DenseMapInfo: support std::optional<T> (#147851)

Author: elijahkin

llvm/include/llvm/ADT/DenseMapInfo.h

@@ -17,6 +17,7 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 #include <tuple>
 #include <type_traits>
 #include <utility>
@@ -320,6 +321,28 @@ struct DenseMapInfo<Enum, std::enable_if_t<std::is_enum_v<Enum>>> {
 
   static bool isEqual(const Enum &LHS, const Enum &RHS) { return LHS == RHS; }
 };
+
+template <typename T> struct DenseMapInfo<std::optional<T>> {
+  using Optional = std::optional<T>;
+  using Info = DenseMapInfo<T>;
+
+  static inline Optional getEmptyKey() { return {Info::getEmptyKey()}; }
+
+  static inline Optional getTombstoneKey() { return {Info::getTombstoneKey()}; }
+
+  static unsigned getHashValue(const Optional &OptionalVal) {
+    return detail::combineHashValue(
+        OptionalVal.has_value(),
+        Info::getHashValue(OptionalVal.value_or(Info::getEmptyKey())));
+  }
+
+  static bool isEqual(const Optional &LHS, const Optional &RHS) {
+    if (LHS && RHS) {
+      return Info::isEqual(LHS.value(), RHS.value());
+    }
+    return !LHS && !RHS;
+  }
+};
 } // end namespace llvm
 
 #endif // LLVM_ADT_DENSEMAPINFO_H

llvm/unittests/ADT/DenseMapTest.cpp

@@ -15,6 +15,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <map>
+#include <optional>
 #include <set>
 #include <utility>
 #include <variant>
@@ -86,6 +87,14 @@ struct CtorTesterMapInfo {
 CtorTester getTestKey(int i, CtorTester *) { return CtorTester(i); }
 CtorTester getTestValue(int i, CtorTester *) { return CtorTester(42 + i); }
 
+std::optional<uint32_t> getTestKey(int i, std::optional<uint32_t> *) {
+  return i;
+}
+
+std::optional<uint32_t> getTestValue(int i, std::optional<uint32_t> *) {
+  return 42 + i;
+}
+
 // Test fixture, with helper functions implemented by forwarding to global
 // function overloads selected by component types of the type parameter. This
 // allows all of the map implementations to be tested with shared
@@ -117,11 +126,13 @@ typedef ::testing::Types<DenseMap<uint32_t, uint32_t>,
                          DenseMap<uint32_t *, uint32_t *>,
                          DenseMap<CtorTester, CtorTester, CtorTesterMapInfo>,
                          DenseMap<EnumClass, uint32_t>,
+                         DenseMap<std::optional<uint32_t>, uint32_t>,
                          SmallDenseMap<uint32_t, uint32_t>,
                          SmallDenseMap<uint32_t *, uint32_t *>,
                          SmallDenseMap<CtorTester, CtorTester, 4,
                                        CtorTesterMapInfo>,
-                         SmallDenseMap<EnumClass, uint32_t>
+                         SmallDenseMap<EnumClass, uint32_t>,
+                         SmallDenseMap<std::optional<uint32_t>, uint32_t>
                          > DenseMapTestTypes;
 // clang-format on