fix #2592 (False positive: 'operator=' should return reference to self)

lib/checkclass.cpp

@@ -872,7 +872,9 @@ void CheckClass::checkReturnPtrThis(const Scope *scope, const Function *func, co
             // check of *this is returned
             else if (!(Token::Match(tok->tokAt(1), "(| * this ;|=") ||
                        Token::Match(tok->tokAt(1), "(| * this +=") ||
-                       Token::simpleMatch(tok->tokAt(1), "operator= (")))
+                       Token::simpleMatch(tok->tokAt(1), "operator= (") ||
+                       (Token::Match(tok->tokAt(1), "%type% :: operator= (") &&
+                        tok->next()->str() == scope->className)))
                 operatorEqRetRefThisError(func->token);
         }
     }

test/testclass.cpp

@@ -113,6 +113,7 @@ private:
         TEST_CASE(operatorEqToSelf6);   // ticket # 1550
         TEST_CASE(operatorEqToSelf7);
         TEST_CASE(operatorEqToSelf8);   // ticket #2179
+        TEST_CASE(operatorEqToSelf9);   // ticket #2592
         TEST_CASE(memsetOnStruct);
         TEST_CASE(memsetVector);
         TEST_CASE(memsetOnClass);
@@ -1299,6 +1300,26 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void operatorEqToSelf9()
+    {
+        checkOpertorEqToSelf(
+            "class Foo\n"
+            "{\n"
+            "public:\n"
+            "    Foo& operator=(Foo* pOther);\n"
+            "    Foo& operator=(Foo& other);\n"
+            "};\n"
+            "Foo& Foo::operator=(Foo* pOther)\n"
+            "{\n"
+            "    return *this;\n"
+            "}\n"
+            "Foo& Foo::operator=(Foo& other)\n"
+            "{\n"
+            "    return Foo::operator=(&other);\n"
+            "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     // Check that base classes have virtual destructors
     void checkVirtualDestructor(const char code[])
     {