Subject: Circular module imports vs. #:select (2.0.9)
From: [email-masked] (Ludovic Courtès)
To: [email-masked]
Date: Sun, 06 Oct 2013 21:36:42 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Consider these two modules:

--8<---------------cut here---------------start------------->8---
(define-module (a) #:use-module (b) #:export (from-a))
(define from-a 1)
--8<---------------cut here---------------end--------------->8---

and:

--8<---------------cut here---------------start------------->8---
(define-module (b) #:use-module ((a) #:select (from-a)) #:export (from-b))
(define from-b 2)
--8<---------------cut here---------------end--------------->8---

This fails:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,use(a)
While executing meta-command:
ERROR: no binding `from-a' in module (a)
--8<---------------cut here---------------end--------------->8---

whereas this succeeds (starting from a fresh Guile):

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,use(b)
scheme@(guile-user)> from-b
$1 = 2
--8<---------------cut here---------------end--------------->8---

Problem is that ‘define-module*’ processes exports after imports.

What about a patch along these lines:

diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index c825b35..24b8f4c 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -2872,11 +2872,8 @@ VALUE."
               (error "expected list of integers for version"))
           (set-module-version! module version)
           (set-module-version! (module-public-interface module) version)))
-    (let ((imports (resolve-imports imports)))
     (call-with-deferred-observers
      (lambda ()
-         (if (pair? imports)
-             (module-use-interfaces! module imports))
        (if (list-of valid-export? exports)
            (if (pair? exports)
                (module-export! module exports))
@@ -2885,6 +2882,9 @@ VALUE."
            (if (pair? replacements)
                (module-replace! module replacements))
            (error "expected replacements to be a list of symbols or symbol pairs"))
+       (let ((imports (resolve-imports module)))
+         (if (pair? imports)
+             (module-use-interfaces! module imports)))
        (if (list-of valid-export? re-exports)
            (if (pair? re-exports)
                (module-re-export! module re-exports))
@@ -2896,7 +2896,7 @@ VALUE."
        ;; handlers.
        (if (pair? duplicates)
            (let ((handlers (lookup-duplicates-handlers duplicates)))
-               (set-module-duplicates-handlers! module handlers))))))
+             (set-module-duplicates-handlers! module handlers)))))
 
     (if transformer
         (if (and (pair? transformer) (list-of symbol? transformer))

Thanks,
Ludo’.