test(tvix/eval): add eval-okay-closure-pointer-compare r/5310

This test case checks two things:

* A sanity check that "pointer equality for functions" means not
  just the lambda, but also the upvalues.

* To be pointer-equal, it is not enough for the upvalues to be
  normal-form equal (i.e. `nix_eq()`-equal); the upvalues must be
  *pointer*-equal.  The second part of the test case checks for
  this.

Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I4e59327a6f199b8212e97197b212e3c3934bb3f0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7372
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

2 files changed, 15 insertions, 0 deletions

diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-closure-pointer-compare.exp b/tvix/eval/src/tests/tvix_tests/eval-okay-closure-pointer-compare.exp
new file mode 100644
index 000000000000..c3bb809c9ffb
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-closure-pointer-compare.exp
@@ -0,0 +1 @@
+[ false false ]
diff --git a/tvix/eval/src/tests/tvix_tests/eval-okay-closure-pointer-compare.nix b/tvix/eval/src/tests/tvix_tests/eval-okay-closure-pointer-compare.nix
new file mode 100644
index 000000000000..7c4333668df8
--- /dev/null
+++ b/tvix/eval/src/tests/tvix_tests/eval-okay-closure-pointer-compare.nix
@@ -0,0 +1,14 @@
+# For an explanation of this behavior see //tvix/docs/value-pointer-equality.md
+let
+  g = x:
+    owo: "th" + x;
+in
+[
+  (
+    { q = g "ia"; } == { q = g ("i"+"a"); }
+  )
+
+  (
+    [ (g "ia") ] == [ (g ("i"+"a")) ]
+  )
+]