Merge pull request #18309 from github/calumgrant/bmn/return-stack-allocated-memory

C++: Fix FPs to cpp/return-stack-allocated-memory

cpp/ql/test/query-tests/Likely Bugs/Memory Management/ReturnStackAllocatedMemory/test.cpp

@@ -248,4 +248,5 @@ char* test_strdupa(const char* s) {
 void* test_strndupa(const char* s, size_t size) {
 	char* s2 = strndupa(s, size);
 	return s2; // BAD
-}
+}
+

cpp/ql/test/query-tests/Likely Bugs/Memory Management/ReturnStackAllocatedMemory/test_errors.cpp

@@ -0,0 +1,16 @@
+// semmle-extractor-options: --expect_errors
+
+UNKNOWN_TYPE test_error_value() {
+	UNKNOWN_TYPE x;
+	return x; // GOOD: Error return type
+}
+
+void* test_error_pointer() {
+	UNKNOWN_TYPE x;
+	return &x; // BAD [FALSE NEGATIVE]
+}
+
+int* test_error_pointer_member() {
+	UNKNOWN_TYPE x;
+	return &x.y; // BAD [FALSE NEGATIVE]
+}