[Spice-devel] messages.h unable to be used in VC++

[Aric Stewart]

Yeah, i am wondering a bit about this also.

I know under c++ sizeof and empty struct will return 1
gnu c will return 0
msvc++ fails.

adding a uint8_t padding member will make it always return 1.  I am not 
sure if that is going to be an issue.

I am totally not an expert on the wire protocol, which is the motivation 
for this question.

We may need to go through and change the parse_SpiceMsgEmpty 
implementation?

-aric

On 4/17/12 12:41 PM, Brian Vetter wrote:
> Not sure if this applies since I'm looking at the spice-gtk 0.11 source,
> but the generated_demarshallers.c code includes a function
> parse_SpiceMsgEmpty. Within it it uses "sizeof(SpiceMsgEmpty)" and some
> pointer/allocator math for demarshalling a SpiceEmptyMsg. I'm no expert
> here, but I would think that might cause an issue for the wire protocol.
>
> Brian
>
> On Apr 17, 2012, at 12:10 PM, spice-devel-request at lists.freedesktop.org
> <mailto:spice-devel-request at lists.freedesktop.org> wrote:
>
>> On Tue, Apr 17, 2012 at 08:15:22AM -0500, Aric Stewart wrote:
>>> Hello all,
>>>
>>> Working away at making the current tip of spice build the win32 client. I
>>> have run into another problem.
>>>
>>> Since the last working win32 cllient build the code generated by
>>> spice_codegen.py has shifted from CPP files to C files. The generated
>>> files
>>> include messages.h.
>>>
>>> Inside messages.h there is a structure SpiceMsgEmpty which is empty.
>>> Empty
>>> structures in C have 0 bytes and are not defined in the spec. VC++ treats
>>> this as a hard error (C2015) and so refuses to compile the code. gcc does
>>> not treat this as an error, so mingw and gcc builds have not noticed
>>> this.
>>>
>>> How do we want to handle this.
>>>
>>> We could put a single padding member in that structure that would allow
>>> the compile to work, but it would make the structure size expand to a
>>> byte
>>> and have an unused member.
>>
>> Looks like this should just work. Maybe you could try this?
>>
>>>
>>> If I have the VC++ build path continue to generate cpp files instead of C
>>> files then there are issues with the bindings defined in
>>> client_demarshallers.h and the SPICE_BEGIN_DECLS lines will have to be
>>> #ifdefed out for win32.
>>>
>>> Thanks!
>>> -aric
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>>
>
>
>
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