Fixes for CheckStl::string_c_str():

PKEuS · PKEuS · commit 896582ce5687 · 2016-05-06T17:25:00.000+02:00
- Fixed false positive danmar#7480 - Fixed false negative: Show performance message also for non-local objects
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
@@ -1047,14 +1047,18 @@ void CheckStl::string_c_str()
                 }
 
                 bool local = false;
+                bool ptr = false;
                 const Variable* lastVar = nullptr;
                 const Function* lastFunc = nullptr;
                 bool funcStr = false;
                 if (Token::Match(tok2, "%var% .")) {
                     local = isLocal(tok2);
+                    ptr = tok2->variable() && tok2->variable()->isPointer();
                 }
                 while (tok2) {
                     if (Token::Match(tok2, "%var% .|::")) {
+                        if (ptr)
+                            local = false;
                         lastVar = tok2->variable();
                         tok2 = tok2->tokAt(2);
                     } else if (Token::Match(tok2, "%name% (") && Token::simpleMatch(tok2->linkAt(1), ") .")) {
@@ -1067,7 +1071,7 @@ void CheckStl::string_c_str()
                 }
 
                 if (Token::Match(tok2, "c_str|data ( ) ;")) {
-                    if (local && lastVar && lastVar->isStlStringType())
+                    if ((local || returnType != charPtr) && lastVar && lastVar->isStlStringType())
                         err = true;
                     else if (funcStr && lastVar && lastVar->isStlType(stl_string_stream))
                         err = true;
diff --git a/test/teststl.cpp b/test/teststl.cpp
@@ -2303,6 +2303,34 @@ class TestStl : public TestFixture {
               "    return String::Format(\"%s:\", name).c_str();\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        // #7480
+        check("struct InternalMapInfo {\n"
+              "    std::string author;\n"
+              "};\n"
+              "const char* GetMapAuthor(int index) {\n"
+              "    const InternalMapInfo* mapInfo = &internal_getMapInfo;\n"
+              "    return mapInfo->author.c_str();\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        check("struct InternalMapInfo {\n"
+              "    std::string author;\n"
+              "};\n"
+              "std::string GetMapAuthor(int index) {\n"
+              "    const InternalMapInfo* mapInfo = &internal_getMapInfo;\n"
+              "    return mapInfo->author.c_str();\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:6]: (performance) Returning the result of c_str() in a function that returns std::string is slow and redundant.\n", errout.str());
+
+        check("struct InternalMapInfo {\n"
+              "    std::string author;\n"
+              "};\n"
+              "const char* GetMapAuthor(int index) {\n"
+              "    const InternalMapInfo mapInfo = internal_getMapInfo;\n"
+              "    return mapInfo.author.c_str();\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:6]: (error) Dangerous usage of c_str(). The value returned by c_str() is invalid after this call.\n", errout.str());
     }
 
     void autoPointer() {
