Fix #13167 FP invalidLifetime when constructing string from c_str() (#7231)

Author: chrchr-github

lib/valueflow.cpp

@@ -2647,6 +2647,8 @@ static void valueFlowLifetimeClassConstructor(Token* tok,
                 if (it == scope->varlist.cend())
                     return;
                 const Variable& var = *it;
+                if (var.valueType() && var.valueType()->container && var.valueType()->container->stdStringLike && !var.valueType()->container->view)
+                    return; // TODO: check in isLifetimeBorrowed()?
                 if (var.isReference() || var.isRValueReference()) {
                     ls.byRef(tok, tokenlist, errorLogger, settings);
                 } else if (ValueFlow::isLifetimeBorrowed(ls.argtok, settings)) {

test/testautovariables.cpp

@@ -148,7 +148,7 @@ class TestAutoVariables : public TestFixture {
         TEST_CASE(danglingLifetime);
         TEST_CASE(danglingLifetimeFunction);
         TEST_CASE(danglingLifetimeUserConstructor);
-        TEST_CASE(danglingLifetimeAggegrateConstructor);
+        TEST_CASE(danglingLifetimeAggregateConstructor);
         TEST_CASE(danglingLifetimeInitList);
         TEST_CASE(danglingLifetimeImplicitConversion);
         TEST_CASE(danglingTemporaryLifetime);
@@ -3796,7 +3796,7 @@ class TestAutoVariables : public TestFixture {
         ASSERT_EQUALS("", errout_str());
     }
 
-    void danglingLifetimeAggegrateConstructor() {
+    void danglingLifetimeAggregateConstructor() {
         check("struct A {\n"
               "    const int& x;\n"
               "    int y;\n"
@@ -3893,6 +3893,30 @@ class TestAutoVariables : public TestFixture {
               "    return { m.data() };\n"
               "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check("struct S { std::string s; };\n" // #13167
+              "std::vector<S> f() {\n"
+              "    std::vector<S> v;\n"
+              "    {\n"
+              "        std::string a{ \"abc\" };\n"
+              "        v.push_back({ a.c_str() });\n"
+              "    }\n"
+              "    return v;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+
+        check("struct S { std::string_view sv; };\n"
+              "std::vector<S> f() {\n"
+              "    std::vector<S> v;\n"
+              "    {\n"
+              "        std::string a{ \"abc\" };\n"
+              "        v.push_back({ a.c_str() });\n"
+              "    }\n"
+              "    return v;\n"
+              "}\n");
+        ASSERT_EQUALS(
+            "[test.cpp:6] -> [test.cpp:6] -> [test.cpp:6] -> [test.cpp:5] -> [test.cpp:8]: (error) Returning object that points to local variable 'a' that will be invalid when returning.\n",
+            errout_str());
     }
 
     void danglingLifetimeInitList() {