APPEND file-port crash

[rebolbot]

Submitted by: Ladislav

The code below crashes the interpreter

port: open/new %pokus.txt
append port newline

^{CC - Data [ Version: alpha 111 Type: Bug Platform: All Category: Ports Reproduce: Always Fixed-in:none ]}

[rebolbot]

Submitted by: BrianH

File ports don't support the APPEND action - you're supposed to use WRITE/append instead, like this:

port: open/new %pokus.txt
write/append port to-string newline  ; You can't write a character without converting it to string or binary first

Still, it shouldn't crash. The relevant code may be in the host source, and if so we can fix it ourselves.

[rebolbot]

Submitted by: Ladislav

in the core-tests suite

[rebolbot]

Submitted by: abolka

Currently, APPEND on a file port! is just a shortcut for WRITE/append. Should we keep that behaviour, or disallow APPEND on file port!s altogether, for now?

[rebolbot]

Submitted by: abolka

Fix for the crash submitted:

https://github.com/rebol/rebol/pull/212

Note that this fix tightens the effective type spec for APPEND on file ports. Disallowing APPEND on file ports altogether should still be discussed. We could also discuss relaxing APPEND on file ports so that it automatically converts to binary for non-binary values.