Add ArrayRef constructor from None, and do the cleanups that this constructor enables

Patch by Robert Wilhelm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181138 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 1 deletions

diff --git a/include/llvm/ADT/ArrayRef.h b/include/llvm/ADT/ArrayRef.h
index c555c1c2b1..d4152ec727 100644
--- a/include/llvm/ADT/ArrayRef.h
+++ b/include/llvm/ADT/ArrayRef.h
@@ -10,6 +10,7 @@
 #ifndef LLVM_ADT_ARRAYREF_H
 #define LLVM_ADT_ARRAYREF_H
 
+#include "llvm/ADT/None.h"
 #include "llvm/ADT/SmallVector.h"
 #include <vector>
 
@@ -49,6 +50,9 @@ namespace llvm {
     /// Construct an empty ArrayRef.
     /*implicit*/ ArrayRef() : Data(0), Length(0) {}
 
+    /// Construct an empty ArrayRef from None.
+    /*implicit*/ ArrayRef(NoneType) : Data(0), Length(0) {}
+
     /// Construct an ArrayRef from a single element.
     /*implicit*/ ArrayRef(const T &OneElt)
       : Data(&OneElt), Length(1) {}
@@ -174,9 +178,12 @@ namespace llvm {
   public:
     typedef T *iterator;
 
-    /// Construct an empty ArrayRef.
+    /// Construct an empty MutableArrayRef.
     /*implicit*/ MutableArrayRef() : ArrayRef<T>() {}
 
+    /// Construct an empty MutableArrayRef from None.
+    /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {}
+
     /// Construct an MutableArrayRef from a single element.
     /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}