[cfe-commits] [PATCH] Make behavior of RecordLayoutBuilder overridable

[Charles Davis]

On 8/14/10 8:03 PM, Sean Hunt wrote:
> On 08/14/2010 07:34 PM, Charles Davis wrote:
>> On 8/14/10 1:55 PM, John McCall wrote:
>>> This seems fine, though yeah, I guess I'd prefer that you checked it in with
>>> the MS layout code.
>> Here's a version that includes some MS-specific code. It handles the
>> case where a class has both a virtual method and a virtual base (in such
>> cases, VC would give it two virtual pointers).
> 
> Does every member function need to be virtual? A lot of those seem like 
> overriding them is possibly a bad idea,
Most C++ ABIs might be compatible with C, but how do we know that
someone won't come up with a novel ABI that has completely different
conceptions about everything--including class layout?
> and in any case it's not very 
> useful to make them virtual if we aren't overriding them.
I concede to you on that. As much as I don't want to end up breaking
backwards compatibility later on, it might be worth removing most of the
'virtual's from the patch to minimize the (tiny) performance impact of
virtual calls. The Clang C++ API is supposed to be "unstable", after all...

Chip