Hi all, Here's a pretty straightforward patch to prevent a module from importing itself. This fixes #1506.
Cheers, Peter
From a0c126423c0de8be4e5f997b1a82e51aef953bbf Mon Sep 17 00:00:00 2001
From: Peter Bex <pe...@more-magic.net>
Date: Fri, 5 Apr 2019 16:15:23 +0200
Subject: [PATCH] Reject import of module currently being defined (fixes #1506)
---
NEWS | 6 ++++++
expand.scm | 6 +++++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/NEWS b/NEWS
index 825acbfb..dba12ad9 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,12 @@
- When using (set-file-position!) on a port, its EOF status will now
be reset.
+- Module system
+ - When you try to import the module you are currently defining into
+ itself, an error will be raised. This prevents an infinite loop
+ in the compiler when later trying to import that same module.
+ (fixes #1506, thanks to Kristian Lein-Mathisen)
+
5.0.1
- Type system
diff --git a/expand.scm b/expand.scm
index ec302d48..7517b052 100644
--- a/expand.scm
+++ b/expand.scm
@@ -969,7 +969,11 @@
(lambda (x r c)
`(##core#begin
,@(map (lambda (x)
- (let-values (((name lib spec v s i) (##sys#decompose-import x r c 'import)))
+ (let*-values (((name lib spec v s i) (##sys#decompose-import x r c 'import))
+ ((mod) (##sys#current-module)))
+ (when (and mod (eq? name (##sys#module-name mod)))
+ (##sys#syntax-error-hook
+ 'import "cannot import from module currently being defined" name))
(if (not spec)
(##sys#syntax-error-hook
'import "cannot import from undefined module" name)
--
2.11.0
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