Merge ControlFlowTreeBase and AstNode

Author: hvitved

ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll

@@ -25,9 +25,7 @@ private module CfgInput implements CfgShared::InputSig<Location> {
   private import Splitting as Splitting
   private import codeql.ruby.CFG as Cfg
 
-  class ControlFlowTreeBase = Impl::AstNode;
-
-  class AstNode = ControlFlowTreeBase;
+  class AstNode = Impl::AstNode;
 
   class Completion = Comp::Completion;
 

shared/controlflow/codeql/controlflow/Cfg.qll

@@ -7,18 +7,15 @@ private import codeql.util.Location
 
 /** Provides the language-specific input specification. */
 signature module InputSig<LocationSig Location> {
-  /** The base class for `ControlFlowTree`. */
-  class ControlFlowTreeBase {
+  /** An AST node. */
+  class AstNode {
     /** Gets a textual representation of this element. */
     string toString();
 
     /** Gets the location of this element. */
     Location getLocation();
   }
 
-  /** An AST node. */
-  class AstNode extends ControlFlowTreeBase;
-
   /** A control-flow completion. */
   class Completion {
     /** Gets a textual representation of this completion. */
@@ -127,10 +124,10 @@ signature module InputSig<LocationSig Location> {
 module Make<LocationSig Location, InputSig<Location> Input> {
   private import Input
 
-  final private class ControlFlowTreeBaseFinal = ControlFlowTreeBase;
+  final private class AstNodeFinal = AstNode;
 
   /** An element with associated control flow. */
-  abstract class ControlFlowTree extends ControlFlowTreeBaseFinal {
+  abstract class ControlFlowTree extends AstNodeFinal {
     /** Holds if `first` is the first element executed within this element. */
     pragma[nomagic]
     abstract predicate first(AstNode first);
@@ -809,8 +806,6 @@ module Make<LocationSig Location, InputSig<Location> Input> {
     private predicate splitsBlockContains(AstNode start, AstNode n) =
       fastTC(intraSplitsSucc/2)(start, n)
 
-    final private class AstNodeFinal = AstNode;
-
     /**
      * A block of control flow elements where the set of splits is guaranteed
      * to remain unchanged, represented by the first element in the block.