Re: Linking error when changing > to >>

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
>
I thought changing rule::parse as shown here:

https://github.com/cppljevans/spirit/blob/e6a6dbcb6b5b2041cb6a14f7afcb0978d25032bd/include/boost/spirit/home/x3/nonterminal/rule.hpp#L140

should work.  My reasoning was that attr must contain, somewhere,
the actual rule's attribute; hence, just provide the needed
extract_rule_attr overloads.  I tried it with just the
fusion::iterator_range overload; however, that lead to a compile
error which lead to the variant overload, but that lead to
another compiler error about context.  That error is shown here:

https://github.com/cppljevans/spirit/commit/e6a6dbcb6b5b2041cb6a14f7afcb0978d25032bd

I'm trying to figure out a workaround, but maybe you have
some ideas about a workaround, are am I going in wrong
direction?

TIA.

-regards,
Larry




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