Improve error message for old-style backquotes

* src/lread.c (load_error_old_style_backquotes): Improve error message
if no file is being loaded.

* test/src/lread-tests.el (lread-tests--force-new-style-backquotes):
Adapt test.

2 files changed, 11 insertions, 4 deletions

diff --git a/src/lread.c b/src/lread.c
index d675b563916..bcf3b7f55c7 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -1006,8 +1006,16 @@ load_error_handler (Lisp_Object data)
 static _Noreturn void
 load_error_old_style_backquotes (void)
 {
-  AUTO_STRING (format, "Loading `%s': old-style backquotes detected!");
-  xsignal1 (Qerror, CALLN (Fformat_message, format, Vload_file_name));
+  if (NILP (Vload_file_name))
+    {
+      AUTO_STRING (message, "Old-style backquotes detected!");
+      xsignal1 (Qerror, message);
+    }
+  else
+    {
+      AUTO_STRING (format, "Loading `%s': old-style backquotes detected!");
+      xsignal1 (Qerror, CALLN (Fformat_message, format, Vload_file_name));
+    }
 }
 
 static void
diff --git a/test/src/lread-tests.el b/test/src/lread-tests.el
index 693c6c09bf3..daf53438811 100644
--- a/test/src/lread-tests.el
+++ b/test/src/lread-tests.el
@@ -183,8 +183,7 @@ literals (Bug#20852)."
 
 (ert-deftest lread-tests--force-new-style-backquotes ()
   (let ((data (should-error (read "(` (a b))"))))
-    (should (equal (cdr data)
-                   '("Loading `nil': old-style backquotes detected!"))))
+    (should (equal (cdr data) '("Old-style backquotes detected!"))))
   (should (equal (let ((force-new-style-backquotes t))
                    (read "(` (a b))"))
                  '(`(a b)))))