services: configuration: Report the location of field type errors.

Previously field type errors would be reported in a non-standard way,
and without any source location information.  This fixes it.

* gnu/services/configuration.scm (configuration-field-error): Add a
'loc' parameter and honor it.  Use 'formatted-message' instead of plain
'format'.
(define-configuration-helper)[field-sanitizer]: New procedure.
Use it.  Use STEM as the identifier of the syntactic constructor of the
record type.  Add a 'sanitize' property to each field.  Remove now
useless STEM macro that would call 'validate-configuration'.
* gnu/services/mail.scm (serialize-listener-configuration): Adjust to
new 'configuration-field-error' prototype.
* tests/services/configuration.scm ("wrong type for a field"): New test.
* po/guix/POTFILES.in: Add gnu/services/configuration.scm.

1 files changed, 1 insertions, 1 deletions

diff --git a/gnu/services/mail.scm b/gnu/services/mail.scm
index d99743ac311..c2fd4d8670b 100644
--- a/gnu/services/mail.scm
+++ b/gnu/services/mail.scm
@@ -285,7 +285,7 @@ the section name.")
     (serialize-fifo-listener-configuration field-name val))
    ((inet-listener-configuration? val)
     (serialize-inet-listener-configuration field-name val))
-   (else (configuration-field-error field-name val))))
+   (else (configuration-field-error #f field-name val))))
 (define (listener-configuration-list? val)
   (and (list? val) (and-map listener-configuration? val)))
 (define (serialize-listener-configuration-list field-name val)