Fixed false negative danmar#4306: Detect loop access of empty STL container

PKEuS · PKEuS · commit 865df4e207ed · 2014-08-09T10:06:44.000+02:00
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
@@ -1551,10 +1551,14 @@ void CheckStl::readingEmptyStlContainer()
         if (i->type != Scope::eFunction)
             continue;
 
+        const Token* restartTok = nullptr;
         for (const Token *tok = i->classStart->next(); tok != i->classEnd; tok = tok->next()) {
-            if (Token::Match(tok, "for|while|do|}")) { // Loops and end of scope clear the sets.
+            if (Token::Match(tok, "for|while")) { // Loops and end of scope clear the sets.
+                restartTok = tok->linkAt(1); // Check condition to catch looping over empty containers
+            } else if (tok == restartTok || Token::Match(tok, "do|}")) {
                 empty_map.clear();
                 empty_nonmap.clear();
+                restartTok = nullptr;
             }
 
             if (!tok->varId())
diff --git a/test/teststl.cpp b/test/teststl.cpp
@@ -2565,6 +2565,13 @@ class TestStl : public TestFixture {
               "    std::string strValue2 = CMap[1];\n"
               "}\n", true);
         ASSERT_EQUALS("[test.cpp:3]: (style, inconclusive) Reading from empty STL container\n", errout.str());
+
+        // #4306
+        check("void f(std::vector<int> v) {\n"
+              "    v.clear();\n"
+              "    for(int i = 0; i < v.size(); i++) { cout << v[i]; }\n"
+              "}", true);
+        ASSERT_EQUALS("[test.cpp:3]: (style, inconclusive) Reading from empty STL container\n", errout.str());
     }
 };
 
