Supported language levels

This topic describes the C/C++ programming language specifications that IBM Open XL C/C++ for AIX 17.1.3 supports.

C language specifications

ISO/IEC 9899:2017 (referred to as C17)¹
ISO/IEC 9899:2011 (referred to as C11)¹
ISO/IEC 9899:1999 (referred to as C99)
ISO/IEC 9899:1990 (referred to as C89)

Note:

The compiler partially supports atomics and threads, which are optional C11 features.

C++ language specifications

ISO/IEC 14882:2020 (referred to as C++20) (experimental support)
ISO/IEC 14882:2017 (referred to as C++17)
ISO/IEC 14882:2014 (referred to as C++14)
ISO/IEC 14882:2011 (referred to as C++11)
ISO/IEC 14882:2003 (referred to as C++03)
ISO/IEC 14882:1998, the first official specification of the C++ language (referred to as C++98)

Note:

IBM® Open XL C/C++ adopts LLVM technology which leverages the Clang front-end and libc++ to provide C/C++ standard support. Subject to the C++ standard implementation status of the Clang/LLVM community, C++17 support and experimental C++20 features are available in this release.

The implementation of a language level might change with each release, as the implementation of C++ language and library features progress. The compatibility of language levels from release to release is subject to changes made by the Clang/LLVM community.

For additional details, refer to the following materials:

Clang - C Programming Language Status
Clang - C Defect Report Status
Clang - C++ Programming Language Status
Clang - C++ Defect Report Status
libc++ C++17 Status (Refer to the "libc++ C++17 Status" section in the libc++ documentation)
libc++ C++20 Status (Refer to the "libc++ C++20 Status" section in the libc++ documentation)

IBM Open XL C/C++ for AIX 17.1.3 has the following limitations to the C++ language standard support:

The function of cuchar.h and uchar.h is not available without an update to the AIX® uchar.h header.
C++17 parallel algorithms are not supported.
The parameter types can be double and long double for std::atomic<T> templates only when the compilation mode is 64-bit.
Functions enabled by the _LIBCPP_ENABLE_CXX17_REMOVED_FEATURES and _LIBCPP_ENABLE_CXX20_REMOVED_FEATURES macros are available as they are. IBM does not guarantee that these features will continue to be supported in future releases.
The C++11 sized deallocation feature is enabled only when -fsized-deallocation is in effect, which is not enabled by default.
The timespec_get function is not available without an update to the time.h header file in AIX 7.3 TL2.
The libc++ library for IBM Open XL C/C++ for AIX 17.1.3 is the same as the one for IBM Open XL C/C++ for AIX 17.1.1. The library is compatible with previous versions of libc++ for AIX, with the exceptions that are noted in the following LLVM libc++ release notes: