GCC-16

GCC 16 is a major release of the GNU Compiler Collection that brings substantial upgrades to standard language support, diagnostics, and optimizations. A primary milestone in this version is the transition of the default C++ language standard to GNU++20, bringing features like concepts, coroutines, and ranges out-of-the-box.

Beyond upgrading defaults, GCC 16 serves as an early testing ground for future standards, introducing rich experimental support for the C++26 reflection specification (via -freflection), C++26 contracts, and expansion statements. It also introduces a new experimental compiler front-end for the Algol 68 programming language (ga68).

Diagnostics and tooling are greatly improved with the introduction of experimental HTML rendering and the transition to SARIF as the primary machine-readable output format. Furthermore, target architectures have been expanded with new optimization support for AMD Zen 6, Intel Wildcat Lake and Nova Lake (including APX instruction sets), and Armv9.6-A.