From 1b47fd85fef2590a7da252d0a2f5d9dcc3ace81c Mon Sep 17 00:00:00 2001
From: Nick Drozd <nicholasdrozd@gmail.com>
Date: Sat, 11 Jul 2020 10:02:27 -0500
Subject: [PATCH] Clean up Tramp version check

* aclocal.m4
(TRAMP_EMACS_VERSION_CHECK): Rewrite
* trampver.el.in
(tramp-minimum-emacs-version): New variable
(tramp-check-version): New function
(tramp-tests.el): New test
---
 aclocal.m4          | 17 +++++++++++++----
 lisp/trampver.el.in |  4 +---
 test/tramp-tests.el |  8 ++++++++
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/aclocal.m4 b/aclocal.m4
index d4a82cf9..4940fbef 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -75,10 +75,19 @@ AC_DEFUN(AC_EMACS_INFO, [
   AC_SUBST(TRAMP_EMACS_REQUIRED_VERSION)
   dnl Starting with Emacs 26.1, we could use `string-version-lessp'.
   TRAMP_EMACS_VERSION_CHECK="\
-  (if (not (string-lessp emacs-version \"${TRAMP_EMACS_REQUIRED_VERSION}\"))
-      \"ok\"
-    (format \"${PACKAGE_STRING} is not fit for %s\"
-            (replace-regexp-in-string \"\\n\" \"\" (emacs-version))))"
+(progn  ; <-- don't touch this progn
+  (defconst tramp-minimum-emacs-version \"${TRAMP_EMACS_REQUIRED_VERSION}\"
+    \"The minimum Emacs version required by Tramp.\")
+
+  (defun tramp-check-version ()
+    \"Error if `emacs-version' is less than `tramp-minimum-emacs-version'.\"
+    (progn  ; <-- don't touch this progn
+      (when (string-lessp emacs-version tramp-minimum-emacs-version)
+        (error \"${PACKAGE_VERSION} is not fit for %s\"
+               (replace-regexp-in-string \"\n\" \"\" (emacs-version))))
+      \"ok\"))
+
+  (tramp-check-version))"
   AC_SUBST(TRAMP_EMACS_VERSION_CHECK)
 
   AC_MSG_CHECKING([for $EMACS version])
diff --git a/lisp/trampver.el.in b/lisp/trampver.el.in
index f487b332..04dd4006 100644
--- a/lisp/trampver.el.in
+++ b/lisp/trampver.el.in
@@ -69,9 +69,7 @@
 	   (emacs-repository-get-version dir))))
   "The repository revision of the Tramp sources.")
 
-;; Check for Emacs version.
-(let ((x @TRAMP_EMACS_VERSION_CHECK@))
-  (unless (string-equal "ok" x) (error "%s" x)))
+@TRAMP_EMACS_VERSION_CHECK@
 
 ;; Tramp versions integrated into Emacs.  If a user option declares a
 ;; `:package-version' which doesn't belong to an integrated Tramp
diff --git a/test/tramp-tests.el b/test/tramp-tests.el
index 51722210..f0f8d079 100644
--- a/test/tramp-tests.el
+++ b/test/tramp-tests.el
@@ -6670,6 +6670,14 @@ Since it unloads Tramp, it shall be the last test to run."
 	  (ignore-errors (all-completions "tramp" (symbol-value x)))
 	  (ert-fail (format "Hook `%s' still contains Tramp function" x))))))
 
+(ert-deftest tramp-test47-version ()
+  "Check that the version check checks out."
+  (should (string-equal "ok" (tramp-check-version)))
+  (let ((emacs-version "20.3"))
+    (should-error (tramp-check-version)))
+  (let ((tramp-minimum-emacs-version "40.1"))
+    (should-error (tramp-check-version))))
+
 (defun tramp-test-all (&optional interactive)
   "Run all tests for \\[tramp].
 If INTERACTIVE is non-nil, the tests are run interactively."
-- 
2.17.1