Silencing compilation warnings when calling compiler explicitly

[Jean Abou Samra <jean@abou-samra.fr>]

Hi,

I'm wondering if there is a simple way to shut up warnings emitted
when calling compile in Guile 2.2. For example:

(use-modules (system base compile))

(display
  (compile '(lambda (x)
              (case x
                ((5 5) 5)
                ((6) 6)))
           #:env (current-module)
           #:opts '(#:warnings ())))


 From the code of compile in module/system/base/compile.scm (when
checking out the v2.2.7 tag in the repository), it seems that
the use of #:warning () in opts should turn off warnings, but
this seems not to be the case, as the output is

;;; <unknown-location>: warning: duplicate datum 5 in clause ((5 5) 5) 
of case expression (case x ((5 5) 5) ((6) 6))
#<procedure 56451d956b58 (x)>


So far, I've found


(use-modules (system base compile))

(define (make-null-port)
   (make-soft-port
    (vector
     (lambda _ #f) ; output 1 char
     (lambda _ #f) ; output string
     (lambda () #f) ; flush output
     #f ; get char
     (lambda () #f) ; close
     )
    "w"))

(display
  (parameterize ((current-warning-port (make-null-port)))
    (compile '(lambda (x)
                (case x
                  ((5 5) 5)
                  ((6) 6)))
             #:env (current-module))))


This seems a bit heavy-handed, so I'd appreciate if there
is a better way.

I know that in Guile 3.0 I can do #:warning-level 0,
and it works, but this is for LilyPond, which has to
support Guile 2.2 for now.

Thanks,
Jean