Building a _local_ system

[iamFIREcracker]

Currently, there are at least two different ways of dealing with locally defined systems, i.e. systems defined in the working directory:

1. Create a symlink inside ~/quicklisp/local-projects (or ~/common-lisp), pointing to the current directory
2. Add the current directory to ASDF:*CENTRAL-REPOSITORY* ((pushnew '*default-pathname-defaults* asdf:*central-registry*))

Now, with the first option, everything works as expected: you call TRIVIAL-BUILD:BUILD, it spawns a new CL image, it runs ASDF:LOAD-SYSTEM in it, and since the current directory is inside ~/quicklisp/local-projects (or ~/common-lisp), your system will be loaded just fine.

Unfortunately the current implementation does not seem to play nicely with the second option, i.e. updating ADSF:*CENTRAL-REPOSITORY*; that's because the newly spawn CL image, the one in which ASDF:LOAD-SYSTEM is called, has ASDF:*CENTRAL-REPOSITORY* in its default state, i.e. without our customizations.

Is there any interest in supporting this use case, or instead you prefer to push people to use option 1 instead? Because if there was, here is how I patched LOAD-AND-BUILD-CODE (note the line right above the ASDF:LOAD-SYSTEM call):

• I serialize the current value of ASDF:CENTRAL-REGISTRY, in reverse order, so while loading them later with PUSH, the original order is preserved; note: this happens on the host image, i.e. the one where :CERAMIC is run
• For each entry, I push it back into ASDF:CENTRAL-REGISTRY -- this instead is run on the final app image, the newly spawned one

(defun load-and-build-code (system-name entry-point binary-pathname)
  "Return a list of code strings to eval."
  (list
   "(setf *debugger-hook* #'(lambda (c h) (declare (ignore h)) (uiop:print-condition-backtrace c) (uiop:quit -1)))"
   (format nil "(dolist (entry '~W) (push entry asdf:*central-registry*))" (reverse asdf:*central-registry*))
   (format nil "(asdf:load-system :~A)" system-name)
   (format nil "(setf uiop:*image-entry-point* #'(lambda () ~A))"
           entry-point)
   (format nil "(uiop:dump-image ~S :executable t
  #+sb-core-compression :compression #+sb-core-compression t)"
           binary-pathname)))

Let me know if you see any problems with this and most importantly if you find this somewhat interesting, in which case, I would not mind creating a pull request for this.

Ciao,
M.