read-print: Report missing closing parens instead of looping.

Fixes <https://issues.guix.gnu.org/57093>.
Reported by Mohammed AMAR-BENSABER <renken@shione.net>.

Previously 'read-with-comments' would enter an infinite loop.

* guix/read-print.scm (read-with-comments)[missing-closing-paren-error]:
New procedure.
Call it when 'loop' as called from 'liip' returns EOF.
* tests/read-print.scm ("read-with-comments: missing closing paren"):
New test.

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/read-print.scm b/tests/read-print.scm
index b484e280227..4dabcc1e64c 100644
--- a/tests/read-print.scm
+++ b/tests/read-print.scm
@@ -19,6 +19,8 @@
 (define-module (tests-style)
   #:use-module (guix read-print)
   #:use-module (guix gexp)                        ;for the reader extensions
+  #:use-module (srfi srfi-34)
+  #:use-module (srfi srfi-35)
   #:use-module (srfi srfi-64)
   #:use-module (ice-9 match))
 
@@ -46,6 +48,11 @@ expressions."
 
 (test-begin "read-print")
 
+(test-assert "read-with-comments: missing closing paren"
+  (guard (c ((error? c) #t))
+    (call-with-input-string "(what is going on?"
+      read-with-comments)))
+
 (test-equal "read-with-comments: dot notation"
   (cons 'a 'b)
   (call-with-input-string "(a . b)"