Following up on the discussion from earlier this month among GCC developers over switching to C++20 by default for the GCC compiler as the default C++ standard when not otherwise set, that change has indeed happened. Merged now is the change defaulting to C++20 (well, the GNU++20 dialect) rather than C++17/GNU++17 when not otherwise specified when compiling C++ code.

GCC developers had discovered that their own codebase wasn't entire C++20 ready but they have been landing those fixes too this week so GCC 16 can jive happy with a C++20 default.