[PATCH] [libcxx] Delay evaluation of __make_tuple_types to prevent blowing the max template instantiation depth. Fixes Bug #18345

[Howard Hinnant]

On Oct 1, 2014, at 12:16 PM, Howard Hinnant <howard.hinnant at gmail.com> wrote:
>> or
>> 
>>   using A = std::array<double,3>;
>>   A a;
>>   std::tuple<double,double,double> t;
>>   t = a;
> 
> This is another extension.  This example would already work if A is pair, instead of std::array.  libc++ introduces the concept of “tuple-like”, and tuple cleanly interoperates with tuple-like types.  The set of tuple-like types are pair and array.  One might imagine making complex tuple-like as well.
> 
> See <__tuple> for the __tuple_like<T> trait which controls this behavior.
> 
> This extension has not been proposed for standardization.

tuple-like now seen in the wild:

http://stackoverflow.com/a/26454142/576911

:-)

Howard