Backport: Use default exec-suffixes when needed (bug#81280, bug#81517)

* lisp/files.el (executable-find): Use (default-value 'exec-suffixes).

* src/callproc.c (Qexec_suffixes): Declare.
(call_process):
* src/process.c (Fmake_process): Use Fdefault_value (Qexec_suffixes).

* test/lisp/files-x-tests.el (files-x-test--variables6):
New defconst.
(files-x-test-connection-local-special-variables): New test.

(cherry picked from commit dcdd76f89e)

lisp/files.el

@@ -1331,7 +1331,7 @@ remote, otherwise search locally."
     ;; Use 1 rather than file-executable-p to better match the
     ;; behavior of call-process.
     (let ((default-directory (file-name-quote default-directory 'top)))
-      (locate-file command exec-path exec-suffixes 1))))
+      (locate-file command exec-path (default-value 'exec-suffixes) 1))))
 
 (declare-function read-library-name "find-func" nil)
 

src/callproc.c

@@ -520,7 +520,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
   {
     int ok;
 
-    ok = openp (Vexec_path, args[0], Vexec_suffixes, &path,
+    ok = openp (Vexec_path, args[0], Fdefault_value (Qexec_suffixes), &path,
 		make_fixnum (X_OK), false, false, NULL);
     if (ok < 0)
       report_file_error ("Searching for program", args[0]);
@@ -2258,4 +2258,5 @@ multiple times on subsequent partitions of the list of arguments.
   DEFSYM (Qafter_insert_file_set_buffer_file_coding_system,
 	  "after-insert-file-set-buffer-file-coding-system");
   DEFSYM (Qcoding_system_for_write, "coding-system-for-write");
+  DEFSYM (Qexec_suffixes, "exec-suffixes");
 }

src/process.c

@@ -2032,7 +2032,7 @@ usage: (make-process &rest ARGS)  */)
 	       && IS_DEVICE_SEP (SREF (program, 1))))
 	{
 	  tem = Qnil;
-	  openp (Vexec_path, program, Vexec_suffixes, &tem,
+	  openp (Vexec_path, program, Fdefault_value (Qexec_suffixes), &tem,
 		 make_fixnum (X_OK), false, false, NULL);
 	  if (NILP (tem))
 	    report_file_error ("Searching for program", program);

test/lisp/files-x-tests.el

@@ -39,6 +39,9 @@
 (defconst files-x-test--variables5
   '((remote-lazy-var . nil)
     (remote-null-device . "/dev/null")))
+(defconst files-x-test--variables6
+  '((exec-suffixes . ("foo"))
+    (path-separator . "foo")))
 (defvar remote-shell-file-name)
 (defvar remote-null-device)
 (defvar remote-lazy-var nil)
@@ -601,5 +604,39 @@ If it's not initialized yet, initialize it."
      `(connection-local-profile-alist ',clpa now)
      `(connection-local-criteria-alist ',clca now))))
 
+(ert-deftest files-x-test-connection-local-special-variables ()
+  "Test special local variables.
+The connection-local variables `exec-suffixes' and `path-separator' are
+used for remote processes.  When calling `call-process', `make-process'
+or `executable-find', their default value must be used nonetheless."
+
+  (let ((clpa connection-local-profile-alist)
+	(clca connection-local-criteria-alist)
+        (program (file-name-sans-extension
+                  (file-name-concat invocation-directory invocation-name)))
+        proc)
+    (connection-local-set-profile-variables
+     'special-variables files-x-test--variables6)
+    (connection-local-set-profiles
+     nil 'special-variables)
+
+    (unwind-protect
+        (with-temp-buffer
+          (let ((enable-connection-local-variables t))
+            (hack-connection-local-variables-apply nil)
+            (should (zerop (call-process program nil nil nil "--help")))
+            (should
+             (processp
+              (setq proc
+                    (make-process
+                     :name invocation-name :command `(,program "--help")))))
+            (should (executable-find program))))
+
+      ;; Cleanup.
+      (when (processp proc) (kill-process proc))
+      (custom-set-variables
+       `(connection-local-profile-alist ',clpa now)
+       `(connection-local-criteria-alist ',clca now)))))
+
 (provide 'files-x-tests)
 ;;; files-x-tests.el ends here