bug#12202: psyntax defeats autoload

[Andy Wingo <wingo@pobox.com>]

On Tue 14 Aug 2012 18:14, ludo@gnu.org (Ludovic Courtès) writes:

> (define-module (foo) #:autoload (does-not-exist) (baz))
> (define (chbouib) (baz))
> (pk 'hello)
>
> Trying to evaluate it fails this way:
>
> $ guile --no-auto-compile t.scm 
> Backtrace:
> In ice-9/boot-9.scm:
>
> [...]
>
>  292: 3 [get-global-definition-hook baz (hygiene foo)]
> In unknown file:
>    ?: 2 [module-variable #<directory (foo) b3b510> baz]
> In ice-9/boot-9.scm:
> 2732: 1 [b #<autoload (does-not-exist) b3b3f0> baz #f]
> In unknown file:
>    ?: 0 [scm-error misc-error #f ...]
>
> ERROR: In procedure scm-error:
> ERROR: missing interface for module (does-not-exist)
>
> ... which defeats the whole purpose of autoloads.
>
> What about something along these lines (untested)?

This is a great idea.  We should assume that autoloads are not macros.
Not sure we can change it in 2.0 though, because there could be uses of
autoloaded macros.

However your patch won't work:

> diff --git a/module/ice-9/psyntax.scm b/module/ice-9/psyntax.scm
> index 6c264a6..8a30f82 100644
> --- a/module/ice-9/psyntax.scm
> +++ b/module/ice-9/psyntax.scm
> @@ -289,15 +289,20 @@
>          (lambda (symbol module)
>            (if (and (not module) (current-module))
>                (warn "module system is booted, we should have a module" symbol))
> -          (let ((v (module-variable (if module
> +          (let ((m (if module
>                         (resolve-module (cdr module))
> -                                        (current-module))
> -                                    symbol)))
> +                       (current-module))))
> +            (case (module-kind m)
> +              ((autoload)
> +               ;; don't try to actually load the module
> +               #t)
> +              (else
> +               (let ((v (module-variable m symbol)))
>                   (and v (variable-bound? v)
>                        (let ((val (variable-ref v)))
>                          (and (macro? val) (macro-type val)
>                               (cons (macro-type val)
> -                              (macro-binding val)))))))))
> +                                   (macro-binding val))))))))))))
>  

because the module-kind of the module will never be `autoload' here.  As
you can see in your backtrace, the module-kind is `directory' -- the
autoload only ends up getting loaded while grovelling (foo)'s import
array.

Andy
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