Problems setting byte-compile-warnings to t

[Glenn Morris <rgm@gnu.org>]

Create a file foo.el with first (and only) line:

;; -*- byte-compile-warnings: t; -*-

Then try to byte-compile it:

1.el:Error: Wrong type argument: listp, t

Perhaps one of the `(memq foo byte-compile-warnings)' in bytecomp.el
is being run outside byte-compile-close-variables?

edebug says the error comes from
byte-compile-warn-about-unresolved-functions, but I don't see how.