1 files changed, 32 insertions, 20 deletions

diff --git a/include/llvm/Support/ErrorOr.h b/include/llvm/Support/ErrorOr.h
index 0742a2d..84763de 100644
--- a/include/llvm/Support/ErrorOr.h
+++ b/include/llvm/Support/ErrorOr.h
@@ -13,8 +13,8 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_SUPPORT_ERROR_OR_H
-#define LLVM_SUPPORT_ERROR_OR_H
+#ifndef LLVM_SUPPORT_ERROROR_H
+#define LLVM_SUPPORT_ERROROR_H
 
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Support/AlignOf.h"
@@ -68,9 +68,9 @@ public:
 /// \endcode
 ///
 ///
-/// An implicit conversion to bool provides a way to check if there was an
-/// error. The unary * and -> operators provide pointer like access to the
-/// value. Accessing the value when there is an error has undefined behavior.
+/// Implicit conversion to bool returns true if there is a usable value. The
+/// unary * and -> operators provide pointer like access to the value. Accessing
+/// the value when there is an error has undefined behavior.
 ///
 /// When T is a reference type the behaivor is slightly different. The reference
 /// is held in a std::reference_wrapper<std::remove_reference<T>::type>, and
@@ -115,19 +115,19 @@ public:
   }
 
   template <class OtherT>
-  ErrorOr(const ErrorOr<OtherT> &Other) {
+  ErrorOr(
+      const ErrorOr<OtherT> &Other,
+      typename std::enable_if<std::is_convertible<OtherT, T>::value>::type * =
+          nullptr) {
     copyConstruct(Other);
   }
 
-  ErrorOr &operator =(const ErrorOr &Other) {
-    copyAssign(Other);
-    return *this;
-  }
-
   template <class OtherT>
-  ErrorOr &operator =(const ErrorOr<OtherT> &Other) {
-    copyAssign(Other);
-    return *this;
+  explicit ErrorOr(
+      const ErrorOr<OtherT> &Other,
+      typename std::enable_if<
+          !std::is_convertible<OtherT, const T &>::value>::type * = nullptr) {
+    copyConstruct(Other);
   }
 
   ErrorOr(ErrorOr &&Other) {
@@ -135,17 +135,29 @@ public:
   }
 
   template <class OtherT>
-  ErrorOr(ErrorOr<OtherT> &&Other) {
+  ErrorOr(
+      ErrorOr<OtherT> &&Other,
+      typename std::enable_if<std::is_convertible<OtherT, T>::value>::type * =
+          nullptr) {
     moveConstruct(std::move(Other));
   }
 
-  ErrorOr &operator =(ErrorOr &&Other) {
-    moveAssign(std::move(Other));
+  // This might eventually need SFINAE but it's more complex than is_convertible
+  // & I'm too lazy to write it right now.
+  template <class OtherT>
+  explicit ErrorOr(
+      ErrorOr<OtherT> &&Other,
+      typename std::enable_if<!std::is_convertible<OtherT, T>::value>::type * =
+          nullptr) {
+    moveConstruct(std::move(Other));
+  }
+
+  ErrorOr &operator=(const ErrorOr &Other) {
+    copyAssign(Other);
     return *this;
   }
 
-  template <class OtherT>
-  ErrorOr &operator =(ErrorOr<OtherT> &&Other) {
+  ErrorOr &operator=(ErrorOr &&Other) {
     moveAssign(std::move(Other));
     return *this;
   }
@@ -161,7 +173,7 @@ public:
   }
 
   reference get() { return *getStorage(); }
-  const_reference get() const { return const_cast<ErrorOr<T> >(this)->get(); }
+  const_reference get() const { return const_cast<ErrorOr<T> *>(this)->get(); }
 
   std::error_code getError() const {
     return HasError ? *getErrorStorage() : std::error_code();