What policy for BUG_ON()?

[Adrian Bunk <bunk@fs.tum.de>]

Let me try to summarize the different options regarding BUG_ON, 
concerning whether the argument to BUG_ON might contain side effects, 
and whether it should be allowed in some "do this only if you _really_ 
know what you are doing" situations to let BUG_ON do nothing.

Options:
1. BUG_ON must not be defined to do nothing
1a. side effects are allowed in the argument of BUG_ON
1b. side effects are not allowed in the argument of BUG_ON
2. BUG_ON is allowed to be defined to do nothing
2a. side effects are allowed in the argument of BUG_ON
2b. side effects are not allowed in the argument of BUG_ON

It would be good if there was a decision which of the four choices 
should become documented policy.


<--  snip  -->

My personal opinions:

IMHO, 1b doesn't make much sense, since in the case of 1. side effects 
are never a problem.

IMHO, 2b is bad since it might cause nasty heisenbugs if BUG_ON does  
nothing, and preserving the side effects is easy.

<--  snip  -->


cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed