Don't casemap erc-sasl-user when set to :nick

* lisp/erc/erc-sasl.el (erc-sasl-user): Fix doc string.
(erc-sasl--get-user): Don't apply casemapping when the option
`erc-sasl-user' is set to `:nick'.  While many servers and
auth-services providers perform case-folding when comparing SASL
usernames, only some recognize RFC1459 mappings, which ERC previously
applied blindly.  Instead, ERC now behaves like other clients in
leaving such preparation in the hands of the server.  This bug was
introduced with changes new to ERC 5.5 and Emacs 29 (bug#29108).

diff --git a/lisp/erc/erc-sasl.el b/lisp/erc/erc-sasl.el
index a0b36d076134fa7764e2d7efd727641d7de18376..97c7c54a5177d120668f2bc34428904c4baa7fb1 100644 (file)
--- a/lisp/erc/erc-sasl.el
+++ b/lisp/erc/erc-sasl.el
@@ -67,12 +67,11 @@ Note that any value other than nil or `external' likely requires
 
 (defcustom erc-sasl-user :user
   "Account username to send when authenticating.
-This is also referred to as the authentication identity or
+This option specifies the SASL authentication identity, or
 \"authcid\".  A value of `:user' or `:nick' indicates that the
-corresponding connection parameter on file should be used.  These
-are most often derived from arguments provided to the `erc' and
-`erc-tls' entry points.  In the case of `:nick', a downcased
-version is used."
+corresponding connection parameter on file should be used.  ERC
+typically obtains these from arguments given to its entry-point
+commands, `erc' and `erc-tls'."
   :type '(choice string (const :user) (const :nick)))
 
 (defcustom erc-sasl-password :password
@@ -129,7 +128,7 @@ integration."
 (defun erc-sasl--get-user ()
   (pcase (alist-get 'user erc-sasl--options)
     (:user erc-session-username)
-    (:nick (erc-downcase (erc-current-nick)))
+    (:nick (erc-current-nick))
     (v v)))
 
 (defun erc-sasl-auth-source-password-as-host (&rest plist)