This might sound crazy, but I think it's better to enable the GC by
default to avoid surprises. It costs 1130 bytes of flash and 16 bytes of
RAM (plus heap overhead) so it's not exactly free, but if needed it can
easily be disabled with `-gc=leaking`. On the Uno (32kB flash, 2kB RAM)
that's not massive, on the DigiSpark (8kB flash, 0.5kB RAM) that may be
too much depending on the application.
False positives (pointers that point to nowhere but happen to point into
the heap) would result in the block just before that pointer to be
marked. This is clearly not intended, so ignore such a pointer.
This is directly useful to avoid some unsafety around runtime.alloc and
should be useful in general.
This pragma has the same form as in the main Go compiler:
https://github.com/golang/go/issues/12312
dumb -> leaking:
make it more clear what this "GC" does: leak everything.
marksweep -> conservative:
"marksweep" is too generic, use "conservative" to differentiate
between future garbage collectors: precise marksweep / mark-compact /
refcounting.