fix(tvix/eval): distinguish statically between StackIdx and LocalIdx r/4670

Previously the functions in the scope module returned usize values,
which - sometimes from the same function - were either indexes into
the runtime stack *or* indexes into the compiler's local stack.

This is extremely confusing because it requires the caller to be aware
of the difference, and it actually caused subtle bugs.

To avoid this, there is now a new LocalIdx wrapper type which is used
by the scope module to return indexes into the compiler's stack, as
well as helpers for accounting for the differences between these
indexes and the runtime indexes.

Change-Id: I58f0b50ad94b28a304e3372fd9731b6590b3fdb8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6340
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

0 files changed, 0 insertions, 0 deletions