This fixes a very subtle ABI problem concerning the copy constructor of pair, and a couple of pair-like implementation detail types. The C++98/03 and 11 standards all specify that the copy constructor of pair<int, int> is trivial. However as libc++ tracked the draft C++11 standard over the years, this copy constructor became non-trivial, and then just recently was corrected back to trivial for C++11. Unfortunately (for libc++1) the Itanium ABI specifies different calling conventions for trivial and non-trivial copy constructors. Therefore currently the C++03 libc++ copy constructor for pair<int, int> is ABI incompatible with the C++11 libc++ copy constructor for pair<int, int>. This is Bad(tm). This patch corrects the situation by making this copy constructor trivial in C++03 mode as well. Just in case it is needed for an incomplete C++11 compiler, libc++ retains the ability to support pair with rvalue references, but without defaulted special members. However the pair needs non-trivial special members to implement this special case, (as it did when clang was in this place a couple of years ago). During this work a bug was also found and fixed in is_trivially_constructible. And there is a minor drive-by fix in <__config> regarding __type_visibility__. A test is updated to ensure that the copy constructor of pair<int, int> is trivial in both C++03 and C++11. This test will necessarily fail for a compiler that implements rvalue references but not defaulted special members. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@194536 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config index a45b02d..43fbf87 100644 --- a/include/__config +++ b/include/__config
@@ -174,7 +174,7 @@ #endif #ifndef _LIBCPP_TYPE_VIS -# if __has_attribute(type_visibility) +# if __has_attribute(__type_visibility__) # define _LIBCPP_TYPE_VIS __attribute__ ((__type_visibility__("default"))) # else # define _LIBCPP_TYPE_VIS __attribute__ ((__visibility__("default"))) 