Make defvar affect the default binding outside of any let.

* src/eval.c (default_toplevel_binding): New function.
(Fdefvar): Use it.
(unbind_to, backtrace_eval_unrewind): Do a bit of CSE simplification.
(Fdefault_toplevel_value, Fset_default_toplevel_value): New subrs.
(syms_of_eval): Export them.
* src/data.c (Fdefault_value): Micro cleanup.
* src/term.c (init_tty): Use "false".
* lisp/custom.el (custom-initialize-default, custom-initialize-set)
(custom-initialize-reset, custom-initialize-changed): Affect the
toplevel-default-value (bug#6275, bug#14586).
* lisp/emacs-lisp/advice.el (ad-compile-function): Undo previous workaround
for bug#6275.
* test/automated/core-elisp-tests.el: New file.

1 files changed, 2 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 170f369d104..299c247c344 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -524,6 +524,8 @@ low-level libraries gfilenotify.c, inotify.c or w32notify.c.
 
 * Incompatible Lisp Changes in Emacs 24.4
 
+** `defvar' and `defcustom' in a let-binding affect the "external" default.
+
 ** The syntax of ?» and ?« is now punctuation instead of matched parens.
 Some languages match those as »...« and others as «...» so better stay neutral.