Fix crash when giving -D without argument.

Fixes ticket #2476 (Crash when -D used without parameters.)

cli/cmdlineparser.cpp

@@ -225,12 +225,28 @@ bool CmdLineParser::ParseFromArgs(int argc, const char* const argv[])
         // User define
         else if (strncmp(argv[i], "-D", 2) == 0)
         {
+            std::string define;
+
+            // "-D define"
+            if (strcmp(argv[i], "-D") == 0)
+            {
+                ++i;
+                if (i >= argc)
+                {
+                    PrintMessage("cppcheck: argument to '-D' is missing");
+                    return false;
+                }
+                define = argv[i];
+            }
+            // "-Ddefine"
+            else
+            {
+                define = 2 + argv[i];
+            }
+
             if (!_settings->userDefines.empty())
                 _settings->userDefines += ";";
-            if (strcmp(argv[i], "-D") == 0)
-                _settings->userDefines += argv[++i];
-            else
-                _settings->userDefines += 2 + argv[i];
+            _settings->userDefines += define;
         }
 
         // Include paths

test/testcmdlineparser.cpp

@@ -46,6 +46,7 @@ private:
         TEST_CASE(forcelong);
         TEST_CASE(quietshort);
         TEST_CASE(quietlong);
+        TEST_CASE(defines_noarg);
         TEST_CASE(defines);
         TEST_CASE(defines2);
         TEST_CASE(defines3);
@@ -230,6 +231,15 @@ private:
         ASSERT_EQUALS(true, settings._errorsOnly);
     }
 
+    void defines_noarg()
+    {
+        REDIRECT;
+        const char *argv[] = {"cppcheck", "-D"};
+        Settings settings;
+        CmdLineParser parser(&settings);
+        ASSERT_EQUALS(false, parser.ParseFromArgs(2, argv));
+    }
+
     void defines()
     {
         REDIRECT;