GC in callbacks will invalidate references to Scheme data used in "crunch" code

[felix winkelmann]

When code compiled with crunch manipulates number-vectors or strings allocated in Scheme, then a callback is likely to trigger a GC, which will move those data-structures, rendering existing references to them on the crunch side invalid.

It may be possible to use a special vector/buffer type for data-objects passed from Scheme to crunch.

[felix winkelmann]

Replying to felix:

When code compiled with crunch manipulates number-vectors or strings allocated in Scheme, then a callback is likely to trigger a GC, which will move those data-structures, rendering existing references to them on the crunch side invalid.

This also applies to normal foreign code that uses callbacks, so this is not a problem with crunch, but with the question of how to handle such data in general.