Except in this case the OP presented a situation where it really made an actual difference.

Oh, but I'm sure that someone somewhere once ran into each of these things - maybe that guy who once ported some SMS messaging platform from the IBM mainframe to Solaris and had to use some specific commercial compiler, or the other one who wrote some software that had to work on every version of Linux from the 1.0 kernels up and had to link to specific binary libraries so it had to work on versions of gcc spanning 15 years.

What I'm saying is that knowing these minute details doesn't make one a proficient developer with the language, nor does getting every one of this list wrong a bad developer. Sure, with 10 years of experience most people would run into one or two on the list and know about it; still doesn't make the premise that not knowing or caring about trivia competitions makes one not 'know' the language.

The amount of exploits caused by such issues, is not as irrelevant as you hint at, after all if Apple developers get it wrong [1], what about all those that work in boring enterprises 9-5 and don't care one second about mundane stuff like static analyzers, warnings as errors, unit tests, code reviews.

The moment one needs to work with more than one compiler, including different versions of the same compiler, one needs to become a language lawyer to keep some sanity.

[1] I know the source of error wasn't related to these exact questions.

Or you could just not worry about it and assume the language is well-defined with precise methodologies grounded on common sense like Ada.

https://gcc.gnu.org/onlinedocs/gnat_rm/Value_005fSize-and-Ob...

On second thought, who cares about reading its for squares and nerds. I would rather spend 2 hours Google searching what is an octet and finding out how enums are represented... :p