[dmd-internals] Mixin forward reference semantic runs and field declarations

[Daniel Murphy]

The first.  The compiler shouldn't emit the declaration more than once.

On Fri, Aug 31, 2012 at 10:20 PM, Jason House
<jason.james.house at gmail.com> wrote:
> Do you mean LDC should work around it? Or that it's something that should get fixed in the front end?
>
> Sent from my iPhone
>
> On Aug 30, 2012, at 9:39 PM, Walter Bright <walter at digitalmars.com> wrote:
>
>> That looks like a compiler bug.
>>
>> On 8/30/2012 4:00 PM, David Nadlinger wrote:
>>> I am currently working on ironing out the last few kinks in the LDC
>>> merge of the 2.060 frontend. The following snippet, a test case for
>>> Bugzilla issue 7974, currently doesn't work with LDC:
>>>
>>> ---
>>> mixin template mix7974() {
>>>   uint _x;
>>> }
>>>
>>> struct Foo7974 {
>>>   immutable fa = Foo7974(0);
>>>
>>>   this(uint x) {
>>>     _x = x;
>>>   }
>>>   mixin mix7974!();
>>> }
>>> ---
>>>
>>> The problem is that the fix Walter applied to the frontend for 7974
>>> causes the semantic pass, including the arrayCopy() of the mixin
>>> contents into the structs, to run twice, which leads to two separate
>>> VarDeclarations for Foo7974._x being present at codegen time: one
>>> instance, the one from the »forward reference« semantic run, is
>>> referred to by the struct constructor, the other instance from the
>>> second, »proper« run is e.g. what ends up in
>>> StructDeclaration::fields.
>>>
>>> As we tuck on IR construction metadata to field declarations in LDC,
>>> having two instances for the same field breaks our codegen in
>>> interesting ways – is this an unforeseen consequence of the fix in DMD
>>> and  possibly a bug, or do I have to find a way to work around this in
>>> LDC?
>>>
>>> Thanks,
>>> David
>>>
>>>
>>
>>
>> _______________________________________________
>> dmd-internals mailing list
>> dmd-internals at puremagic.com
>> http://lists.puremagic.com/mailman/listinfo/dmd-internals
> _______________________________________________
> dmd-internals mailing list
> dmd-internals at puremagic.com
> http://lists.puremagic.com/mailman/listinfo/dmd-internals