> On Dec 16, 2017, at 10:31 AM, John McCall via swift-dev <swift-dev@swift.org>
> wrote:
>
>>
>> On Dec 16, 2017, at 9:08 AM, David Zarzycki via swift-dev
>> <swift-dev@swift.org> wrote:
>>
>> Hello,
>>
>> I’m trying to improve SILNode memory layout density by adopting the AST
>> bitfield macros. Unfortunately, multiple inheritance doesn’t seem to get
>> along with anonymous/unnamed unions. Here is a distillation of the problem:
>>
>> class B {
>> protected:
>> int i;
>> union { int j; };
>> };
>>
>> class X : public B { };
>> class Y : public B { };
>>
>> class Z : public X, public Y {
>> int a() { return X::i; } // works
>> int b() { return X::j; } // fails
>> };
>>
>> Is this expected C++ behavior? I can certainly workaround this by naming the
>> unnamed union, but before I do, I thought that I should check here first.
>
> This seems like a bug; anonymous unions are just supposed to inject their
> member names into the containing scope as if there was an ordinary member
> there, and the explicit scope-qualification should resolve which subobject is
> meant for such injected names the same it resolves them for ordinary fields.
> But if it's a bug in all existing clangs, it's a bug we're going to have to
> work around.
Which should not prevent Dave from still reporting it on
https://bugs.llvm.org/enter_bug.cgi?product=clang :-)
-- adrian
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