tree 7a49a295ca8d956850d2531560e92d46bb432ef6
parent 3e541a6172e39ead4fad233ec02c1898c006a0ac
author Eric Fiselier <eric@efcs.ca> 1481241428 +0000
committer Eric Fiselier <eric@efcs.ca> 1481241428 +0000

Fix PR27374 - Remove the implicit reduced-arity-extension in tuple.

This patch removes libc++'s tuple extension which allowed it to be
constructed from fewer initializers than elements; with the remaining
elements being default constructed. However the implicit version of
this extension breaks conforming code. For example:

    int fun(std::string);
    int fun(std::tuple<std::string, int>);
    int x = fun("hello"); // ambigious

Because existing code may already depend on this extension it can be re-enabled
by defining _LIBCPP_ENABLE_TUPLE_IMPLICIT_REDUCED_ARITY_EXTENSION.

Note that the explicit version of this extension is still supported,
although it's somewhat less useful than the implicit one.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@289158 91177308-0d34-0410-b5e6-96231b3b80d8