Having a micropython.const identity function, and writing "from micropython
import const" at the start of scripts that use the const feature, allows to
write scripts which are compatible with CPython, and with uPy builds that
don't include const optimisation.
This patch adds such a function and updates the tests to do the import.
Assignments of the form "_id = const(value)" are treated as private
(following a similar CPython convention) and code is no longer emitted
for the assignment to a global variable.
See issue #2111.
This allows you to pass a number (being an address) to a viper function
that expects a pointer, and also allows casting of integers to pointers
within viper functions.
This was actually the original behaviour, but it regressed due to native
type identifiers being promoted to 4 bits in width.
If heap allocation for the Python-stack of a function fails then we may
as well allocate the Python-stack on the C stack. This will allow to
run more code without using the heap.
This allows to do "ar[i]" and "ar[i] = val" in viper when ar is a Python
object and i and/or val are native viper types (eg ints).
Patch also includes tests for this feature.
Damien George
Paul Sokolovsky