fix(tvix/eval): place plain inherits in correct stack slots r/4809

We need to make sure that we compile all plain inherits in a let
expression before declaring any other locals. Plain inherits are special
in the sense that they can never be recursive, instead resolving to a
higher scope. Thus we need to compile their value, before declaring
them. If we don't do that, before any other local can be declared,
we cause a situation where the plain inherits' values are placed into
other locals' stack slots.

Note that we can't integrate the plain inherit compilation into the
regular 2-3 phase model where we defer the compilation of the value or
we'd compile `let inherit x; in …` as `let x = x; in …`.

Change-Id: I951d5df3c9661a054e12401546875f4685b5bf08
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6496
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: sterni <sternenseemann@systemli.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-let-useful-plain-inherit-mixed.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-let-useful-plain-inherit-mixed.exp
new file mode 100644
index 0000000000..3bed31f76e
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-let-useful-plain-inherit-mixed.exp
@@ -0,0 +1 @@
+[ 1 2 3 4 ]