dev-lang/erlang: backport emacs-28 compatibility patch

Signed-off-by: Matthew Smith <matthew@gentoo.org>

2 files changed, 138 insertions, 0 deletions

diff --git a/dev-lang/erlang/erlang-23.3.4.14.ebuild b/dev-lang/erlang/erlang-23.3.4.14-r1.ebuild
index 689ece693ee0..4ec3b42e084e 100644
--- a/dev-lang/erlang/erlang-23.3.4.14.ebuild
+++ b/dev-lang/erlang/erlang-23.3.4.14-r1.ebuild
@@ -47,6 +47,7 @@ S="${WORKDIR}/otp-OTP-${PV}"
 PATCHES=(
 	"${FILESDIR}"/18.2.1-wx3.0.patch
 	"${FILESDIR}"/${PN}-22.0-dont-ignore-LDFLAGS.patch
+	"${FILESDIR}"/${PN}-23.3.4.14-emacs28-compat.patch
 )
 
 SITEFILE=50"${PN}"-gentoo.el
diff --git a/dev-lang/erlang/files/erlang-23.3.4.14-emacs28-compat.patch b/dev-lang/erlang/files/erlang-23.3.4.14-emacs28-compat.patch
new file mode 100644
index 000000000000..32844d8dd1a8
--- /dev/null
+++ b/dev-lang/erlang/files/erlang-23.3.4.14-emacs28-compat.patch
@@ -0,0 +1,137 @@
+From 22a7522ef3f0f3c13618214e61f60cb01d80eef4 Mon Sep 17 00:00:00 2001
+From: Justin Davis <jrcd83@gmail.com>
+Date: Tue, 26 Oct 2021 13:28:16 -0400
+Subject: [PATCH] Fix emacs erlang-mode: xref switched to CL-Lib
+
+Fix for GitHub issue #5314.
+
+Xref is a package which is also bundled with emacs:
+http://elpa.gnu.org/packages/xref.html
+
+Xref switched its own internally defined classes from EIEIO to
+CL-lib (emacs-mirror/emacs@86da812afb2572c7fead2bb07570b976bffd7c55).
+erlang-mode subclasses xref-file-location in order to add a function
+arity slot to xrefs.
+
+If xref-file-location is a class, use defclass to subclass it. Otherwise
+use cl-defstruct. Avoids referencing make-instance, slot-value functions
+from EIEIO. Only references constructor, accessor, and predicate
+functions.  Updates comments that make references to classes.
+
+Testing:
+- cd into lib/tools/emacs.
+- Run the tests included with erlang-mode from the shell:
+  emacs -Q -batch -L . -l erlang.el -l erlang-test.el \
+        -f ert-run-tests-batch-and-exit
+- Copy xref.el from the xref package (>=1.3.1) into the
+  lib/tools/emacs directory.
+- Run the tests again. This will load xref.el automatically
+  and use the new interface.
+---
+ lib/tools/emacs/erlang.el | 48 +++++++++++++++++++++++++--------------
+ 1 file changed, 31 insertions(+), 17 deletions(-)
+
+diff --git a/lib/tools/emacs/erlang.el b/lib/tools/emacs/erlang.el
+index 69a5fdaeb55..40fe32689e7 100644
+--- a/lib/tools/emacs/erlang.el
++++ b/lib/tools/emacs/erlang.el
+@@ -5120,8 +5120,8 @@ about Erlang modules."
+ ;;
+ ;; As mentioned this xref implementation is based on the etags xref
+ ;; implementation.  But in the cases where arity is considered the
+-;; etags information structures (class xref-etags-location) will be
+-;; translated to our own structures which include arity (class
++;; etags information structures (struct xref-etags-location) will be
++;; translated to our own structures which include arity (struct
+ ;; erlang-xref-location).  This translation is started in the function
+ ;; `erlang-refine-xrefs'.
+ 
+@@ -5129,6 +5129,11 @@ about Erlang modules."
+ ;; with xref items with xref-etags-location and some deal with xref
+ ;; items with erlang-xref-location.
+ 
++;; NOTE: Around Sept 2021, the xrefs package changed all of its defined types
++;; (i.e.  xref-location, xref-file-location) from EIEIO classes to CL-Lib
++;; structures. These are both supported. Older Emacsen with earlier versions of
++;; xref will continue to use defclass. Newer Emacsen will use cl-defstruct.
++
+ (defun erlang-etags--xref-backend () 'erlang-etags)
+ 
+ (defun erlang-soft-require (feature)
+@@ -5137,6 +5142,7 @@ about Erlang modules."
+ 
+ (when (and (erlang-soft-require 'xref)
+            (erlang-soft-require 'cl-generic)
++           (erlang-soft-require 'cl-lib)
+            (erlang-soft-require 'eieio)
+            (erlang-soft-require 'etags))
+   ;; The purpose of using eval here is to avoid compilation
+@@ -5165,10 +5171,20 @@ about Erlang modules."
+         (let ((erlang-replace-etags-tags-completion-table t))
+           (tags-completion-table)))
+ 
+-      (defclass erlang-xref-location (xref-file-location)
+-        ((arity :type fixnum :initarg :arity
+-                :reader erlang-xref-location-arity))
+-        :documentation "An erlang location is a file location plus arity.")
++      ;; Xref 1.3.1 bundled with Emacs 28+ switched from using EIEIO classes to
++      ;; using CL-Lib structs.
++      (if (find-class 'xref-file-location)
++          (progn
++            (defclass erlang-xref-location (xref-file-location)
++              ((arity :type fixnum :initarg :arity
++                      :reader erlang-xref-location-arity))
++              :documentation "An erlang location is a file location plus arity.")
++            ;; Make a constructor with the same name that a CL structure would have.
++            (defalias 'make-erlang-xref-location 'erlang-xref-location))
++        (cl-defstruct (erlang-xref-location
++                       (:include xref-file-location))
++          "An erlang location is a file location plus arity."
++          (arity 0 :type fixnum)))
+ 
+       ;; This method definition only calls the superclass which is
+       ;; the default behaviour if it was not defined.  It is only
+@@ -5331,8 +5347,7 @@ is non-nil then TAG is a regexp."
+       xrefs
+     (when (and xrefs
+                (fboundp 'xref-item-location)
+-               (fboundp 'xref-location-group)
+-               (fboundp 'slot-value))
++               (fboundp 'xref-location-group))
+       (let (files)
+         (cl-loop for xref in xrefs
+                  for loc = (xref-item-location xref)
+@@ -5357,7 +5372,8 @@ is non-nil then TAG is a regexp."
+            t))))
+ 
+ (defun erlang-xrefs-in-file (file kind tag is-regexp)
+-  (when (fboundp 'make-instance)
++  (when (and (fboundp 'make-erlang-xref-location)
++             (fboundp 'xref-make))
+     (with-current-buffer (find-file-noselect file)
+       (save-excursion
+         (goto-char (point-min))
+@@ -5369,17 +5385,15 @@ is non-nil then TAG is a regexp."
+                    for name = (match-string-no-properties 1)
+                    for arity = (save-excursion
+                                  (erlang-get-arity))
+-                   for loc = (make-instance 'erlang-xref-location
+-                                            :file file
+-                                            :line (line-number-at-pos)
+-                                            :column 0
+-                                            :arity arity)
++                   for loc = (make-erlang-xref-location
++                              :file file
++                              :line (line-number-at-pos)
++                              :column 0
++                              :arity arity)
+                    for sum = (erlang-xref-summary kind name arity)
+                    when (and arity
+                              (not (eq arity last-arity)))
+-                   collect (make-instance 'xref-item
+-                                          :summary sum
+-                                          :location loc)
++                   collect (xref-make sum loc)
+                    do (setq last-arity arity)))))))
+ 
+ (defun erlang-xref-summary (kind tag arity)