Stack frames larger than 4K should be rejected, but what if I want more

[IGotD-]

On Monday, 28 June 2021 at 11:39:27 UTC, SealabJaster wrote:
>
> Slightly related, but I was recently learning how to implement 
> coroutines myself and it was crashing because MSCV's `printf` 
> allocates a rather large buffer on the stack. Can't remember 
> the exact size, but I'm pretty sure it was at least 4K.
>
> So in other words, you can't prove it for foreign functions I 
> believe.

printf and conversion functions are usually a typical example of 
functions that use large buffers on the stack. There is usually 
no problem with this as rich OSes have plenty of virtual stack 
space. If this wasn't allowed you would need to dynamically 
allocate memory of every printf call if not several depending 
what you print. This would slow down the printing function and 
another problem for embedded systems/systems programming is that 
you might want to print something before malloc/free are 
initialized.

Big buffers on the stack is not always because the programmer is 
an amateur.