Update constexpr implementation to match CWG's chosen approach for core issues

1358, 1360, 1452 and 1453.
 - Instantiations of constexpr functions are always constexpr. This removes the
   need for separate declaration/definition checking, which is now gone.
 - This makes it possible for a constexpr function to be virtual, if they are
   only dependently virtual. Virtual calls to such functions are not constant
   expressions.
 - Likewise, it's now possible for a literal type to have virtual base classes.
   A constexpr constructor for such a type cannot actually produce a constant
   expression, though, so add a special-case diagnostic for a constructor call
   to such a type rather than trying to evaluate it.
 - Classes with trivial default constructors (for which value initialization can
   produce a fully-initialized value) are considered literal types.
 - Classes with volatile members are not literal types.
 - constexpr constructors can be members of non-literal types. We do not yet use
   static initialization for global objects constructed in this way.

llvm-svn: 150359

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/test/SemaCXX/constexpr-value-init.cpp b/clang/test/SemaCXX/constexpr-value-init.cpp
index efa9e94da12..db4b68dcc6d 100644
--- a/clang/test/SemaCXX/constexpr-value-init.cpp
+++ b/clang/test/SemaCXX/constexpr-value-init.cpp
@@ -26,6 +26,6 @@ struct D : C { int d; };
 constexpr C c1; // expected-error {{requires a user-provided default constructor}}
 constexpr C c2 = C(); // ok
 constexpr D d1; // expected-error {{requires a user-provided default constructor}}
-constexpr D d2 = D(); // expected-error {{constant expression}} expected-note {{non-literal type 'const D'}}
+constexpr D d2 = D(); // ok with DR1452
 static_assert(D().c == 0, "");
 static_assert(D().d == 0, "");