[Emacs-diffs] emacs-26 9a10c87: Fix dynamic binding wrapper in iter-lambda (bug#25965)

[Gemini Lasswell]

branch: emacs-26
commit 9a10c8713b8dd46738365d35263ae0687e2063cc
Author: Gemini Lasswell <address@hidden>
Commit: Gemini Lasswell <address@hidden>

    Fix dynamic binding wrapper in iter-lambda (bug#25965)
    
    * lisp/emacs-lisp/generator.el (cps--make-dynamic-binding-wrapper):
    Remove extra evaluation of form.
    * test/lisp/emacs-lisp/generator-tests.el
    (cps-iter-lambda-with-dynamic-binding): New test.
---
 lisp/emacs-lisp/generator.el            |  3 +--
 test/lisp/emacs-lisp/generator-tests.el | 10 ++++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lisp/emacs-lisp/generator.el b/lisp/emacs-lisp/generator.el
index f3597cc..3e98859 100644
--- a/lisp/emacs-lisp/generator.el
+++ b/lisp/emacs-lisp/generator.el
@@ -142,8 +142,7 @@ the CPS state machinery.
     `(let ((,dynamic-var ,static-var))
        (unwind-protect ; Update the static shadow after evaluation is done
             ,form
-         (setf ,static-var ,dynamic-var))
-       ,form)))
+         (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
diff --git a/test/lisp/emacs-lisp/generator-tests.el 
b/test/lisp/emacs-lisp/generator-tests.el
index 4cc6c84..cbb136a 100644
--- a/test/lisp/emacs-lisp/generator-tests.el
+++ b/test/lisp/emacs-lisp/generator-tests.el
@@ -282,3 +282,13 @@ identical output.
 (ert-deftest cps-test-declarations-preserved ()
   (should (equal (documentation 'generator-with-docstring) "Documentation!"))
   (should (equal (get 'generator-with-docstring 'lisp-indent-function) 5)))
+
+(ert-deftest cps-iter-lambda-with-dynamic-binding ()
+  "`iter-lambda' with dynamic binding produces correct result (bug#25965)."
+  (should (= 1
+             (iter-next
+              (funcall (iter-lambda ()
+                         (let* ((fill-column 10) ;;any special variable will do
+                                (i 0)
+                                (j (setq i (1+ i))))
+                           (iter-yield i))))))))