feat(tvix/eval): implement nested '?' operator r/4496

Implements the nested presence check operator for attribuet sets by
traversing the chain of lookups through instructions that push/pop
sequentially deeper attribute sets onto the stack.

Note that this commit introduces a bug in case of nested attributes
not being found, which is fixed in a later commit.

Change-Id: Ic8b4c8648736f6cb048e3aa52592e4d075bf0544
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6163
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: grfn <grfn@gws.fyi>

0 files changed, 0 insertions, 0 deletions