Try #1036:

Author: iohk-bors[bot]

builder/shell-for.nix

@@ -59,8 +59,8 @@ let
   # Given a list of derivations, removes those which are components of packages which were selected as part of the shell.
   removeSelectedInputs =
     # All the components of the selected packages: we shouldn't add any of these as dependencies
-    let selectedPackageComponents = lib.concatMap haskellLib.getAllComponents selectedPackages;
-    in lib.filter (input: !(builtins.elem input selectedPackageComponents));
+    let selectedPackageComponents = map (x: x.name) (lib.concatMap haskellLib.getAllComponents selectedPackages);
+    in lib.filter (input: !(builtins.elem input.name selectedPackageComponents));
 
   # We need to remove any dependencies which are selected packages (see above).
   # `depends` contains packages so we use 'removeSelectedPackages`.

ci.nix

@@ -43,7 +43,7 @@
     # We need to use the actual nixpkgs version we're working with here, since the values
     # of 'lib.systems.examples' are not understood between all versions
     let lib = nixpkgs.lib;
-    in lib.optionalAttrs (nixpkgsName == "R2009" && (__elem compiler-nix-name ["ghc865" "ghc884"])) {
+    in lib.optionalAttrs (nixpkgsName == "unstable" && (__elem compiler-nix-name ["ghc865" "ghc884"])) {
     inherit (lib.systems.examples) ghcjs;
   } // lib.optionalAttrs (system == "x86_64-linux" && (
          (nixpkgsName == "R2009" && __elem compiler-nix-name ["ghc8101" "ghc8102" "ghc8103" "ghc8104" "ghc810220201118"])

lib/materialize.nix

@@ -56,7 +56,14 @@ let
         builtins.trace sha256message (builtins.trace materializeMessage calculateNoHash);
 
   # Build fully and check the hash and materialized versions
-  checked = runCommand name {} (''
+  checked =
+    # Let the user know what we are checking.  This is useful for debugging issues
+    # where materialization fails to prevent infinite recurstion when:
+    #   checkMaterialization = true;
+    (if materialized != null
+      then __trace "Checking materialization in ${toString materialized}"
+      else x: x)
+    runCommand name {} (''
         ERR=$(mktemp -d)/errors.txt
       ''
     + (pkgs.lib.optionalString (sha256 != null) ''