From: Mark Oteiza <mvoteiza@udel.edu>
Date: Thu, 16 Feb 2017 01:40:46 +0000 (-0500)
Subject: Don't expand body inside a let-binding when there are no bindings
X-Git-Tag: emacs-26.0.90~818
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=1b4442bee921d6698fc8ecac1c95c39f7ca2efe4;p=emacs.git

Don't expand body inside a let-binding when there are no bindings

* lisp/emacs-lisp/pcase.el (pcase-codegen): Only let-bind if VARS
is non-nil.
---

diff --git a/lisp/emacs-lisp/pcase.el b/lisp/emacs-lisp/pcase.el
index 46a5eedd150..289265abf27 100644
--- a/lisp/emacs-lisp/pcase.el
+++ b/lisp/emacs-lisp/pcase.el
@@ -437,8 +437,10 @@ to this macro."
   ;; Don't use let*, otherwise macroexp-let* may merge it with some surrounding
   ;; let* which might prevent the setcar/setcdr in pcase--expand's fancy
   ;; codegen from later metamorphosing this let into a funcall.
-  `(let ,(mapcar (lambda (b) (list (car b) (cdr b))) vars)
-     ,@code))
+  (if vars
+      `(let ,(mapcar (lambda (b) (list (car b) (cdr b))) vars)
+         ,@code)
+    `(progn ,@code)))
 
 (defun pcase--small-branch-p (code)
   (and (= 1 (length code))