Switch from checkInputs to nativeCheckInputs on >= NixOS 23.05

This unbreaks package tests on the current nixpkgs-unstable branch, as
`buildPythonPackage` has been adjusted to rename `checkInputs` to
`nativeCheckInputs`, breaking existing checkInputs specifications
because of `strictDeps = 1;`. For more information, check out the
corresponding PR at [1]. This implements the proposed workaround[2]
for supporting both the current nixos-unstable and the last release
branch (NixOS 22.11).

[1]: NixOS/nixpkgs#206742
[2]: NixOS/nixpkgs#206742 (comment)

Signed-off-by: Leon Schuermann <leon@is.currently.online>

pkgs/litedram.nix

@@ -58,7 +58,9 @@ buildPythonPackage rec {
     pytest -v test/
   '';
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ./pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     # For test summary
     pandas
     numpy

pkgs/liteeth.nix

@@ -24,7 +24,9 @@ buildPythonPackage rec {
     litex
   ];
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ./pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     # Some of these are really only required because litex-boards
     # needs them for importing all targets in its __init__.py.
     liteiclink

pkgs/litepcie.nix

@@ -27,7 +27,9 @@ buildPythonPackage rec {
     migen
   ];
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ./pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     litex-boards
     litedram
     liteeth

pkgs/litescope.nix

@@ -26,7 +26,9 @@ buildPythonPackage rec {
     litex
   ];
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ./pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     litex
     litex-boards
     liteiclink

pkgs/litex-boards.nix

@@ -58,7 +58,9 @@ buildPythonPackage rec {
 
   doCheck = true;
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ./pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     pytest
   ];
   checkPhase = ''

pkgs/litex/default.nix

@@ -59,7 +59,9 @@ buildPythonPackage rec {
     packaging
   ];
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ../pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     litedram
     liteeth
     liteiclink

pkgs/pythonCheckInputsMagic.nix

@@ -0,0 +1,44 @@
+# In the current NixOS unstable branch (to be nixos-23.05), `buildPythonPackage`
+# has been adjusted to rename `checkInputs` to `nativeCheckInputs`, breaking
+# existing checkInputs specifications because of `strictDeps = 1;`. For more
+# information, check out the corresponding PR at [1]. This implements the
+# proposed workaround[2] for supporting both the current nixos-unstable and the
+# last release branch (NixOS 22.11).
+#
+# It furthermore attempts to identify revisions of the 23.05pre-git
+# unstable which did not include this patch.
+#
+# It returns either "checkInputs" or "nativeCheckInputs", whichever seems
+# appropriate.
+#
+# [1]: https://github.com/NixOS/nixpkgs/pull/206742
+# [2]: https://github.com/NixOS/nixpkgs/pull/206742#issuecomment-1417674430
+
+lib: buildPythonPackage:
+
+let
+  # We check for whether a `buildPythonPackage` derivation with
+  # `nativeCheckInputs` explicit set propagates this attribute. Commits which
+  # use `nativeCheckInputs` to actually specify checkPhase dependencies will
+  # stop this attribute from being propagated.
+  #
+  # This does rely on the inner workings of `buildPythonPackage` and hence
+  # should only be used on revisions where this is known to work.
+  hasNativeCheckInputs = !(
+    builtins.hasAttr "nativeCheckInputs" (
+      buildPythonPackage {
+        name = "test";
+        nativeCheckInputs = [ ];
+      })
+  );
+
+in
+
+# We limit the nixpkgs revisions of where the `hasNativeCheckInputs` test is
+  # used to versions older than 23.05 (including 23.05-pre). This is to avoid
+  # `buildPythonPackage` changing and thus breaking this test in the future.
+if lib.versionAtLeast lib.version "23.05" || hasNativeCheckInputs then
+  "nativeCheckInputs"
+else
+  "checkInputs"
+

pkgs/valentyusb/valentyusb-hw_cdc_eptri.nix

@@ -15,7 +15,9 @@ buildPythonPackage rec {
     litex
   ];
 
-  checkInputs = [
+  # For more information on why this hack is needed, see the
+  # `pythonCheckInputsMagic.nix` file.
+  ${import ../pythonCheckInputsMagic.nix lib buildPythonPackage} = [
     cocotb
     sigrok-cli
     verilog