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

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);
In this short example we could easily work around this issue by not omitting the result of the
 char_ parser in the start rule or by changing the attribute types to what boost 1.61+ expects
In our full code it is not as simple as we rely on the types being unique when traversing the 
ast using variant visitors.

/Peter




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