Ruby: CFG: make VariableReferencePattern a PreOrder node

Author: aibaars

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

@@ -227,6 +227,8 @@ private predicate inMatchingContext(AstNode n) {
   or
   n instanceof CasePattern
   or
+  n = any(VariableReferencePattern p).getVariableAccess()
+  or
   n = any(CasePattern c).getDesugared()
   or
   n.(Trees::DefaultValueParameterTree).hasDefaultValue()

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

@@ -722,7 +722,7 @@ module Trees {
     override ControlFlowTree getChildElement(int i) { result = this.getPattern() and i = 0 }
   }
 
-  private class VariableReferencePatternTree extends StandardPostOrderTree, VariableReferencePattern {
+  private class VariableReferencePatternTree extends StandardPreOrderTree, VariableReferencePattern {
     override ControlFlowTree getChildElement(int i) { result = this.getVariableAccess() and i = 0 }
   }
 

ruby/ql/test/library-tests/controlflow/graph/Cfg.expected

@@ -1046,14 +1046,14 @@ case.rb:
 #-----| match -> exit case_match_various (normal)
 
 #   74| in ... then ...
-#-----|  -> foo
+#-----|  -> ^...
 
 #   74| ^...
-#-----| no-match -> in ... then ...
-#-----| match -> exit case_match_various (normal)
+#-----|  -> foo
 
 #   74| foo
-#-----|  -> ^...
+#-----| no-match -> in ... then ...
+#-----| match -> exit case_match_various (normal)
 
 #   75| in ... then ...
 #-----|  -> "string"
@@ -1154,15 +1154,15 @@ case.rb:
 #-----|  -> 5
 
 #   83| 5
-#-----| no-match -> foo
+#-----| no-match -> ^...
 #-----| match -> exit case_match_various (normal)
 
 #   83| ^...
-#-----| no-match -> "string"
-#-----| match -> exit case_match_various (normal)
+#-----|  -> foo
 
 #   83| foo
-#-----|  -> ^...
+#-----| no-match -> "string"
+#-----| match -> exit case_match_various (normal)
 
 #   83| "string"
 #-----| no-match -> in ... then ...