Welcome to the CHICKEN Scheme pasting service

// C Function signature:
DOS_API DosQMetaObjectConnection* DOS_CALL dos_qobject_connect_lambda_static(DosQObject *sender, const char *signal,
                                                                             DosQObjectConnectLambdaCallback callback, void* callbackData,
                                                                             DosQtConnectionType connection_type);

;; Chicken foreign lambda:
(define-foreign-type DosQMetaObjectConnection "DosQMetaObjectConnection")
(define-foreign-type DosQObject "DosQObject")
(define-foreign-type DosQtConnectionType (enum "DosQtConnectionType"))
(define dos_qobject_connect_lambda_static
  (foreign-lambda (c-pointer DosQMetaObjectConnection) "dos_qobject_connect_lambda_static"
    (c-pointer DosQObject)                         ;; sender
    c-string                                       ;; signal
    (function void (c-pointer int pointer-vector)) ;; callback
    c-pointer                                      ;; callbackData
    DosQtConnectionType))                          ;; connection_type

;; Stack trace:
segmentation violation

[] 
...more...
qml.core.scm:348: coops#slot-value
qml.core.scm:354: chicken.memory#object->pointer
qml.core.scm:378: chicken.base#print
qml.core.scm:379: val
qml.core.scm:170: coops#slot-value
qml.core.scm:379: chicken.base#print
qml.core.scm:380: ptr
qml.core.scm:272: coops#slot-value
qml.core.scm:381: pointer
qml.core.scm:354: obj
qml.core.scm:348: coops#slot-value
qml.core.scm:354: chicken.memory#object->pointer
qml.core.scm:382: val
qml.core.scm:170: coops#slot-value
qml.core.scm:380: qml.lowlevel#dos_qobject_connect_lambda_static
qml.lowlevel.scm:875: ##sys#make-c-string       <--

;; The function gets called with a pointer, string, procedure (windowCloseCallback cbdata argc argv), pointer, int.
;; Repository: https://codeberg.org/zilti/qml
;; One-liner to reproduce segmentation violation:
chicken-install -s && csc -X r7rs -R r7rs -gui examples/helloworld.scm && examples/helloworld