Re: [boost] [variant2] never-empty guarantee, again

Subject: Re: [boost] [variant2] never-empty guarantee, again
From: Peter Dimov (pdimov_at_[hidden])
Date: 2019-04-03 21:54:17

Andrzej Krzemienski wrote:

> This is analogous to a (potentially smart) pointer:  normally you can call 
> `*p`, but sometimes (on nullptr) it is UB, so you may need to check what 
> state it is in.

If it were analogous you wouldn't be making all these arguments about 
destructors and stack unwinding. Null pointers aren't only null during stack 
unwinding or in destructors, they can be null anywhere. So you don't need to 
partition your functions into "dereferences pointers" and "does not 
dereference pointers". All functions need to check the pointer for being 
null before dereferencing it, regardless of whether they are part of normal 
code, or stack unwinding code.