[PATCH] Fix tuple<A> to A conversion in SFINAE for tuple(_Up...) constructor

[Eric Fiselier]

Tuple is tricky. If there is a bug in tuple you can bet that SFINAE is both the problem and the solution. constexpr constructors are becoming a frequent problem in the tuple SFINAE because they tend to cause hard compile errors. The SFINAE you added could easily introduce an almost identical bug in a different scenario.

Another reason I'm so hesitant to move forward with this patch is because they essentially contradicts http://reviews.llvm.org/D8178.

The first step to solving both of these bugs is to drastically increase the test coverage of tuple. The tests need to cover a much wider range of types than they currently do. Until then I think both these patches will need to wait in limbo.


REPOSITORY
  rL LLVM

http://reviews.llvm.org/D9085

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/