| 9 Nov 2025 |
 raitobezarius | Ugh, OK, thanks | 15:48:21 |
| raitobezarius | We will start bisecting on Monday if pennae doesn't beat me to it | 15:48:31 |
 Sergei Zimmerman (xokdvium) | I get the same error as the above for nix eval "github:nixos/nixpkgs?rev=a999c1cc0c9eb2095729d5aa03e0d8f7ed256780#pkgsCross.gnu64.bitwarden" --no-eval-cache. So that's why I suspect that nixpkgs machinery is misled into thinking it's cross while it's not | 15:51:28 |
| Sergei Zimmerman (xokdvium) | And that's both for cppnix/lix | 15:52:13 |
 aloisw | 2.93:
nix-repl> nixosConfigurations.nixos.config.nixpkgs.hostPlatform == nixosConfigurations.nixos.config.nixpkgs.buildPlatform
true
main:
nix-repl> nixosConfigurations.nixos.config.nixpkgs.hostPlatform == nixosConfigurations.nixos.config.nixpkgs.buildPlatform
false
So it indeed thinks there's cross now where there wasn't before. | 16:19:34 |
| aloisw | Slightly reduced reproducer:
let
inherit (import <nixpkgs> { }) lib;
in
(lib.evalModules {
modules = [
(
{ config, ... }:
{
options = {
buildPlatform = lib.mkOption {
type = lib.types.either lib.types.str lib.types.attrs;
apply = lib.systems.elaborate;
default = config.hostPlatform;
};
hostPlatform = lib.mkOption {
type = lib.types.either lib.types.str lib.types.attrs;
apply = lib.systems.elaborate;
default = "x86_64-linux";
};
isCross = lib.mkOption { type = lib.types.bool; };
};
config = {
isCross = config.buildPlatform == config.hostPlatform;
};
}
)
];
}).config.isCross
| 16:34:50 |
| aloisw | Fully reduced reproducer:
with rec {
a = {
f = x: x;
meow = true;
};
b = a // {
meow = true;
};
};
a == b
| 16:39:41 |
| raitobezarius | oh wow | 16:46:16 |
| raitobezarius | thx | 16:46:17 |
| raitobezarius | a fix may rain in the next hours | 16:47:18 |
| raitobezarius | i want to go and say that zomg the fact that we broke eval based on this behavior :') | 16:51:32 |
 Lunaphied | Dear gods that's horrifying | 16:58:33 |
 Winter | i fucking hate it | 16:58:49 |
| Sergei Zimmerman (xokdvium) | What's even more cursed is this:
nix::EvalState::eqValues (this=0x555555e8b770, v1=..., v2=..., pos=..., errorCtx="while testing two values for equality") at lix/libexpr/eval.cc:2613
2613 forceValue(v2, pos);
(gdb)
2616 if (v1.type() == nInt && v2.type() == nFloat) {
(gdb)
2619 if (v1.type() == nFloat && v2.type() == nInt) {
(gdb)
2624 if (v1.type() != v2.type()) return false;
(gdb)
2629 auto pointerEq = [&] { return v1.pointerEqProxy() == v2.pointerEqProxy(); };
(gdb)
2631 switch (v1.type()) {
(gdb)
2658 if (pointerEq()) return true;
(gdb)
2661 if (isDerivation(v1) && isDerivation(v2)) {
(gdb)
2669 if (v1.attrs()->size() != v2.attrs()->size()) return false;
(gdb) p v1.attrs()->size()
$1 = 2
(gdb) p v2.attrs()->size()
$2 = 3
It's not equal because the attrset size is incorrect? How???
| 17:21:56 |
| aloisw | I'd guess because it forgot to shrink after noticing that the update replaced one entry? | 17:24:59 |
| Sergei Zimmerman (xokdvium) | Updates never replace anything - they copy to a new attribute set though. It's puzzling | 17:25:38 |
| aloisw | In reply to @raitobezarius:matrix.org
i want to go and say that zomg the fact that we broke eval based on this behavior :') Honestly I didn't even know before tracing this down that true is the expected value in this place. | 17:25:58 |
| Sergei Zimmerman (xokdvium) | Ah I see, that might be my SNAFU hmmm | 17:26:33 |
| aloisw | In reply to @xokdvium:matrix.org
Updates never replace anything - they copy to a new attribute set though. It's puzzling "Replace" not in the sense that it's an in-place update, but that the keys overlap. I think it allocates sum of the sizes many entries and then is supposed to shrink if not all were needed due to overlap. | 17:28:12 |
| Sergei Zimmerman (xokdvium) | Capacity never actually gets shrunk and size is only incremented when doing a push_back to the bindings. Something looks broken in the ExprOpUpdate::eval code. | 17:35:41 |
| aloisw | Weirdly nrOpUpdateValuesCopied is still 2 on my machine. | 17:41:18 |
| Sergei Zimmerman (xokdvium) | Ah sorry I was confused omg lol. Don't mind the noise | 17:43:37 |
| aloisw | Also it doesn't give false if replacing f by an integer. So it's related to the pointer/function mess. | 17:45:45 |
| Sergei Zimmerman (xokdvium) | Yeah so doing this does help:
diff --git a/lix/libexpr/eval.cc b/lix/libexpr/eval.cc
index f1ba9e01c..5a5acd6aa 100644
--- a/lix/libexpr/eval.cc
+++ b/lix/libexpr/eval.cc
@@ -2682,6 +2682,7 @@ bool EvalState::eqValues(Value & v1, Value & v2, const PosIdx pos, std::string_v
/* Functions are incomparable. */
case nFunction:
+ if (pointerEq()) return true;
return false;
case nExternal:
But I'm not sure about all the consequences :)
| 17:49:35 |
| Sergei Zimmerman (xokdvium) | * Yeah so doing this does help:
diff --git a/lix/libexpr/eval.cc b/lix/libexpr/eval.cc
index f1ba9e01c..5a5acd6aa 100644
--- a/lix/libexpr/eval.cc
+++ b/lix/libexpr/eval.cc
@@ -2682,6 +2682,7 @@ bool EvalState::eqValues(Value & v1, Value & v2, const PosIdx pos, std::string_v
/* Functions are incomparable. */
case nFunction:
+ if (pointerEq()) return true;
return false;
case nExternal:
But I'm not sure about all the consequences :)
| 17:49:49 |
| Sergei Zimmerman (xokdvium) | * ~~What's even more cursed is this~~:
- xokdvium got confused, don't mind the noise *
| 17:53:14 |
| aloisw | let a = { f = x: x; }; in a.f == a.f would now return true. | 17:58:31 |
| aloisw | I think https://git.lix.systems/lix-project/lix/commit/80654b84b610f4c0622dd10f0af78a8a2ce97048 is the offending change btw. Currently building that and its parent to confirm. | 18:01:20 |
| Sergei Zimmerman (xokdvium) | Worth mentioning on https://gerrit.lix.systems/c/lix/+/4556. But the cat is out of the bag on this and compat with cppnix wasn't a design decision for that patch? | 18:01:28 |
| aloisw | In reply to @aloisw:julia0815.de
I think https://git.lix.systems/lix-project/lix/commit/80654b84b610f4c0622dd10f0af78a8a2ce97048 is the offending change btw. Currently building that and its parent to confirm. It's not, weirdly enough I get true there? | 18:06:22 |
