From 23eae35ec6f7fe5bd371c29236c9cf34b5d5c8be Mon Sep 17 00:00:00 2001
From: Daniel Firth <daniel.firth@iohk.io>
Date: Mon, 13 May 2024 12:45:07 +0000
Subject: [PATCH] Add -Werror checks

---
 .github/workflows/ci-nix.yaml          | 25 ++++++++++++++++++++
 CONTRIBUTING.md                        |  5 ++--
 cabal.project                          |  4 ----
 flake.nix                              | 32 +++++++++++++++++++++++++-
 hydra-node/test/Hydra/Model/Payment.hs |  1 +
 5 files changed, 59 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/ci-nix.yaml b/.github/workflows/ci-nix.yaml
index ee45bc3068b..1781355e711 100644
--- a/.github/workflows/ci-nix.yaml
+++ b/.github/workflows/ci-nix.yaml
@@ -233,6 +233,31 @@ jobs:
         body-file: comment-body.md
         reactions: rocket
 
+  nix-flake-check:
+    name: "nix flake check"
+    runs-on: ubuntu-latest
+    steps:
+    - name: 📥 Checkout repository
+      uses: actions/checkout@v4
+
+    - name: ❄ Prepare nix
+      uses: cachix/install-nix-action@v26
+      with:
+        extra_nix_config: |
+          accept-flake-config = true
+          log-lines = 1000
+
+    - name: ❄ Cachix cache of nix derivations
+      uses: cachix/cachix-action@v14
+      with:
+        name: cardano-scaling
+        authToken: '${{ secrets.CACHIX_CARDANO_SCALING_AUTH_TOKEN }}'
+
+    - name: ❄ Nix Flake Check
+      run: |
+        nix flake check -L
+
+
   build-specification:
     name: "Build specification using nix"
     runs-on: ubuntu-latest
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 65e3dbacac6..3183c2998eb 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -112,9 +112,8 @@ Besides these general build instructions, some components might document
 additional steps and useful tools in their `README.md` files, e.g. the
 [docs](./docs/README.md) or the [hydra-cluster](./hydra-cluster/README.md)
 
-Warnings are treated as errors for the whole project. To ease development, it
-might be handy to it off locally in a `cabal.project.local` with: `cabal
-configure --ghc-options -Wwarn`.
+While warnings are not treated as errors during builds, CI will check for it
+before we merge any contributions.
 
 ### Coding standards
 
diff --git a/cabal.project b/cabal.project
index e995e5630b0..1bf666579ab 100644
--- a/cabal.project
+++ b/cabal.project
@@ -35,10 +35,6 @@ packages:
 package *
   ghc-options: -j8
 
--- Warnings as errors for local packages
-program-options
-  ghc-options: -Werror
-
 -- Always build tests and benchmarks of local packages
 tests: True
 benchmarks: True
diff --git a/flake.nix b/flake.nix
index 5a6f2985718..fbc505fc62d 100644
--- a/flake.nix
+++ b/flake.nix
@@ -98,6 +98,23 @@
             with pkgs.lib.attrsets;
             mapAttrs' (name: value: nameValuePair (s + name) value) attrs;
 
+          addWerror = x: x.override { ghcOptions = [ "-Werror" ]; };
+
+          componentsToWerrors = n: x:
+            builtins.listToAttrs
+              ([
+                {
+                  name = "${n}-werror";
+                  value = addWerror x.components.library;
+                }
+              ]) // lib.attrsets.mergeAttrsList (map
+              (y:
+                lib.mapAttrs'
+                  (k: v: {
+                    name = "${n}-${y}-${k}-werror";
+                    value = addWerror v;
+                  })
+                  x.components."${y}") [ "benchmarks" "exes" "sublibs" "tests" ]);
         in
         rec {
           legacyPackages = hsPkgs;
@@ -133,7 +150,20 @@
               src = self;
               exe = "${packages.plutus-merkle-tree-tests}/bin/tests";
             };
-          } //
+          } // lib.attrsets.mergeAttrsList (map (x: componentsToWerrors x hsPkgs.${x}) [
+            "cardano-api-classy"
+            "hydra-cardano-api"
+            "hydra-chain-observer"
+            "hydra-cluster"
+            "hydra-explorer"
+            "hydra-node"
+            "hydra-plutus"
+            "hydra-plutus-extras"
+            "hydra-test-utils"
+            "hydra-tui"
+            "plutus-cbor"
+            "plutus-merkle-tree"
+          ]) //
           (if pkgs.stdenv.isLinux then
             {
               inherit (packages)
diff --git a/hydra-node/test/Hydra/Model/Payment.hs b/hydra-node/test/Hydra/Model/Payment.hs
index 6be421cc140..b5ef6dab88f 100644
--- a/hydra-node/test/Hydra/Model/Payment.hs
+++ b/hydra-node/test/Hydra/Model/Payment.hs
@@ -86,6 +86,7 @@ instance IsTx Payment where
   type UTxOType Payment = [(CardanoSigningKey, Value)]
   type ValueType Payment = Value
   txId = error "undefined"
+  txSpendingUTxO = error "undefined"
   balance = foldMap snd
   hashUTxO = encodeUtf8 . show @Text