Re: [PATCH 1/5] usage.c: add a non-fatal bug() function to go with BUG()

> Junio C Hamano <gitster@pobox.com> writes:
>
>>> +/* usage.c: if bug() is called we should have a BUG_if_bug() afterwards */
>>> +extern int bug_called_must_BUG;
>>
>> I am not sure about the name, ...
>
> I finally figured out why I found this name so disturbing.  This is
> written from the viewpoint of somebody who is trying to catch a
> programmer's error of calling bug() without calling BUG_if_bug();
> it is not named to help the users of API to understand it better.

> I wonder if it makes sense to make the call to BUG_if_bug() totally
> optional.  The rule becomes slightly different:
>
>  * You can call bug() zero or more times.  It issues a fatal error
>    message, and internally remembers the fact that we detected a
>    programming error that invalidates the execution of this program,
>    without immediately terminating the program.
>
>  * When you exit() from the program, the runtime consults that "did
>    we call bug()?" record and makes the program exit with known exit
>    code (we could arrange it to abort() just like BUG, but I'd
>    prefer controlled crash).
>
>  * But it is inconvenient to always keep going, after you may have
>    called one or more bug(), to the normal program completion.  So
>    there is a helper exit_if_called_bug(), which is an equivalent to
>    checking the "did we call bug()?" record and calling exit().
>
> By making BUG_if_bug() optional, we can lose a handful of lines from
> the test helper, because it makes it a non-issue to exit the program
> without calling it.