Warn about missing backslashes during load

* src/lread.c (load_warn_unescaped_character_literals, Fload, read1)
(syms_of_lread): Warn if unescaped character literals are
found (Bug#20152).
* lisp/emacs-lisp/bytecomp.el (byte-compile-from-buffer): Check for
unescaped character literals during byte compilation.
* test/src/lread-tests.el (lread-tests--unescaped-char-literals): New
unit test.
(lread-tests--with-temp-file, lread-tests--last-message): Helper
functions for unit test.
* test/lisp/emacs-lisp/bytecomp-tests.el
(bytecomp-tests--unescaped-char-literals): New unit test.
* test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-tests--with-temp-file):
Helper macro for unit test.

1 files changed, 7 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 15dc24060aa..25102548a9d 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -2027,12 +2027,19 @@ With argument ARG, insert value in current buffer after the form."
           (setq byte-compile-read-position (point)
                 byte-compile-last-position byte-compile-read-position)
           (let* ((old-style-backquotes nil)
+                 (lread--unescaped-character-literals nil)
                  (form (read inbuffer)))
             ;; Warn about the use of old-style backquotes.
             (when old-style-backquotes
               (byte-compile-warn "!! The file uses old-style backquotes !!
 This functionality has been obsolete for more than 10 years already
 and will be removed soon.  See (elisp)Backquote in the manual."))
+            (when lread--unescaped-character-literals
+              (byte-compile-warn
+               "unescaped character literals %s detected!"
+               (mapconcat #'string
+                          (sort lread--unescaped-character-literals #'<)
+                          ", ")))
             (byte-compile-toplevel-file-form form)))
         ;; Compile pending forms at end of file.
         (byte-compile-flush-pending)