Hi Adrian,
Feel free to file a bug if you’re motivated. Personally speaking, I don’t
expect this bug to be on anybody’s priority list. The workaround of using named
structs/unions has no downside for most projects, and Swift is no exception.
Dave
--
Sent from my iPad
> On Jan 4, 2018, at 20:11, Adrian Prantl <apra...@apple.com> wrote:
>
>
>
>>> 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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