Fixed danmar#7930 (Improve check: Missing stlcstr warning for reference variable)

danmar · danmar · commit 279425499e44 · 2017-03-01T02:03:08.000+01:00
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
@@ -1106,7 +1106,14 @@ void CheckStl::string_c_str()
                 bool funcStr = false;
                 if (Token::Match(tok2, "%var% .")) {
                     local = isLocal(tok2);
-                    ptrOrRef = tok2->variable() && (tok2->variable()->isPointer() || tok2->variable()->isReference());
+                    bool refToNonLocal = false;
+                    if (tok2->variable() && tok2->variable()->isReference()) {
+                        const Token *refTok = tok2->variable()->nameToken();
+                        refToNonLocal = true; // safe assumption is default to avoid FPs
+                        if (Token::Match(refTok, "%var% = %var% .|;|["))
+                            refToNonLocal = !isLocal(refTok->tokAt(2));
+                    }
+                    ptrOrRef = refToNonLocal || (tok2->variable() && tok2->variable()->isPointer());
                 }
                 while (tok2) {
                     if (Token::Match(tok2, "%var% .|::")) {
diff --git a/test/teststl.cpp b/test/teststl.cpp
@@ -2375,6 +2375,16 @@ class TestStl : public TestFixture {
               "    return s.data.c_str();\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        check("struct S {\n" // #7930
+              "    std::string data;\n"
+              "};\n"
+              "const char* test() {\n"
+              "    S s;\n"
+              "    std::string &ref = s.data;\n"
+              "    return ref.c_str();\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:7]: (error) Dangerous usage of c_str(). The value returned by c_str() is invalid after this call.\n", errout.str());
     }
 
     void autoPointer() {
