[cfe-commits] [PATCH] Instantiate dependent attributes in template code.

[Delesley Hutchins]

Cool.  Thanks for the clarification; I'll refactor as needed.

  -DeLesley

On Tue, Jan 17, 2012 at 10:42 AM, Richard Smith <richard at metafoo.co.uk> wrote:
> On Tue, January 17, 2012 16:07, Delesley Hutchins wrote:
>> I'm still a bit unclear -- I want to make sure I understand which
>> dependencies cause a layering violation, so I can avoid this mistake in the
>> future.  There's still no dependency in the call graph, because
>> instantiateFromTemplate is only called from within Sema.  There is a
>> dependency in the object file though, because Attr must be linked against Sema
>> to instantiate the virtual method table.  Is the goal to be able to package
>> the AST classes into a separate library that does not need to be linked
>> against Sema?
>
> Yes. Sorry for not stating this explicitly!
>
>> On Fri, Jan 13, 2012 at 5:13 PM, Richard Smith <richard at metafoo.co.uk> wrote:
>>> On Fri, January 13, 2012 23:03, Delesley Hutchins wrote:
>>>> The instantiateFromTemplate method is only called from within Sema.
>>>> Is the layering violation introduced by the forward declaration of
>>>> class Sema within Attr.h?
>>>
>>> It's introduced by the call of Sema::SubstExpr from
>>> instantiateFromTemplate.
>>>
>>>> On Fri, Jan 13, 2012 at 2:33 PM, Richard Smith <richard at metafoo.co.uk>
>>>> wrote:
>>>>> Hi Delesley,
>>>>>
>>>>> Apologies for the huge delay in getting this patch reviewed!
>>>>>
>>>>> On Tue, December 13, 2011 23:08, Delesley Hutchins wrote:
>>>>>> This patch modifies Sema::InstantiateAttrs so that attributes in
>>>>>> template code are properly instantiated; the previous behavior was to
>>>>>> clone them.  The main motivation for the patch are thread safety
>>>>>> attributes, which make extensive use of expressions.
>>>>>>
>>>>>> A new method named instantiateFromTemplate is now generated for all
>>>>>> attributes.  The behavior of this method is identical to clone() for
>>>>>> all arguments except ExprArgument and VariadicExprArgument; expression
>>>>>>  arguments are instantiated rather than cloned.
>>>>>
>>>>> This patch introduces a layering violation: AST code is not permitted
>>>>> to use Sema. In order to resolve this, I suggest you instead modify
>>>>> TableGen to
>>>>>  synthesize some Sema code which performs attribute instantiation (using
>>>>> a switch over the attribute kind).
>
>



-- 
DeLesley Hutchins | Software Engineer | delesley at google.com | 505-206-0315