Add "typedef T value_type;" to llvm::Optional<T>.

Inspired by std::experimental::optional from the "Library Fundamentals" C++ TS.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218617 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/ADT/Optional.h b/include/llvm/ADT/Optional.h
index ae8344da76a625d48663891c52fbef4dd134f634..cb45c78e2c1fffa1cc3701be61532174ae89f3fc 100644 (file)
--- a/include/llvm/ADT/Optional.h
+++ b/include/llvm/ADT/Optional.h
@@ -29,6 +29,8 @@ class Optional {
   AlignedCharArrayUnion<T> storage;
   bool hasVal;
 public:
+  typedef T value_type;
+
   Optional(NoneType) : hasVal(false) {}
   explicit Optional() : hasVal(false) {}
   Optional(const T &y) : hasVal(true) {