unified: Add test with flow through Argument[self]

Author: asgerf

unified/ql/test/library-tests/dataflow/flow-summaries.swift

@@ -70,3 +70,9 @@ func t10() {
     sink(x)  // $ hasValueFlow=t10.2 SPURIOUS: hasValueFlow=t10.1
     sink(y)  // $ hasValueFlow=t10.1 SPURIOUS: hasValueFlow=t10.2
 }
+
+func t11() {
+    let t = TestType()
+    t.setField(source("t11.1"))
+    sink(t.getField())  // $ MISSING: hasValueFlow=t11.1
+}

unified/ql/test/library-tests/dataflow/test.ext.yml

@@ -16,3 +16,5 @@ extensions:
       - ["", "TestType", true, "taintFlow(_:)", "", "", "Argument[0]", "ReturnValue", "taint", "manual"]
       - ["", "TestType", true, "swap(_:_:)", "", "", "Argument[0]", "Argument[1]", "value", "manual"]
       - ["", "TestType", true, "swap(_:_:)", "", "", "Argument[1]", "Argument[0]", "value", "manual"]
+      - ["", "TestType", true, "getField()", "", "", "Argument[self].Member[field]", "ReturnValue", "value", "manual"]
+      - ["", "TestType", true, "setField(_:)", "", "", "Argument[0]", "Argument[self].Member[field]", "value", "manual"]