1
/usr/include/etip.h:#define HAVE_VALUES_H 0
/usr/include/expat_config.h:#define HAVE_ARC4RANDOM 1
/usr/include/expat_config.h:#define HAVE_ARC4RANDOM_BUF 1
/usr/include/expat_config.h:#define HAVE_CXX11 1
/usr/include/expat_config.h:#define HAVE_DLFCN_H 1
/usr/include/expat_config.h:#define HAVE_FCNTL_H 1
/usr/include/expat_config.h:#define HAVE_GETENTROPY 1
/usr/include/expat_config.h:#define HAVE_GETPAGESIZE 1
/usr/include/expat_config.h:#define HAVE_GETRANDOM 1
/usr/include/expat_config.h:#define HAVE_INTTYPES_H 1
/usr/include/expat_config.h:#define HAVE_MMAP 1
/usr/include/expat_config.h:#define HAVE_STDINT_H 1
/usr/include/expat_config.h:#define HAVE_STDIO_H 1
/usr/include/expat_config.h:#define HAVE_STDLIB_H 1
/usr/include/expat_config.h:#define HAVE_STRINGS_H 1
/usr/include/expat_config.h:#define HAVE_STRING_H 1
/usr/include/expat_config.h:#define HAVE_SYSCALL_GETRANDOM 1
/usr/include/expat_config.h:#define HAVE_SYS_PARAM_H 1
/usr/include/expat_config.h:#define HAVE_SYS_STAT_H 1
/usr/include/expat_config.h:#define HAVE_SYS_TYPES_H 1
/usr/include/expat_config.h:#define HAVE_UNISTD_H 1
/usr/include/freetype2/freetype/config/ftconfig-64.h:#define HAVE_UNISTD_H 1
/usr/include/freetype2/freetype/config/ftconfig-64.h:#define HAVE_FCNTL_H 1
/usr/include/tcl-private/unix/tclUnixPort.h:#	    define HAVE_PUTENV_THAT_COPIES	1

Projects built with <Python.h> should implement their own function and header checks, not rely on HAVE_xxx macros. For example, Python can built on a machine and installed on a different machine where HAVE_xxx macros are outdated.

[serhiy-storchaka]

Then the problem is not in having HAVE_* names, but in exposing them in Python.h. What other libraries do to avoid this?

[vstinner]

Then the problem is not in having HAVE_* names, but in exposing them in Python.h. What other libraries do to avoid this?

It seems like they do no include the "config.h" file in their public C API.