Add operator==

Reviewed By: ispeters

Differential Revision: D72884582

fbshipit-source-id: d33645226c1ffbad57eee65b3552a7fca7a3d09b

Author: snarkmaster

third-party/folly/src/folly/ExceptionWrapper.h

@@ -228,6 +228,12 @@ class exception_wrapper final {
   std::exception_ptr to_exception_ptr() const noexcept;
   std::exception_ptr const& exception_ptr_ref() const noexcept;
 
+  //! \return `true` if the wrappers point to the same exception object
+  friend inline bool operator==(
+      exception_wrapper const& lhs, exception_wrapper const& rhs) noexcept {
+    return lhs.ptr_ == rhs.ptr_;
+  }
+
   //! Returns the `typeid` of the wrapped exception object. If there is no
   //!     wrapped exception object, returns `nullptr`.
   std::type_info const* type() const noexcept;

third-party/folly/src/folly/result/result.h

@@ -286,8 +286,7 @@ class result_crtp {
       return b.exp_.hasValue() && a.exp_.value() == b.exp_.value();
     } else if (a.exp_.hasError()) {
       return b.exp_.hasError() &&
-          a.exp_.error().error().exception_ptr_ref() ==
-          b.exp_.error().error().exception_ptr_ref();
+          a.exp_.error().error() == b.exp_.error().error();
     } else { // `a` empty
       return b.is_expected_empty(); // equal iff both are empty
     }

third-party/folly/src/folly/result/test/result_test.cpp

@@ -202,9 +202,7 @@ TEST(Result, copyMethod) {
 
   result<int> rErr{make_exception_wrapper<MyError>("grr")};
   auto rErrToo = rErr.copy();
-  EXPECT_TRUE(
-      rErr.non_value().error().exception_ptr_ref() ==
-      rErrToo.non_value().error().exception_ptr_ref());
+  EXPECT_EQ(rErr.non_value().error(), rErrToo.non_value().error());
   EXPECT_TRUE(rErr == rErrToo);
 
   EXPECT_TRUE(rErr != r);

third-party/folly/src/folly/test/ExceptionWrapperTest.cpp

@@ -100,6 +100,21 @@ TEST(ExceptionWrapper, members) {
   EXPECT_EQ(ew.class_name(), kRuntimeErrorClassName);
 }
 
+TEST(ExceptionWrapper, equality) {
+  auto ew = make_exception_wrapper<std::runtime_error>("wat");
+  EXPECT_EQ(ew, ew);
+
+  auto ewSame = ew;
+  EXPECT_EQ(ew, ewSame);
+
+  // Before C++20, operator!= is not defaulted based on operator==
+#if FOLLY_CPLUSPLUS >= 202002L
+  auto ewDiff = make_exception_wrapper<std::runtime_error>("wat");
+  EXPECT_NE(ewDiff, ew);
+  EXPECT_NE(ewDiff, ewSame);
+#endif
+}
+
 TEST(ExceptionWrapper, tryAndCatchTest) {
   auto ew4 = try_and_catch([] { throw 17; });
   EXPECT_TRUE(bool(ew4));