bug#46777: Updated patch

[Olivier Certner <olce.emacs@certner.fr>]

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Patch slightly edited (commit message, doc text) and rebased on top of a 
recent 'master'. Ready to apply. Easy to backport to 27 as well.

-- 
Olivier Certner

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From 70d13beadc2c2d6dbb36e277ab47fa6cc1ae3903 Mon Sep 17 00:00:00 2001
From: Olivier Certner <olce.emacs@certner.fr>
Date: Fri, 5 Feb 2021 15:34:50 +0100
Subject: [PATCH] ERC: NickServ: Prompt for password last, overall
 simplifications (bug#46777)

When `erc-prompt-for-nickserv-password' is true, don't ignore the
other forms of identification.  Instead, process them first, and
prompt for the password last.  Separate concerns (determination of the
nick to use, of the password to use, and actual message sending).

Note that the user can be interactively prompted for a password on
reception of a Nickserv request, as before (on
`erc-prompt-for-nickserv-password').

* lisp/erc/erc-services.el (erc-nickserv-identify): Don't take the
password anymore as an argument (and don't prompt for it
interactively).  On the contrary, now take the nick to use for
identification (interactively, ask for it, defaulting to the current
one).  Move actual message sending into the new
`erc-nickserv-send-identify', and password prompting into
`erc-nickserv-get-password'.

(erc-nickserv-send-identify): New function containing the sending
code, given the nick and password.

(erc-nickserv-get-password): Try each password source in turn, in this
order: `erc-nickserv-passwords', auth-source (if
`erc-use-auth-source-for-nickserv-password' is true), and in the end
prompt the user interactively (if `erc-prompt-for-nickserv-password'
is true).  If one source returns a string, the function returns it, or
nil if the string is empty.

(erc-nickserv-call-identify-function): Remove.  It was necessary as a
cumbersome workaround for the fact that the code for password
prompting was in the `interactive' form of function
`erc-nickserv-identify' before this change.

(erc-nickserv-identify-autodetect, erc-nickserv-identify-on-connect)
(erc-nickserv-identify-on-nick-change): Call `erc-nickserv-identify'
directly (`erc-nickserv-call-identify-function' was removed).  For the
last two functions, remove the redundant checks on the Nickserv
identification flags (additionally, it is doubtful they have any
measurable impact on performance).
---
 etc/NEWS                 |  14 +++-
 lisp/erc/erc-services.el | 157 ++++++++++++++++++++++-----------------
 2 files changed, 99 insertions(+), 72 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index c3eaf5fcbb..af2aa21905 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1948,14 +1948,20 @@ https://www.w3.org/TR/xml/#charsets).  Now it rejects such strings.
 
 ** erc
 
----
-*** erc-services.el now supports NickServ passwords from auth-source.
+*** NickServ passwords can now be retrieved from auth-source
 The 'erc-use-auth-source-for-nickserv-password' user option enables
 querying auth-source for NickServ passwords.  To enable this, add the
 following to your init file:
 
-    (setq erc-prompt-for-nickserv-password nil
-          erc-use-auth-source-for-nickserv-password t)
+    (setq erc-use-auth-source-for-nickserv-password t)
+
+*** NickServ identification now prompts for password last
+When 'erc-prompt-for-nickserv-password' is true, the user used to be
+unconditionally prompted interactively for a password, regardless of
+the content of `erc-nickserv-passwords', which was effectively ignored
+(same for the new 'erc-use-auth-source-for-nickserv-password').  This
+limitation is now removed, and the user is interactively prompted
+last, after the other identification methods have run.
 
 ---
 *** The '/ignore' command will now ask for a timeout to stop ignoring the user.
diff --git a/lisp/erc/erc-services.el b/lisp/erc/erc-services.el
index 61006e0c02..4233b4a322 100644
--- a/lisp/erc/erc-services.el
+++ b/lisp/erc/erc-services.el
@@ -169,9 +169,8 @@ erc-prompt-for-nickserv-password
 
 (defcustom erc-use-auth-source-for-nickserv-password nil
   "Query auth-source for a password when identifiying to NickServ.
-This option has an no effect if `erc-prompt-for-nickserv-password'
-is non-nil, and passwords from `erc-nickserv-passwords' take
-precedence."
+Passwords from `erc-nickserv-passwords' take precedence.  See
+function `erc-nickserv-get-password'."
   :version "28.1"
   :type 'boolean)
 
@@ -405,85 +404,107 @@ erc-nickserv-identify-autodetect
 		 identify-regex
 		 (string-match identify-regex msg))
 	(erc-log "NickServ IDENTIFY request detected")
-	(erc-nickserv-call-identify-function nick)
+	(erc-nickserv-identify nick)
 	nil))))
 
 (defun erc-nickserv-identify-on-connect (_server nick)
   "Identify to Nickserv after the connection to the server is established."
-  (unless (or (and (null erc-nickserv-passwords)
-                   (null erc-prompt-for-nickserv-password)
-                   (null erc-use-auth-source-for-nickserv-password))
-              (and (eq erc-nickserv-identify-mode 'both)
-                   (erc-nickserv-alist-regexp (erc-network))))
-    (erc-nickserv-call-identify-function nick)))
+  (unless (and (eq erc-nickserv-identify-mode 'both)
+               (erc-nickserv-alist-regexp (erc-network)))
+    (erc-nickserv-identify nick)))
 
 (defun erc-nickserv-identify-on-nick-change (nick _old-nick)
   "Identify to Nickserv whenever your nick changes."
-  (unless (or (and (null erc-nickserv-passwords)
-                   (null erc-prompt-for-nickserv-password)
-                   (null erc-use-auth-source-for-nickserv-password))
-              (and (eq erc-nickserv-identify-mode 'both)
-                   (erc-nickserv-alist-regexp (erc-network))))
-    (erc-nickserv-call-identify-function nick)))
+  (unless (and (eq erc-nickserv-identify-mode 'both)
+               (erc-nickserv-alist-regexp (erc-network)))
+    (erc-nickserv-identify nick)))
 
-(defun erc-nickserv-get-password (nickname)
-  "Return the password for NICKNAME from configured sources.
+(defun erc-nickserv-get-password (nick)
+  "Return the password for NICK from configured sources.
+First, a password for NICK is looked up in
+`erc-nickserv-passwords'.  Then, it is looked up in auth-source
+if `erc-use-auth-source-for-nickserv-password' is not nil.
+Finally, interactively prompt the user, if
+`erc-prompt-for-nickserv-password' is true.
 
-It uses `erc-nickserv-passwords' and additionally auth-source
-when `erc-use-auth-source-for-nickserv-password' is not nil."
-  (or
-   (when erc-nickserv-passwords
-     (cdr (assoc nickname
-                 (nth 1 (assoc (erc-network)
-                               erc-nickserv-passwords)))))
-   (when erc-use-auth-source-for-nickserv-password
-     (let* ((secret (nth 0 (auth-source-search
-                            :max 1 :require '(:secret)
-                            :host (erc-with-server-buffer erc-session-server)
-                            :port (format ; ensure we have a string
-                                   "%s" (erc-with-server-buffer erc-session-port))
-                            :user nickname))))
-       (when secret
-         (let ((passwd (plist-get secret :secret)))
-           (if (functionp passwd) (funcall passwd) passwd)))))))
-
-(defun erc-nickserv-call-identify-function (nickname)
-  "Call `erc-nickserv-identify'.
-Either call it interactively or run it with NICKNAME's password,
-depending on the value of `erc-prompt-for-nickserv-password'."
-  (if erc-prompt-for-nickserv-password
-      (call-interactively 'erc-nickserv-identify)
-    (erc-nickserv-identify (erc-nickserv-get-password nickname))))
+As soon as some source returns a password, the sequence of
+lookups stops and this function returns it (or returns nil if it
+is empty).  Otherwise, no corresponding password was found, and
+it returns nil."
+  (let (network server port)
+    ;; Fill in local vars, switching to the server buffer once only
+    (erc-with-server-buffer
+     (setq network erc-network
+           server erc-session-server
+           port erc-session-port))
+    (let ((ret
+           (or
+            (when erc-nickserv-passwords
+              (cdr (assoc nick
+                          (cl-second (assoc network
+                                            erc-nickserv-passwords)))))
+            (when erc-use-auth-source-for-nickserv-password
+              (let ((secret (cl-first (auth-source-search
+                                       :max 1 :require '(:secret)
+                                       :host server
+                                       ;; Ensure a string for :port
+                                       :port (format "%s" port)
+                                       :user nick))))
+                (when secret
+                  (let ((passwd (plist-get secret :secret)))
+                    (if (functionp passwd) (funcall passwd) passwd)))))
+            (when erc-prompt-for-nickserv-password
+              (read-passwd
+               (format "NickServ password for %s on %s (RET to cancel): "
+                       nick network))))))
+      (when (and ret (not (string= ret "")))
+        ret))))
 
 (defvar erc-auto-discard-away)
 
-;;;###autoload
-(defun erc-nickserv-identify (password)
+(defun erc-nickserv-send-identify (nick password)
   "Send an \"identify <PASSWORD>\" message to NickServ.
-When called interactively, read the password using `read-passwd'."
+Returns t if the message could be sent, nil otherwise."
+  (let* ((erc-auto-discard-away nil)
+         (network (erc-network))
+         (nickserv-info (assoc network erc-nickserv-alist))
+         (nickserv (or (erc-nickserv-alist-nickserv nil nickserv-info)
+                       "NickServ"))
+         (identify-word (or (erc-nickserv-alist-ident-keyword
+                             nil nickserv-info)
+                            "IDENTIFY"))
+         (nick (if (erc-nickserv-alist-use-nick-p nil nickserv-info)
+                   (concat nick " ")
+                 ""))
+         (msgtype (or (erc-nickserv-alist-ident-command nil nickserv-info)
+                      "PRIVMSG")))
+    (erc-message msgtype
+                 (concat nickserv " " identify-word " " nick password))))
+
+;;;###autoload
+(defun erc-nickserv-identify (&optional nick)
+  "Identify to NickServ immediately.
+Identification will either use NICK or the current nick if not
+provided, and some password obtained through
+`erc-nickserv-get-password' (which see).  If no password can be
+found, an error is reported trough `erc-error'.
+
+Interactively, the user will be prompted for NICK, an empty
+string meaning to default to the current nick.
+
+Returns t if the identify message could be sent, nil otherwise."
   (interactive
-   (list (read-passwd
-	  (format "NickServ password for %s on %s (RET to cancel): "
-		  (erc-current-nick)
-		  (or (and (erc-network)
-			   (symbol-name (erc-network)))
-		      "Unknown network")))))
-  (when (and password (not (string= "" password)))
-    (let* ((erc-auto-discard-away nil)
-	   (network (erc-network))
-	   (nickserv-info (assoc network erc-nickserv-alist))
-	   (nickserv (or (erc-nickserv-alist-nickserv nil nickserv-info)
-			 "NickServ"))
-	   (identify-word (or (erc-nickserv-alist-ident-keyword
-			       nil nickserv-info)
-			      "IDENTIFY"))
-	   (nick (if (erc-nickserv-alist-use-nick-p nil nickserv-info)
-		     (concat (erc-current-nick) " ")
-		   ""))
-	   (msgtype (or (erc-nickserv-alist-ident-command nil nickserv-info)
-			"PRIVMSG")))
-      (erc-message msgtype
-		   (concat nickserv " " identify-word " " nick password)))))
+   (list
+    (read-from-minibuffer "Nickname: " nil nil nil
+                          'erc-nick-history-list (erc-current-nick))))
+  (unless (and nick (not (string= nick "")))
+    (setq nick (erc-current-nick)))
+  (let ((password (erc-nickserv-get-password nick)))
+    (if password
+        (erc-nickserv-send-identify nick password)
+      (erc-error "Cannot find a password for nickname %s"
+                 nick)
+      nil)))
 
 (provide 'erc-services)
 
-- 
2.30.0