C#: Adopt shared CFG construction library from shared `controlflow` pack

config/identical-files.json

@@ -484,10 +484,6 @@
     "ruby/ql/lib/codeql/ruby/security/internal/SensitiveDataHeuristics.qll",
     "swift/ql/lib/codeql/swift/security/internal/SensitiveDataHeuristics.qll"
   ],
-  "CFG": [
-    "csharp/ql/lib/semmle/code/csharp/controlflow/internal/ControlFlowGraphImplShared.qll",
-    "swift/ql/lib/codeql/swift/controlflow/internal/ControlFlowGraphImplShared.qll"
-  ],
   "TypeTracker": [
     "python/ql/lib/semmle/python/dataflow/new/internal/TypeTracker.qll",
     "ruby/ql/lib/codeql/ruby/typetracking/TypeTracker.qll"

csharp/ql/consistency-queries/CfgConsistency.ql

@@ -2,15 +2,14 @@ import csharp
 import semmle.code.csharp.controlflow.internal.Completion
 import semmle.code.csharp.controlflow.internal.PreBasicBlocks
 import ControlFlow
-import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl
+import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl::Consistency
 import semmle.code.csharp.controlflow.internal.Splitting
-import Consistency
 
 private predicate splitBB(ControlFlow::BasicBlock bb) {
   exists(ControlFlow::Node first |
     first = bb.getFirstNode() and
     first.isJoin() and
-    strictcount(first.getAPredecessor().getElement()) = 1
+    strictcount(first.getAPredecessor().getAstNode()) = 1
   )
 }
 

csharp/ql/consistency-queries/DataFlowConsistency.ql

@@ -10,7 +10,7 @@ private class MyConsistencyConfiguration extends ConsistencyConfiguration {
     // TODO: Remove once static initializers are folded into the
     // static constructors
     exists(ControlFlow::Node cfn |
-      cfn.getElement() = any(FieldOrProperty f | f.isStatic()).getAChild+() and
+      cfn.getAstNode() = any(FieldOrProperty f | f.isStatic()).getAChild+() and
       cfn = n.getControlFlowNode()
     )
   }
@@ -19,7 +19,7 @@ private class MyConsistencyConfiguration extends ConsistencyConfiguration {
     // TODO: Remove once static initializers are folded into the
     // static constructors
     exists(ControlFlow::Node cfn |
-      cfn.getElement() = any(FieldOrProperty f | f.isStatic()).getAChild+() and
+      cfn.getAstNode() = any(FieldOrProperty f | f.isStatic()).getAChild+() and
       cfn = call.getControlFlowNode()
     )
   }

csharp/ql/lib/qlpack.yml

@@ -6,6 +6,7 @@ extractor: csharp
 library: true
 upgrades: upgrades
 dependencies:
+  codeql/controlflow: ${workspace}
   codeql/dataflow: ${workspace}
   codeql/mad: ${workspace}
   codeql/ssa: ${workspace}

csharp/ql/lib/semmle/code/csharp/commons/Assertions.qll

@@ -1,12 +1,9 @@
 /** Provides classes for assertions. */
 
-private import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl
 private import semmle.code.csharp.frameworks.system.Diagnostics
 private import semmle.code.csharp.frameworks.system.diagnostics.Contracts
 private import semmle.code.csharp.frameworks.test.VisualStudio
 private import semmle.code.csharp.frameworks.System
-private import ControlFlow
-private import ControlFlow::BasicBlocks
 
 private newtype TAssertionFailure =
   TExceptionAssertionFailure(Class c) or

csharp/ql/lib/semmle/code/csharp/controlflow/BasicBlocks.qll

@@ -400,13 +400,13 @@ class ExitBasicBlock extends BasicBlock {
 
 private module JoinBlockPredecessors {
   private import ControlFlow::Nodes
-  private import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl
+  private import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl as Impl
 
   int getId(JoinBlockPredecessor jbp) {
-    exists(ControlFlowTree::Range_ t | ControlFlowTree::idOf(t, result) |
-      t = jbp.getFirstNode().getElement()
+    exists(Impl::AstNode n | result = n.getId() |
+      n = jbp.getFirstNode().getAstNode()
       or
-      t = jbp.(EntryBasicBlock).getCallable()
+      n = jbp.(EntryBasicBlock).getCallable()
     )
   }
 

csharp/ql/lib/semmle/code/csharp/controlflow/ControlFlowElement.qll

@@ -7,7 +7,7 @@ private import ControlFlow
 private import ControlFlow::BasicBlocks
 private import SuccessorTypes
 private import semmle.code.csharp.Caching
-private import internal.ControlFlowGraphImpl
+private import internal.ControlFlowGraphImpl as Impl
 
 /**
  * A program element that can possess control flow. That is, either a statement or
@@ -39,20 +39,20 @@ class ControlFlowElement extends ExprOrStmtParent, @control_flow_element {
    * several `ControlFlow::Node`s, for example to represent the continuation
    * flow in a `try/catch/finally` construction.
    */
-  Nodes::ElementNode getAControlFlowNode() { result.getElement() = this }
+  Nodes::ElementNode getAControlFlowNode() { result.getAstNode() = this }
 
   /**
    * Gets a first control flow node executed within this element.
    */
   Nodes::ElementNode getAControlFlowEntryNode() {
-    result = getAControlFlowEntryNode(this).getAControlFlowNode()
+    result = Impl::getAControlFlowEntryNode(this).(ControlFlowElement).getAControlFlowNode()
   }
 
   /**
    * Gets a potential last control flow node executed within this element.
    */
   Nodes::ElementNode getAControlFlowExitNode() {
-    result = getAControlFlowExitNode(this).getAControlFlowNode()
+    result = Impl::getAControlFlowExitNode(this).(ControlFlowElement).getAControlFlowNode()
   }
 
   /**
@@ -88,7 +88,7 @@ class ControlFlowElement extends ExprOrStmtParent, @control_flow_element {
   ) {
     // Only calculate dominance by explicit recursion for split nodes;
     // all other nodes can use regular CFG dominance
-    this instanceof SplitControlFlowElement and
+    this instanceof Impl::SplitAstNode and
     cb.getLastNode() = this.getAControlFlowNode() and
     succ = cb.getASuccessorByType(s)
   }
@@ -111,7 +111,7 @@ class ControlFlowElement extends ExprOrStmtParent, @control_flow_element {
       succ.dominates(pred)
       or
       // `pred` might be another split of this element
-      pred.getLastNode().getElement() = this and
+      pred.getLastNode().getAstNode() = this and
       t = s
     )
   }

csharp/ql/lib/semmle/code/csharp/controlflow/ControlFlowGraph.qll

@@ -7,7 +7,7 @@ module ControlFlow {
   private import semmle.code.csharp.controlflow.BasicBlocks as BBs
   import semmle.code.csharp.controlflow.internal.SuccessorType
   private import SuccessorTypes
-  private import internal.ControlFlowGraphImpl
+  private import internal.ControlFlowGraphImpl as Impl
   private import internal.Splitting as Splitting
 
   /**
@@ -25,18 +25,16 @@ module ControlFlow {
    * Only nodes that can be reached from the callable entry point are included in
    * the CFG.
    */
-  class Node extends TCfgNode {
-    /** Gets a textual representation of this control flow node. */
-    string toString() { none() }
-
+  class Node extends Impl::Node {
     /** Gets the control flow element that this node corresponds to, if any. */
-    ControlFlowElement getElement() { none() }
+    final ControlFlowElement getAstNode() { result = super.getAstNode() }
 
-    /** Gets the location of this control flow node. */
-    Location getLocation() { result = this.getElement().getLocation() }
-
-    /** Holds if this control flow node has conditional successors. */
-    predicate isCondition() { exists(this.getASuccessorByType(any(ConditionalSuccessor e))) }
+    /**
+     * DEPRECATED: Use `getAstNode` instead.
+     *
+     * Gets the control flow element that this node corresponds to, if any.
+     */
+    deprecated ControlFlowElement getElement() { result = this.getAstNode() }
 
     /** Gets the basic block that this control flow node belongs to. */
     BasicBlock getBasicBlock() { result.getANode() = this }
@@ -183,7 +181,7 @@ module ControlFlow {
     }
 
     /** Gets a successor node of a given type, if any. */
-    Node getASuccessorByType(SuccessorType t) { result = getASuccessor(this, t) }
+    Node getASuccessorByType(SuccessorType t) { result = this.getASuccessor(t) }
 
     /** Gets an immediate successor, if any. */
     Node getASuccessor() { result = this.getASuccessorByType(_) }
@@ -234,80 +232,39 @@ module ControlFlow {
       result = this.getASuccessorByType(any(BooleanSuccessor t | t.getValue() = false))
     }
 
-    /** Holds if this node has more than one predecessor. */
-    predicate isJoin() { strictcount(this.getAPredecessor()) > 1 }
-
-    /** Holds if this node has more than one successor. */
-    predicate isBranch() { strictcount(this.getASuccessor()) > 1 }
-
     /** Gets the enclosing callable of this control flow node. */
-    final Callable getEnclosingCallable() { result = getNodeCfgScope(this) }
+    final Callable getEnclosingCallable() { result = Impl::getNodeCfgScope(this) }
   }
 
   /** Provides different types of control flow nodes. */
   module Nodes {
     /** A node for a callable entry point. */
-    class EntryNode extends Node, TEntryNode {
+    class EntryNode extends Node instanceof Impl::EntryNode {
       /** Gets the callable that this entry applies to. */
-      Callable getCallable() { this = TEntryNode(result) }
+      Callable getCallable() { result = this.getScope() }
 
       override BasicBlocks::EntryBlock getBasicBlock() { result = Node.super.getBasicBlock() }
-
-      private Assignable getAssignable() { this = TEntryNode(result) }
-
-      override Location getLocation() {
-        result in [this.getCallable().getLocation(), this.getAssignable().getLocation()]
-      }
-
-      override string toString() {
-        result = "enter " + [this.getCallable().toString(), this.getAssignable().toString()]
-      }
     }
 
     /** A node for a callable exit point, annotated with the type of exit. */
-    class AnnotatedExitNode extends Node, TAnnotatedExitNode {
-      private CfgScope scope;
-      private boolean normal;
-
-      AnnotatedExitNode() { this = TAnnotatedExitNode(scope, normal) }
+    class AnnotatedExitNode extends Node instanceof Impl::AnnotatedExitNode {
+      /** Holds if this node represent a normal exit. */
+      final predicate isNormal() { super.isNormal() }
 
       /** Gets the callable that this exit applies to. */
-      CfgScope getCallable() { result = scope }
-
-      /** Holds if this node represents a normal exit. */
-      predicate isNormal() { normal = true }
+      Callable getCallable() { result = this.getScope() }
 
       override BasicBlocks::AnnotatedExitBlock getBasicBlock() {
         result = Node.super.getBasicBlock()
       }
-
-      override Location getLocation() { result = scope.getLocation() }
-
-      override string toString() {
-        exists(string s |
-          normal = true and s = "normal"
-          or
-          normal = false and s = "abnormal"
-        |
-          result = "exit " + scope + " (" + s + ")"
-        )
-      }
     }
 
     /** A node for a callable exit point. */
-    class ExitNode extends Node, TExitNode {
-      private CfgScope scope;
-
-      ExitNode() { this = TExitNode(scope) }
-
+    class ExitNode extends Node instanceof Impl::ExitNode {
       /** Gets the callable that this exit applies to. */
-      Callable getCallable() { result = scope }
+      Callable getCallable() { result = this.getScope() }
 
       override BasicBlocks::ExitBlock getBasicBlock() { result = Node.super.getBasicBlock() }
-
-      override Location getLocation() { result = scope.getLocation() }
-
-      override string toString() { result = "exit " + scope }
     }
 
     /**
@@ -317,35 +274,19 @@ module ControlFlow {
      * the element is in unreachable (dead) code, and multiple when there are
      * different splits for the element.
      */
-    class ElementNode extends Node, TElementNode {
-      private Splits splits;
-      private ControlFlowElement cfe;
-
-      ElementNode() { this = TElementNode(_, cfe, splits) }
-
-      override ControlFlowElement getElement() { result = cfe }
-
-      override string toString() {
-        result = "[" + this.getSplitsString() + "] " + cfe.toString()
-        or
-        not exists(this.getSplitsString()) and result = cfe.toString()
-      }
-
+    class ElementNode extends Node instanceof Impl::AstCfgNode {
       /** Gets a comma-separated list of strings for each split in this node, if any. */
-      string getSplitsString() {
-        result = splits.toString() and
-        result != ""
-      }
+      final string getSplitsString() { result = super.getSplitsString() }
 
       /** Gets a split for this control flow node, if any. */
-      Split getASplit() { result = splits.getASplit() }
+      final Split getASplit() { result = super.getASplit() }
     }
 
     /** A control-flow node for an expression. */
     class ExprNode extends ElementNode {
       Expr e;
 
-      ExprNode() { e = unique(Expr e_ | e_ = this.getElement() | e_) }
+      ExprNode() { e = unique(Expr e_ | e_ = this.getAstNode() | e_) }
 
       /** Gets the expression that this control-flow node belongs to. */
       Expr getExpr() { result = e }

csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll

@@ -1946,7 +1946,7 @@ module Internal {
       |
         def =
           guarded
-              .getElement()
+              .getAstNode()
               .(AccessOrCallExpr)
               .getAnSsaQualifier(guarded.getBasicBlock().getANode()) and
         if v.isReferentialProperty()

csharp/ql/lib/semmle/code/csharp/controlflow/internal/ControlFlowGraphImplSpecific.qll

@@ -1,69 +0,0 @@
-private import csharp as CS
-private import ControlFlowGraphImpl as Impl
-private import Completion as Comp
-private import Splitting as Splitting
-private import SuccessorType as ST
-private import semmle.code.csharp.Caching
-
-class ControlFlowTreeBase = Impl::ControlFlowTree::Range;
-
-class ControlFlowElement = CS::ControlFlowElement;
-
-class Completion = Comp::Completion;
-
-/**
- * Hold if `c` represents normal evaluation of a statement or an
- * expression.
- */
-predicate completionIsNormal(Completion c) { c instanceof Comp::NormalCompletion }
-
-/**
- * Hold if `c` represents simple (normal) evaluation of a statement or an
- * expression.
- */
-predicate completionIsSimple(Completion c) { c instanceof Comp::SimpleCompletion }
-
-/** Holds if `c` is a valid completion for `e`. */
-predicate completionIsValidFor(Completion c, ControlFlowElement e) { c.isValidFor(e) }
-
-class CfgScope = Impl::CfgScope;
-
-/** Gets the CFG scope for `e`. */
-CfgScope getCfgScope(ControlFlowElement e) {
-  Stages::ControlFlowStage::forceCachingInSameStage() and
-  result = e.getEnclosingCallable()
-}
-
-predicate scopeFirst = Impl::scopeFirst/2;
-
-predicate scopeLast = Impl::scopeLast/3;
-
-/** The maximum number of splits allowed for a given node. */
-int maxSplits() { result = 5 }
-
-class SplitKindBase = Splitting::TSplitKind;
-
-class Split = Splitting::Split;
-
-class SuccessorType = ST::SuccessorType;
-
-/** Gets a successor type that matches completion `c`. */
-SuccessorType getAMatchingSuccessorType(Completion c) { result = c.getAMatchingSuccessorType() }
-
-/**
- * Hold if `c` represents simple (normal) evaluation of a statement or an
- * expression.
- */
-predicate successorTypeIsSimple(SuccessorType t) {
-  t instanceof ST::SuccessorTypes::NormalSuccessor
-}
-
-/** Holds if `t` is an abnormal exit type out of a callable. */
-predicate isAbnormalExitType(SuccessorType t) {
-  t instanceof ST::SuccessorTypes::ExceptionSuccessor or
-  t instanceof ST::SuccessorTypes::ExitSuccessor
-}
-
-class Location = CS::Location;
-
-class Node = CS::ControlFlow::Node;

csharp/ql/lib/semmle/code/csharp/controlflow/internal/PreBasicBlocks.qll

@@ -12,7 +12,7 @@
 import csharp
 private import Completion
 private import ControlFlowGraphImpl
-private import semmle.code.csharp.controlflow.ControlFlowGraph::ControlFlow
+private import semmle.code.csharp.controlflow.ControlFlowGraph::ControlFlow as Cfg
 
 private predicate startsBB(ControlFlowElement cfe) {
   not succ(_, cfe, _) and
@@ -55,7 +55,7 @@ private predicate bbIDominates(PreBasicBlock dom, PreBasicBlock bb) =
 class PreBasicBlock extends ControlFlowElement {
   PreBasicBlock() { startsBB(this) }
 
-  PreBasicBlock getASuccessorByType(SuccessorType t) {
+  PreBasicBlock getASuccessorByType(Cfg::SuccessorType t) {
     succ(this.getLastElement(), result, any(Completion c | t = c.getAMatchingSuccessorType()))
   }
 
@@ -116,7 +116,7 @@ class ConditionBlock extends PreBasicBlock {
   }
 
   pragma[nomagic]
-  predicate controls(PreBasicBlock controlled, SuccessorTypes::ConditionalSuccessor s) {
+  predicate controls(PreBasicBlock controlled, Cfg::SuccessorTypes::ConditionalSuccessor s) {
     exists(PreBasicBlock succ, ConditionalCompletion c | this.immediatelyControls(succ, c) |
       succ.dominates(controlled) and
       s = c.getAMatchingSuccessorType()

csharp/ql/lib/semmle/code/csharp/controlflow/internal/Splitting.qll

@@ -7,8 +7,7 @@
 import csharp
 private import Completion
 private import ControlFlowGraphImpl
-private import SuccessorTypes
-private import semmle.code.csharp.controlflow.ControlFlowGraph::ControlFlow
+private import semmle.code.csharp.controlflow.ControlFlowGraph::ControlFlow as Cfg
 private import semmle.code.csharp.controlflow.internal.PreSsa
 
 cached
@@ -83,7 +82,7 @@ module InitializerSplitting {
      * Gets a control flow element that is a syntactic descendant of the
      * initializer expression.
      */
-    ControlFlowElement getAnInitializerDescendant() {
+    AstNode getAnInitializerDescendant() {
       result = this.getInitializer()
       or
       result = this.getAnInitializerDescendant().getAChild()
@@ -193,49 +192,49 @@ module InitializerSplitting {
   private class InitializerSplitKind extends SplitKind, TInitializerSplitKind {
     override int getListOrder() { result = 0 }
 
-    override predicate isEnabled(ControlFlowElement cfe) { this.appliesTo(cfe) }
+    override predicate isEnabled(AstNode cfe) { this.appliesTo(cfe) }
 
     override string toString() { result = "Initializer" }
   }
 
   int getNextListOrder() { result = 1 }
 
-  private class InitializerSplitImpl extends SplitImpl, InitializerSplit {
+  private class InitializerSplitImpl extends SplitImpl instanceof InitializerSplit {
     override InitializerSplitKind getKind() { any() }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
       exists(ConstructorInitializer ci |
         last(ci, pred, c) and
         succ(pred, succ, c) and
         succ = any(InitializedInstanceMember m).getAnInitializerDescendant() and
-        this.getConstructor() = ci.getConstructor()
+        super.getConstructor() = ci.getConstructor()
       )
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) {
+    override predicate hasEntryScope(CfgScope scope, AstNode first) {
       scopeFirst(scope, first) and
-      scope = this.getConstructor() and
+      scope = super.getConstructor() and
       first = any(InitializedInstanceMember m).getAnInitializerDescendant()
     }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       this.appliesTo(pred) and
       succ(pred, succ, c) and
       not succ = any(InitializedInstanceMember m).getAnInitializerDescendant() and
-      succ.getEnclosingCallable() = this.getConstructor()
+      succ.(ControlFlowElement).getEnclosingCallable() = super.getConstructor()
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       this.appliesTo(last) and
       scopeLast(scope, last, c) and
-      scope = this.getConstructor()
+      scope = super.getConstructor()
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) {
       this.appliesSucc(pred, succ, c) and
       succ =
         any(InitializedInstanceMember m |
-          constructorInitializes(this.getConstructor(), m.getInitializer())
+          constructorInitializes(super.getConstructor(), m.getInitializer())
         ).getAnInitializerDescendant()
     }
   }
@@ -267,17 +266,22 @@ module ConditionalCompletionSplitting {
   private class ConditionalCompletionSplitKind extends SplitKind, TConditionalCompletionSplitKind {
     override int getListOrder() { result = InitializerSplitting::getNextListOrder() }
 
-    override predicate isEnabled(ControlFlowElement cfe) { this.appliesTo(cfe) }
+    override predicate isEnabled(AstNode cfe) { this.appliesTo(cfe) }
 
     override string toString() { result = "ConditionalCompletion" }
   }
 
   int getNextListOrder() { result = InitializerSplitting::getNextListOrder() + 1 }
 
-  private class ConditionalCompletionSplitImpl extends SplitImpl, ConditionalCompletionSplit {
+  private class ConditionalCompletionSplitImpl extends SplitImpl instanceof ConditionalCompletionSplit
+  {
+    ConditionalCompletion completion;
+
+    ConditionalCompletionSplitImpl() { this = TConditionalCompletionSplit(completion) }
+
     override ConditionalCompletionSplitKind getKind() { any() }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
       succ(pred, succ, c) and
       last(succ, _, completion) and
       (
@@ -334,23 +338,21 @@ module ConditionalCompletionSplitting {
       )
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) { none() }
+    override predicate hasEntryScope(CfgScope scope, AstNode first) { none() }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       this.appliesTo(pred) and
       succ(pred, succ, c) and
       if c instanceof ConditionalCompletion then completion = c else any()
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       this.appliesTo(last) and
       scopeLast(scope, last, c) and
       if c instanceof ConditionalCompletion then completion = c else any()
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
-      none()
-    }
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) { none() }
   }
 }
 
@@ -358,7 +360,7 @@ module AssertionSplitting {
   import semmle.code.csharp.commons.Assertions
   private import semmle.code.csharp.ExprOrStmtParent
 
-  private ControlFlowElement getAnAssertionDescendant(Assertion a) {
+  private AstNode getAnAssertionDescendant(Assertion a) {
     result = a
     or
     result = getAnAssertionDescendant(a).getAChild()
@@ -401,17 +403,23 @@ module AssertionSplitting {
   private class AssertionSplitKind extends SplitKind, TAssertionSplitKind {
     override int getListOrder() { result = ConditionalCompletionSplitting::getNextListOrder() }
 
-    override predicate isEnabled(ControlFlowElement cfe) { this.appliesTo(cfe) }
+    override predicate isEnabled(AstNode cfe) { this.appliesTo(cfe) }
 
     override string toString() { result = "Assertion" }
   }
 
   int getNextListOrder() { result = ConditionalCompletionSplitting::getNextListOrder() + 1 }
 
-  private class AssertionSplitImpl extends SplitImpl, AssertionSplit {
+  private class AssertionSplitImpl extends SplitImpl instanceof AssertionSplit {
+    Assertion a;
+    boolean success;
+    int i;
+
+    AssertionSplitImpl() { this = TAssertionSplit(a, i, success) }
+
     override AssertionSplitKind getKind() { any() }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
       exists(AssertMethod m |
         last(a.getExpr(i), pred, c) and
         succ(pred, succ, c) and
@@ -440,9 +448,9 @@ module AssertionSplitting {
       )
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) { none() }
+    override predicate hasEntryScope(CfgScope scope, AstNode first) { none() }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       this.appliesTo(pred) and
       pred = a and
       succ(pred, succ, c) and
@@ -455,7 +463,7 @@ module AssertionSplitting {
       )
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       this.appliesTo(last) and
       last = a and
       scopeLast(scope, last, c) and
@@ -468,7 +476,7 @@ module AssertionSplitting {
       )
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) {
       this.appliesSucc(pred, succ, c) and
       succ = getAnAssertionDescendant(a)
     }
@@ -484,8 +492,8 @@ module FinallySplitting {
    * then the `finally` block must end with a `return` as well (provided that
    * the `finally` block exits normally).
    */
-  class FinallySplitType extends SuccessorType {
-    FinallySplitType() { not this instanceof ConditionalSuccessor }
+  class FinallySplitType extends Cfg::SuccessorType {
+    FinallySplitType() { not this instanceof Cfg::SuccessorTypes::ConditionalSuccessor }
 
     /** Holds if this split type matches entry into a `finally` block with completion `c`. */
     predicate isSplitForEntryCompletion(Completion c) {
@@ -493,22 +501,22 @@ module FinallySplitting {
       then
         // If the entry into the `finally` block completes with any normal completion,
         // it simply means normal execution after the `finally` block
-        this instanceof NormalSuccessor
+        this instanceof Cfg::SuccessorTypes::NormalSuccessor
       else this = c.getAMatchingSuccessorType()
     }
   }
 
   /** A control flow element that belongs to a `finally` block. */
-  private class FinallyControlFlowElement extends ControlFlowElement {
+  private class FinallyAstNode extends AstNode {
     private Statements::TryStmtTree try;
 
-    FinallyControlFlowElement() { this = try.getAFinallyDescendant() }
+    FinallyAstNode() { this = try.getAFinallyDescendant() }
 
     /** Gets the immediate `try` block that this node belongs to. */
     Statements::TryStmtTree getTryStmt() { result = try }
 
     /** Holds if this node is the entry node in the `finally` block it belongs to. */
-    predicate isEntryNode() { first(try.getFinally(), this) }
+    predicate isEntryNode() { first(try.(TryStmt).getFinally(), this) }
   }
 
   /**
@@ -547,7 +555,7 @@ module FinallySplitting {
     int getNestLevel() { result = nestLevel }
 
     override string toString() {
-      if type instanceof NormalSuccessor
+      if type instanceof Cfg::SuccessorTypes::NormalSuccessor
       then result = ""
       else
         if nestLevel > 0
@@ -577,38 +585,34 @@ module FinallySplitting {
     override string toString() { result = "Finally (" + nestLevel + ")" }
   }
 
-  pragma[noinline]
-  private predicate hasEntry0(
-    ControlFlowElement pred, FinallyControlFlowElement succ, int nestLevel, Completion c
-  ) {
+  pragma[nomagic]
+  private predicate hasEntry0(AstNode pred, FinallyAstNode succ, int nestLevel, Completion c) {
     succ.isEntryNode() and
     nestLevel = succ.getTryStmt().nestLevel() and
     succ(pred, succ, c)
   }
 
-  private class FinallySplitImpl extends SplitImpl, FinallySplit {
-    override FinallySplitKind getKind() { result.getNestLevel() = this.getNestLevel() }
+  private class FinallySplitImpl extends SplitImpl instanceof FinallySplit {
+    override FinallySplitKind getKind() { result.getNestLevel() = super.getNestLevel() }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
-      hasEntry0(pred, succ, this.getNestLevel(), c) and
-      this.getType().isSplitForEntryCompletion(c)
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
+      hasEntry0(pred, succ, super.getNestLevel(), c) and
+      super.getType().isSplitForEntryCompletion(c)
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) { none() }
+    override predicate hasEntryScope(CfgScope scope, AstNode first) { none() }
 
     /**
      * Holds if this split applies to control flow element `pred`, where `pred`
      * is a valid predecessor.
      */
-    private predicate appliesToPredecessor(ControlFlowElement pred) {
+    private predicate appliesToPredecessor(AstNode pred) {
       this.appliesTo(pred) and
       (succ(pred, _, _) or scopeLast(_, pred, _))
     }
 
     pragma[noinline]
-    private predicate exit0(
-      ControlFlowElement pred, Statements::TryStmtTree try, int nestLevel, Completion c
-    ) {
+    private predicate exit0(AstNode pred, Statements::TryStmtTree try, int nestLevel, Completion c) {
       this.appliesToPredecessor(pred) and
       nestLevel = try.nestLevel() and
       last(try, pred, c)
@@ -619,10 +623,10 @@ module FinallySplitting {
      * `inherited` indicates whether `c` is an inherited completion from a `try`/
      * `catch` block.
      */
-    private predicate exit(ControlFlowElement pred, Completion c, boolean inherited) {
+    private predicate exit(AstNode pred, Completion c, boolean inherited) {
       exists(TryStmt try, FinallySplitType type |
-        this.exit0(pred, try, this.getNestLevel(), c) and
-        type = this.getType()
+        this.exit0(pred, try, super.getNestLevel(), c) and
+        type = super.getType()
       |
         if last(try.getFinally(), pred, c)
         then
@@ -635,14 +639,14 @@ module FinallySplitting {
             or
             not c instanceof NormalCompletion
             or
-            type instanceof NormalSuccessor
+            type instanceof Cfg::SuccessorTypes::NormalSuccessor
           )
         else (
           // Finally block can exit with completion `c` inherited from try/catch
           // block: must match this split
           inherited = true and
           type = c.getAMatchingSuccessorType() and
-          not type instanceof NormalSuccessor
+          not type instanceof Cfg::SuccessorTypes::NormalSuccessor
         )
       )
       or
@@ -672,15 +676,15 @@ module FinallySplitting {
       // is "normal" (corresponding to `b1 = true` and `b2 = false`), then the inner
       // split must be able to exit with an `ExceptionA` completion.
       this.appliesToPredecessor(pred) and
-      exists(FinallySplitImpl outer |
-        outer.getNestLevel() = this.getNestLevel() - 1 and
-        outer.exit(pred, c, inherited) and
-        this.getType() instanceof NormalSuccessor and
+      exists(FinallySplit outer |
+        outer.getNestLevel() = super.getNestLevel() - 1 and
+        outer.(FinallySplitImpl).exit(pred, c, inherited) and
+        super.getType() instanceof Cfg::SuccessorTypes::NormalSuccessor and
         inherited = true
       )
     }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       succ(pred, succ, c) and
       (
         this.exit(pred, c, _)
@@ -689,7 +693,7 @@ module FinallySplitting {
       )
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       scopeLast(scope, last, c) and
       (
         this.exit(last, c, _)
@@ -698,17 +702,17 @@ module FinallySplitting {
       )
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) {
       this.appliesSucc(pred, succ, c) and
       succ =
-        any(FinallyControlFlowElement fcfe |
+        any(FinallyAstNode fcfe |
           if fcfe.isEntryNode()
           then
             // entering a nested `finally` block
-            fcfe.getTryStmt().nestLevel() > this.getNestLevel()
+            fcfe.getTryStmt().nestLevel() > super.getNestLevel()
           else
             // staying in the same (possibly nested) `finally` block as `pred`
-            fcfe.getTryStmt().nestLevel() >= this.getNestLevel()
+            fcfe.getTryStmt().nestLevel() >= super.getNestLevel()
         )
     }
   }
@@ -774,20 +778,20 @@ module ExceptionHandlerSplitting {
 
   int getNextListOrder() { result = FinallySplitting::getNextListOrder() + 1 }
 
-  private class ExceptionHandlerSplitImpl extends SplitImpl, ExceptionHandlerSplit {
+  private class ExceptionHandlerSplitImpl extends SplitImpl instanceof ExceptionHandlerSplit {
     override ExceptionHandlerSplitKind getKind() { any() }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
       // Entry into first catch clause
       exists(Statements::TryStmtTree ts |
-        this.getExceptionClass() = ts.getAThrownException(pred, c)
+        super.getExceptionClass() = ts.getAThrownException(pred, c)
       |
         succ(pred, succ, c) and
-        succ = ts.getCatchClause(0).(SpecificCatchClause)
+        succ = ts.(TryStmt).getCatchClause(0).(SpecificCatchClause)
       )
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) { none() }
+    override predicate hasEntryScope(CfgScope scope, AstNode first) { none() }
 
     /**
      * Holds if this split applies to catch clause `scc`. The parameter `match`
@@ -796,9 +800,9 @@ module ExceptionHandlerSplitting {
      */
     private predicate appliesToCatchClause(SpecificCatchClause scc, TMatch match) {
       exists(Statements::TryStmtTree ts, ExceptionClass ec |
-        ec = this.getExceptionClass() and
+        ec = super.getExceptionClass() and
         ec = ts.getAThrownException(_, _) and
-        scc = ts.getACatchClause()
+        scc = ts.(TryStmt).getACatchClause()
       |
         if scc.getCaughtExceptionType() = ec.getABaseType*()
         then match = TAlways()
@@ -813,7 +817,7 @@ module ExceptionHandlerSplitting {
      * Holds if this split applies to control flow element `pred`, where `pred`
      * is a valid predecessor with completion `c`.
      */
-    private predicate appliesToPredecessor(ControlFlowElement pred, Completion c) {
+    private predicate appliesToPredecessor(AstNode pred, Completion c) {
       this.appliesTo(pred) and
       (succ(pred, _, c) or scopeLast(_, pred, c)) and
       (
@@ -843,18 +847,18 @@ module ExceptionHandlerSplitting {
      * with throw completion `c`, because it belongs to the last `catch` clause
      * in a `try` statement.
      */
-    private predicate hasLastExit(ControlFlowElement pred, ThrowCompletion c) {
+    private predicate hasLastExit(AstNode pred, ThrowCompletion c) {
       this.appliesToPredecessor(pred, c) and
       exists(TryStmt ts, SpecificCatchClause scc, int last |
         last(ts.getCatchClause(last), pred, c)
       |
         ts.getCatchClause(last) = scc and
         scc.isLast() and
-        c.getExceptionClass() = this.getExceptionClass()
+        c.getExceptionClass() = super.getExceptionClass()
       )
     }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       this.appliesToPredecessor(pred, c) and
       succ(pred, succ, c) and
       (
@@ -869,13 +873,13 @@ module ExceptionHandlerSplitting {
       )
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       // Exit out from last `catch` clause (no catch clauses match)
       this.hasLastExit(last, c) and
       scopeLast(scope, last, c)
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) {
       this.appliesToPredecessor(pred, c) and
       this.appliesSucc(pred, succ, c) and
       not first(any(SpecificCatchClause scc).getBlock(), succ) and
@@ -916,7 +920,7 @@ module BooleanSplitting {
     abstract predicate correlatesConditions(ConditionBlock cb1, ConditionBlock cb2, boolean inverted);
 
     /** Holds if control flow element `cfe` starts a split of this kind. */
-    predicate startsSplit(ControlFlowElement cfe) {
+    predicate startsSplit(AstNode cfe) {
       this.correlatesConditions(any(ConditionBlock cb | cb.getLastElement() = cfe), _, _)
     }
 
@@ -1078,27 +1082,26 @@ module BooleanSplitting {
     override string toString() { result = kind.toString() }
   }
 
-  pragma[noinline]
+  pragma[nomagic]
   private predicate hasEntry0(
-    ControlFlowElement pred, ControlFlowElement succ, BooleanSplitSubKind kind, boolean b,
-    Completion c
+    AstNode pred, AstNode succ, BooleanSplitSubKind kind, boolean b, Completion c
   ) {
     kind.startsSplit(pred) and
     succ(pred, succ, c) and
     b = c.getInnerCompletion().(BooleanCompletion).getValue()
   }
 
-  private class BooleanSplitImpl extends SplitImpl, BooleanSplit {
-    override BooleanSplitKind getKind() { result.getSubKind() = this.getSubKind() }
+  private class BooleanSplitImpl extends SplitImpl instanceof BooleanSplit {
+    override BooleanSplitKind getKind() { result.getSubKind() = super.getSubKind() }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
-      hasEntry0(pred, succ, this.getSubKind(), this.getBranch(), c)
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
+      hasEntry0(pred, succ, super.getSubKind(), super.getBranch(), c)
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) { none() }
+    override predicate hasEntryScope(CfgScope scope, AstNode first) { none() }
 
     private ConditionBlock getACorrelatedCondition(boolean inverted) {
-      this.getSubKind().correlatesConditions(_, result, inverted)
+      super.getSubKind().correlatesConditions(_, result, inverted)
     }
 
     /**
@@ -1107,35 +1110,35 @@ module BooleanSplitting {
      */
     private predicate appliesToBlock(PreBasicBlock bb, Completion c) {
       this.appliesTo(bb) and
-      exists(ControlFlowElement last | last = bb.getLastElement() |
+      exists(AstNode last | last = bb.getLastElement() |
         (succ(last, _, c) or scopeLast(_, last, c)) and
         // Respect the value recorded in this split for all correlated conditions
         forall(boolean inverted | bb = this.getACorrelatedCondition(inverted) |
           c.getInnerCompletion() instanceof BooleanCompletion
           implies
           c.getInnerCompletion().(BooleanCompletion).getValue() =
-            this.getBranch().booleanXor(inverted)
+            super.getBranch().booleanXor(inverted)
         )
       )
     }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       exists(PreBasicBlock bb | this.appliesToBlock(bb, c) |
         pred = bb.getLastElement() and
         succ(pred, succ, c) and
         // Exit this split if we can no longer reach a correlated condition
-        not this.getSubKind().canReachCorrelatedCondition(succ)
+        not super.getSubKind().canReachCorrelatedCondition(succ)
       )
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       exists(PreBasicBlock bb | this.appliesToBlock(bb, c) |
         last = bb.getLastElement() and
         scopeLast(scope, last, c)
       )
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) {
       exists(PreBasicBlock bb, Completion c0 | this.appliesToBlock(bb, c0) |
         pred = bb.getAnElement() and
         this.appliesSucc(pred, succ, c) and
@@ -1144,7 +1147,7 @@ module BooleanSplitting {
           implies
           (
             // We must still be able to reach a correlated condition to stay in this split
-            this.getSubKind().canReachCorrelatedCondition(succ) and
+            super.getSubKind().canReachCorrelatedCondition(succ) and
             c = c0
           )
         )
@@ -1174,15 +1177,15 @@ module LoopSplitting {
    */
   abstract class AnalyzableLoopStmt extends LoopStmt {
     /** Holds if the step `pred --c--> succ` should start the split. */
-    abstract predicate start(ControlFlowElement pred, ControlFlowElement succ, Completion c);
+    abstract predicate start(AstNode pred, AstNode succ, Completion c);
 
     /** Holds if the step `pred --c--> succ` should stop the split. */
-    abstract predicate stop(ControlFlowElement pred, ControlFlowElement succ, Completion c);
+    abstract predicate stop(AstNode pred, AstNode succ, Completion c);
 
     /**
      * Holds if any step `pred --c--> _` should be pruned from the control flow graph.
      */
-    abstract predicate pruneLoopCondition(ControlFlowElement pred, ConditionalCompletion c);
+    abstract predicate pruneLoopCondition(AstNode pred, ConditionalCompletion c);
 
     /**
      * Holds if the body is guaranteed to be executed at least once. If not, the
@@ -1219,17 +1222,17 @@ module LoopSplitting {
         )
     }
 
-    override predicate start(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate start(AstNode pred, AstNode succ, Completion c) {
       last(this.getIterableExpr(), pred, c) and
       succ = this
     }
 
-    override predicate stop(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate stop(AstNode pred, AstNode succ, Completion c) {
       pred = this and
       succ(pred, succ, c)
     }
 
-    override predicate pruneLoopCondition(ControlFlowElement pred, ConditionalCompletion c) {
+    override predicate pruneLoopCondition(AstNode pred, ConditionalCompletion c) {
       pred = this and
       c = any(EmptinessCompletion ec | if v.isEmpty() then not ec.isEmpty() else ec.isEmpty())
     }
@@ -1298,36 +1301,40 @@ module LoopSplitting {
     override string toString() { result = "Unroll" }
   }
 
-  private class LoopUnrollingSplitImpl extends SplitImpl, LoopSplit {
+  private class LoopUnrollingSplitImpl extends SplitImpl instanceof LoopSplit {
+    AnalyzableLoopStmt loop;
+
+    LoopUnrollingSplitImpl() { this = TLoopSplit(loop) }
+
     override LoopSplitKind getKind() { result = TLoopSplitKind(loop) }
 
-    override predicate hasEntry(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasEntry(AstNode pred, AstNode succ, Completion c) {
       loop.start(pred, succ, c)
     }
 
-    override predicate hasEntryScope(CfgScope scope, ControlFlowElement first) { none() }
+    override predicate hasEntryScope(CfgScope scope, AstNode first) { none() }
 
     /**
      * Holds if this split applies to control flow element `pred`, where `pred`
      * is a valid predecessor.
      */
-    private predicate appliesToPredecessor(ControlFlowElement pred, Completion c) {
+    private predicate appliesToPredecessor(AstNode pred, Completion c) {
       this.appliesTo(pred) and
       (succ(pred, _, c) or scopeLast(_, pred, c)) and
       not loop.pruneLoopCondition(pred, c)
     }
 
-    override predicate hasExit(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasExit(AstNode pred, AstNode succ, Completion c) {
       this.appliesToPredecessor(pred, c) and
       loop.stop(pred, succ, c)
     }
 
-    override predicate hasExitScope(CfgScope scope, ControlFlowElement last, Completion c) {
+    override predicate hasExitScope(CfgScope scope, AstNode last, Completion c) {
       this.appliesToPredecessor(last, c) and
       scopeLast(scope, last, c)
     }
 
-    override predicate hasSuccessor(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
+    override predicate hasSuccessor(AstNode pred, AstNode succ, Completion c) {
       this.appliesToPredecessor(pred, c) and
       this.appliesSucc(pred, succ, c) and
       not loop.stop(pred, succ, c)

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

@@ -411,7 +411,7 @@ module Ssa {
      * This is either an expression, for example `x = 0`, a parameter, or a
      * callable. Phi nodes have no associated syntax element.
      */
-    Element getElement() { result = this.getControlFlowNode().getElement() }
+    Element getElement() { result = this.getControlFlowNode().getAstNode() }
 
     /** Gets the callable to which this SSA definition belongs. */
     final Callable getEnclosingCallable() {

csharp/ql/lib/semmle/code/csharp/dataflow/internal/ControlFlowReachability.qll

@@ -24,11 +24,11 @@ private ControlFlowElement getANonExactScopeChild(ControlFlowScope scope) {
 
 pragma[noinline]
 private ControlFlow::BasicBlock getABasicBlockInScope(ControlFlowScope scope, boolean exactScope) {
-  result.getANode().getElement() = getANonExactScopeChild(scope) and
+  result.getANode().getAstNode() = getANonExactScopeChild(scope) and
   exactScope = false
   or
   scope.isExact() and
-  result.getANode().getElement() = scope and
+  result.getANode().getAstNode() = scope and
   exactScope = true
 }
 

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

@@ -104,10 +104,10 @@ private module Cached {
   newtype TDataFlowCall =
     TNonDelegateCall(ControlFlow::Nodes::ElementNode cfn, DispatchCall dc) {
       DataFlowImplCommon::forceCachingInSameStage() and
-      cfn.getElement() = dc.getCall()
+      cfn.getAstNode() = dc.getCall()
     } or
     TExplicitDelegateLikeCall(ControlFlow::Nodes::ElementNode cfn, DelegateLikeCall dc) {
-      cfn.getElement() = dc
+      cfn.getAstNode() = dc
     } or
     TTransitiveCapturedCall(ControlFlow::Nodes::ElementNode cfn, Callable target) {
       transitiveCapturedCallTarget(cfn, target)

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

@@ -819,7 +819,7 @@ private module Cached {
 
   cached
   newtype TNode =
-    TExprNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getElement() instanceof Expr } or
+    TExprNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getAstNode() instanceof Expr } or
     TCilExprNode(CIL::Expr e) { e.getImplementation() instanceof CIL::BestImplementation } or
     TCilSsaDefinitionExtNode(CilSsaImpl::DefinitionExt def) or
     TSsaDefinitionExtNode(SsaImpl::DefinitionExt def) {
@@ -835,19 +835,19 @@ private module Cached {
       not c.(Modifiable).isStatic()
     } or
     TYieldReturnNode(ControlFlow::Nodes::ElementNode cfn) {
-      any(Callable c).canYieldReturn(cfn.getElement())
+      any(Callable c).canYieldReturn(cfn.getAstNode())
     } or
     TAsyncReturnNode(ControlFlow::Nodes::ElementNode cfn) {
-      any(Callable c | c.(Modifiable).isAsync()).canReturn(cfn.getElement())
+      any(Callable c | c.(Modifiable).isAsync()).canReturn(cfn.getAstNode())
     } or
     TImplicitCapturedArgumentNode(ControlFlow::Nodes::ElementNode cfn, LocalScopeVariable v) {
       exists(Ssa::ExplicitDefinition def | def.isCapturedVariableDefinitionFlowIn(_, cfn, _) |
         v = def.getSourceVariable().getAssignable()
       )
     } or
-    TMallocNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getElement() instanceof ObjectCreation } or
+    TMallocNode(ControlFlow::Nodes::ElementNode cfn) { cfn.getAstNode() instanceof ObjectCreation } or
     TObjectInitializerNode(ControlFlow::Nodes::ElementNode cfn) {
-      cfn.getElement().(ObjectCreation).hasInitializer()
+      cfn.getAstNode().(ObjectCreation).hasInitializer()
     } or
     TExprPostUpdateNode(ControlFlow::Nodes::ExprNode cfn) {
       cfn = LocalFlow::getAPostUpdateNodeForArg(_)
@@ -1256,7 +1256,7 @@ private module ArgumentNodes {
       result.asCallable() = cfn.getEnclosingCallable()
     }
 
-    override Type getTypeImpl() { result = cfn.getElement().(Expr).getType() }
+    override Type getTypeImpl() { result = cfn.getAstNode().(Expr).getType() }
 
     override Location getLocationImpl() { result = cfn.getLocation() }
 
@@ -1397,7 +1397,7 @@ private module ReturnNodes {
     private ControlFlow::Nodes::ElementNode cfn;
     private Expr expr;
 
-    AsyncReturnNode() { this = TAsyncReturnNode(cfn) and expr = cfn.getElement() }
+    AsyncReturnNode() { this = TAsyncReturnNode(cfn) and expr = cfn.getAstNode() }
 
     Expr getExpr() { result = expr }
 
@@ -2106,7 +2106,7 @@ private module PostUpdateNodes {
       result.asCallable() = cfn.getEnclosingCallable()
     }
 
-    override Type getTypeImpl() { result = cfn.getElement().(Expr).getType() }
+    override Type getTypeImpl() { result = cfn.getAstNode().(Expr).getType() }
 
     override ControlFlow::Node getControlFlowNodeImpl() { none() }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPublic.qll

@@ -90,7 +90,7 @@ class ExprNode extends Node, TExprNode_ {
    */
   Expr getExprAtNode(ControlFlow::Nodes::ElementNode cfn) {
     this = TExprNode(cfn) and
-    result = cfn.getElement()
+    result = cfn.getAstNode()
   }
 }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll

@@ -71,7 +71,7 @@ module ExposedForTestingOnly {
  * Holds if the `i`th node of basic block `bb` reads source variable `v`.
  */
 private predicate variableReadActual(ControlFlow::BasicBlock bb, int i, Ssa::SourceVariable v) {
-  v.getAnAccess().(AssignableRead) = bb.getNode(i).getElement()
+  v.getAnAccess().(AssignableRead) = bb.getNode(i).getAstNode()
 }
 
 private module SourceVariableImpl {
@@ -939,7 +939,7 @@ private module CapturedVariableLivenessImpl {
     CapturedReadLocalScopeVariable captured, Callable c, boolean libraryDelegateCall
   ) {
     implicitReadCandidate(v, call) and
-    c = getARuntimeTarget(call.getElement(), libraryDelegateCall) and
+    c = getARuntimeTarget(call.getAstNode(), libraryDelegateCall) and
     captured = v.getAssignable() and
     capturerReads(_, captured)
   }

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/ControlFlowReachability.qll

@@ -24,11 +24,11 @@ private ControlFlowElement getANonExactScopeChild(ControlFlowScope scope) {
 
 pragma[noinline]
 private ControlFlow::BasicBlock getABasicBlockInScope(ControlFlowScope scope, boolean exactScope) {
-  result.getANode().getElement() = getANonExactScopeChild(scope) and
+  result.getANode().getAstNode() = getANonExactScopeChild(scope) and
   exactScope = false
   or
   scope.isExact() and
-  result.getANode().getElement() = scope and
+  result.getANode().getAstNode() = scope and
   exactScope = true
 }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/SsaReadPositionSpecific.qll

@@ -22,10 +22,10 @@ private class PhiInputEdgeBlock extends BasicBlock {
 }
 
 private int getId(PhiInputEdgeBlock bb) {
-  exists(CfgImpl::ControlFlowTree::Range_ t | CfgImpl::ControlFlowTree::idOf(t, result) |
-    t = bb.getFirstNode().getElement()
+  exists(CfgImpl::AstNode n | result = n.getId() |
+    n = bb.getFirstNode().getAstNode()
     or
-    t = bb.(ControlFlow::BasicBlocks::EntryBlock).getCallable()
+    n = bb.(ControlFlow::BasicBlocks::EntryBlock).getCallable()
   )
 }
 

csharp/ql/src/Concurrency/FutileSyncOnField.ql

@@ -16,7 +16,7 @@
 import csharp
 
 predicate lockedFieldUpdate(LockStmt lock, Field f, AssignableDefinition def) {
-  lock.getAChild+() = def.getAControlFlowNode().getElement() and
+  lock.getAChild+() = def.getAControlFlowNode().getAstNode() and
   def.getTarget() = f
 }
 

csharp/ql/src/Concurrency/UnsynchronizedStaticAccess.ql

@@ -28,7 +28,7 @@ ControlFlow::Node unlockedReachable(Callable a) {
   result = a.getEntryPoint()
   or
   exists(ControlFlow::Node mid | mid = unlockedReachable(a) |
-    not mid.getElement() instanceof LockingCall and
+    not mid.getAstNode() instanceof LockingCall and
     result = mid.getASuccessor()
   )
 }

csharp/ql/src/Likely Bugs/NestedLoopsSameVariable.ql

@@ -81,20 +81,20 @@ class NestedForLoopSameVariable extends ForStmt {
 
   /** Finds elements inside the outer loop that are no longer guarded by the loop invariant. */
   private ControlFlow::Node getAnUnguardedNode() {
-    hasChild(this.getOuterForStmt().getBody(), result.getElement()) and
+    hasChild(this.getOuterForStmt().getBody(), result.getAstNode()) and
     (
       result =
         this.getCondition().(ControlFlowElement).getAControlFlowExitNode().getAFalseSuccessor()
       or
       exists(ControlFlow::Node mid | mid = this.getAnUnguardedNode() |
         mid.getASuccessor() = result and
-        not exists(this.getAComparisonTest(result.getElement()))
+        not exists(this.getAComparisonTest(result.getAstNode()))
       )
     )
   }
 
   private VariableAccess getAnUnguardedAccess() {
-    result = this.getAnUnguardedNode().getElement() and
+    result = this.getAnUnguardedNode().getAstNode() and
     result.getTarget() = iteration
   }
 }

csharp/ql/src/Likely Bugs/Statements/UseBraces.ql

@@ -15,9 +15,9 @@ import csharp
 
 // Iterate the control flow until we reach a Stmt
 Stmt findSuccessorStmt(ControlFlow::Node n) {
-  result = n.getElement()
+  result = n.getAstNode()
   or
-  not n.getElement() instanceof Stmt and result = findSuccessorStmt(n.getASuccessor())
+  not n.getAstNode() instanceof Stmt and result = findSuccessorStmt(n.getASuccessor())
 }
 
 // Return a successor statement to s

csharp/ql/src/Likely Bugs/UncheckedCastInEquals.ql

@@ -19,13 +19,13 @@ private predicate equalsMethodChild(EqualsMethod equals, Element child) {
 }
 
 predicate nodeBeforeParameterAccess(ControlFlow::Node node) {
-  exists(EqualsMethod equals | equals.getBody() = node.getElement())
+  exists(EqualsMethod equals | equals.getBody() = node.getAstNode())
   or
   exists(EqualsMethod equals, Parameter param, ControlFlow::Node mid |
     equals.getParameter(0) = param and
-    equalsMethodChild(equals, mid.getElement()) and
+    equalsMethodChild(equals, mid.getAstNode()) and
     nodeBeforeParameterAccess(mid) and
-    not param.getAnAccess() = mid.getElement() and
+    not param.getAnAccess() = mid.getAstNode() and
     mid.getASuccessor() = node
   )
 }

csharp/ql/src/Security Features/CWE-384/AbandonSession.ql

@@ -58,16 +58,16 @@ predicate sessionUse(MemberAccess ma) {
 /** A control flow step that is not sanitised by a call to clear the session. */
 predicate controlStep(ControlFlow::Node s1, ControlFlow::Node s2) {
   s2 = s1.getASuccessor() and
-  not sessionEndMethod(s2.getElement().(MethodCall).getTarget())
+  not sessionEndMethod(s2.getAstNode().(MethodCall).getTarget())
 }
 
 from
   ControlFlow::Node loginCall, Method loginMethod, ControlFlow::Node sessionUse,
   ControlFlow::SuccessorType fromLoginFlow
 where
-  loginMethod = loginCall.getElement().(MethodCall).getTarget() and
+  loginMethod = loginCall.getAstNode().(MethodCall).getTarget() and
   loginMethod(loginMethod, fromLoginFlow) and
-  sessionUse(sessionUse.getElement()) and
+  sessionUse(sessionUse.getAstNode()) and
   controlStep+(loginCall.getASuccessorByType(fromLoginFlow), sessionUse)
 select sessionUse, "This session has not been invalidated following the call to $@.", loginCall,
   loginMethod.getName()

csharp/ql/test/library-tests/cil/dataflow/ControlFlow.ql

@@ -2,5 +2,5 @@ import csharp
 
 query predicate deadCode(MethodCall c) {
   c.getTarget().getName() = "DeadCode" and
-  not exists(ControlFlow::Node node | node.getElement() = c)
+  not exists(ControlFlow::Node node | node.getAstNode() = c)
 }

csharp/ql/test/library-tests/controlflow/graph/NodeGraph.ql

@@ -4,6 +4,6 @@
 
 import csharp
 import Common
-import semmle.code.csharp.controlflow.internal.ControlFlowGraphImplShared::TestOutput
+import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl::TestOutput
 
 private class MyRelevantNode extends RelevantNode, SourceControlFlowNode { }

csharp/ql/test/library-tests/controlflow/graph/Nodes.ql

@@ -1,7 +1,7 @@
 import csharp
 import ControlFlow
 import Common
-import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl
+import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl as Impl
 import semmle.code.csharp.controlflow.internal.Splitting as Splitting
 import Nodes
 
@@ -16,11 +16,11 @@ class MyFinallySplitControlFlowNode extends ElementNode {
     )
   }
 
-  Statements::TryStmtTree getTryStmt() { this.getElement() = result.getAFinallyDescendant() }
+  Impl::Statements::TryStmtTree getTryStmt() { this.getAstNode() = result.getAFinallyDescendant() }
 }
 
 query predicate finallyNode(MyFinallySplitControlFlowNode f, TryStmt try) { try = f.getTryStmt() }
 
 query predicate entryPoint(Callable c, SourceControlFlowElement cfn) {
-  c.getEntryPoint().getASuccessor().getElement() = cfn
+  c.getEntryPoint().getASuccessor().getAstNode() = cfn
 }

csharp/ql/test/library-tests/controlflow/splits/SplittingStressTest.ql

@@ -2,7 +2,7 @@ import csharp
 
 query predicate countSplits(ControlFlowElement cfe, int i) {
   not cfe.fromLibrary() and
-  i = strictcount(ControlFlow::Nodes::ElementNode n | n.getElement() = cfe)
+  i = strictcount(ControlFlow::Nodes::ElementNode n | n.getAstNode() = cfe)
 }
 
 query predicate ssaDef(Ssa::Definition def) { any() }

csharp/ql/test/library-tests/dataflow/ssa/PreSsaConsistency.ql

@@ -4,7 +4,7 @@ import semmle.code.csharp.controlflow.internal.ControlFlowGraphImpl
 import semmle.code.csharp.dataflow.internal.SsaImpl as SsaImpl
 
 class CallableWithSplitting extends Callable {
-  CallableWithSplitting() { this = any(SplitControlFlowElement e).getEnclosingCallable() }
+  CallableWithSplitting() { this = any(SplitAstNode n).getEnclosingCallable() }
 }
 
 query predicate defReadInconsistency(
@@ -57,8 +57,8 @@ query predicate readReadInconsistency(
     not PreSsa::adjacentReadPairSameVar(read1, read2) and
     // Exclude split CFG elements because SSA may be more precise than pre-SSA
     // in those cases
-    not read1 instanceof SplitControlFlowElement and
-    not read2 instanceof SplitControlFlowElement
+    not read1 instanceof SplitAstNode and
+    not read2 instanceof SplitAstNode
   )
 }
 
@@ -78,7 +78,7 @@ query predicate phiInconsistency(
       |
         edef.getADefinition() = adef and
         phi.definesAt(_, bb, _) and
-        cfe = bb.getFirstNode().getElement()
+        cfe = bb.getFirstNode().getAstNode()
       )
     )
     or
@@ -89,7 +89,7 @@ query predicate phiInconsistency(
       edef = phi.getAnUltimateDefinition() and
       edef.getADefinition() = adef and
       phi.definesAt(_, bb, _) and
-      cfe = bb.getFirstNode().getElement() and
+      cfe = bb.getFirstNode().getAstNode() and
       not exists(PreSsa::PhiNode prePhi |
         adef = prePhi.getAnInput+().getDefinition() and
         cfe = prePhi.getBasicBlock().getFirstElement()

csharp/ql/test/library-tests/goto/Goto1.ql

@@ -1,7 +1,7 @@
 import csharp
 
 query predicate edges(ControlFlow::Node node, ControlFlow::Node successor, string attr, string val) {
-  not node.getElement().fromLibrary() and
+  not node.getAstNode().fromLibrary() and
   exists(ControlFlow::SuccessorType t | successor = node.getASuccessorByType(t) |
     attr = "semmle.label" and
     val = t.toString()

csharp/ql/test/library-tests/standalone/controlflow/cfg.ql

@@ -12,5 +12,5 @@ class UnknownCall extends Call {
 }
 
 query predicate edges(ControlFlow::Node n1, ControlFlow::Node n2) {
-  not n1.getElement().fromLibrary() and n2 = n1.getASuccessor()
+  not n1.getAstNode().fromLibrary() and n2 = n1.getASuccessor()
 }

shared/controlflow/codeql/controlflow/Cfg.qll

@@ -937,23 +937,6 @@ module Make<LocationSig Location, InputSig<Location> Input> {
       )
     }
 
-    /**
-     * Gets the CFG scope of node `n`. Unlike `getCfgScope`, this predicate
-     * is calculated based on reachability from an entry node, and it may
-     * yield different results for AST elements that are split into multiple
-     * scopes.
-     */
-    cached
-    CfgScope getNodeCfgScope(Node n) {
-      n = TEntryNode(result)
-      or
-      n = TAnnotatedExitNode(result, _)
-      or
-      n = TExitNode(result)
-      or
-      n = TAstNode(result, _, _)
-    }
-
     cached
     module Public {
       /**
@@ -974,6 +957,23 @@ module Make<LocationSig Location, InputSig<Location> Input> {
        */
       cached
       AstNode getAControlFlowExitNode(AstNode n) { last(n, result, _) }
+
+      /**
+       * Gets the CFG scope of node `n`. Unlike `getCfgScope`, this predicate
+       * is calculated based on reachability from an entry node, and it may
+       * yield different results for AST elements that are split into multiple
+       * scopes.
+       */
+      cached
+      CfgScope getNodeCfgScope(Node n) {
+        n = TEntryNode(result)
+        or
+        n = TAnnotatedExitNode(result, _)
+        or
+        n = TExitNode(result)
+        or
+        n = TAstNode(result, _, _)
+      }
     }
   }