Re: [PATCH v3 0/2] Stop some of the abuse of BUG() where compile time checks should be used.

[David Daney <ddaney@caviumnetworks.com>]

On 11/24/2011 10:31 AM, Linus Torvalds wrote:
> On Thu, Nov 24, 2011 at 2:24 AM, David Howells<dhowells@redhat.com>  wrote:
>>
>> Have you tried asking the gcc folks if this is likely to get fixed soon?
>
> I actually don't think it's a bug. The error message is associated
> with the function declaration symbol, so it actually makes sense that
> there can be only one error message per callee - not per caller.
>

Yes, that is correct.

> Using "__LINE__" to then create fairly unique symbols (modulo
> #include, of course) gets around it in a pretty natural way as ddaney
> said, so if we care enough.  I don't think it's a big issue (as
> mentioned, I'd worry more about us making sure it's reliable enough to
> be used - we've had gcc sometimes fail to compile things out just
> because some optimization was not working well enough).
>

Since these are *build* bugs, they are of a different nature than the 
*runtime* variety.  They will never be seen at random times by someone 
running the kernel, so making it easier to determine their cause is less 
important.  Really, I would expect it to never really be an issue.

We will always know which file is the culprit.  Finding the line number 
can be done like this:

objdump -r $file | grep build_bug | addr2line -e $file

David Daney