[ADT] Add operator! to BitmaskEnum (llvm#139958)

Add a logical (boolean) "not" operator.

Author: kparzysz

llvm/include/llvm/ADT/BitmaskEnum.h

@@ -92,6 +92,7 @@
   using ::llvm::BitmaskEnumDetail::operator^=;                                 \
   using ::llvm::BitmaskEnumDetail::operator<<=;                                \
   using ::llvm::BitmaskEnumDetail::operator>>=;                                \
+  using ::llvm::BitmaskEnumDetail::operator!;                                  \
   /* Force a semicolon at the end of this macro. */                            \
   using ::llvm::BitmaskEnumDetail::any
 
@@ -141,6 +142,11 @@ constexpr unsigned bitWidth(uint64_t Value) {
   return Value ? 1 + bitWidth(Value >> 1) : 0;
 }
 
+template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
+constexpr bool operator!(E Val) {
+  return Val == static_cast<E>(0);
+}
+
 template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
 constexpr bool any(E Val) {
   return Val != static_cast<E>(0);

llvm/unittests/ADT/BitmaskEnumTest.cpp

@@ -176,6 +176,17 @@ TEST(BitmaskEnumTest, BitwiseNot) {
   EXPECT_EQ(15, ~V0);
 }
 
+TEST(BitmaskEnumTest, BooleanNot) {
+  bool b0 = !F0;
+  EXPECT_TRUE(b0);
+
+  bool b1 = !(F1 & F2);
+  EXPECT_TRUE(b1);
+
+  bool b2 = !(F2 | F4);
+  EXPECT_FALSE(b2);
+}
+
 enum class FlagsClass {
   F0 = 0,
   F1 = 1,