Merge from origin/emacs-26

02d114d6b8 * lisp/tree-widget.el (tree-widget-end-guide): Escape it. ...
0a85d12474 Fix ELisp "Warning Tips"
06d05fec84 Fix Bug#29163
ac64fdb248 Harden exec_byte_code against redefining 'error'
700f74e4c8 Fix Edebug specs for if-let* and and-let* (Bug#29236)
0ded1b41a9 Fix Edebug's handling of dotted specs (bug#6415)
16358d4fcb Improve documentation of "constant" symbols

1 files changed, 2 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 6e3412c3d05..c6f9eb28e25 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5620,6 +5620,8 @@ file I/O and the behavior of various editing commands.
 
 This variable is buffer-local but you cannot set it directly;
 use the function `set-buffer-multibyte' to change a buffer's representation.
+To prevent any attempts to set it or make it buffer-local, Emacs will
+signal an error in those cases.
 See also Info node `(elisp)Text Representations'.  */);
   make_symbol_constant (intern_c_string ("enable-multibyte-characters"));