[Sbcl-devel] redefining alien types fails silently

[Neil H. <gne...@us...>]

The following is unexpected and appears to be inconsistent behavior in
Windows/SBCL v 1.0.7.14.  Is this a bug or a feature?

 

 

Redefining a simple alien type behaves the way I'd expect:

 

CL-USER> (define-alien-type xtype short)

==> XTYPE

CL-USER> (with-alien ((myvar xtype 1024))

           myvar)

==> 1024

CL-USER> (define-alien-type xtype char)

==>

WARNING: redefining XTYPE to be:

  (SIGNED 8),

was

  (SIGNED 16)

XTYPE

CL-USER> (with-alien ((myvar xtype 1024))

           myvar)

==>; Evaluation aborted

; in: LAMBDA NIL

The value 1024 is not of type (SIGNED-BYTE 8)...

 

but redefining a more-complex alien type does not behave the same way:

 

CL-USER> (define-alien-type nil (struct mystruct (myshort short) (mychar
char)))

==> NIL

CL-USER> (with-alien ((myst (struct mystruct)))

           (with-alien ((mysh short (slot myst 'myshort)))

             mysh))

==> 0 

CL-USER> (define-alien-type nil (struct mystruct (myint int) (mychar char)))

==> NIL

CL-USER> (with-alien ((myst (struct mystruct)))

           (with-alien ((myin int (slot myst 'myint)))

             myin))

==> ; Evaluation aborted

; in: LAMBDA NIL

There is no slot named MYINT...