Provide a better error message when ASSERT and SKIP macros are used in methods that return values

PiperOrigin-RevId: 788083860
Change-Id: I91583f0c0f816144428d56ab07e58fd035c532d1

Author: Abseil Team

googletest/include/gtest/gtest.h

@@ -1610,6 +1610,8 @@ GTEST_API_ AssertionResult DoubleNearPredFormat(const char* expr1,
                                                 double val1, double val2,
                                                 double abs_error);
 
+using GoogleTest_NotSupported_OnFunctionReturningNonVoid = void;
+
 // INTERNAL IMPLEMENTATION - DO NOT USE IN USER CODE.
 // A class that enables one to stream messages to assertion macros
 class GTEST_API_ AssertHelper {
@@ -1621,7 +1623,8 @@ class GTEST_API_ AssertHelper {
 
   // Message assignment is a semantic trick to enable assertion
   // streaming; see the GTEST_MESSAGE_ macro below.
-  void operator=(const Message& message) const;
+  GoogleTest_NotSupported_OnFunctionReturningNonVoid operator=(
+      const Message& message) const;
 
  private:
   // We put our data in a struct so that the size of the AssertHelper class can