Re: Linking error when changing > to >>

On 11/21/2016 08:05 AM, Larry Evans wrote:
> On 11/12/2016 09:07 PM, Seth wrote:
>> On 12-11-16 23:14, Seth wrote:
>>> On 11-11-16 21:06, Exagon wrote:
>>>> So I think it has something to do with the type parser.
>>>> Maybe I did something wrong, please correct me if I did anything anywhere in
>>>> this example I shouldnt do when using boost spirit x3.
>>>> I spoke to Joel before to ask whether I could expect such a behaviour in
>>>> spirit x3 and he said no, so I think this is a bug.
>>> FWIW I tried to look into this with the bag-of-tricks I know for this
>>>
>>>  * It's not about attribute synthesis AFAICT (using semantic actions to
>>> sense the synthesized attributes confirms identical types).
>>>
>>> The linker error indicates that it is trying to invoke the `type` rule
>>> with the attribute bound to a fusion iterator, instead of the actual
>>> object. It's interesting that this works when compiling single-TU.
>>>
>>> This would mean that this is supported but a forgotten usage-patten of
>>> `parse_rule` which needs to be added to the macros for explicit
>>> instantiation?
>>>
>>>
>>> $0.02
>>>
>>> Seth
>>
>> After (much) more tinkering, indeed the problem seems to be that
>> `call_rule_definition` is called from inside `parse_rule`.
>>
>> However, the attribute transformation on the partitioned fusion
>> sequences (iterator ranges) happen only inside `call_rule_definition`.
>> Turns out, this is simply too late, because that means for TU-separation
>> we need to anticipate all the different ActualAttribute types that might
>> be passed to `parse_rule`.
>>
>> We might be able to move the attribute transformation into the
>> `parse_rule` stub - although I'm sure there could be a more elegant solution
>
> By `parse_rule` stub, do you mean what's generated by the
> BOOST_SPIRIT_DEFINE_ macro?
>
> By `attribute transformation` do you mean something like the
> extract_rule_attr overloads from here:
>
> https://github.com/cppljevans/spirit/blob/ExagonLinkingError/include/boost/spirit/home/x3/nonterminal/rule.hpp#L112
>
> or something else?
>
Or maybe by `attribute transformation` you mean the code in
lines 312-323 of:

 
https://github.com/cppljevans/spirit/blob/ExagonLinkingError/include/boost/spirit/home/x3/nonterminal/detail/rule.hpp

What about moving that code into a replacement for the
existing extract_rule_attr?  Using gdb it produces the same
value as the existing extract_rule_attr at least in one case.
However, I can't tell yet from reading the code if it will
produce an attribute of types rule<...>::attribute_type,
which is needed to get the BOOST_SPIRIT_INSTANTIATE to work.

-regards,
Larry




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