Preserve point in pascal-mode completion (bug#41740)

Failure to do so caused errors in several cases.
Reported by Shinichi Sakata.

* lisp/progmodes/pascal.el (pascal-type-completion)
(pascal-completion): Wrap code that may move point in save-excursion.
* test/lisp/progmodes/pascal-tests.el: New file.

1 files changed, 55 insertions, 0 deletions

diff --git a/test/lisp/progmodes/pascal-tests.el b/test/lisp/progmodes/pascal-tests.el
new file mode 100644
index 00000000000..10d6e0433d0
--- /dev/null
+++ b/test/lisp/progmodes/pascal-tests.el
@@ -0,0 +1,55 @@
+;;; pascal-tests.el --- tests for pascal.el    -*- lexical-binding: t -*-
+
+;; Copyright (C) 2020 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+(require 'ert)
+(require 'pascal)
+
+(ert-deftest pascal-completion ()
+  ;; Bug#41740: completion functions must preserve point.
+  (let ((pascal-completion-cache nil))
+    (with-temp-buffer
+      (pascal-mode)
+      (insert "program test; var")
+      (let* ((point-before (point))
+             (completions (pascal-completion "var" nil 'metadata))
+             (point-after (point)))
+        (should (equal completions nil))
+        (should (equal point-before point-after)))))
+
+  (let ((pascal-completion-cache nil))
+    (with-temp-buffer
+      (pascal-mode)
+      (insert "program test; function f(x : i")
+      (let* ((point-before (point))
+             (completions (pascal-completion "i" nil 'metadata))
+             (point-after (point)))
+        (should (equal completions nil))
+        (should (equal point-before point-after)))))
+
+  (let ((pascal-completion-cache nil))
+    (with-temp-buffer
+      (pascal-mode)
+      (insert "program test; function f(x : integer) : real")
+      (let* ((point-before (point))
+             (completions (pascal-completion "real" nil 'metadata))
+             (point-after (point)))
+        (should (equal completions nil))
+        (should (equal point-before point-after))))))
+
+(provide 'pascal-tests)