That doesn't work on MSVC, and ignores multiple other issues with the 3 lines of code I shared (and as you correctly identified doesn't work with runtime format

That doesn't work on MSVC, and ignores multiple other issues with the 3 lines of code I shared (and as you correctly identified doesn't work with runtime format strings. It also doesn't work if your code isn't a textbook example of being wrong. [0] is _slightly_ more contrived but still suffers all of the exact same problems, despite all of the information being available at compile time. [0] https://gcc.godbolt.org/z/9vK3W4bYh https://gcc.godbolt.org/z/9vK3W4bYh