C++: Add a failing test with a default argument constructor.

Author: MathiasVP

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

@@ -49,6 +49,7 @@ extensions:
       - ["", "Container", True, "emplace", "", "", "Argument[forward].Parameter[-1]", "Argument[-1].Element", "value", "manual"]
       - ["", "Container", True, "get", "", "", "Argument[-1].Element", "ReturnValue[*]", "value", "manual"]
       - ["", "Element", True, "Element", "", "", "Argument[0]", "Argument[-1].Field[Element::x]", "value", "manual"]
+      - ["", "ElementWithDefaultArgument", True, "ElementWithDefaultArgument", "", "", "Argument[0]", "Argument[-1].Field[ElementWithDefaultArgument::x]", "value", "manual"]
   - addsTo:
       pack: codeql/cpp-all
       extensible: forwardsModel

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

@@ -48,3 +48,4 @@
 | test.cpp:374:15:374:15 | s | test-sink |
 | test.cpp:375:15:375:16 | ul | test-sink |
 | test.cpp:398:13:398:13 | x | test-sink |
+| test.cpp:412:13:412:13 | x | test-sink |

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

@@ -22,6 +22,7 @@
 | test.cpp:361:15:361:23 | call to ymlSource | local |
 | test.cpp:370:24:370:32 | call to ymlSource | local |
 | test.cpp:394:11:394:19 | call to ymlSource | local |
+| test.cpp:408:11:408:19 | call to ymlSource | local |
 | windows.cpp:22:15:22:29 | call to GetCommandLineA | local |
 | windows.cpp:34:17:34:38 | call to GetEnvironmentStringsA | local |
 | windows.cpp:39:36:39:38 | GetEnvironmentVariableA output argument | local |

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

@@ -396,4 +396,18 @@ void forward_test_model() {
 
   Element e = c.get();
   ymlSink(e.x); // $ ir
+}
+
+struct ElementWithDefaultArgument {
+  int x;
+  ElementWithDefaultArgument(int x, int = 0);
+};
+
+void forward_test_model_with_default_argument() {
+  Container<ElementWithDefaultArgument> c;
+  int x = ymlSource();
+  c.emplace(0, x);
+
+  ElementWithDefaultArgument e = c.get();
+  ymlSink(e.x); // $ MISSING: ir
 }