From 34d0c0cef5e3a3307653159018727ea32d8bde30 Mon Sep 17 00:00:00 2001
From: Marc Scholten <marc@digitallyinduced.com>
Date: Sun, 16 Nov 2025 12:15:24 -0800
Subject: [PATCH 1/2] haskellPackages.mkDerivation: pass -j to haddock

---
 pkgs/development/haskell-modules/generic-builder.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pkgs/development/haskell-modules/generic-builder.nix b/pkgs/development/haskell-modules/generic-builder.nix
index 5cebe4aec5d0..4ff85fe5d540 100644
--- a/pkgs/development/haskell-modules/generic-builder.nix
+++ b/pkgs/development/haskell-modules/generic-builder.nix
@@ -805,6 +805,7 @@ lib.fix (
             ${optionalString doHoogle "--hoogle"} \
             ${optionalString doHaddockQuickjump "--quickjump"} \
             ${optionalString (isLibrary && hyperlinkSource) "--hyperlink-source"} \
+            ${optionalString enableParallelBuilding "--haddock-option=-j$NIX_BUILD_CORES"} \
             ${lib.concatStringsSep " " haddockFlags}
         ''}
         runHook postHaddock

From 5b7296475fe2027be0a76dc743b50fc2a299f4f3 Mon Sep 17 00:00:00 2001
From: Marc Scholten <marc@digitallyinduced.com>
Date: Sun, 16 Nov 2025 12:16:18 -0800
Subject: [PATCH 2/2] haskellPackages.mkDerivation: pass --no-tmp-comp-dir to
 haddock

this avoids file operations that are not needed in nixpkgs
---
 pkgs/development/haskell-modules/generic-builder.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pkgs/development/haskell-modules/generic-builder.nix b/pkgs/development/haskell-modules/generic-builder.nix
index 4ff85fe5d540..cefd2927e1b5 100644
--- a/pkgs/development/haskell-modules/generic-builder.nix
+++ b/pkgs/development/haskell-modules/generic-builder.nix
@@ -806,6 +806,7 @@ lib.fix (
             ${optionalString doHaddockQuickjump "--quickjump"} \
             ${optionalString (isLibrary && hyperlinkSource) "--hyperlink-source"} \
             ${optionalString enableParallelBuilding "--haddock-option=-j$NIX_BUILD_CORES"} \
+            --haddock-option=--no-tmp-comp-dir \
             ${lib.concatStringsSep " " haddockFlags}
         ''}
         runHook postHaddock