(byte-compile-file-form-defvar)

(byte-compile-file-form-defvar)
(byte-compile-file-form-define-abbrev-table)
(byte-compile-file-form-custom-declare-variable)
(byte-compile-variable-ref, byte-compile-defvar):
Whether or not a warning is enabled should only affect whether we issue
the warning, not whether or not we collect the relevant data.
Eg warnings can be turned on and off throughout the course of a file.