(defmacro declare-function (_fn _file &rest _args)
"Tell the byte-compiler that function FN is defined, in FILE.
-Optional ARGLIST is the argument list used by the function.
The FILE argument is not used by the byte-compiler, but by the
`check-declare' package, which checks that FILE contains a
definition for FN. Remaining ARGS are used by both the
them without error if they are not.
ARGS can contain one or two optional args. First optional arg
-ARGLIST specifies the function arguments. Second optional arg
-FILEONLY non-nil means that `check-declare' will only check that
-FILE exists, not that it defines FN. This is intended for
-function-definitions that `check-declare' does not recognize, e.g.
-`defstruct'.
-
-To specify a value for FILEONLY without passing an argument list,
-set ARGLIST to t. This is necessary because nil means an
-empty argument list, rather than an unspecified one.
+ARGLIST specifies FN's arguments, or is t to not specify FN's
+arguments. An omitted ARGLIST defaults to t, not nil: a nil
+ARGLIST specifies an empty argument list, and an explicit t
+ARGLIST is a placeholder that allows supplying a later arg.
+Second optional arg FILEONLY non-nil means that `check-declare'
+will check only that FILE exists, not that it defines FN. This
+is intended for function definitions that `check-declare' does
+not recognize, e.g., `defstruct'.
Note that for the purposes of `check-declare', this statement
must be the first non-whitespace on a line.