Supported C++ and C Language Features

[The following information reflects version 6.6 of the C++ front end, which was released in December 2023.]

The front end accepts the C++ language as defined by the ISO/IEC 14882:2020 ("C++20") standard (and can be configured to accept earlier versions of the standard, i.e., ISO/IEC 14882:2003, ISO/IEC 14882:2011, ISO/IEC 14882:2014, and ISO/IEC 14882:2017). It also accepts the C language as defined by the ISO/IEC 9899:2018 ("C17"), ISO/IEC 9899:2011 ("C11"), ISO/IEC 9899:1999 ("C99") and ISO/IEC 9899:1990 ("C89") standards and the "Embedded C" extensions of ISO/IEC TR 18037.

A list of C++26 features and their current implementation status can be found here.

A list of C++23 features and their current implementation status can be found here.

A list of C++20 features and their current implementation status can be found here.

A list of the C++17 features and the EDG releases in which they've been implemented can be retrieved by clicking here.

A list of the C++14 features and the EDG releases in which they've been implemented can be retrieved by clicking here.

The list of C++11 features and the EDG releases can be retrieved by clicking here.

A list of C23 features and their implementation status can be retrieved by clicking here.

Accepting standard C++ and C is nice, but in the real world hardly any programs are written in completely standard-conforming C++ or C. The front end's "strict" standard C++ and C modes are useful for running test suites and ensuring that a program contains no nonstandard usage, but may be a bit too pedantic for everyday use. Therefore, the front end also offers slightly more relaxed default modes for C++ and C, and compatibility modes for some of the most popular compilers' dialects:

• A Microsoft C and C++ compatibility mode, which provides the extensions supported by the Microsoft Visual C++ compiler (through Visual Studio 2017, including the C++/CLI features), along with various undocumented features and bugs.
• A GNU C and C++ compatibility mode, which provides the extensions supported by GCC (versions 3.2-7.3), along with various undocumented features and bugs. The compatibility is good enough that the front end can compile the Linux kernel and utilities.
• A Clang C and C++ compatibility mode.
• A Sun C++ compatibility mode.
• A cfront compatibility mode, which emulates the old AT&T cfront processor.