RobotToaster parent
Am I right to think this is really unobjectionable, and is only being objected to because MS "invented" it?
Even if it was some other vendor the fact that it's non-standard isn't great.
The "vendor" in this case is GCC and there are plenty of non-standard GCC extensions in use today. The Linux kernel standard gnu89, not C89, after all. I doubt you can even compile a usable Linux kernel sticking purely to the official C standard.
The same tricks are also enabled in the plan9 extensions, but enabling plan9 extensions also enables a bunch of other tricks and those changes landed later than the Microsoft ones. Aiming to enable plan9 instead probably could've saved the Linux kernel half a decade of "Microsoft bad" comments, though.
border-box says hi [1]
[1]: https://www.paulirish.com/2012/box-sizing-border-box-ftw/
(Funnily, tables always default to border-box, so the objections in CSS standardization at the time is really silly.)