>From aaf22460711d8d669da296dfbf024053270e1cef Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <jp@neverwas.me>
Date: Tue, 17 May 2022 05:43:52 -0700
Subject: [PATCH 0/4] *** NOT A PATCH ***

*** BLURB HERE ***

F. Jason Park (4):
  Fix regression in erc-send-input-line
  Add some ERC test helpers
  Improve ERC's handling of multiline prompt input
  Optionally prevent sending multiline input in ERC

 lisp/erc/erc.el            | 195 +++++++++++++++++++++------
 test/lisp/erc/erc-tests.el | 267 +++++++++++++++++++++++++++++++++++--
 2 files changed, 410 insertions(+), 52 deletions(-)

Interdiff:
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 14194492e8..17bf3c9c0c 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -1068,11 +1068,12 @@ erc-pre-send-functions
   :type 'hook
   :version "27.1")
 
-;; This is being auditioned for possible exporting (as a custom
+;; This is being auditioned for possible exporting (as a custom hook
 ;; option).  Likewise for (public versions of) `erc--input-split' and
 ;; `erc--discard-trailing-multiline-nulls'.  If unneeded, we'll just
 ;; run the latter on the input after `erc-pre-send-functions', and
-;; remove this hook and the struct completely.
+;; remove this hook and the struct completely.  It you need this,
+;; please say so!
 
 (defvar erc--pre-send-split-functions '(erc--discard-trailing-multiline-nulls)
   "Special hook for modifying individual lines in multiline prompt input.
@@ -5594,18 +5595,6 @@ erc--blank-in-multiline-input-p
                 (string-match (rx bot (* (in " \t\f")) eot) line))
           (throw 'return t))))))
 
-(defun erc--discard-trailing-multiline-nulls (state)
-  "Ensure last line of `erc-input' STATE's string is non-null.
-But only when `erc-send-whitespace-lines' is non-nil."
-  (when erc-send-whitespace-lines
-    (when (string-match "[\r\n]+\\'" (erc-input-string state))
-      (setf (erc--input-split-lines state)
-            (split-string (substring (erc-input-string state)
-                                     0
-                                     (match-beginning 0))
-                          erc--input-line-delim-regexp)
-            (erc--input-split-cmdp state) nil))))
-
 (defun erc--check-prompt-input-for-excess-lines (_ lines)
   "Return non-nil when trying to send too many LINES."
   (when erc-inhibit-multiline-input
@@ -5715,6 +5704,17 @@ erc-input
 (cl-defstruct (erc--input-split (:include erc-input))
   lines cmdp)
 
+(defun erc--discard-trailing-multiline-nulls (state)
+  "Ensure last line of STATE's string is non-null.
+But only when `erc-send-whitespace-lines' is non-nil.  STATE is an
+`erc--input-split' object."
+  (when (and erc-send-whitespace-lines (erc--input-split-lines state))
+    (let ((reversed (nreverse (erc--input-split-lines state))))
+      (when (string-empty-p (car reversed))
+        (pop reversed)
+        (setf (erc--input-split-cmdp state) nil))
+      (nreverse (seq-drop-while #'string-empty-p reversed)))))
+
 (defun erc-send-input (input &optional skip-ws-chk)
   "Treat INPUT as typed in by the user.
 It is assumed that the input and the prompt is already deleted.
diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index fa39f4fcc6..e956538afa 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -115,6 +115,8 @@ erc-with-all-buffers-of-server
     (kill-buffer "#spam")))
 
 (defun erc-tests--send-prep ()
+  ;; Caller should probably shadow `erc-insert-modify-hook' or
+  ;; populate user tables for erc-button.
   (erc-mode)
   (insert "\n\n")
   (setq erc-input-marker (make-marker)
@@ -483,13 +485,19 @@ erc-send-whitespace-lines
        (should-not (funcall next)))
 
      (ert-info ("Multiline command with trailing blank filtered")
-       (insert "/msg #chan hi\r")
-       (erc-send-current-line)
-       (ert-info ("Input cleared")
+       (pcase-dolist (`(,p . ,q)
+                      '(("/a b\r" "/a b\n") ("/a b\n" "/a b\n")
+                        ("/a b\n\n" "/a b\n") ("/a b\r\n" "/a b\n")
+                        ("a b\nc\n\n" "c\n" "a b\n")
+                        ("/a b\nc\n\n" "c\n" "/a b\n")
+                        ("/a b\n\nc\n\n" "c\n" "\n" "/a b\n")))
+         (insert p)
+         (erc-send-current-line)
          (erc-bol)
-         (should (eq (point) (point-max))))
-       (should (equal (funcall next) '("/msg #chan hi\n" nil t)))
-       (should-not (funcall next)))
+         (should (eq (point) (point-max)))
+         (while q
+           (should (equal (funcall next) (list (pop q) nil t))))
+         (should-not (funcall next))))
 
      (ert-info ("Multiline hunk with trailing whitespace not filtered")
        (insert "there\n ")
-- 
2.36.1