diff options
Diffstat (limited to 'lisp/subr.el')
| -rw-r--r-- | lisp/subr.el | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/lisp/subr.el b/lisp/subr.el index 426e8145cae..d5c461346cb 100644 --- a/lisp/subr.el +++ b/lisp/subr.el @@ -507,8 +507,10 @@ If COUNT is negative, shifting is actually to the right. In this case, if VALUE is a negative fixnum treat it as unsigned, i.e., subtract 2 * `most-negative-fixnum' from VALUE before shifting it. -This function is provided for compatibility. In new code, use `ash' -instead." +Most uses of this function turn out to be mistakes. We recommend +to use `ash' instead, unless COUNT could ever be negative, and +if, when COUNT is negative, your program really needs the special +treatment of negative COUNT provided by this function." (declare (compiler-macro (lambda (form) (macroexp-warn-and-return "avoid `lsh'; use `ash' instead" |