C++: Add regression test

Author: calumgrant

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

@@ -10,3 +10,6 @@
 | test.c:15:2:15:7 | call to printf | Format for printf expects 3 arguments but given 2 |
 | test.c:19:2:19:7 | call to printf | Format for printf expects 2 arguments but given 1 |
 | test.c:29:3:29:8 | call to printf | Format for printf expects 2 arguments but given 1 |
+| test.c:51:2:51:10 | call to my_logger | Format for my_logger expects 6 arguments but given 1 |
+| test.c:52:2:52:10 | call to my_logger | Format for my_logger expects 3 arguments but given 0 |
+| test.c:53:2:53:10 | call to my_logger | Format for my_logger expects 3 arguments but given 0 |

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

@@ -44,3 +44,6 @@ void test_custom_printf2()
 	printf("",           "%i %i",  100, 200); // GOOD
 	printf("%i %i",      ""        );         // GOOD
 }
+
+extern "C" void my_logger(int param, char *fmt, ...) __attribute__((format(printf, 2, 3))) {}
+

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

@@ -46,4 +46,12 @@ void test(int i, const char *str)
 	printf("%Y", 1, 2); // GOOD (unknown format character, this might be correct)
 	printf("%1.1Y", 1, 2); // GOOD (unknown format character, this might be correct)
 	printf("%*.*Y", 1, 2); // GOOD (unknown format character, this might be correct)
+
+	// Implicit logger function declaration
+	my_logger(0, "%i %i %i %i %i %i\n", 1, 2, 3, 4, 5, 6); // GOOD (FP)
+	my_logger(0, "%i %i %i\n", 1, 2, 3); // GOOD (FP)
+	my_logger(0, "%i %i %i\n", 1, 2); // BAD (too few format arguments)
 }
+
+// A spurious definition of my_logger
+extern void my_logger(int param, char *fmt, int, int, int, int, int);