Hi,

>> 1- encodings...

> The fix should be in the MKCL git repo master head now.

It works perfectly.

However, somehow ASDF upgrade is broken:
> (require :asdf)
("ASDF" "asdf" "UIOP")
> (asdf:load-system :asdf)
Debugger called in: #<thread "Initial" active (4648) 0x7f7c4f74b700
0000000001be2000>.

#<a INVALID-SLOT 89384352>:
    The index 35 (max: 33) is not a valid slot index in the object
#<ASDF/PACKAGE-SYSTEM:PACKAGE-SYSTEM "asdf">.

It looks like you're failing to call upgrade-instance-for-redefined-class
before you're calling a new method on an extended class.

>> 3- if I uncomment the lines:
>>   ;;(unless (or #+ecl (use-ecl-byte-compiler-p))
>>   ;;  (setf *load-system-operation* 'load-bundle-op))
>>   I get an error in test-logical-pathname,
>>   with the .fasb apparently mapped to the wrong directory.
>
> I am still scratching my head on this one.  It feels so much like an
> optimization concern of questionable wisdom...  Is it the fear of hitting
> some wall I am unaware of, like the 1024 file descriptor one, or something
> else I haven't seen yet?  Is it some concern about memory consumption in a
> development environment where memory use is through the roof already anyway?
> I don't get it, and I am ready to wait until this becomes a real/confirmed
> problem before I address it (I bet it will take a very long time to see that
> happen). Can't we just drop this one?
>

We can drop it, but the bugs it uncovers are real.
It does appear to work with MKCL, though.
I suspect it's related to some bad shadowing of initialization function
in ECL, whereby the version from the old object file is called, instead
of the version from the new one.

Did you change something in MKCL regarding initialization functions,
e.g. using attributes to mark some functions as being in an initialization
section that will cause them to be called at by the linker,
when ECL for portability to old systems still makes its own function
and calls it?