Fix 11024: FP returnDanglingLifetime with c_str() passed to constructor (#4072)

Author: pfultz2

lib/valueflow.cpp

@@ -3888,6 +3888,8 @@ static void valueFlowLifetimeConstructor(Token* tok,
             const Token* expr = tok2->astOperand2();
             if (!var)
                 continue;
+            if (!isLifetimeBorrowed(expr, settings))
+                continue;
             const Variable* argvar = getLifetimeVariable(expr);
             if (var->isReference() || var->isRValueReference()) {
                 if (argvar && argvar->isArgument() && (argvar->isReference() || argvar->isRValueReference())) {

test/testautovariables.cpp

@@ -3269,6 +3269,17 @@ class TestAutoVariables : public TestFixture {
               "}\n",
               true);
         ASSERT_EQUALS("", errout.str());
+
+        check("struct S {\n"
+              "    std::string msg;\n"
+              "    explicit S(const char* m) : msg(m) {}\n"
+              "};\n"
+              "S f() {\n"
+              "    std::string s(\"abc\");\n"
+              "    return S(s.c_str());\n"
+              "}\n",
+              true);
+        ASSERT_EQUALS("", errout.str());
     }
 
     void danglingLifetimeAggegrateConstructor() {