C++: Add a test that needs an access path at the source.

Author: MathiasVP

cpp/ql/test/library-tests/dataflow/external-models/flow.ext.yml

@@ -4,6 +4,7 @@ extensions:
       extensible: sourceModel
     data: # namespace, type, subtypes, name, signature, ext, output, kind, provenance
       - ["", "", False, "ymlSource", "", "", "ReturnValue", "local", "manual"]
+      - ["", "", False, "ymlFieldSource", "", "", "ReturnValue.Field[SourceWrapper::value]", "local", "manual"]
   - addsTo:
       pack: codeql/cpp-all
       extensible: sinkModel

cpp/ql/test/library-tests/dataflow/external-models/sinks.expected

@@ -23,3 +23,4 @@
 | test.cpp:201:10:201:10 | x | test-sink |
 | test.cpp:218:11:218:11 | x | test-sink |
 | test.cpp:224:11:224:11 | c | test-sink |
+| test.cpp:236:18:236:22 | value | test-sink |

cpp/ql/test/library-tests/dataflow/external-models/test.cpp

@@ -223,4 +223,16 @@ void test_reverse_flow(unsigned i, unsigned j) {
 		char c = s[j];
 		ymlSink(c); // $ ir
 	}
-}
+}
+
+struct SourceWrapper {
+	int value;
+};
+
+SourceWrapper ymlFieldSource();
+
+void test_source_access_path() {
+	SourceWrapper wrapper = ymlFieldSource();
+	ymlSink(wrapper.value); // $ MISSING: ir
+}
+