Merge pull request #44356 from ElvishJerricco/callcabal2nix-passthru-deriver

callCabal2nix: Passthru deriver

pkgs/development/haskell-modules/make-package-set.nix

@@ -159,6 +159,13 @@ let
         # Generated from ${src}
         ${orig.preConfigure or ""}
       '';
+      passthru = orig.passthru or {} // {
+        # When using callCabal2nix or callHackage, it is often useful
+        # to debug a failure by inspecting the Nix expression
+        # generated by cabal2nix. This can be accessed via this
+        # cabal2nixDeriver field.
+        cabal2nixDeriver = src;
+      };
     });
 
 in package-set { inherit pkgs stdenv callPackage; } self // {