feat(tvix/eval): Implement builtins.listToAttrs r/5073

Implement the listToAttrs builtin, which constructs an attribute set
from a list of attribute sets with keys name and value.

This is tested using an adaptation of the nix `eval-ok-listtoattrs.nix`,
with the utilities from `lib.nix` inlined.

Change-Id: Ib5bf743466dda9722c2c1e00797df4b58448cf0f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6894
Autosubmit: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

2 files changed, 16 insertions, 0 deletions

diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-listtoattrs.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-listtoattrs.exp
new file mode 100644
index 000000000000..74abef7bc6ed
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-listtoattrs.exp
@@ -0,0 +1 @@
+"AAbar"
diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-listtoattrs.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-listtoattrs.nix
new file mode 100644
index 000000000000..89888fd56178
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-listtoattrs.nix
@@ -0,0 +1,15 @@
+with builtins;
+let
+  fold = op: nul: list:
+    if list == []
+    then nul
+    else op (head list) (fold op nul (tail list));
+  concat =
+    fold (x: y: x + y) "";
+  asi = name: value : { inherit name value; };
+  list = [ ( asi "a" "A" ) ( asi "b" "B" ) ];
+  a = builtins.listToAttrs list;
+  b = builtins.listToAttrs ( list ++ list );
+  r = builtins.listToAttrs [ (asi "result" [ a b ]) ( asi "throw" (throw "this should not be thrown")) ];
+  x = builtins.listToAttrs [ (asi "foo" "bar") (asi "foo" "bla") ];
+in concat (map (x: x.a) r.result) + x.foo