[cfe-commits] [Review] First step towards PR13231 - vftable generation with -cxx-abi microsoft

[João Matos]

I've researched MS ctor/dtor behaviour a bit, check PR 12784 (
http://llvm.org/bugs/show_bug.cgi?id=12784) for a simple file that shows
the different types we will expect.

On Wed, Dec 5, 2012 at 2:28 PM, Timur Iskhodzhanov <timurrrr at google.com>wrote:

> On Tue, Dec 4, 2012 at 8:09 PM, Timur Iskhodzhanov <timurrrr at google.com>
> wrote:
> >>> d) The complete/deleting dtor logic will change when we support MSVC
> >>> dtor types, but not now
> >>>    [shouldn't matter now that we still don't support virtual
> inheritance]
> >>
> >> You're thinking about complete vs. base destructors.  Complete vs.
> deleting
> >> destructors isn't about virtual inheritance;  it's about whether the
> destructor
> >> calls operator delete.
> > Yeah, now I see it... [see below]
> >
> >> (This is important because the 'delete' operator uses
> >> the operator delete from the most-derived class.)
> >>
> >> How does MSVC handle the difference between
> >>   foo->~Foo(); // virtually dispatched but doesn't call operator delete
> >> and
> >>   delete foo; // virtually dispatched and calls operator delete
> >> ?
> > Clang with my patch behaves badly on such code.
> > It seems to work fine at least on simple code where you don't use
> > virtual destructors.
> >
> > Actually, the whole idea of base vs complete dtors doesn't apply to
> > -cxx-abi microsoft.
> > Anyways, had plans to work on ctor and dtor compatibility as a
> > separate patch - is that OK?
> > I've put a couple of more FIXME into the code for that. (in
> > ::AddMethod and ::ComputeMethodVTableIndices).
>
> Attached is the patch which is similar to bug_13231_2 but puts the
> complete dtor rather than deleting.
> Both are basically broken anyways but at least you can choose what you
> think fits better :)
> Investigating compatible dtor behavior is definitely on my TODO-soon
> list now [as a separate change if this works]
>
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>


-- 
João Matos
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