C++20 fixes

include/llvm/ADT/DenseMap.h

@@ -1244,30 +1244,19 @@ public:
     return Ptr;
   }
 
-#ifdef __clang__
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wambiguous-reversed-operator"
-#endif
-  bool operator==(const ConstIterator &RHS) const {
-    assert((!Ptr || isHandleInSync()) && "handle not in sync!");
+  friend bool operator==(const DenseMapIterator &LHS,
+                         const DenseMapIterator &RHS) {
+    assert((!LHS.Ptr || LHS.isHandleInSync()) && "handle not in sync!");
     assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
-    assert(getEpochAddress() == RHS.getEpochAddress() &&
+    assert(LHS.getEpochAddress() == RHS.getEpochAddress() &&
            "comparing incomparable iterators!");
-    return Ptr == RHS.Ptr;
+    return LHS.Ptr == RHS.Ptr;
   }
-#ifdef __clang__
-#pragma clang diagnostic pop
-#endif
-#if __cpp_impl_three_way_comparison >= 201711
-#else
-  bool operator!=(const ConstIterator &RHS) const {
-    assert((!Ptr || isHandleInSync()) && "handle not in sync!");
-    assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
-    assert(getEpochAddress() == RHS.getEpochAddress() &&
-           "comparing incomparable iterators!");
-    return Ptr != RHS.Ptr;
+
+  friend bool operator!=(const DenseMapIterator &LHS,
+                         const DenseMapIterator &RHS) {
+    return !(LHS == RHS);
   }
-#endif
 
   inline DenseMapIterator& operator++() {  // Preincrement
     assert(isHandleInSync() && "invalid iterator access!");

include/llvm/ADT/STLExtras.h

@@ -558,12 +558,12 @@ public:
     return *this;
   }
 
-  using BaseT::operator==;
-  bool operator==(const early_inc_iterator_impl &RHS) const {
+  friend bool operator==(const early_inc_iterator_impl &LHS,
+                         const early_inc_iterator_impl &RHS) {
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
-    assert(!IsEarlyIncremented && "Cannot compare after dereferencing!");
+    assert(!LHS.IsEarlyIncremented && "Cannot compare after dereferencing!");
 #endif
-    return BaseT::operator==(RHS);
+    return (const BaseT &)LHS == (const BaseT &)RHS;
   }
 };
 

include/llvm/ADT/iterator.h

@@ -142,9 +142,11 @@ public:
     return tmp;
   }
 
+#ifndef __cpp_impl_three_way_comparison
   bool operator!=(const DerivedT &RHS) const {
-    return !static_cast<const DerivedT *>(this)->operator==(RHS);
+    return !(static_cast<const DerivedT &>(*this) == RHS);
   }
+#endif
 
   bool operator>(const DerivedT &RHS) const {
     static_assert(
@@ -260,12 +262,16 @@ public:
     return *static_cast<DerivedT *>(this);
   }
 
-  bool operator==(const DerivedT &RHS) const { return I == RHS.I; }
-  bool operator<(const DerivedT &RHS) const {
+  friend bool operator==(const iterator_adaptor_base &LHS,
+                         const iterator_adaptor_base &RHS) {
+    return LHS.I == RHS.I;
+  }
+  friend bool operator<(const iterator_adaptor_base &LHS,
+                        const iterator_adaptor_base &RHS) {
     static_assert(
         BaseT::IsRandomAccess,
         "Relational operators are only defined for random access iterators.");
-    return I < RHS.I;
+    return LHS.I < RHS.I;
   }
 
   ReferenceT operator*() const { return *I; }

lib/ObjectYAML/DWARFEmitter.cpp

@@ -397,7 +397,7 @@ Error DWARFYAML::emitDebugAddr(raw_ostream &OS, const Data &DI) {
     writeInteger((uint8_t)TableEntry.SegSelectorSize, OS, DI.IsLittleEndian);
 
     for (const SegAddrPair &Pair : TableEntry.SegAddrPairs) {
-      if (TableEntry.SegSelectorSize != 0)
+      if (TableEntry.SegSelectorSize != yaml::Hex8{0})
         if (Error Err = writeVariableSizedInteger(Pair.Segment,
                                                   TableEntry.SegSelectorSize,
                                                   OS, DI.IsLittleEndian))