From 50db6916c824741542e7f4ef496358120540121a Mon Sep 17 00:00:00 2001
From: Tom Hvitved <hvitved@github.com>
Date: Thu, 31 Aug 2023 13:17:05 +0200
Subject: [PATCH] Ruby: Get rid of unused `EmptinessSuccessor`

---
 .../ruby/controlflow/ControlFlowGraph.qll     | 41 +------------------
 .../internal/ControlFlowGraphImpl.qll         |  1 -
 2 files changed, 2 insertions(+), 40 deletions(-)

diff --git a/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll b/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll
index 9a386369e91..3ff85f5553d 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/ControlFlowGraph.qll
@@ -73,16 +73,14 @@ module SuccessorTypes {
   }
 
   /**
-   * A conditional control flow successor. Either a Boolean successor (`BooleanSuccessor`),
-   * an emptiness successor (`EmptinessSuccessor`), or a matching successor
-   * (`MatchingSuccessor`)
+   * A conditional control flow successor. Either a Boolean successor (`BooleanSuccessor`)
+   * or a matching successor (`MatchingSuccessor`)
    */
   class ConditionalSuccessor extends SuccessorType {
     boolean value;
 
     ConditionalSuccessor() {
       this = CfgImpl::TBooleanSuccessor(value) or
-      this = CfgImpl::TEmptinessSuccessor(value) or
       this = CfgImpl::TMatchingSuccessor(value)
     }
 
@@ -109,41 +107,6 @@ module SuccessorTypes {
    */
   class BooleanSuccessor extends ConditionalSuccessor, CfgImpl::TBooleanSuccessor { }
 
-  /**
-   * An emptiness control flow successor.
-   *
-   * For example, this program fragment:
-   *
-   * ```rb
-   * for arg in args do
-   *   puts arg
-   * end
-   * puts "done";
-   * ```
-   *
-   * has a control flow graph containing emptiness successors:
-   *
-   * ```
-   *           args
-   *            |
-   *          for------<-----
-   *           / \           \
-   *          /   \          |
-   *         /     \         |
-   *        /       \        |
-   *     empty    non-empty  |
-   *       |          \      |
-   *  puts "done"      \     |
-   *                  arg    |
-   *                    |    |
-   *                puts arg |
-   *                     \___/
-   * ```
-   */
-  class EmptinessSuccessor extends ConditionalSuccessor, CfgImpl::TEmptinessSuccessor {
-    override string toString() { if value = true then result = "empty" else result = "non-empty" }
-  }
-
   /**
    * A matching control flow successor.
    *
diff --git a/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll b/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll
index c7a3b27afc8..0aa93e573eb 100644
--- a/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll
+++ b/ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImpl.qll
@@ -1513,7 +1513,6 @@ private module Cached {
   newtype TSuccessorType =
     TSuccessorSuccessor() or
     TBooleanSuccessor(boolean b) { b in [false, true] } or
-    TEmptinessSuccessor(boolean isEmpty) { isEmpty in [false, true] } or
     TMatchingSuccessor(boolean isMatch) { isMatch in [false, true] } or
     TReturnSuccessor() or
     TBreakSuccessor() or