Partly fixes bug#20241.
* lisp/emacs-lisp/bytecomp.el (byte-compile-setq): Issue a warning when a
`setq' form with an odd number of arguments is compiled.
(let ((args (cdr form)))
(if args
(while args
- (byte-compile-form (car (cdr args)))
+ (if (eq (length args) 1)
+ (byte-compile-warn
+ "missing value for `%S' at end of setq"
+ (car args)))
+ (byte-compile-form (car (cdr args)))
(or byte-compile--for-effect (cdr (cdr args))
(byte-compile-out 'byte-dup 0))
(byte-compile-variable-set (car args))