cuda-modules: fix sort predicate stability

[trofi]

Incorrect sorting predicate was found as part of
NixOS/nix#12106 where nix was crashing on the code like:

$ nix eval --expr 'builtins.sort (a: b: true) [ 1 2 3 ]'
...
Aborted (core dumped)

Note: the crash happens here because sorting predicate does not implement isLess and triggers assertion failures for std::stable_sort that backs builtins.sort.

THe change restore isLess semantic for preferable.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

---

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[SomeoneSerge]

This should be good, but off the top of my head I can't immediately tell why Ofborg failed with

       error: attribute 'lib' missing

       at /ofborg/checkout/2/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/ofborg-evaluator-4/pkgs/development/python-modules/torch/default.nix:369:30:

          368|       export CUDNN_INCLUDE_DIR=${lib.getLib cudnn}/include
          369|       export CUDNN_LIB_DIR=${cudnn.lib}/lib

...a riddle for the next morning

[trofi]

Trying eval fix as:

--- a/pkgs/development/python-modules/torch/default.nix
+++ b/pkgs/development/python-modules/torch/default.nix
@@ -354,7 +354,7 @@ buildPythonPackage rec {
     ''
     + lib.optionalString (cudaSupport && cudaPackages ? cudnn) ''
       export CUDNN_INCLUDE_DIR=${lib.getLib cudnn}/include
-      export CUDNN_LIB_DIR=${cudnn.lib}/lib
+      export CUDNN_LIB_DIR=${lib.getLib cudnn}/lib
     ''
     + lib.optionalString rocmSupport ''
       export ROCM_PATH=${rocmtoolkit_joined}

I'm not sure if existing export CUDNN_INCLUDE_DIR=${lib.getLib cudnn}/include is correct (I would normally expect ${lib.getDev cudnn}/include). But I'm leaving it as is as it does not cause eval problems for now.

[SomeoneSerge]

Thanks for the bump. Let's wait for OfBorg and merge

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/5425

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/5447

[SomeoneSerge]

github got confused by torch/default.nix -> torch/source/default.nix