CFG: make 'while' post-order

ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll

@@ -1223,26 +1223,12 @@ module Trees {
     }
   }
 
-  private class ConditionalLoopTree extends PreOrderTree, ConditionalLoopAstNode {
+  private class ConditionalLoopTree extends PostOrderTree, ConditionalLoopAstNode {
     final override predicate propagatesAbnormal(AstNode child) { child = this.getConditionNode() }
 
-    final override predicate last(AstNode last, Completion c) {
-      last(this.getConditionNode(), last, c) and
-      this.endLoop(c)
-      or
-      last(this.getBodyNode(), last, c) and
-      not c.continuesLoop() and
-      not c instanceof BreakCompletion and
-      not c instanceof RedoCompletion
-      or
-      last(this.getBodyNode(), last, c.(NestedBreakCompletion).getAnInnerCompatibleCompletion())
-    }
+    final override predicate first(AstNode first) { first(this.getConditionNode(), first) }
 
     final override predicate succ(AstNode pred, AstNode succ, Completion c) {
-      pred = this and
-      first(this.getConditionNode(), succ) and
-      c instanceof SimpleCompletion
-      or
       last(this.getConditionNode(), pred, c) and
       this.continueLoop(c) and
       first(this.getBodyNode(), succ)
@@ -1254,6 +1240,19 @@ module Trees {
       last(this.getBodyNode(), pred, c) and
       first(this.getBodyNode(), succ) and
       c instanceof RedoCompletion
+      or
+      succ = this and
+      (
+        last(this.getConditionNode(), pred, c) and
+        this.endLoop(c)
+        or
+        last(this.getBodyNode(), pred, c) and
+        not c.continuesLoop() and
+        not c instanceof BreakCompletion and
+        not c instanceof RedoCompletion
+        or
+        last(this.getBodyNode(), pred, c.(NestedBreakCompletion).getAnInnerCompatibleCompletion())
+      )
     }
   }
 }

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

@@ -683,7 +683,7 @@ cfg.rb:
 #-----|  -> &...
 
 #   29| call to new
-#-----|  -> while ...
+#-----|  -> true
 
 #   29| Proc
 #-----|  -> new
@@ -707,13 +707,13 @@ cfg.rb:
 #-----|  -> call to call
 
 #   31| while ...
-#-----|  -> true
+#-----|  -> false
 
 #   31| true
 #-----| true -> 1
 
 #   32| Break
-#-----| break -> false
+#-----| break -> while ...
 
 #   32| 1
 #-----|  -> Break
@@ -1824,7 +1824,7 @@ cfg.rb:
 #-----|  -> call to puts
 
 #  171| ... unless ...
-#-----|  -> until ...
+#-----|  -> x
 
 #  171| call to puts
 #-----|  -> ... unless ...
@@ -1846,11 +1846,11 @@ cfg.rb:
 #-----|  -> ... == ...
 
 #  173| until ...
-#-----|  -> x
+#-----|  -> 0
 
 #  173| ... > ...
+#-----| true -> until ...
 #-----| false -> x
-#-----| true -> 0
 
 #  173| x
 #-----|  -> 10
@@ -1877,7 +1877,7 @@ cfg.rb:
 #-----|  -> call to puts
 
 #  175| ... = ...
-#-----|  -> ... until ...
+#-----|  -> i
 
 #  175| i
 #-----|  -> ... = ...
@@ -1886,7 +1886,7 @@ cfg.rb:
 #-----|  -> i
 
 #  176| ... until ...
-#-----|  -> i
+#-----|  -> 0
 
 #  176| (...; ...)
 #-----|  -> i
@@ -1910,8 +1910,8 @@ cfg.rb:
 #-----|  -> ... += ...
 
 #  176| ... == ...
+#-----| true -> ... until ...
 #-----| false -> puts
-#-----| true -> 0
 
 #  176| i
 #-----|  -> 10
@@ -1920,7 +1920,7 @@ cfg.rb:
 #-----|  -> ... == ...
 
 #  178| ... = ...
-#-----|  -> while ...
+#-----|  -> x
 
 #  178| x
 #-----|  -> ... = ...
@@ -1929,11 +1929,11 @@ cfg.rb:
 #-----|  -> x
 
 #  179| while ...
-#-----|  -> x
+#-----|  -> i
 
 #  179| ... < ...
+#-----| false -> while ...
 #-----| true -> x
-#-----| false -> ... while ...
 
 #  179| x
 #-----|  -> 10
@@ -1976,7 +1976,7 @@ cfg.rb:
 #-----|  -> call to puts
 
 #  185| ... while ...
-#-----|  -> i
+#-----|  -> run_block
 
 #  185| (...; ...)
 #-----|  -> i
@@ -2000,8 +2000,8 @@ cfg.rb:
 #-----|  -> ... -= ...
 
 #  185| ... != ...
+#-----| false -> ... while ...
 #-----| true -> puts
-#-----| false -> run_block
 
 #  185| i
 #-----|  -> 0
@@ -2523,14 +2523,14 @@ loops.rb:
 #-----|  -> m1
 
 #    1| x
-#-----|  -> while ...
-
-#    2| while ...
 #-----|  -> x
 
+#    2| while ...
+#-----|  -> exit m1 (normal)
+
 #    2| ... >= ...
+#-----| false -> while ...
 #-----| true -> puts
-#-----| false -> exit m1 (normal)
 
 #    2| x
 #-----|  -> 0
@@ -2563,14 +2563,14 @@ loops.rb:
 #-----|  -> m2
 
 #    8| x
-#-----|  -> while ...
-
-#    9| while ...
 #-----|  -> x
 
+#    9| while ...
+#-----|  -> puts
+
 #    9| ... >= ...
+#-----| false -> while ...
 #-----| true -> puts
-#-----| false -> puts
 
 #    9| x
 #-----|  -> 0
@@ -2610,7 +2610,7 @@ loops.rb:
 #-----|  -> ... > ...
 
 #   13| Break
-#-----| break -> puts
+#-----| break -> while ...
 
 #   14| elsif ...
 #-----|  -> if ...