C++: Add a test for cpp/wrong-number-format-arguments

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:6:5:6:10 | call to printf | Format for printf expects 1 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

@@ -0,0 +1,7 @@
+// semmle-extractor-options: --expect_errors
+
+extern int printf(const char *fmt, ...);
+
+void test_syntax_error() {
+    printf("Error code %d: " FMT_MSG, 0, "");
+}