Recompiling DEFPACKAGE should allow for simply taking new definition

[Peter Seibel]

Various changes to the definition of a package in a DEFPACKAGE form can not be achieved without deleting the package or carefully undoing things "by hand". It would be nice to have a restart when recompiling a DEFPACKAGE that just says, "Take the new definition as gospel".

SBCL 1.0.53

[Nikodemus Siivola (nikodemus)]

https://github.com/nikodemus/SBCL/tree/wip-defpackage-variance

is my work-in-progress branch. It currently breaks the contrib build as it detects variances in imports that we didn't care about before.

You can hotpatch an existing SBCL by C-c C-c'ing the DEFINE-CONDITION PACKAGE-VARIANCE-ERROR and the DEFUN UPDATE-PACKAGE-WITH-VARIANCE to try it out.

Please let me know if this is what you had in mind.

[Nikodemus Siivola (nikodemus)]

commit 447788f1b408a8e9ec15ca822851dcd0bee52f82
Author: Nikodemus Siivola <email address hidden>
Date: Fri Feb 1 14:49:41 2013 +0200

    DEFPACKAGE at variance restarts

      Signal a full error on variances, in each case offering the user the
      choice of keeping the old stuff or dropping it.

      Fixes lp#891351.