Fix: #2942 (segmentation fault of cppcheck ( #elif (){ ))

http://sourceforge.net/apps/trac/cppcheck/ticket/2942

lib/preprocessor.cpp

@@ -1451,7 +1451,12 @@ void Preprocessor::simplifyCondition(const std::map<std::string, std::string> &c
     Settings settings;
     Tokenizer tokenizer(&settings, NULL);
     std::istringstream istr(("(" + condition + ")").c_str());
-    tokenizer.tokenize(istr, "", "", true);
+    if (!tokenizer.tokenize(istr, "", "", true))
+    {
+        // If tokenize returns false, then there is syntax error in the
+        // code which we can't handle. So stop here.
+        return;
+    }
 
     if (Token::Match(tokenizer.tokens(), "( %var% )"))
     {

test/testpreprocessor.cpp

@@ -230,6 +230,7 @@ private:
 
         // Test Preprocessor::simplifyCondition
         TEST_CASE(simplifyCondition);
+        TEST_CASE(invalidElIf); // #2942 segfault
     }
 
 
@@ -2925,6 +2926,15 @@ private:
         Preprocessor::simplifyCondition(cfg, condition, true);
         ASSERT_EQUALS("1", condition);
     }
+
+    void invalidElIf()
+    {
+        // #2942 - segfault
+        const char code[] = "#elif (){\n";
+        const Settings settings;
+        const std::string actual = Preprocessor::getcode(code, "TEST", "test.c", &settings, this);
+        ASSERT_EQUALS("\n", actual);
+    }
 };
 
 REGISTER_TEST(TestPreprocessor)