opencloud-desktop: fix client startup (#456008)

pkgs/by-name/op/opencloud-desktop/package.nix

@@ -3,6 +3,7 @@
   cmake,
   kdePackages,
   fetchFromGitHub,
+  fetchFromGitLab,
   libre-graph-api-cpp-qt-client,
   kdsingleapplication,
   nix-update-script,
@@ -10,6 +11,25 @@
   versionCheckHook,
   stdenv,
 }:
+let
+  # See issue https://github.com/NixOS/nixpkgs/issues/455981
+  # It was spotted upstream that ecm 6.19.0 caused this issue
+  # Therefore we pin ecm 6.18.0 which makes opencloud function correctly
+  ecm618 = kdePackages.extra-cmake-modules.overrideAttrs (
+    finalAttrs: prevAttrs: {
+      version = "6.18.0";
+      src = fetchFromGitLab {
+        domain = "invent.kde.org";
+        owner = "frameworks";
+        repo = "extra-cmake-modules";
+        tag = "v${finalAttrs.version}";
+        hash = "sha256-hpqczRaV32yyXXRWxR30tOBEUNWDkeSzVrv0SHMrz1Y=";
+      };
+      patches = [ ];
+    }
+  );
+
+in
 stdenv.mkDerivation (finalAttrs: {
   pname = "opencloud-desktop";
   version = "2.0.0";
@@ -21,7 +41,7 @@ stdenv.mkDerivation (finalAttrs: {
   };
 
   buildInputs = [
-    kdePackages.extra-cmake-modules
+    ecm618
     qt6.qtbase
     qt6.qtdeclarative
     qt6.qttools