LLVM_ATTRIBUTE_UNUSED_RESULT has become LLVM_NODISCARD.

Author: Greg Parker

stdlib/public/SwiftShims/RefCount.h

@@ -383,7 +383,7 @@ class RefCountBitsT {
   // (for example, because UseSlowRC is set
   // or because the refcount is now zero and should deinit).
   template <ClearPinnedFlag clearPinnedFlag>
-  LLVM_ATTRIBUTE_ALWAYS_INLINE LLVM_ATTRIBUTE_UNUSED_RESULT
+  LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE
   bool doDecrementStrongExtraRefCount(uint32_t dec) {
 #ifndef NDEBUG
     if (!hasSideTable()) {
@@ -544,7 +544,7 @@ class RefCountBitsT {
   // Returns true if the increment is a fast-path result.
   // Returns false if the increment should fall back to some slow path
   // (for example, because UseSlowRC is set or because the refcount overflowed).
-  LLVM_ATTRIBUTE_ALWAYS_INLINE LLVM_ATTRIBUTE_UNUSED_RESULT
+  LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE
   bool incrementStrongExtraRefCount(uint32_t inc) {
     // This deliberately overflows into the UseSlowRC field.
     bits += BitsType(inc) << Offsets::StrongExtraRefCountShift;
@@ -553,7 +553,7 @@ class RefCountBitsT {
 
   // FIXME: I don't understand why I can't make clearPinned a template argument
   // (compiler balks at calls from class RefCounts that way)
-  LLVM_ATTRIBUTE_ALWAYS_INLINE LLVM_ATTRIBUTE_UNUSED_RESULT
+  LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE
   bool decrementStrongExtraRefCount(uint32_t dec, bool clearPinned = false) {
     if (clearPinned) 
       return doDecrementStrongExtraRefCount<DoClearPinnedFlag>(dec);
@@ -1275,7 +1275,7 @@ class HeapObjectSideTableEntry {
 
   // WEAK
 
-  LLVM_ATTRIBUTE_UNUSED_RESULT
+  LLVM_NODISCARD
   HeapObjectSideTableEntry* incrementWeak() {
     // incrementWeak need not be atomic w.r.t. concurrent deinit initiation.
     // The client can't actually get a reference to the object without