bug#68265: 30.0.50; ERC 5.6: Simplify alternate text insertion for outgoing messages

From 572d24e5b37cdc1a89a5ea4f328ac6446ab36a8c Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <[email protected]>
Date: Mon, 1 Jan 2024 00:34:53 -0800
Subject: [PATCH 1/4] [5.6] Make erc--send-input-lines a normal function

* lisp/erc/erc.el (erc--send-input-lines): Revert portion of
174b3dd9bd78c662ce9fff78404dcfa02259d21b "Make nested input handling
more robust in ERC" that converted this from a function to a method.
Instead, defer change until it's needed, likely for bug#49860.  Also,
don't overload `insertp' because user code can legitimately set that
to a function, which we then blindly call.
---
 lisp/erc/erc.el | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index e639a6278fc..1243a331bca 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -7878,14 +7878,12 @@ erc--run-send-hooks
     (user-error "Multiline command detected" ))
   lines-obj)
 
-(cl-defmethod erc--send-input-lines (lines-obj)
+(defun erc--send-input-lines (lines-obj)
   "Send lines in `erc--input-split-lines' object LINES-OBJ."
   (when (erc--input-split-sendp lines-obj)
     (dolist (line (erc--input-split-lines lines-obj))
       (when (erc--input-split-insertp lines-obj)
-        (if (functionp (erc--input-split-insertp lines-obj))
-            (funcall (erc--input-split-insertp lines-obj) line)
-          (erc-display-msg line)))
+        (erc-display-msg line))
       (erc-process-input-line (concat line "\n")
                               (null erc-flood-protect)
                               (not (erc--input-split-cmdp lines-obj))))))
-- 
2.42.0

From 980201aa92598de00a4d600dd85bc9c69e263755 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <[email protected]>
Date: Wed, 3 Jan 2024 02:00:45 -0800
Subject: [PATCH 2/4] [5.6] Allow setting `erc-split-line-length' to zero

* etc/ERC-NEWS: Mention `erc-flood-protect' no longer affects line
splitting.
* lisp/erc/erc-backend.el (erc-split-line-length): Mention ways to
suppress line splitting entirely.
(erc--split-line): Exit loop instead of asserting progress has been
made.
* lisp/erc/erc.el (erc--split-lines): Don't split input when
`erc-split-line-length is zero.
* test/lisp/erc/erc-tests.el (erc--split-line): Assert behavior when
`erc-split-line-length' is 0.
---
 etc/ERC-NEWS               | 6 ++++++
 lisp/erc/erc-backend.el    | 9 +++++++--
 lisp/erc/erc.el            | 2 +-
 test/lisp/erc/erc-tests.el | 8 ++++++++
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/etc/ERC-NEWS b/etc/ERC-NEWS
index c51b6f05458..3eb929063b2 100644
--- a/etc/ERC-NEWS
+++ b/etc/ERC-NEWS
@@ -560,6 +560,12 @@ third-party code, the key takeaway is that more 'font-lock-face'
 properties encountered in the wild may be combinations of faces rather
 than lone ones.
 
+*** 'erc-flood-protect' no longer influences input splitting.
+This variable's role has been narrowed to affecting rate limiting
+only.  ERC used to suppress protocol line-splitting when its value was
+nil, but that's now handled by setting 'erc-split-line-length' to
+zero.
+
 *** 'erc-pre-send-functions' visits prompt input post-split.
 ERC now adjusts input lines to fall within allowed length limits
 before showing hook members the result.  For compatibility,
diff --git a/lisp/erc/erc-backend.el b/lisp/erc/erc-backend.el
index 4162df00595..95207e56fd1 100644
--- a/lisp/erc/erc-backend.el
+++ b/lisp/erc/erc-backend.el
@@ -433,7 +433,11 @@ erc-server-reconnect-function
 
 (defcustom erc-split-line-length 440
   "The maximum length of a single message.
-If a message exceeds this size, it is broken into multiple ones.
+ERC normally splits chat input submitted at its prompt into
+multiple messages when the initial size exceeds this value in
+bytes.  Modules can tell ERC to forgo splitting entirely by
+setting this to zero locally or, preferably, by binding it around
+a remapped `erc-send-current-line' command.
 
 IRC allows for lines up to 512 bytes.  Two of them are CR LF.
 And a typical message looks like this:
@@ -596,7 +600,8 @@ erc--split-line
                 (if (= (car cmp) (point-min))
                     (goto-char (nth 1 cmp))
                   (goto-char (car cmp)))))
-            (cl-assert (/= (point-min) (point)))
+            (when (= (point-min) (point))
+              (goto-char (point-max)))
             (push (buffer-substring-no-properties (point-min) (point)) out)
             (delete-region (point-min) (point)))
           (or (nreverse out) (list "")))
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 1243a331bca..abb9d3830dd 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -7821,7 +7821,7 @@ erc--split-lines
   "Partition non-command input into lines of protocol-compliant length."
   ;; Prior to ERC 5.6, line splitting used to be predicated on
   ;; `erc-flood-protect' being non-nil.
-  (unless (erc--input-split-cmdp state)
+  (unless (or (zerop erc-split-line-length) (erc--input-split-cmdp state))
     (setf (erc--input-split-lines state)
           (mapcan #'erc--split-line (erc--input-split-lines state)))))
 
diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index 2cd47ec3f89..a9aa255718d 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -1298,6 +1298,14 @@ erc-log-irc-protocol
     (should-not erc-debug-irc-protocol)))
 
 (ert-deftest erc--split-line ()
+  (let ((erc-split-line-length 0))
+    (should (equal (erc--split-line "") '("")))
+    (should (equal (erc--split-line " ") '(" ")))
+    (should (equal (erc--split-line "1") '("1")))
+    (should (equal (erc--split-line " 1") '(" 1")))
+    (should (equal (erc--split-line "1 ") '("1 ")))
+    (should (equal (erc--split-line "abc") '("abc"))))
+
   (let ((erc-default-recipients '("#chan"))
         (erc-split-line-length 10))
     (should (equal (erc--split-line "") '("")))
-- 
2.42.0

From 43501ac2e921829bff21b0253fed5a17c2294b06 Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <[email protected]>
Date: Wed, 3 Jan 2024 23:10:55 -0800
Subject: [PATCH 3/4] [5.6] Make ERC's format catalogs more extensible

* lisp/erc/erc-common.el (erc--define-catalog): Accept a `:parent'
keyword to allow for extending an existing catalog by overriding some
subset of defined entries.
(erc-define-message-format-catalog): Add edebug spec.
* lisp/erc/erc.el (erc-retrieve-catalog-entry): Check parent for
definition before `default-toplevel-value'.
* test/lisp/erc/erc-tests.el (erc-retrieve-catalog-entry): Add test
case for inheritance.
* test/lisp/erc/resources/erc-tests-common.el
(erc-tests-common-pp-propertized-parts): Fix bug in helper.
(Bug#67677)
---
 lisp/erc/erc-common.el                      | 17 +++++++++++++++--
 lisp/erc/erc.el                             |  6 ++++++
 test/lisp/erc/erc-tests.el                  | 16 +++++++++++++++-
 test/lisp/erc/resources/erc-tests-common.el |  2 +-
 4 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/lisp/erc/erc-common.el b/lisp/erc/erc-common.el
index b8ba0673355..2581e40f850 100644
--- a/lisp/erc/erc-common.el
+++ b/lisp/erc/erc-common.el
@@ -554,9 +554,21 @@ erc--define-catalog
 ENTRIES, an alist, and `erc-tests-common-pp-propertized-parts' in
 tests/lisp/erc/erc-tests.el for a convenience command to convert
 a literal string into a sequence of `propertize' forms, which are
-much easier to review and edit."
+much easier to review and edit.  When ENTRIES begins with a
+sequence of keyword-value pairs remove them and consider their
+evaluated values before processing the alist proper.
+
+Currently, the only recognized keyword is `:parent', which tells
+ERC to search recursively for a given template key using the
+keyword's associated value, another catalog symbol, if not found
+in catalog NAME."
   (declare (indent 1))
   (let (out)
+    (while (keywordp (car entries))
+      (push (pcase-exhaustive (pop entries)
+              (:parent `(put ',name 'erc--base-format-catalog
+                             ,(pop entries))))
+            out))
     (dolist (e entries (cons 'progn (nreverse out)))
       (push `(defvar ,(intern (format "erc-message-%s-%s" name (car e)))
                ,(cdr e)
@@ -575,7 +587,8 @@ erc-define-message-format-catalog
 `format-spec'.  Expect modules that only define a handful of
 entries to do so manually, instead of using this macro, so that
 the resulting variables will end up with more useful doc strings."
-  (declare (indent 1))
+  (declare (indent 1)
+           (debug (symbolp [&rest [keywordp form]] &rest (symbolp . form))))
   `(erc--define-catalog ,language ,entries))
 
 (defmacro erc--doarray (spec &rest body)
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index abb9d3830dd..1e208b8204f 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -9317,6 +9317,12 @@ erc-retrieve-catalog-entry
   (unless catalog (setq catalog erc-current-message-catalog))
   (symbol-value
    (or (erc--make-message-variable-name catalog key 'softp)
+       (let ((parent catalog)
+             last)
+         (while (and (setq parent (get parent 'erc--base-format-catalog))
+                     (not (setq last (erc--make-message-variable-name
+                                      parent key 'softp)))))
+         last)
        (let ((default (default-toplevel-value 'erc-current-message-catalog)))
          (or (and (not (eq default catalog))
                   (erc--make-message-variable-name default key 'softp))
diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index a9aa255718d..a71cc806f6a 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -3533,6 +3533,20 @@ erc-retrieve-catalog-entry
   (should (equal (erc-retrieve-catalog-entry 's221) "test-top 221 val"))
 
   (makunbound (intern "erc-message-test-top-s221"))
-  (unintern "erc-message-test-top-s221" obarray))
+  (unintern "erc-message-test-top-s221" obarray)
+
+  ;; Inheritance.
+  (let ((obarray (obarray-make)))
+    (set (intern "erc-message-test1-abc") "val test1 abc")
+    (set (intern "erc-message-test2-abc") "val test2 abc")
+    (set (intern "erc-message-test2-def") "val test2 def")
+    (put (intern "test0") 'erc--base-format-catalog (intern "test1"))
+    (put (intern "test1") 'erc--base-format-catalog (intern "test2"))
+    (should (equal (erc-retrieve-catalog-entry 'abc (intern "test0"))
+                   "val test1 abc"))
+    (should (equal (erc-retrieve-catalog-entry 'def (intern "test0"))
+                   "val test2 def"))
+    ;; Terminates.
+    (should-not (erc-retrieve-catalog-entry 'ghi (intern "test0")))))
 
 ;;; erc-tests.el ends here
diff --git a/test/lisp/erc/resources/erc-tests-common.el b/test/lisp/erc/resources/erc-tests-common.el
index fc5649798b5..906aa891352 100644
--- a/test/lisp/erc/resources/erc-tests-common.el
+++ b/test/lisp/erc/resources/erc-tests-common.el
@@ -150,7 +150,7 @@ erc-tests-common-pp-propertized-parts
 For simplicity, assume string evaluates to itself."
   (interactive "P")
   (let ((sexp (erc-tests-common-string-to-propertized-parts (pp-last-sexp))))
-    (if arg (insert (pp-to-string sexp)) (pp-eval-expression sexp))))
+    (if arg (insert (pp-to-string sexp)) (pp-macroexpand-expression sexp))))
 
 ;; The following utilities are meant to help prepare tests for
 ;; `erc--get-inserted-msg-bounds' and friends.
-- 
2.42.0

From 9f2f807297bf8cbab9ab507a06f3621f0fa74f8d Mon Sep 17 00:00:00 2001
From: "F. Jason Park" <[email protected]>
Date: Mon, 1 Jan 2024 06:37:25 -0800
Subject: [PATCH 4/4] [5.6] Add replacement-text field to erc-input struct

* etc/ERC-NEWS: Promote `refoldp' slot from simulated to real.
* lisp/erc/erc-common.el (erc-input): Add `substxt' and `refoldp'
slots.
(erc--input-split): Move `refoldp' to "superclass".
* lisp/erc/erc-goodies.el (erc--command-indicator-permit-insertion):
Use `substxt' field instead of `insertp'.
(erc--command-indicator-display): Accept extra lines.
* lisp/erc/erc.el (erc-pre-send-functions): Revise doc.
(erc--input-ensure-hook-context, erc-input-refoldp): Remove unused
functions.
(erc--run-send-hooks): Copy data from additional fields of `erc-input'
object to `erc--input-split' object.
(erc--send-input-lines): Handle `substxt' field of `erc-input' object
when it's non-nil.
---
 etc/ERC-NEWS            | 14 +++++--
 lisp/erc/erc-common.el  | 19 ++++++++-
 lisp/erc/erc-goodies.el |  7 +++-
 lisp/erc/erc.el         | 86 ++++++++++++++++++++---------------------
 4 files changed, 74 insertions(+), 52 deletions(-)

diff --git a/etc/ERC-NEWS b/etc/ERC-NEWS
index 3eb929063b2..416c302f16f 100644
--- a/etc/ERC-NEWS
+++ b/etc/ERC-NEWS
@@ -571,9 +571,17 @@ ERC now adjusts input lines to fall within allowed length limits
 before showing hook members the result.  For compatibility,
 third-party code can request that the final input be adjusted again
 prior to being sent.  To facilitate this, the 'erc-input' object
-shared among hook members has gained a "phony" 'refoldp' slot that's
-only accessible from 'erc-pre-send-functions'.  See doc string for
-details.
+shared among hook members has gained a 'refoldp' slot.  See doc string
+for details.
+
+*** More flexibility in sending and displaying prompt input.
+The abnormal hook 'erc-pre-send-functions' previously married outgoing
+message text to its inserted representation in an ERC target buffer.
+Going forward, users can populate the new slot 'substxt' with
+alternate text to insert in place of the 'string' slot's contents,
+which ERC still sends to the server.  This dichotomy lets users
+completely avoid the often fiddly 'erc-send-modify-hook' and friends
+for use cases like language translation and subprotocol encoding.
 
 *** ERC's prompt survives the insertion of user input and messages.
 Previously, ERC's prompt and its input marker disappeared while
diff --git a/lisp/erc/erc-common.el b/lisp/erc/erc-common.el
index 2581e40f850..80554d6d187 100644
--- a/lisp/erc/erc-common.el
+++ b/lisp/erc/erc-common.el
@@ -49,7 +49,23 @@ erc-session-server
 (declare-function widget-type "wid-edit" (widget))
 
 (cl-defstruct erc-input
-  string insertp sendp)
+  "Object shared among members of `erc-pre-send-functions'.
+Any use outside of the hook is not supported."
+  ( string "" :type string
+    :documentation "String to send and, without `substxt', insert.
+ERC treats separate lines as separate messages.")
+  ( insertp nil :type boolean
+    :documentation "Whether to insert outgoing message.
+When nil, ERC still sends `string'.")
+  ( sendp nil :type boolean
+    :documentation "Whether to send and (for compat reasons) insert.
+To insert without sending, define a (slash) command.")
+  ( substxt nil :type (or function string null)
+    :documentation "Alternate string to insert without splitting.
+The function form is for internal use.")
+  ( refoldp nil :type boolean
+    :documentation "Whether to resplit a possibly overlong `string'.
+ERC only refolds `string', never `substxt'."))
 
 (cl-defstruct (erc--input-split (:include erc-input
                                           (string :read-only)
@@ -57,7 +73,6 @@ erc-input
                                           (sendp (with-suppressed-warnings
                                                      ((obsolete erc-send-this))
                                                    erc-send-this))))
-  (refoldp nil :type boolean)
   (lines nil :type (list-of string))
   (abortp nil :type (list-of symbol))
   (cmdp nil :type boolean))
diff --git a/lisp/erc/erc-goodies.el b/lisp/erc/erc-goodies.el
index c5ab25bea98..38c14687a9c 100644
--- a/lisp/erc/erc-goodies.el
+++ b/lisp/erc/erc-goodies.el
@@ -579,15 +579,18 @@ erc--command-indicator-permit-insertion
   "Insert `erc-input' STATE's message if it's an echoed command."
   (cl-assert erc-command-indicator-mode)
   (when (erc--input-split-cmdp state)
-    (setf (erc--input-split-insertp state) #'erc--command-indicator-display)
+    (setf (erc--input-split-insertp state) t
+          (erc--input-split-substxt state) #'erc--command-indicator-display)
     (erc-send-distinguish-noncommands state)))
 
 ;; This function used to be called `erc-display-command'.  It was
 ;; neutered in ERC 5.3.x (Emacs 24.5), commented out in 5.4, removed
 ;; in 5.5, and restored in 5.6.
-(defun erc--command-indicator-display (line)
+(defun erc--command-indicator-display (line &rest rest)
   "Insert command LINE as echoed input resembling that of REPLs and shells."
   (when erc-insert-this
+    (when rest
+      (setq line (string-join (cons line rest) "\n")))
     (save-excursion
       (erc--assert-input-bounds)
       (let ((insert-position (marker-position (goto-char erc-insert-marker)))
diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index 1e208b8204f..00963d24a32 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -1211,30 +1211,30 @@ erc-send-pre-hook
 (make-obsolete-variable 'erc-send-pre-hook 'erc-pre-send-functions "27.1")
 
 (defcustom erc-pre-send-functions nil
-  "Special hook run to possibly alter the string that is sent.
-The functions are called with one argument, an `erc-input' struct,
-and should alter that struct.
+  "Special hook to possibly alter the string to send and insert.
+ERC calls the member functions with one argument, an `erc-input'
+struct instance to modify as needed.
 
-The struct has three slots:
-
-  `string': The current input string.
-  `insertp': Whether the string should be inserted into the erc buffer.
-  `sendp': Whether the string should be sent to the irc server.
-
-And one \"phony\" slot only accessible by hook members at runtime:
+The struct has five slots:
 
-  `refoldp': Whether the string should be re-split per protocol limits.
+  `string': String to send, originally from prompt input.
+  `insertp': Whether a string should be inserted in the buffer.
+  `sendp': Whether `string' should be sent to the IRC server.
+  `substxt': String to display (but not send) instead of `string'.
+  `refoldp': Whether to re-split `string' per protocol limits.
 
 This hook runs after protocol line splitting has taken place, so
-the value of `string' is originally \"pre-filled\".  If you need
-ERC to refill the entire payload before sending it, set the phony
-`refoldp' slot to a non-nil value.  Note that this refilling is
-only a convenience, and modules with special needs, such as
-preserving \"preformatted\" text or encoding for subprotocol
-\"tunneling\", should handle splitting manually."
-  :group 'erc
-  :type 'hook
-  :version "27.1")
+the value of `string' comes \"pre-split\" according to the option
+`erc-split-line-length'.  If you need ERC to refill the entire
+payload before sending it, set the `refoldp' slot to a non-nil
+value.  Note that this refilling is only a convenience, and
+modules with special needs, such as preserving \"preformatted\"
+text or encoding for subprotocol \"tunneling\", should handle
+splitting manually and possibly also specify replacement text to
+display via the `substxt' slot."
+  :package-version '(ERC . "5.3")
+  :group 'erc-hooks
+  :type 'hook)
 
 (define-obsolete-variable-alias 'erc--pre-send-split-functions
   'erc--input-review-functions "30.1")
@@ -7825,22 +7825,6 @@ erc--split-lines
     (setf (erc--input-split-lines state)
           (mapcan #'erc--split-line (erc--input-split-lines state)))))
 
-(defun erc--input-ensure-hook-context ()
-  (unless (erc--input-split-p erc--current-line-input-split)
-    (error "Invoked outside of `erc-pre-send-functions'")))
-
-(defun erc-input-refoldp (_)
-  "Impersonate accessor for phony `erc-input' `refoldp' slot.
-This function only works inside `erc-pre-send-functions' members."
-  (declare (gv-setter (lambda (v)
-                        `(progn
-                           (erc--input-ensure-hook-context)
-                           (setf (erc--input-split-refoldp
-                                  erc--current-line-input-split)
-                                 ,v)))))
-  (erc--input-ensure-hook-context)
-  (erc--input-split-refoldp erc--current-line-input-split))
-
 (defun erc--run-send-hooks (lines-obj)
   "Run send-related hooks that operate on the entire prompt input.
 Sequester some of the back and forth involved in honoring old
@@ -7858,12 +7842,17 @@ erc--run-send-hooks
              (state (progn
                       ;; This may change `str' and `erc-*-this'.
                       (run-hook-with-args 'erc-send-pre-hook str)
-                      (make-erc-input :string str
-                                      :insertp erc-insert-this
-                                      :sendp erc-send-this))))
+                      (make-erc-input
+                       :string str
+                       :insertp erc-insert-this
+                       :sendp erc-send-this
+                       :substxt (erc--input-split-substxt lines-obj)
+                       :refoldp (erc--input-split-refoldp lines-obj)))))
         (run-hook-with-args 'erc-pre-send-functions state)
         (setf (erc--input-split-sendp lines-obj) (erc-input-sendp state)
               (erc--input-split-insertp lines-obj) (erc-input-insertp state)
+              (erc--input-split-substxt lines-obj) (erc-input-substxt state)
+              (erc--input-split-refoldp lines-obj) (erc-input-refoldp state)
               ;; See note in test of same name re trailing newlines.
               (erc--input-split-lines lines-obj)
               (let ((lines (split-string (erc-input-string state)
@@ -7881,12 +7870,19 @@ erc--run-send-hooks
 (defun erc--send-input-lines (lines-obj)
   "Send lines in `erc--input-split-lines' object LINES-OBJ."
   (when (erc--input-split-sendp lines-obj)
-    (dolist (line (erc--input-split-lines lines-obj))
-      (when (erc--input-split-insertp lines-obj)
-        (erc-display-msg line))
-      (erc-process-input-line (concat line "\n")
-                              (null erc-flood-protect)
-                              (not (erc--input-split-cmdp lines-obj))))))
+    (let ((insertp (erc--input-split-insertp lines-obj))
+          (substxt (erc--input-split-substxt lines-obj)))
+      (when (and insertp substxt)
+        (setq insertp nil)
+        (if (functionp substxt)
+            (apply substxt (erc--input-split-lines lines-obj))
+          (erc-display-msg substxt)))
+      (dolist (line (erc--input-split-lines lines-obj))
+        (when insertp
+          (erc-display-msg line))
+        (erc-process-input-line (concat line "\n")
+                                (null erc-flood-protect)
+                                (not (erc--input-split-cmdp lines-obj)))))))
 
 (defun erc-send-input (input &optional skip-ws-chk)
   "Treat INPUT as typed in by the user.
-- 
2.42.0