Fix code review findings

Author: tamasvajk

csharp/ql/src/semmle/code/csharp/dataflow/CallContext.qll

@@ -82,12 +82,8 @@ class DelegateLikeCallArgumentCallContext extends ArgumentCallContext {
 
 /** An argument of a delegate call. */
 class DelegateCallArgumentCallContext extends DelegateLikeCallArgumentCallContext,
-  TArgDelegateCallContext {
-  DelegateCallArgumentCallContext() { this = TArgDelegateCallContext(dc, arg) }
-}
+  TArgDelegateCallContext { }
 
 /** An argument of a function pointer call. */
 class FunctionPointerCallArgumentCallContext extends DelegateLikeCallArgumentCallContext,
-  TArgFunctionPointerCallContext {
-  FunctionPointerCallArgumentCallContext() { this = TArgFunctionPointerCallContext(dc, arg) }
-}
+  TArgFunctionPointerCallContext { }

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowDispatch.qll

@@ -101,7 +101,7 @@ private module Cached {
     TNonDelegateCall(ControlFlow::Nodes::ElementNode cfn, DispatchCall dc) {
       cfn.getElement() = dc.getCall()
     } or
-    TExplicitDelegateCall(ControlFlow::Nodes::ElementNode cfn, DelegateCall dc) {
+    TExplicitDelegateLikeCall(ControlFlow::Nodes::ElementNode cfn, DelegateLikeCall dc) {
       cfn.getElement() = dc
     } or
     TTransitiveCapturedCall(ControlFlow::Nodes::ElementNode cfn, Callable target) {
@@ -308,12 +308,12 @@ abstract class DelegateDataFlowCall extends DataFlowCall {
   override DataFlowCallable getARuntimeTarget() { result = this.getARuntimeTarget(_) }
 }
 
-/** An explicit delegate call relevant for data flow. */
-class ExplicitDelegateDataFlowCall extends DelegateDataFlowCall, TExplicitDelegateCall {
+/** An explicit delegate or function pointer call relevant for data flow. */
+class ExplicitDelegateLikeDataFlowCall extends DelegateDataFlowCall, TExplicitDelegateLikeCall {
   private ControlFlow::Nodes::ElementNode cfn;
-  private DelegateCall dc;
+  private DelegateLikeCall dc;
 
-  ExplicitDelegateDataFlowCall() { this = TExplicitDelegateCall(cfn, dc) }
+  ExplicitDelegateLikeDataFlowCall() { this = TExplicitDelegateLikeCall(cfn, dc) }
 
   override DataFlowCallable getARuntimeTarget(CallContext::CallContext cc) {
     result = getCallableForDataFlow(dc.getARuntimeTarget(cc))

csharp/ql/src/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -1394,7 +1394,7 @@ private module OutNodes {
 
   private DataFlowCall csharpCall(Expr e, ControlFlow::Node cfn) {
     e = any(DispatchCall dc | result = TNonDelegateCall(cfn, dc)).getCall() or
-    result = TExplicitDelegateCall(cfn, e)
+    result = TExplicitDelegateLikeCall(cfn, e)
   }
 
   /** A valid return type for a method that uses `yield return`. */

csharp/ql/src/semmle/code/csharp/dataflow/internal/DelegateDataFlow.qll

@@ -15,9 +15,9 @@ private import semmle.code.csharp.dispatch.Dispatch
 private import semmle.code.csharp.frameworks.system.linq.Expressions
 
 /** A source of flow for a delegate or function pointer expression. */
-private class DelegateLikeFlowSource extends DataFlow::ExprNode {
+abstract private class DelegateLikeFlowSource extends DataFlow::ExprNode {
   /** Gets the callable that is referenced in this delegate or function pointer flow source. */
-  Callable getCallable() { none() }
+  abstract Callable getCallable();
 }
 
 /** A source of flow for a delegate expression. */
@@ -41,10 +41,13 @@ private class FunctionPointerFlowSource extends DelegateLikeFlowSource {
   Callable c;
 
   FunctionPointerFlowSource() {
-    this.getExpr() =
-      any(Expr e |
-        c = e.(AddressOfExpr).getOperand().(CallableAccess).getTarget().getUnboundDeclaration()
-      )
+    c =
+      this.getExpr()
+          .(AddressOfExpr)
+          .getOperand()
+          .(CallableAccess)
+          .getTarget()
+          .getUnboundDeclaration()
   }
 
   /** Gets the callable that is referenced in this function pointer flow source. */
@@ -115,28 +118,12 @@ abstract private class DelegateLikeFlowSink extends DataFlow::Node {
 
 /** A delegate or function pointer call expression. */
 class DelegateLikeCallExpr extends DelegateLikeFlowSink, DataFlow::ExprNode {
-  /** Gets the delegate or function pointer call that this expression belongs to. */
-  DelegateLikeCall getCall() { none() }
-}
-
-/** A delegate call expression. */
-class DelegateCallExpr extends DelegateLikeCallExpr {
-  DelegateCall dc;
+  DelegateLikeCall dc;
 
-  DelegateCallExpr() { this.getExpr() = dc.getExpr() }
+  DelegateLikeCallExpr() { this.getExpr() = dc.getExpr() }
 
-  /** Gets the delegate call that this expression belongs to. */
-  override DelegateCall getCall() { result = dc }
-}
-
-/** A function pointer call expression. */
-class FunctionPointerCallExpr extends DelegateLikeCallExpr {
-  FunctionPointerCall fptrc;
-
-  FunctionPointerCallExpr() { this.getExpr() = fptrc.getExpr() }
-
-  /** Gets the function pointer call that this expression belongs to. */
-  override FunctionPointerCall getCall() { result = fptrc }
+  /** Gets the delegate or function pointer call that this expression belongs to. */
+  DelegateLikeCall getCall() { result = dc }
 }
 
 /** A parameter of delegate type belonging to a callable with a flow summary. */

csharp/ql/src/semmle/code/csharp/exprs/Call.qll

@@ -527,17 +527,24 @@ class MutatorOperatorCall extends OperatorCall {
   predicate isPostfix() { mutator_invocation_mode(this, 2) }
 }
 
+private class DelegateLikeCall_ = @delegate_invocation_expr or @function_pointer_invocation_expr;
+
 /**
  * A function pointer or delegate call.
  */
-abstract class DelegateLikeCall extends Call {
+class DelegateLikeCall extends Call, DelegateLikeCall_ {
   override Callable getTarget() { none() }
 
   /**
    * Gets a potential run-time target of this delegate or function pointer call in the given
    * call context `cc`.
    */
-  Callable getARuntimeTarget(CallContext::CallContext cc) { none() }
+  Callable getARuntimeTarget(CallContext::CallContext cc) {
+    exists(DelegateLikeCallExpr call |
+      this = call.getCall() and
+      result = call.getARuntimeTarget(cc)
+    )
+  }
 
   /**
    * Gets the delegate or function pointer expression of this call. For example, the
@@ -579,10 +586,7 @@ class DelegateCall extends DelegateLikeCall, @delegate_invocation_expr {
    * call context `cc`.
    */
   override Callable getARuntimeTarget(CallContext::CallContext cc) {
-    exists(DelegateCallExpr call |
-      this = call.getCall() and
-      result = call.getARuntimeTarget(cc)
-    )
+    result = DelegateLikeCall.super.getARuntimeTarget(cc)
     or
     exists(AddEventSource aes, CallContext::CallContext cc2 |
       aes = this.getAnAddEventSource(_) and
@@ -634,17 +638,6 @@ class DelegateCall extends DelegateLikeCall, @delegate_invocation_expr {
  * ```
  */
 class FunctionPointerCall extends DelegateLikeCall, @function_pointer_invocation_expr {
-  /**
-   * Gets a potential run-time target of this function pointer call in the given
-   * call context `cc`.
-   */
-  override Callable getARuntimeTarget(CallContext::CallContext cc) {
-    exists(FunctionPointerCallExpr call |
-      this = call.getCall() and
-      result = call.getARuntimeTarget(cc)
-    )
-  }
-
   override string toString() { result = "function pointer call" }
 
   override string getAPrimaryQlClass() { result = "FunctionPointerCall" }