C#: Simplify SummarizedCallableDefaultClearsContent

Author: hvitved

csharp/ql/lib/semmle/code/csharp/dataflow/FlowSummary.qll

@@ -79,14 +79,14 @@ module SummaryComponentStack {
 class SummarizedCallable = Impl::Public::SummarizedCallable;
 
 private class SummarizedCallableDefaultClearsContent extends Impl::Public::SummarizedCallable {
-  SummarizedCallable c;
-
-  SummarizedCallableDefaultClearsContent() { this = c }
+  SummarizedCallableDefaultClearsContent() {
+    this instanceof Impl::Public::SummarizedCallable or none()
+  }
 
   // By default, we assume that all stores into arguments are definite
   override predicate clearsContent(int i, DataFlow::Content content) {
     exists(SummaryComponentStack output |
-      c.propagatesFlow(_, output, _) and
+      this.propagatesFlow(_, output, _) and
       output.drop(_) =
         SummaryComponentStack::push(SummaryComponent::content(content),
           SummaryComponentStack::argument(i)) and

csharp/ql/test/library-tests/dataflow/external-models/steps.expected

@@ -21,3 +21,6 @@ summarySetterStep
 | Steps.cs:30:34:30:34 | 0 | Steps.cs:30:13:30:16 | [post] this access | Steps.cs:57:13:57:17 | field Field |
 | Steps.cs:34:37:34:37 | 0 | Steps.cs:34:13:34:16 | [post] this access | Steps.cs:63:13:63:20 | property Property |
 | Steps.cs:38:36:38:36 | 0 | Steps.cs:38:13:38:16 | [post] this access | file://:0:0:0:0 | element |
+clearsContent
+| Steps.cs:61:14:61:28 | StepFieldSetter | Steps.cs:57:13:57:17 | field Field | -1 |
+| Steps.cs:67:14:67:31 | StepPropertySetter | Steps.cs:63:13:63:20 | property Property | -1 |

csharp/ql/test/library-tests/dataflow/external-models/steps.ql

@@ -1,6 +1,7 @@
 import csharp
 import DataFlow
 import semmle.code.csharp.dataflow.ExternalFlow
+import semmle.code.csharp.dataflow.FlowSummary
 import semmle.code.csharp.dataflow.internal.FlowSummaryImpl as FlowSummaryImpl
 import CsvValidation
 
@@ -40,3 +41,8 @@ query predicate summaryGetterStep(DataFlow::Node arg, DataFlow::Node out, Conten
 query predicate summarySetterStep(DataFlow::Node arg, DataFlow::Node out, Content c) {
   FlowSummaryImpl::Private::Steps::summarySetterStep(arg, c, out)
 }
+
+query predicate clearsContent(SummarizedCallable c, DataFlow::Content k, int i) {
+  c.clearsContent(i, k) and
+  c.fromSource()
+}