shazred: undo

Author: owen-mc

shared/controlflow/codeql/controlflow/ControlFlowGraph.qll

@@ -148,39 +148,13 @@ signature module AstSig<LocationSig Location> {
 
   /** A for-loop that iterates over the elements of a collection. */
   class ForeachStmt extends LoopStmt {
-    /**
-     * Gets the variable declaration of this `foreach` loop, if any.
-     *
-     * A `foreach` loop that binds more than one variable per iteration (for
-     * example when destructuring is used, as in `for k, v := range m` in Go, or
-     * `for (a, b) in ...` in Rust/Python/Swift) should instead opt in to the
-     * synthesized per-iteration element node (see `foreachHasElementNode`) and
-     * destructure that element into its variables, in which case this predicate
-     * need not have a result.
-     */
+    /** Gets the variable declaration of this `foreach` loop. */
     Expr getVariable();
 
     /** Gets the collection expression of this `foreach` loop. */
     Expr getCollection();
   }
 
-  /**
-   * Holds if `foreach` has a synthesized per-iteration "element" node, that is,
-   * an additional control flow node representing the element produced by each
-   * iteration of the loop.
-   *
-   * When this holds, the shared library routes control flow from the loop
-   * header (and from the non-empty collection) into the element node, but the
-   * language is then responsible for wiring control flow out of the element
-   * node and on to the loop body (typically destructuring the element into the
-   * loop variables). In this mode the shared `getVariable` routing is not used.
-   *
-   * This is useful for languages whose loop variables are bound by extracting
-   * components from an implicit "current element" value (as opposed to being
-   * evaluated as ordinary target expressions).
-   */
-  default predicate foreachHasElementNode(ForeachStmt foreach) { none() }
-
   /**
    * A `break` statement.
    *
@@ -723,8 +697,6 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
 
     private string patternMatchTrueTag() { result = "[MatchTrue]" }
 
-    private string foreachElementTag() { result = "[ForeachElement]" }
-
     /**
      * Holds if an additional node tagged with `tag` should be created for
      * `n`. Edges targeting such nodes are labeled with `t` and therefore `t`
@@ -744,10 +716,6 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
       tag = loopHeaderTag() and
       t instanceof DirectSuccessor
       or
-      foreachHasElementNode(n) and
-      tag = foreachElementTag() and
-      t instanceof DirectSuccessor
-      or
       n instanceof PatternMatchExpr and
       tag = patternMatchTrueTag() and
       t.(BooleanSuccessor).getValue() = true
@@ -1817,21 +1785,7 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
           n2.isAfter(loopstmt)
         )
         or
-        exists(ForeachStmt foreachstmt, PreControlFlowNode iterentry |
-          // `iterentry` is where each iteration begins, after the loop header
-          // (or after the collection is found to be non-empty): the element
-          // node if the language opts in, otherwise the loop variable, or the
-          // body directly if there is no variable.
-          foreachHasElementNode(foreachstmt) and
-          iterentry.isAdditional(foreachstmt, foreachElementTag())
-          or
-          not foreachHasElementNode(foreachstmt) and
-          (
-            iterentry.isBefore(foreachstmt.getVariable())
-            or
-            not exists(foreachstmt.getVariable()) and iterentry.isBefore(foreachstmt.getBody())
-          )
-        |
+        exists(ForeachStmt foreachstmt |
           n1.isBefore(foreachstmt) and
           n2.isBefore(foreachstmt.getCollection())
           or
@@ -1845,14 +1799,8 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
           or
           n1.isAfterValue(foreachstmt.getCollection(),
             any(EmptinessSuccessor t | t.getValue() = false)) and
-          n2 = iterentry
+          n2.isBefore(foreachstmt.getVariable())
           or
-          n1.isAdditional(foreachstmt, loopHeaderTag()) and
-          n2 = iterentry
-          or
-          // After the loop variable, enter the body. When the language opts in
-          // to the element node, it is instead responsible for wiring the
-          // element node through to the body itself.
           n1.isAfter(foreachstmt.getVariable()) and
           n2.isBefore(foreachstmt.getBody())
           or
@@ -1865,6 +1813,9 @@ module Make0<LocationSig Location, AstSig<Location> Ast> {
             or
             not exists(getLoopElse(foreachstmt)) and n2.isAfter(foreachstmt)
           )
+          or
+          n1.isAdditional(foreachstmt, loopHeaderTag()) and
+          n2.isBefore(foreachstmt.getVariable())
         )
         or
         exists(ForStmt forstmt, PreControlFlowNode condentry |