1 files changed, 17 insertions, 14 deletions
diff --git a/lisp/emacs-lisp/generator.el b/lisp/emacs-lisp/generator.el
index be48699a278..8fbc3b03648 100644
--- a/lisp/emacs-lisp/generator.el
+++ b/lisp/emacs-lisp/generator.el
@@ -143,8 +143,7 @@ the CPS state machinery."
          (setf ,static-var ,dynamic-var)))))
 
 (defmacro cps--with-dynamic-binding (dynamic-var static-var &rest body)
-  "Evaluate BODY such that generated atomic evaluations run with
-DYNAMIC-VAR bound to STATIC-VAR."
+  "Run BODY's atomic evaluations run with DYNAMIC-VAR bound to STATIC-VAR."
   (declare (indent 2))
   `(cps--with-value-wrapper
        (cps--make-dynamic-binding-wrapper ,dynamic-var ,static-var)
@@ -291,22 +290,28 @@ DYNAMIC-VAR bound to STATIC-VAR."
                         (cps--transform-1 `(progn ,@rest)
                                           next-state)))
 
-    ;; Process `let' in a helper function that transforms it into a
-    ;; let* with temporaries.
+    (`(,(or 'let 'let*) () . ,body)
+      (cps--transform-1 `(progn ,@body) next-state))
+
+    ;; Transform multi-variable `let' into `let*':
+    ;;    (let ((v1 e1) ... (vN eN)) BODY)
+    ;; -> (let* ((t1 e1) ... (tN-1 eN-1) (vN eN) (v1 t1) (vN-1 tN-1)) BODY)
 
     (`(let ,bindings . ,body)
       (let* ((bindings (cl-loop for binding in bindings
                           collect (if (symbolp binding)
                                       (list binding nil)
                                     binding)))
-             (temps (cl-loop for (var _value-form) in bindings
+             (butlast-bindings (butlast bindings))
+             (temps (cl-loop for (var _value-form) in butlast-bindings
                        collect (cps--add-binding var))))
         (cps--transform-1
          `(let* ,(append
-                  (cl-loop for (_var value-form) in bindings
+                  (cl-loop for (_var value-form) in butlast-bindings
                      for temp in temps
                      collect (list temp value-form))
-                  (cl-loop for (var _binding) in bindings
+                  (last bindings)
+                  (cl-loop for (var _binding) in butlast-bindings
                      for temp in temps
                      collect (list var temp)))
             ,@body)
@@ -315,9 +320,6 @@ DYNAMIC-VAR bound to STATIC-VAR."
     ;; Process `let*' binding: process one binding at a time.  Flatten
     ;; lexical bindings.
 
-    (`(let* () . ,body)
-      (cps--transform-1 `(progn ,@body) next-state))
-
     (`(let* (,binding . ,more-bindings) . ,body)
       (let* ((var (if (symbolp binding) binding (car binding)))
              (value-form (car (cdr-safe binding)))
@@ -642,12 +644,11 @@ modified copy."
                          (iter-close iterator)))))
          iterator))))
 
-(defun iter-yield (value)
+(defun iter-yield (_value)
   "When used inside a generator, yield control to caller.
 The caller of `iter-next' receives VALUE, and the next call to
 `iter-next' resumes execution with the form immediately following this
 `iter-yield' call."
-  (identity value)
   (error "`iter-yield' used outside a generator"))
 
 (defmacro iter-yield-from (value)
@@ -689,8 +690,10 @@ of values.  Callers can retrieve each value using `iter-next'."
   (declare (indent defun)
            (debug (&define lambda-list lambda-doc &rest sexp)))
   (cl-assert lexical-binding)
-  `(lambda ,arglist
-     ,(cps-generate-evaluator body)))
+  (pcase-let* ((`(,declarations . ,exps) (macroexp-parse-body body)))
+    `(lambda ,arglist
+       ,@declarations
+       ,(cps-generate-evaluator exps))))
 
 (defmacro iter-make (&rest body)
   "Return a new iterator."