CPP: Add a test of PartialDefinitions.

Author: geoffw0

cpp/ql/test/library-tests/dataflow/partialdefinitions/partialdefinitions.cpp

@@ -0,0 +1,16 @@
+
+struct MyStruct
+{
+	int x;
+	struct MySubStruct {
+		int z;
+	} y;
+};
+
+void test()
+{
+	MyStruct s;
+
+	s.x = 1;
+	s.y.z = 1;
+}

cpp/ql/test/library-tests/dataflow/partialdefinitions/partialdefinitions.expected

@@ -0,0 +1,2 @@
+| partialdefinitions.cpp:14:2:14:2 | partial def of s | partialdefinitions.cpp:14:2:14:2 | s | partialdefinitions.cpp:14:2:14:8 | ... = ... |
+| partialdefinitions.cpp:15:4:15:4 | partial def of y | partialdefinitions.cpp:15:4:15:4 | y | partialdefinitions.cpp:15:2:15:10 | ... = ... |

cpp/ql/test/library-tests/dataflow/partialdefinitions/partialdefinitions.ql

@@ -0,0 +1,4 @@
+import semmle.code.cpp.dataflow.internal.FlowVar
+
+from PartialDefinition def
+select def, def.getDefinedExpr(), def.getSubBasicBlockStart()