ccwl: Error out on prefixes that are not strings.

* ccwl/ccwl.scm (run-args): Error out on prefixes that are not
strings.
* tests/ccwl.scm ("command definitions with non-string prefixes in
prefixed inputs must raise a &ccwl-violation condition"): New test.

1 files changed, 6 insertions, 0 deletions

diff --git a/ccwl/ccwl.scm b/ccwl/ccwl.scm
index a476406..f9243aa 100644
--- a/ccwl/ccwl.scm
+++ b/ccwl/ccwl.scm
@@ -307,6 +307,12 @@ identifiers defined in the commands."
                     ((prefix string-arg) (and (string? (syntax->datum #'prefix))
                                               (string? (syntax->datum #'string-arg)))
                      (list #'prefix #'string-arg))
+                    ;; Prefixes that are not strings
+                    ((prefix _)
+                     (raise-exception
+                      (condition (ccwl-violation #'prefix)
+                                 (formatted-message "Invalid prefix ~a. Prefixes must be strings."
+                                                    (syntax->datum #'prefix)))))
                     (_
                      (raise-exception
                       (condition (ccwl-violation x)