[OskarS]

What are you talking about? For lots of functions, it is perfectly possible to statically determine a maximum stack size (not all functions obviously, that would be the halting problem). An trivial example would be a function that calls no other functions, but you can imagine others: functions with static call trees (i.e. no function pointers), don’t use VLAs or alloca, and that are not recursive (mutually, indirectly, or otherwise) will have a static limit on possible stack usage.

If you’ve formally verified that function X uses at most Y pages of stack, and the remaining stack is smaller than that, you could return an OUT_OF_STACK error instead of calling it. Most libraries/functions wouldn’t need this, but there are C libraries which place an extraordinary importance on reliability, and it seems like it would be a useful feature for them.

There might be other reasons why these functions shouldn’t be in the standard (or are impossible on some platforms), but ”the information is worthless” is not one of them. Of course this information can be useful.

[vasama]

The information is indeed worthless unless the standard were to also define such things as the stack layout and a closed set of operations which are allowed to consume more stack, such as defining a VLA, or calling a function.