C#: Copy dotnet.Expr implementation.

Author: michaelnebel

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

@@ -8,15 +8,14 @@ import Expr
 private import semmle.code.csharp.dataflow.internal.DataFlowDispatch
 private import semmle.code.csharp.dataflow.internal.DataFlowImplCommon
 private import semmle.code.csharp.dispatch.Dispatch
-private import dotnet
 
 /**
  * A call. Either a method call (`MethodCall`), a constructor initializer call
  * (`ConstructorInitializer`), a call to a user-defined operator (`OperatorCall`),
  * a delegate call (`DelegateCall`), an accessor call (`AccessorCall`), a
  * constructor call (`ObjectCreation`), or a local function call (`LocalFunctionCall`).
  */
-class Call extends DotNet::Call, Expr, @call {
+class Call extends Expr, @call {
   /**
    * Gets the static (compile-time) target of this call. For example, the
    * static target of `x.M()` on line 9 is `A.M` in
@@ -38,13 +37,19 @@ class Call extends DotNet::Call, Expr, @call {
    * Use `getARuntimeTarget()` instead to get a potential run-time target (will
    * include `B.M` in the example above).
    */
-  override Callable getTarget() { none() }
+  Callable getTarget() { none() }
 
-  override Expr getArgument(int i) { result = this.getChild(i) and i >= 0 }
+  /** Gets the `i`th argument to this call, if any. */
+  Expr getArgument(int i) { result = this.getChild(i) and i >= 0 }
 
-  override Expr getRawArgument(int i) { result = this.getArgument(i) }
+  /**
+   * Gets the `i`th "raw" argument to this call, if any.
+   * For instance methods, argument 0 is the qualifier.
+   */
+  Expr getRawArgument(int i) { result = this.getArgument(i) }
 
-  override Expr getAnArgument() { result = this.getArgument(_) }
+  /** Gets an argument to this call. */
+  Expr getAnArgument() { result = this.getArgument(_) }
 
   /** Gets the number of arguments of this call. */
   int getNumberOfArguments() { result = count(this.getAnArgument()) }
@@ -59,7 +64,7 @@ class Call extends DotNet::Call, Expr, @call {
    * consider default arguments.
    */
   cached
-  override Expr getArgumentForParameter(DotNet::Parameter p) {
+  Expr getArgumentForParameter(DotNet::Parameter p) {
     // Appears in the positional part of the call
     result = this.getImplicitArgument(p)
     or
@@ -144,7 +149,7 @@ class Call extends DotNet::Call, Expr, @call {
    * - Line 16: There is no static target (delegate call) but the delegate `i => { }`
    *   (line 20) is a run-time target.
    */
-  override Callable getARuntimeTarget() {
+  Callable getARuntimeTarget() {
     exists(DispatchCall dc | dc.getCall() = this | result = dc.getADynamicTarget())
   }
 

csharp/ql/lib/semmle/code/csharp/exprs/Expr.qll

@@ -38,11 +38,11 @@ private import semmle.code.csharp.TypeRef
  * interpolated string (`InterpolatedStringExpr`), a qualifiable expression
  * (`QualifiableExpr`), or a literal (`Literal`).
  */
-class Expr extends DotNet::Expr, ControlFlowElement, @expr {
+class Expr extends ControlFlowElement, @expr {
   override Location getALocation() { expr_location(this, result) }
 
   /** Gets the type of this expression. */
-  override Type getType() {
+  Type getType() {
     expressions(this, _, result)
     or
     not expressions(this, _, any(Type t)) and
@@ -53,7 +53,10 @@ class Expr extends DotNet::Expr, ControlFlowElement, @expr {
   final AnnotatedType getAnnotatedType() { result.appliesTo(this) }
 
   /** Gets the value of this expression, if any */
-  override string getValue() { expr_value(this, result) }
+  string getValue() { expr_value(this, result) }
+
+  /** Holds if this expression has a value. */
+  final predicate hasValue() { exists(this.getValue()) }
 
   /** Gets the enclosing statement of this expression, if any. */
   final Stmt getEnclosingStmt() { enclosingStmt(this, result) }
@@ -88,6 +91,10 @@ class Expr extends DotNet::Expr, ControlFlowElement, @expr {
    */
   string getExplicitArgumentName() { expr_argument_name(this, result) }
 
+  /**
+   * Gets the parent of this expression. This is for example the element
+   * that uses the result of this expression.
+   */
   override Element getParent() { result = ControlFlowElement.super.getParent() }
 
   /** Holds if the nullable flow state of this expression is not null. */