From 7b4440ef01e1ab0f5276f9f182eaf22f58472b19 Mon Sep 17 00:00:00 2001
From: Gabriella Gonzalez <gabriella@mercury.com>
Date: Mon, 7 Nov 2022 12:27:06 -0800
Subject: [PATCH] Refactor overlay composition
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… so that it's easier to add and remove overlays by creating a list
of overlays to compose.

This should be a behavior-preserving change.
---
 flake.nix | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/flake.nix b/flake.nix
index 1e4a30ab26..94941a4321 100644
--- a/flake.nix
+++ b/flake.nix
@@ -195,17 +195,23 @@
           hlsSources =
             builtins.mapAttrs (_: dir: gitignoreSource dir) sourceDirs;
 
-          extended = hpkgs:
-            (hpkgs.override (old: {
-              overrides = lib.composeExtensions (old.overrides or (_: _: { }))
-                haskellOverrides;
-            })).extend (hself: hsuper:
-              # disable all checks for our packages
-              builtins.mapAttrs (_: drv: haskell.lib.dontCheck drv)
-              (lib.composeExtensions
-                (haskell.lib.packageSourceOverrides hlsSources) tweaks hself
-                hsuper));
-
+          # Disable tests, but only for the packages mentioned in this overlay
+          #
+          # We don't want to disable tests for *all* packages
+          dontCheck = overlay: hself: hsuper:
+            builtins.mapAttrs (_: haskell.lib.dontCheck)
+              (overlay hself hsuper);
+
+          extended = hpkgs: hpkgs.override (old: {
+            overrides =
+              lib.fold
+                lib.composeExtensions
+                (old.overrides or (_: _: { }))
+                [ haskellOverrides
+                  (dontCheck (haskell.lib.packageSourceOverrides hlsSources))
+                  tweaks
+                ];
+          });
         in {
           inherit hlsSources;