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Re: [libvirt] [PATCH 7/7] remote generator: Annotate hyper with the actual C type



On 05/25/2011 10:23 AM, Daniel P. Berrange wrote:
> On Mon, May 23, 2011 at 07:36:10PM +0200, Matthias Bolte wrote:
>> Remove some special case code that took care of mapping hyper to the
>> correct C types.
>>
>> Use macros for hyper to long assignments that perform overflow checks
>> when long is smaller than hyper. Also use such macros for the safe
>> hyper to longlong assignemts as this allows to keep the generator a
>> bit simpler.
> 
>> +    } elsif ($ret_member =~ m/^(unsigned )?hyper (\S+)\[\S+\];/) {
>> +        # error out on unannotated hypers
>> +        die "(unsigned)? hyper without (u)?(long|longlong) annotation: $ret_member";
> 
> 'hyper' in XDR world is a fixed 64 bit type, so IMHO, this
> should automatically map to 'long long' in the API, without
> requiring an annotation.
> 
> eg, we should only annotate if the public API uses the variable
> sized 'long' / 'unsigned long' types in C.

> All the 'longlong' and 'ulonglong' annotations should
> be removed here IMHO, since they should be the default
> for hyper/unsigned hyper.

If we add a new API that uses 'long' but forget the annotation, then we
have silent type mismatch in the generated code.  Since we are using
hyper for both types in C, I find it better to require an annotation on
all uses to be explicit on which type we meant, rather than defaulting
the lack of annotation as 'long long' and only requiring annotation for
'long' - that is, I find that from the maintenance aspect, having the
code generator explicitly fail because you forget an annotation (even if
the annotation is the default of llong) is safer than risking silent
code misgeneration.

But anything is better than nothing, so I won't give any further
complaints if we go with your idea of only annotating the exceptions to
the 'long long' default, rather than all uses of hyper.

-- 
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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