C++: Add another test case

Author: calumgrant

cpp/ql/test/query-tests/Likely Bugs/Format/WrongNumberOfFormatArguments/WrongNumberOfFormatArguments.expected

@@ -5,6 +5,7 @@
 | macros.cpp:14:2:14:37 | call to printf | Format for printf (in a macro expansion) expects 4 arguments but given 3 |
 | macros.cpp:21:2:21:36 | call to printf | Format for printf (in a macro expansion) expects 4 arguments but given 3 |
 | macros.cpp:32:2:32:25 | call to printf | Format for printf (in a macro expansion) expects 1 arguments but given 0 |
+| syntax_errors.c:15:5:15:10 | call to printf | Format for printf expects 2 arguments but given 0 |
 | test.c:9:2:9:7 | call to printf | Format for printf expects 1 arguments but given 0 |
 | test.c:12:2:12:7 | call to printf | Format for printf expects 2 arguments but given 1 |
 | test.c:15:2:15:7 | call to printf | Format for printf expects 3 arguments but given 2 |

cpp/ql/test/query-tests/Likely Bugs/Format/WrongNumberOfFormatArguments/syntax_errors.c

@@ -3,9 +3,16 @@
 extern int printf(const char *fmt, ...);
 
 void test_syntax_error() {
+    // GOOD
     printf("Error code %d: " UNDEFINED_MACRO, 0, "");
 
+    // GOOD
     printf("%d%d",
         (UNDEFINED_MACRO)1,
         (UNDEFINED_MACRO)2);
+
+    // GOOD [FALSE POSITIVE]
+    printf("%d%d"
+        UNDEFINED_MACRO,
+        1, 2);
 }