[cfarm-users] GCC119 and XLC/C++

[Paul Eggert]

On 10/1/23 10:10, Jeffrey Walton via cfarm-users wrote:
> No doubt Clang will define __xlC__ but fail to compile a program
> written for xlC, like one using __vcipher, __vcipherlast, __vshasigmaw
> and __vshasigmad (AES and SHA intrinsics).

There are quite a few changes in Open XL C/C++ for AIX 17.1.1, compared 
to the "classic" XLC; see:

https://www.ibm.com/docs/en/openxl-c-and-cpp-aix/17.1.1?topic=migration-migrating-from-classic-xl-compilers

The functions you mention are not listed as being changed. The 
documentation says that the new compiler does not define __xlC__. It 
does not define __xlc__, __IBMC__, and a whole bunch of other macros 
too; see:

https://www.ibm.com/docs/en/openxl-c-and-cpp-aix/17.1.1?topic=macros-unsupported-compiler

That being said, I took a quick look at the Gnulib portability library 
and don't see a need for changes. All uses of classic xlc macros like 
__IBM__TYPEOF__ were in addition to uses of macros like __clang__ that 
should cause the code to do the right thing anyway.