C#: Migrate the legacy clearContent flow summaries to the new framework.

Author: michaelnebel

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

@@ -132,27 +132,3 @@ private module FrameworkDataFlowAdaptor {
     override predicate required(SummaryComponent c) { c = head }
   }
 }
-
-/** Data flow for `System.Text.StringBuilder`. */
-class SystemTextStringBuilderFlow extends LibraryTypeDataFlow, SystemTextStringBuilderClass {
-  override predicate clearsContent(
-    CallableFlowSource source, Content content, SourceDeclarationCallable callable
-  ) {
-    source = TCallableFlowSourceQualifier() and
-    callable = this.getAMethod("Clear") and
-    content instanceof ElementContent
-  }
-}
-
-/** Data flow for `System.Collections.IEnumerable` (and sub types). */
-class IEnumerableFlow extends LibraryTypeDataFlow, RefType {
-  IEnumerableFlow() { this.getABaseType*() instanceof SystemCollectionsIEnumerableInterface }
-
-  override predicate clearsContent(
-    CallableFlowSource source, Content content, SourceDeclarationCallable callable
-  ) {
-    source = TCallableFlowSourceQualifier() and
-    callable = this.getAMethod("Clear") and
-    content instanceof ElementContent
-  }
-}

csharp/ql/lib/semmle/code/csharp/frameworks/system/Collections.qll

@@ -3,6 +3,7 @@
 import csharp
 private import semmle.code.csharp.frameworks.System
 private import semmle.code.csharp.dataflow.ExternalFlow
+private import semmle.code.csharp.dataflow.FlowSummary
 
 /** The `System.Collections` namespace. */
 class SystemCollectionsNamespace extends Namespace {
@@ -45,6 +46,20 @@ private class SystemCollectionIEnumerableFlowModelCsv extends SummaryModelCsv {
   }
 }
 
+/** Clear content for Clear methods in all subtypes of `System.Collections.IEnumerable`. */
+private class SystemCollectionsIEnumerableClearFlow extends SummarizedCallable {
+  SystemCollectionsIEnumerableClearFlow() {
+    this.getDeclaringType().(RefType).getABaseType*() instanceof
+      SystemCollectionsIEnumerableInterface and
+    this.hasName("Clear")
+  }
+
+  override predicate clearsContent(ParameterPosition pos, DataFlow::Content content) {
+    pos.getPosition() = -1 and
+    content instanceof DataFlow::ElementContent
+  }
+}
+
 /** The `System.Collections.IEnumerator` interface. */
 class SystemCollectionsIEnumeratorInterface extends SystemCollectionsInterface {
   SystemCollectionsIEnumeratorInterface() { this.hasName("IEnumerator") }

csharp/ql/lib/semmle/code/csharp/frameworks/system/Text.qll

@@ -3,6 +3,7 @@
 import csharp
 private import semmle.code.csharp.frameworks.System
 private import semmle.code.csharp.dataflow.ExternalFlow
+private import semmle.code.csharp.dataflow.FlowSummary
 
 /** The `System.Text` namespace. */
 class SystemTextNamespace extends Namespace {
@@ -25,6 +26,19 @@ class SystemTextStringBuilderClass extends SystemTextClass {
   Method getAppendFormatMethod() { result = this.getAMethod("AppendFormat") }
 }
 
+/** Clear content for `System.Text.StringBuilder.Clear`. */
+private class SystemTextStringBuilderClearFlow extends SummarizedCallable {
+  SystemTextStringBuilderClearFlow() {
+    this.getDeclaringType() instanceof SystemTextStringBuilderClass and
+    this.hasName("Clear")
+  }
+
+  override predicate clearsContent(ParameterPosition pos, DataFlow::Content content) {
+    pos.getPosition() = -1 and
+    content instanceof DataFlow::ElementContent
+  }
+}
+
 /** Data flow for `System.Text.StringBuilder`. */
 private class SystemTextStringBuilderFlowModelCsv extends SummaryModelCsv {
   override predicate row(string row) {