Fixed false positive cppcheck-opensource#6481

Author: PKEuS

lib/checkmemoryleak.cpp

@@ -2745,7 +2745,7 @@ void CheckMemoryLeakNoVar::check()
 void CheckMemoryLeakNoVar::checkForUnusedReturnValue(const Scope *scope)
 {
     for (const Token *tok = scope->classStart; tok != scope->classEnd; tok = tok->next()) {
-        if (Token::Match(tok, "%name% (") && (!tok->next()->astParent() || tok->next()->astParent()->str() == "!" || tok->next()->astParent()->isComparisonOp())) {
+        if (Token::Match(tok, "%name% (") && (!tok->next()->astParent() || tok->next()->astParent()->str() == "!" || tok->next()->astParent()->isComparisonOp()) && tok->next()->astOperand1() == tok) {
             const AllocType allocType = getAllocationType(tok, 0);
             if (allocType != No)
                 returnValueNotUsedError(tok, tok->str());

test/testmemleak.cpp

@@ -6503,6 +6503,12 @@ class TestMemleakNoVar : public TestFixture {
               "    if(!malloc(5)) fail();\n"
               "}");
         ASSERT_EQUALS("[test.cpp:3]: (error) Return value of allocation function malloc is not stored.\n", errout.str());
+
+        check("FOO* factory() {\n"
+              "    FOO* foo = new (std::nothrow) FOO;\n"
+              "    return foo;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void smartPointerFunctionParam() {