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test(tvix/eval): genericClosure (pointer) comparison support

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genericClosure has very limited support for pointer equality: It relies
on comparison (not equality!) in C++ Nix, so as soon as C++ Nix supports
comparing lists (langVersion >= 6) we can rely on pointer equality for
key.

Since Tvix uses equality, not comparison for the insert, our behavior is
currently different, as documented by the notyetpassing tests.

Change-Id: Ifcd741ed4fc3ccc3825f7038875d56a9918b786a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8720
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
This commit is contained in:
sterni 2023-06-07 16:08:37 +02:00 committed by clbot
parent 0005737f11
commit 0f71d8f813
5 changed files with 38 additions and 0 deletions
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1
tvix/eval/src/tests/tvix_tests/eval-okay-builtins-genericClosure-pointer-equality.exp Normal file
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@ -0,0 +1 @@
[ { key = [ { foo = <LAMBDA>; } ]; val = null; } ]

15
tvix/eval/src/tests/tvix_tests/eval-okay-builtins-genericClosure-pointer-equality.nix Normal file
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@ -0,0 +1,15 @@
let
foo = x: x;
in
# key needs to be a list since it uses comparison, not equality checks:
# lists are comparable in Nix if all non-comparable items in them are equal (e.g.
# functions, attribute sets).
builtins.genericClosure {
startSet = [
{ key = [ { inherit foo; } ]; val = null; }
];
operator = { val, ... }: if val != null then [] else [
{ key = [ { inherit foo; } ]; val = throw "no pointer equality? 🥺👉👈"; }
];
}

9
tvix/eval/src/tests/tvix_tests/notyetpassing/eval-fail-builtins-genericClosure-uncomparable-keys.nix Normal file
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@ -0,0 +1,9 @@
# Attribute sets can't be compared, only checked for equality
builtins.genericClosure {
startSet = [
{ key = { foo = 21; }; }
];
operator = _: [
{ key = { bar = 21; }; }
];
}

12
tvix/eval/src/tests/tvix_tests/notyetpassing/eval-fail-builtins-genericClosure-uncomparable-keys2.nix Normal file
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@ -0,0 +1,12 @@
let
id = x: x;
in
builtins.genericClosure {
startSet = [ { key = id; first = true; } ];
operator =
{ first, ... }:
if first then [
{ key = id; first = false; }
] else [];
}

1
tvix/verify-lang-tests/default.nix
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@ -55,6 +55,7 @@ let
"eval-okay-sort.nix" = [ nix ];
"eval-okay-compare-lists.nix" = [ nix ];
"eval-okay-value-pointer-compare.nix" = [ nix ];
"eval-okay-builtins-genericClosure-pointer-equality.nix" = [ nix ];
# getAttrPos gains support for functionArgs-returned sets after 2.3
"eval-okay-getattrpos-functionargs.nix" = [ nix ];
# groupBy appeared (long) after 2.3