structs, ~this(), this(this) and reference counting

Sönke Ludwig ludwig at informatik.uni-luebeck.de
Sat Feb 18 07:09:48 PST 2012


Am 18.02.2012 14:25, schrieb Benjamin Thaut:
> Am 18.02.2012 11:32, schrieb Sönke Ludwig:
>> After implementing automatic reference counting for resource management
>> and spending the last two days with trying to figure out where the
>> crashes and leaks come from and write workarounds for the corresponding
>> compiler bugs, I came to the conclusion that this approach is futile.
>> The code base is too large, as is the number of patterns that lead to
>> compiler bugs.
>>
>> Since the number of issues unusually high, instead of posting one bug
>> report for each (posted two), I compiled a small test suite with a
>> number of bug patterns that I discovered (and some working patterns).
>> The list is probably not complete and I know that some cases that are OK
>> in the test suite now failed for me in real code.
>>
>> Anyway, do you think it makes sense to post this test suite as a meta
>> bug for reference counting (excluding phobos RefCounted), so that
>> somebody can look into it as a whole?
>>
>> I get the feeling that otherwise it might take a very long time until
>> everything is stable in this area - and IMO this is an extremely
>> important area for anyone who needs to (partially or fully) avoid the
>> GC. And, last but not least, just like linker crashes and ICEs, it may
>> cause a very fragile impression for anyone who encounters this.
>>
>> Test suite: http://pastebin.com/niZwRKpc
>> (Run with "dmd -g -run" or "dmd -g -version=BAILOUT -run")
>>
>
> You did not implement the assignment operator for your refcounted
> struct. If you do that it should heavily reduce the number of issues you
> have. I actually only run into 1 severe issue with refcounting and that
> is that array slice copying does not call any copy constructor /
> assignment operator

Can you show your assignment operator?

For me it just causes 3 cases to crash, which were simply failing before.

But apart from that, if the assignment operator is defined differently 
than what Michel suggested that's of course one of the bugs.


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