C++: Add tests of strdup (and variants) as allocators.

Author: geoffw0

cpp/ql/test/query-tests/Critical/NewFree/NewFreeMismatch.expected

@@ -18,3 +18,6 @@
 | test.cpp:235:2:235:5 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test.cpp:227:7:227:13 | new | new |
 | test.cpp:239:2:239:5 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test.cpp:228:7:228:17 | new[] | new[] |
 | test.cpp:272:3:272:6 | call to free | There is a new/free mismatch between this free and the corresponding $@. | test.cpp:265:7:265:13 | new | new |
+| test.cpp:441:2:441:10 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:434:13:434:18 | call to strdup | malloc |
+| test.cpp:443:2:443:10 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:436:13:436:19 | call to strndup | malloc |
+| test.cpp:445:2:445:10 | delete | There is a malloc/delete mismatch between this delete and the corresponding $@. | test.cpp:438:16:438:21 | call to wcsdup | malloc |

cpp/ql/test/query-tests/Critical/NewFree/test.cpp

@@ -424,3 +424,24 @@ void test13()
 
 	delete myPointer3.getPointer(); // GOOD
 }
+
+char *strdup(const char *s1);
+char *strndup(const char *s1, size_t n);
+wchar_t* wcsdup(const wchar_t* s1);
+
+void test14()
+{
+	char *s1 = strdup("string");
+	char *s2 = strdup("string");
+	char *s3 = strndup("string", 3);
+	char *s4 = strndup("string", 3);
+	wchar_t *s5 = wcsdup(L"string");
+	wchar_t *s6 = wcsdup(L"string");
+
+	delete s1; // BAD: strdup -> delete
+	free(s2); // GOOD
+	delete s3; // BAD: strndup -> delete
+	free(s4); // GOOD
+	delete s5; // BAD: wcsdup -> delete
+	free(s6); // GOOD
+}