semantics of `eval-and-compile'

[Taylor R Campbell]

The documentation string in Emacs 22.1 reads as follows:

   Like `progn', but evaluates the body at compile time and at load time.

The following program, if put into a file and then compiled and
loaded, suggests otherwise, however:

   (defun foo ()
     (eval-and-compile (message "at compile- or load-time"))
     (message "at run-time"))

When compiled, this file reports `at compile- or load-time'.  When
loaded, this file reports nothing.  When `foo' is called, it reports
`at compile- or load-time' and `at run-time'.  Thus the body is *not*
actually evaluated at load-time; rather, it is evaluated at
compile-time and at run-time.

What is the intended semantics? -- what is documented, what is
implemented, or something else altogether?