LLVM 6.0.0 and Clang 6.0.0 are now available.

Clang 6.0.0 Release Notes

From the announcement:

Clang’s default C++ dialect is now gnu++14 instead of gnu++98. This means Clang will by default accept code using features from C++14 and conforming GNU extensions. Projects incompatible with C++14 can add -std=gnu++98 to their build settings to restore the previous behaviour.

Added support for some features from the C++ standard after C++17 (provisionally known as C++2a but expected to be C++20). This support can be enabled with the -std=c++2a flag. This enables:

• Support for __VA_OPT__, to allow variadic macros to easily provide different expansions when they are invoked without variadic arguments.
• Recognition of the <=> token (the C++2a three-way comparison operator).
• Support for default member initializers for bit-fields.
• Lambda capture of *this.
• Pointer-to-member calls using const &-qualified pointers on temporary objects.

A warning has been added for a <= token followed immediately by a > character. Code containing such constructs will change meaning in C++2a due to the addition of the <=> operator.

Clang implements the “destroying operator delete” feature described in C++ committee paper P0722R1 <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0722r1.html>, which is targeting inclusion in C++2a but has not yet been voted into the C++ working draft. Support for this feature is enabled by the presence of the standard library type std::destroying_delete_t.