fixed #14326 - crash (null-pointer-use) in CheckStl::invalidContainer() with incomplete code

Author: firewave

lib/checkstl.cpp

@@ -1138,7 +1138,7 @@ void CheckStl::invalidContainer()
                     continue;
                 if (!astIsContainer(contTok))
                     continue;
-                for (const Token* tok2 = blockStart; tok2 != blockEnd; tok2 = tok2->next()) {
+                for (const Token* tok2 = blockStart; tok2 && tok2 != blockEnd; tok2 = tok2->next()) {
                     bool bail = false;
                     for (const InvalidContainerAnalyzer::Info::Reference& r : analyzer.invalidatesContainer(tok2)) {
                         if (!astIsContainer(r.tok))

test/teststl.cpp

@@ -6515,6 +6515,13 @@ class TestStl : public TestFixture {
         ASSERT_EQUALS(
             "[test.cpp:7:17] -> [test.cpp:7:24] -> [test.cpp:8:10] -> [test.cpp:9:18]: (error) Reference to vec1 that may be invalid. [invalidContainerReference]\n",
             errout_str());
+
+        // #14326
+        check("void f(const std::vector<std::string>& v)\n"
+              "{\n"
+              "for (const std::string&s : v)\n"
+              "}\n"); // don't crash
+        ASSERT_EQUALS("", errout_str());
     }
 
     void invalidContainerLoop() {