llvm /
libcxx /
2ab98fbcd4f71fde5ead3bc43192d2e45ce35ccc Allow optional to tolerate being used with a nested class.
When Clang tries to complete a type containing `std::optional` it
considers the `in_place_t` constructor with no arguments which checks
if the value type is default constructible. If the value type is a
nested class type, then this check occurs too early and poisons the
is_default_constructible trait.
This patch makes optional deduce `in_place_t` so we can prevent
this early SFINAE evaluation. Technically this could break people
doing weird things with the in_place_t tag, but that seems less
important than making the nested class case work.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@355877 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed
