Re: Horrible compiletimes and memory usage while compiling a parser with X3

On 11/13/2016 07:50 AM, Larry Evans wrote:
> On 11/07/2016 02:44 AM, Peter Gerell wrote:
>> On 07/11/2016 12:38 PM , Joel de Guzman wrote:
>>> On 07/11/2016 1:26 AM, Mikael Asplund wrote:
>>>> This is the reason we're still on 1.60 (with a small
>>>> const-patch from 1.61), since later version have link problems which are just too hard
>>>> to debug.
>>
>>> It would be great if you post a test file that exhibits this problem you mention.
>>> This linking problem doesn't look good and must be fixed.
>>
>> Hi Joel.
>> This is the problem Mikael is referring to.
>> http://melpon.org/wandbox/permlink/X8Awj4wIZ2JqMWIw
>>
>> If KEEP_CHAR is defined the code builds with both boost 1.60 and 1.61.
>> Without KEEP_CHAR it fails with 1.61.
>>
>> The following commit introduced the problem.
>> https://github.com/boostorg/spirit/commit/a8e391bd99dddb3f9ece84bdb1bb9236b0a37cf7
>>
>> The problem seems to be that the attribute types are short-circuited for sequences of one
>> even though we explicitly request a specific binding using FUSION_DEFINE_FOR_STRUCT(ast::Start, count);
> [snip]
>
> More specifically, the change on line 178 causes the
> problem.  That change caused r_pass on line 303 to be
> derived from pass_through_sequence_attribute instead of
> pass_sequence_attribute_front, as was the case with
> boost_1_60_0.  That change, in turn, caused r_attr on line
> 303 to just copy attr, which was type ast::Start, instead of
> the type type of the boost_1_60_0 r_attr which was type
> ast::Count.
>
> Since parser.right has type:
>
>    rule<count_class, ast::Count, false>
>
> the call on line 312 of detail/sequence.hpp:
>
>    && parser.right.parse(first, last, context, rcontext,
>    r_attr))
>
> will, ultimately, cause parse_rule to be called with the
> wrong r_attr(the one with type ast::Start instead of
> ast::Count), and, since the expression.cpp only has:
>
>    BOOST_SPIRIT_INSTANTIATE(count_type, iterator_type,
>    x3::unused_type);
>
> which only instantiates (according to the definition of that
> macro in rule.hpp:173) the parse_rule specializaton for
> attr=ast::Count, the link error happens.
>
> Why not revert the change on detail/sequence.hpp:178 to
> solve the problem?
>
> -regards,
> Larry
Otherwise, as a workaround, one could simply add to the
specialization produced by BOOST_SPIRIT_INSTANTIATE, ans done
in the attached.

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// The adapted include must be among the first (before any file that may include ast.hpp)
#include "ast_adapted.hpp"
#include "expression_def.hpp"

BOOST_SPIRIT_INSTANTIATE(count_type, iterator_type, x3::unused_type);

#if 1
//Workaround the link problem:
    template bool parse_rule<iterator_type, x3::unused_type, ast::Start>( 
        count_type rule_                                                         
      , iterator_type& first, iterator_type const& last                          
      , x3::unused_type const& context, ast::Start& attr);       
#endif