emacs: use string-empty-p

emacs/notmuch-lib.el

@@ -285,7 +285,7 @@ depending on the value of `notmuch-poll-script'."
   (interactive)
   (message "Polling mail...")
   (if (stringp notmuch-poll-script)
-      (unless (string= notmuch-poll-script "")
+      (unless (string-empty-p notmuch-poll-script)
 	(unless (equal (call-process notmuch-poll-script nil nil) 0)
 	  (error "Notmuch: poll script `%s' failed!" notmuch-poll-script)))
     (notmuch-call-notmuch-process "new"))

emacs/notmuch-mua.el

@@ -388,7 +388,7 @@ instead of `message-mode' and SWITCH-FUNCTION is mandatory."
   (interactive)
   (when notmuch-mua-user-agent-function
     (let ((user-agent (funcall notmuch-mua-user-agent-function)))
-      (unless (string= "" user-agent)
+      (unless (string-empty-p user-agent)
 	(push (cons 'User-Agent user-agent) other-headers))))
   (unless (assq 'From other-headers)
     (push (cons 'From (message-make-from

emacs/notmuch-show.el

@@ -333,7 +333,7 @@ operation on the contents of the current buffer."
 	 (header (concat
 		  "Subject: " subject "\n"
 		  "To: " to "\n"
-		  (if (not (string= cc ""))
+		  (if (not (string-empty-p cc))
 		      (concat "Cc: " cc "\n")
 		    "")
 		  "From: " from "\n"
@@ -1790,7 +1790,7 @@ user decision and we should not override it."
 Reshows the current thread with matches defined by the new query-string."
   (interactive (list (notmuch-read-query "Filter thread: ")))
   (let ((msg-id (notmuch-show-get-message-id)))
-    (setq notmuch-show-query-context (if (string= query "") nil query))
+    (setq notmuch-show-query-context (if (string-empty-p query) nil query))
     (notmuch-show-refresh-view t)
     (notmuch-show-goto-message msg-id)))
 

emacs/notmuch-tag.el

@@ -452,7 +452,7 @@ present or a \"-\" to indicate that the tag should be removed
 from TAGS if present."
   (let ((result-tags (copy-sequence tags)))
     (dolist (tag-change tag-changes)
-      (let ((tag (and (not (string= tag-change ""))
+      (let ((tag (and (not (string-empty-p tag-change))
 		      (substring tag-change 1))))
 	(cl-case (aref tag-change 0)
 	  (?+ (unless (member tag result-tags)

emacs/notmuch.el

@@ -814,13 +814,13 @@ non-authors is found, assume that all of the authors match."
 	(setq invisible-string (notmuch-search-author-propertize invisible-string)))
       ;; If there is any invisible text, add it as a tooltip to the
       ;; visible text.
-      (unless (string= invisible-string "")
+      (unless (string-empty-p invisible-string)
 	(setq visible-string
 	      (propertize visible-string
 			  'help-echo (concat "..." invisible-string))))
       ;; Insert the visible and, if present, invisible author strings.
       (insert visible-string)
-      (unless (string= invisible-string "")
+      (unless (string-empty-p invisible-string)
 	(let ((start (point))
 	      overlay)
 	  (insert invisible-string)