Improve unescaped character literal warnings

* src/lread.c (load_warn_unescaped_character_literals)
(syms_of_lread):
lisp/emacs-lisp/bytecomp.el (byte-compile-from-buffer): Improve
formatting of unescaped character literal warnings.

* test/src/lread-tests.el (lread-tests--unescaped-char-literals):
test/lisp/emacs-lisp/bytecomp-tests.el
(bytecomp-tests--unescaped-char-literals): Adapt unit tests.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/lread.c b/src/lread.c
index f0ad0c28e56..0e5b476a9a2 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -963,9 +963,11 @@ load_warn_unescaped_character_literals (Lisp_Object file)
   AUTO_STRING (format,
                "Loading `%s': unescaped character literals %s detected!");
   AUTO_STRING (separator, ", ");
+  AUTO_STRING (inner_format, "`?%c'");
   CALLN (Fmessage,
          format, file,
-         Fmapconcat (Qstring,
+         Fmapconcat (list3 (Qlambda, list1 (Qchar),
+                            list3 (Qformat, inner_format, Qchar)),
                      Fsort (Vlread_unescaped_character_literals, Qlss),
                      separator));
 }
@@ -4855,6 +4857,8 @@ For internal use only.  */);
           "lread--unescaped-character-literals");
 
   DEFSYM (Qlss, "<");
+  DEFSYM (Qchar, "char");
+  DEFSYM (Qformat, "format");
 
   DEFVAR_BOOL ("load-prefer-newer", load_prefer_newer,
                doc: /* Non-nil means `load' prefers the newest version of a file.