Re: [PATCH][4.15] gnttab: work around "may be used uninitialized" warning

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.03.2021 11:04, Ian Jackson wrote:
> Julien Grall writes ("Re: [PATCH][4.15] gnttab: work around "may be used 
> uninitialized" warning"):
>> This is pretty much what we are already doing slowly by initializing 
>> values to shut up older compilers. I agree this is more limited, but we 
>> also waive off diagnostics from every single compiler in that code 
>> rather than just one version.
>>
>> Hence why I suggested dropping -Werror for older compiler. This is not 
>> ideal but it would give us the ability to keep support for dinausor 
>> compiler and not hamper our ability to take advantage of newer compiler 
>> diagnostics.
> 
> I agree with Julien.  I think we should avoid adding these redundant
> initialisers for the reasons he gives.

I find this odd, not only because it is contrary to what we've done so
far. What if more modern gcc issues a false-positive warning? If we'd
fix it there, where would you suggest to draw the line? Imo our tree
should build without issues on all compiler versions which we state we
permit to be used.

Of course in the case here I could add a "default:" to the switch(),
but this would still only work around the compiler issue. Would the
two of you consider this any better?

Also, Ian - do you have any alternative suggestion towards making the
build work again (in the more general case, i.e. irrespective of the
alternative suggestion for this specific case just above)? Not using
-Werror on old compilers (again - where would we draw the line) was
already objected to by me.

Jan