r192494 - Adds Microsoft compatiable C++ record layout code to clang.

[Will Wilson]

Thanks Warren!

FYI: I've been running a patched version for the couple of weeks against a
lot of MSVC code. So far it fixed the problems I was seeing and hasn't
caused any new ones.

- Will.


On 20 February 2014 21:20, Warren Hunt <whunt at google.com> wrote:

> Committed as r201810.
>
> -Warren
>
>
> On Thu, Feb 20, 2014 at 12:15 PM, Warren Hunt <whunt at google.com> wrote:
>
>> After further discussion/investigation, the check is wrong and we should
>> remove it.  Without the check, if we are debugging on windows using lldb
>> and DWARF, we can potentially get the wrong layout during a debugging
>> session in which someone defines a new type.  Given that don't have support
>> debugging on windows using lldb, this is fine.  I'll patch it.
>>
>> -Warren
>>
>>
>> On Thu, Feb 20, 2014 at 6:16 AM, Will Wilson <will at indefiant.com> wrote:
>>
>>> Hi Warren,
>>>
>>> As far as I understand, a PCH is treated much like a simplified clang
>>> module and as such any PCH is an ExternalSource meaning the ExternalSource
>>> is valid in this case. I don't thing DWARF has any relevance here AFAIK.
>>>
>>> It's likely that I was seeing this "delayed" layout behaviour due to the
>>> record in question being a class template declared in the PCH that wasn't
>>> instantiated in the PCH but later in a compiland including the PCH. After
>>> all you can't do record layout for a template class that hasn't yet been
>>> instantiated (well unless all the data members weren't dependent on
>>> template arguments). So even if known record layout are serialized in the
>>> PCH (I don't actually know if they are or not TBH) there will always be
>>> class templates instantiations that would have to be laid out after the
>>> creation of the PCH - as is the case for me.
>>>
>>> Either way, in this case the "&& !D->getASTContext().getExternalSource()"
>>> still does a layout, it just does one without using MS layout rules.
>>>
>>> - Will.
>>>
>>
>>
>


-- 
*Indefiant Ltd.*
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