Merge f1e068d5c577a019f1f6c199f2e3f21859c45d13 into 7140cd416cecd7462a8aae488024abeee55598e4

PiperOrigin-RevId: 925686474
Change-Id: I7b5d7e82dc8618d6914844446fa260468b947ece

docs/gmock_cook_book.md

@@ -3386,30 +3386,6 @@ With this definition, the above assertion will give a better message:
     Actual: 27 (the remainder is 6)
 ```
 
-#### Using EXPECT_ Statements in Matchers
-
-You can also use `EXPECT_...` statements inside custom matcher definitions. In
-many cases, this allows you to write your matcher more concisely while still
-providing an informative error message. For example:
-
-```cpp
-MATCHER(IsDivisibleBy7, "") {
-  const auto remainder = arg % 7;
-  EXPECT_EQ(remainder, 0);
-  return true;
-}
-```
-
-If you write a test that includes the line `EXPECT_THAT(27, IsDivisibleBy7());`,
-you will get an error something like the following:
-
-```shell
-Expected equality of these values:
-  remainder
-    Which is: 6
-  0
-```
-
 #### `MatchAndExplain`
 
 You should let `MatchAndExplain()` print *any additional information* that can
@@ -3429,6 +3405,66 @@ the value of `(arg % 7) == 0` can be implicitly converted to a `bool`. In the
 `arg_type` will be `int`; if it takes an `unsigned long`, `arg_type` will be
 `unsigned long`; and so on.
 
+#### Anti-pattern: Using EXPECT_ Statements in Matchers
+
+Using `EXPECT_...` statements inside custom matcher definitions is an
+**anti-pattern** and should be avoided.
+
+While it might appear to write matchers more concisely and generate informative
+messages, this pattern has critical issues:
+
+1.  **Negation Breakage (`Not`):** If wrapped in `Not(IsDivisibleBy7())`,
+    evaluating it still triggers the internal `EXPECT_EQ`, registering a test
+    failure on the runner even when the overall assertion is expected to
+    succeed.
+2.  **Composition / Container Breakage (`AnyOf`, `AllOf`, `Contains`):** When
+    composed or used inside container matchers, elements that are expected
+    mismatches will trigger the internal `EXPECT_` and register spurious
+    failures.
+3.  **ASSERT_* compilation errors:** `ASSERT_*` macros use `return;` to abort
+    from a void function. Since matchers return `bool`, using `ASSERT_` inside
+    them triggers a compilation error.
+4.  **Purity Violations:** Matchers must be functionally pure (side-effect
+    free), whereas registering global failures is a major side effect.
+5.  **Line Number Confusion:** Failure reports point to the matcher's definition
+    line rather than the calling `EXPECT_THAT`
+    line.
+
+##### The Anti-Pattern
+
+```cpp
+// Anti-pattern: Do not do this!
+MATCHER(IsDivisibleBy7, "") {
+  const auto remainder = arg % 7;
+  EXPECT_EQ(remainder, 0);  // Spurious failures if negated/composed!
+  return true;
+}
+```
+
+##### The Correct Solution
+
+To write concise matchers that delegate to other matchers and safely propagate
+the mismatch explanation, use **`::testing::ExplainMatchResult`** instead,
+passing it the sub-matcher, the value to check, and the `result_listener`:
+
+```cpp
+MATCHER(IsDivisibleBy7, "") {
+  const auto remainder = arg % 7;
+  return ::testing::ExplainMatchResult(::testing::Eq(0), remainder,
+                                       result_listener);
+}
+```
+
+If you write a test that includes the line:
+
+```cpp
+EXPECT_THAT(28, Not(IsDivisibleBy7()));
+```
+
+it will correctly report the mismatch, properly point to the `EXPECT_THAT` line
+number, and support negation (`Not`) and composition (`AllOf`, `AnyOf`, etc.)
+without registering spurious failures.
+
 ### Writing New Parameterized Matchers Quickly
 
 Sometimes you'll want to define a matcher that has parameters. For that you can

googlemock/include/gmock/gmock-spec-builders.h

@@ -1957,6 +1957,11 @@ struct SignatureOf<R(Args...)> {
   using type = R(Args...);
 };
 
+template <typename R, typename... Args>
+struct SignatureOf<R(Args...) const> {
+  using type = R(Args...);
+};
+
 template <template <typename> class C, typename F>
 struct SignatureOf<C<F>,
                    typename std::enable_if<std::is_function<F>::value>::type>

googlemock/test/gmock-function-mocker_test.cc

@@ -942,6 +942,15 @@ static constexpr bool IsMockFunctionTemplateArgumentDeducedTo(
 
 }  // namespace
 
+// Like std::add_const, but for function types.
+template <typename F>
+struct AddConstToFunction;
+
+template <typename R, typename... Args>
+struct AddConstToFunction<R(Args...)> {
+  using type = R(Args...) const;
+};
+
 template <typename F>
 class MockMethodMockFunctionSignatureTest : public Test {};
 
@@ -953,25 +962,69 @@ TYPED_TEST_SUITE(MockMethodMockFunctionSignatureTest,
 
 TYPED_TEST(MockMethodMockFunctionSignatureTest,
            IsMockFunctionTemplateArgumentDeducedForRawSignature) {
-  using Argument = TypeParam;
+  // Non-const
-  MockFunction<Argument> foo;
+  {
-  EXPECT_TRUE(IsMockFunctionTemplateArgumentDeducedTo<TypeParam>(foo));
+    using Argument = TypeParam;
+    MockFunction<Argument> foo;
+    EXPECT_TRUE(IsMockFunctionTemplateArgumentDeducedTo<TypeParam>(foo));
+  }
+
+  // Const
+  {
+    using Argument = typename AddConstToFunction<TypeParam>::type;
+    MockFunction<Argument> foo;
+    EXPECT_TRUE(IsMockFunctionTemplateArgumentDeducedTo<TypeParam>(foo));
+  }
 }
 
 TYPED_TEST(MockMethodMockFunctionSignatureTest,
            IsMockFunctionTemplateArgumentDeducedForStdFunction) {
-  using Argument = std::function<TypeParam>;
+  // Non-const
-  MockFunction<Argument> foo;
+  {
-  EXPECT_TRUE(IsMockFunctionTemplateArgumentDeducedTo<TypeParam>(foo));
+    using Argument = std::function<TypeParam>;
+    MockFunction<Argument> foo;
+    EXPECT_TRUE(IsMockFunctionTemplateArgumentDeducedTo<TypeParam>(foo));
+  }
+
+// As of 2026-05 MSVC doesn't know how to deal with this, providing pages of
+// inscrutable errors about std::_Get_function_impl. But this is fine, since
+// std::function<R(Args...) const> doesn't apply the const qualifier correctly
+// anyway.
+#if !defined(_MSC_VER)
+
+  // Const
+  {
+    using Argument =
+        std::function<typename AddConstToFunction<TypeParam>::type>;
+
+    MockFunction<Argument> foo;
+    EXPECT_TRUE(IsMockFunctionTemplateArgumentDeducedTo<TypeParam>(foo));
+  }
+
+#endif
 }
 
 TYPED_TEST(
     MockMethodMockFunctionSignatureTest,
     IsMockFunctionCallMethodSignatureTheSameForRawSignatureAndStdFunction) {
-  using ForRawSignature = decltype(&MockFunction<TypeParam>::Call);
+  // Non-const
-  using ForStdFunction =
+  {
-      decltype(&MockFunction<std::function<TypeParam>>::Call);
+    using ForRawSignature = decltype(&MockFunction<TypeParam>::Call);
-  EXPECT_TRUE((std::is_same<ForRawSignature, ForStdFunction>::value));
+    using ForStdFunction =
+        decltype(&MockFunction<std::function<TypeParam>>::Call);
+    EXPECT_TRUE((std::is_same<ForRawSignature, ForStdFunction>::value));
+  }
+
+  // Const
+  {
+    using ConstTypeParam = typename AddConstToFunction<TypeParam>::type;
+    using ForRawSignature = decltype(&MockFunction<ConstTypeParam>::Call);
+
+    using ForStdFunction =
+        decltype(&MockFunction<std::function<ConstTypeParam>>::Call);
+
+    EXPECT_TRUE((std::is_same<ForRawSignature, ForStdFunction>::value));
+  }
 }
 
 template <typename F>

googletest/include/gtest/gtest-message.h

@@ -129,7 +129,7 @@ class GTEST_API_ Message {
                               int>::type = 0
 #endif  // GTEST_HAS_ABSL
       >
-  inline Message& operator<<(const T& val) {
+  Message& operator<<(const T& val) {
         // Some libraries overload << for STL containers.  These
     // overloads are defined in the global namespace instead of ::std.
     //
@@ -155,7 +155,7 @@ class GTEST_API_ Message {
   template <typename T,
             typename std::enable_if<absl::HasAbslStringify<T>::value,  // NOLINT
                                     int>::type = 0>
-  inline Message& operator<<(const T& val) {
+  Message& operator<<(const T& val) {
     // ::operator<< is needed here for a similar reason as with the non-Abseil
     // version above
     using ::operator<<;

googletest/include/gtest/internal/gtest-death-test-internal.h

@@ -229,7 +229,8 @@ GTEST_API_ bool ExitedUnsuccessfully(int exit_status);
       goto GTEST_CONCAT_TOKEN_(gtest_label_, __LINE__);                        \
     }                                                                          \
     if (gtest_dt != nullptr) {                                                 \
-      std::unique_ptr< ::testing::internal::DeathTest> gtest_dt_ptr(gtest_dt); \
+      const std::unique_ptr< ::testing::internal::DeathTest> gtest_dt_ptr(     \
+          gtest_dt);                                                           \
       switch (gtest_dt->AssumeRole()) {                                        \
         case ::testing::internal::DeathTest::OVERSEE_TEST:                     \
           if (!gtest_dt->Passed(predicate(gtest_dt->Wait()))) {                \

googletest/include/gtest/internal/gtest-param-util.h

@@ -99,6 +99,7 @@ class [[nodiscard]] ParamGenerator;
 template <typename T>
 class [[nodiscard]] ParamIteratorInterface {
  public:
+  ParamIteratorInterface() = default;
   virtual ~ParamIteratorInterface() = default;
   // A pointer to the base generator instance.
   // Used only for the purposes of iterator comparison
@@ -121,6 +122,9 @@ class [[nodiscard]] ParamIteratorInterface {
   // element in the sequence generated by the generator.
   // Used for implementing ParamGenerator<T>::operator==().
   virtual bool Equals(const ParamIteratorInterface& other) const = 0;
+ protected:
+  // Make available for subclasses to use to implement Clone().
+  ParamIteratorInterface(const ParamIteratorInterface&) = default;
 };
 
 // Class iterating over elements provided by an implementation of
@@ -844,7 +848,7 @@ class [[nodiscard]] CartesianProductGenerator
   template <class I>
   class IteratorImpl;
   template <size_t... I>
-  class IteratorImpl<std::index_sequence<I...>>
+  class IteratorImpl<std::index_sequence<I...>> final
       : public ParamIteratorInterface<ParamType> {
    public:
     IteratorImpl(const ParamGeneratorInterface<ParamType>* base,
@@ -856,7 +860,7 @@ class [[nodiscard]] CartesianProductGenerator
           current_(is_end ? end_ : begin_) {
       ComputeCurrentValue();
     }
-    ~IteratorImpl() override = default;
+    ~IteratorImpl() final = default;
 
     const ParamGeneratorInterface<ParamType>* BaseGenerator() const override {
       return base_;
@@ -900,6 +904,8 @@ class [[nodiscard]] CartesianProductGenerator
     }
 
    private:
+    IteratorImpl(const IteratorImpl&) = default;
+
     template <size_t ThisI>
     void AdvanceIfEnd() {
       if (std::get<ThisI>(current_) != std::get<ThisI>(end_)) return;