Avoid assertion violation in callproc.c

* src/callproc.c (call_process): Avoid assertion violation when
DESTINATION is a cons cell '(:file . "FOO")'.  (Bug#46426)

1 files changed, 5 insertions, 1 deletions

diff --git a/src/callproc.c b/src/callproc.c
index 5b1d8bfb765..3eac38d375a 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -394,7 +394,11 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
       /* If the buffer is (still) a list, it might be a (:file "file") spec. */
       if (CONSP (buffer) && EQ (XCAR (buffer), QCfile))
         {
-          output_file = Fexpand_file_name (XCAR (XCDR (buffer)),
+          Lisp_Object ofile = XCDR (buffer);
+          if (CONSP (ofile))
+            ofile = XCAR (ofile);
+          CHECK_STRING (ofile);
+          output_file = Fexpand_file_name (ofile,
                                            BVAR (current_buffer, directory));
           CHECK_STRING (output_file);
           buffer = Qnil;