Merge pull request #11624 from jcogs33/jcogs33/exclude-paramless-constructors-from-dataflowtargetapi

Java/C#: exclude parameterless constructors from `DataFlowTargetApi`

csharp/ql/lib/semmle/code/csharp/Callable.qll

@@ -358,6 +358,9 @@ class Constructor extends DotNet::Constructor, Callable, Member, Attributable, @
     if this.isStatic() then result = this.getParameter(i) else result = this.getParameter(i - 1)
   }
 
+  /** Holds if this is a constructor without parameters. */
+  predicate isParameterless() { this.getNumberOfParameters() = 0 }
+
   override string getUndecoratedName() { result = ".ctor" }
 }
 

csharp/ql/src/utils/modelgenerator/internal/CaptureModelsSpecific.qll

@@ -38,7 +38,8 @@ private predicate isRelevantForModels(CS::Callable api) {
   api.getDeclaringType().getNamespace().getFullName() != "" and
   not api instanceof CS::ConversionOperator and
   not api instanceof Util::MainMethod and
-  not api instanceof CS::Destructor
+  not api instanceof CS::Destructor and
+  not api.(CS::Constructor).isParameterless()
 }
 
 /**

csharp/ql/test/utils/model-generator/dataflow/NoSummaries.cs

@@ -131,4 +131,15 @@ public class CollectionFlow
     {
         return a;
     }
-}
+}
+
+// A neutral model should not be created for a parameterless constructor.
+public class ParameterlessConstructor
+{
+    public bool IsInitialized;
+
+    public ParameterlessConstructor()
+    {
+        IsInitialized = true;
+    }
+}