[PATCH] D20719: Remove use of is_trivially_constructible.

[Zachary Turner via llvm-commits]

Essentially this code was trying to check "is it safe to reinterpret_cast
sizeof(T) bytes to a T*".

Is there a better way to check that?

On Thu, May 26, 2016 at 10:00 PM David Blaikie <dblaikie at gmail.com> wrote:

> On Thu, May 26, 2016 at 7:53 PM, Rui Ueyama via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> ruiu added inline comments.
>>
>> ================
>> Comment at: include/llvm/DebugInfo/CodeView/StreamArray.h:114-115
>> @@ -113,4 +113,2 @@
>>    friend class FixedStreamArrayIterator<T>;
>> -  static_assert(std::is_trivially_constructible<T>::value,
>> -                "FixedStreamArray must be used with trivial types");
>>
>> ----------------
>> majnemer wrote:
>> > You could go with `std::is_standard_layout<T>::value &&
>> std::is_trivial<T>::value` to get more or less the same thing.
>> This seems a bit too tricky to me. It would just fail if you pass
>> non-trivially-constructible class to this one, so I'm okay without this
>> assertion.
>>
>
> what/how would it fail? Testing for is_trivially_constructible to me would
> indicate that this code is using memory that's perhaps zero'd out without
> invoking the ctor for the type. If the type isn't trivially constructible
> that sort of thing's going to result in subtle behavior, quite often not an
> outright failure.
>
>
>>
>>
>> http://reviews.llvm.org/D20719
>>
>>
>>
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>
>
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