Ruby: test implicit return refactor

Author: aschackmull

ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll

@@ -1643,16 +1643,27 @@ private module ReturnNodes {
     }
   }
 
-  pragma[noinline]
-  private AstNode implicitReturn(Callable c, ExprNode n) {
-    exists(CfgNodes::ExprCfgNode en |
-      en = n.getExprNode() and
-      en.getASuccessor().(CfgNodes::AnnotatedExitNode).isNormal() and
-      n.(NodeImpl).getCfgScope() = c and
-      result = en.getExpr()
-    )
-    or
-    result = implicitReturn(c, n).getParent()
+  // pragma[noinline]
+  // private AstNode implicitReturn(Callable c, ExprNode n) {
+  //   exists(CfgNodes::ExprCfgNode en |
+  //     en = n.getExprNode() and
+  //     en.getASuccessor().(CfgNodes::AnnotatedExitNode).isNormal() and
+  //     n.(NodeImpl).getCfgScope() = c and
+  //     result = en.getExpr()
+  //   )
+  //   or
+  //   result = implicitReturn(c, n).getParent()
+  // }
+  // predicate implicitReturnNested(Callable c, ExprNode n, AstNode parent) {
+  //   implicitReturn(c, n).getParent() = parent and
+  //   c.getBody().getAStmt() = parent
+  //   and not n.getExprNode().getExpr() = parent.getDesugared()
+  // }
+  private AstNode desugar(AstNode n) {
+    result = n.getDesugared()
+    or
+    not exists(n.getDesugared()) and
+    result = n
   }
 
   /**
@@ -1661,7 +1672,10 @@ private module ReturnNodes {
    * last thing that is evaluated in the body of the callable.
    */
   class ExprReturnNode extends SourceReturnNode, ExprNode {
-    ExprReturnNode() { exists(Callable c | implicitReturn(c, this) = c.getBody().getAStmt()) }
+    // ExprReturnNode() { exists(Callable c | implicitReturn(c, this) = c.getBody().getAStmt()) }
+    ExprReturnNode() {
+      this.getExprNode().getExpr() = desugar(any(Callable c).getBody().getLastStmt())
+    }
 
     override ReturnKind getKindSource() {
       exists(CfgScope scope | scope = this.(NodeImpl).getCfgScope() |