Avoid detached HEAD in Update workflow on push events (#2517)

* Fail in Update workflow if push event has detached HEAD

* Exit with error when event is unsupported

* Check out github.ref instead of github.sha on push events

* Factor out nix/hpack.nix from shell.nix

* Factor out nix/fourmolu.nix from shell.nix

* Use unqualified reference for checkout, when applicable

Author: ttuegel

.github/workflows/update.yml

@@ -11,12 +11,12 @@ jobs:
     steps:
       - id: config
         run: |
-          if [ "${{ github.event_name }}" == 'pull_request' ]
-          then
-            echo "::set-output name=ref::${{ github.event.pull_request.head.sha }}"
-          else
-            echo "::set-output name=ref::$GITHUB_SHA"
+          ref=${{ github.ref }}
+          if [ "${{ github.event_name }}" == 'pull_request' ]; then
+            ref="${{ github.event.pull_request.head.sha }}"
           fi
+          ref="${ref#refs/heads/}"
+          echo "::set-output name=ref::$ref"
 
           git config --global user.name github-actions
           git config --global user.email [email protected]
@@ -47,6 +47,13 @@ jobs:
         env:
           GITHUB_EVENT_NAME: ${{ github.event_name }}
         run: |
+          if [[ $GITHUB_EVENT_NAME == 'push' ]]; then
+            if git status -s -b | grep -q '^##.*(no branch)$'; then
+              echo 2>&1 "Error: Git is in detached HEAD state"
+              exit 1
+            fi
+          fi
+
           if [ -n "$(git status --porcelain 'nix/')" ]; then
             if [[ $GITHUB_EVENT_NAME == 'pull_request' ]]; then
               echo 2>&1 "Error: found modified files"
@@ -58,6 +65,7 @@ jobs:
               git push
             else
               echo 2>&1 "Error: event not supported: $GITHUB_EVENT_NAME"
+              exit 1
             fi
           fi
 
@@ -67,12 +75,12 @@ jobs:
     steps:
       - id: config
         run: |
-          if [ "${{ github.event_name }}" == 'pull_request' ]
-          then
-            echo "::set-output name=ref::${{ github.event.pull_request.head.sha }}"
-          else
-            echo "::set-output name=ref::$GITHUB_SHA"
+          ref=${{ github.ref }}
+          if [ "${{ github.event_name }}" == 'pull_request' ]; then
+            ref="${{ github.event.pull_request.head.sha }}"
           fi
+          ref="${ref#refs/heads/}"
+          echo "::set-output name=ref::$ref"
 
           git config --global user.name github-actions
           git config --global user.email [email protected]
@@ -103,6 +111,13 @@ jobs:
         env:
           GITHUB_EVENT_NAME: ${{ github.event_name }}
         run: |
+          if [[ $GITHUB_EVENT_NAME == 'push' ]]; then
+            if git status -s -b | grep -q '^##.*(no branch)$'; then
+              echo 2>&1 "Error: Git is in detached HEAD state"
+              exit 1
+            fi
+          fi
+
           if [ -n "$(git status --porcelain '*.hs')" ]; then
             if [[ $GITHUB_EVENT_NAME == 'pull_request' ]]; then
               echo 2>&1 "Error: found modified files"
@@ -114,5 +129,6 @@ jobs:
               git push
             else
               echo 2>&1 "Error: event not supported: $GITHUB_EVENT_NAME"
+              exit 1
             fi
           fi

default.nix

@@ -90,6 +90,10 @@ let
         name = "kore-${version}";
         paths = pkgs.lib.attrValues project.kore.components.exes;
       };
+
+      # Change the compiler when updating our own resolver.
+      compiler-nix-name = "ghc8104";
+      index-state = "2021-02-09T00:00:00Z";
     };
 
 in default

nix/fourmolu.nix

@@ -0,0 +1,23 @@
+{ default ? import ../default.nix {}
+, checkMaterialization ? false
+}:
+
+let
+  sources = import ./sources.nix;
+
+  inherit (default) compiler-nix-name index-state;
+
+  fourmolu-project = default.pkgs.haskell-nix.cabalProject {
+    src = sources."fourmolu";
+    inherit checkMaterialization compiler-nix-name index-state;
+    materialized = ./fourmolu.nix.d;
+  };
+
+  inherit (fourmolu-project.fourmolu.components.exes) fourmolu;
+in
+
+fourmolu // {
+  passthru =
+    (fourmolu.passthru or {})
+    // { inherit (fourmolu-project.plan-nix.passthru) updateMaterialized; };
+}

nix/fourmolu.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env nix-shell
-#!nix-shell ../shell.nix -i bash
+#!nix-shell shell.fourmolu.nix -i bash
 
 ./scripts/remove-import-groups.sh
 ./scripts/fourmolu.sh

nix/hpack.nix

@@ -0,0 +1,23 @@
+{ default ? import ../default.nix {}
+, checkMaterialization ? false
+}:
+
+let
+  sources = import ./sources.nix;
+
+  inherit (default) compiler-nix-name index-state;
+
+  hpack-project = default.pkgs.haskell-nix.cabalProject {
+    src = sources."hpack";
+    inherit checkMaterialization compiler-nix-name index-state;
+    materialized = ./hpack.nix.d;
+  };
+
+  inherit (hpack-project.hpack.components.exes) hpack;
+in
+
+hpack // {
+  passthru =
+    (hpack.passthru or {})
+    // { inherit (hpack-project.plan-nix.passthru) updateMaterialized; };
+}

nix/rematerialize.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
 
-nix-shell --run 'hpack -f kore'
+nix-shell nix/shell.hpack.nix --run 'hpack -f kore'
 $(nix-build --no-out-link -A rematerialize)
 $(nix-build --no-out-link shell.nix -A passthru.rematerialize)

nix/shell.fourmolu.nix

@@ -0,0 +1,10 @@
+let
+  default = import ../default.nix {};
+  fourmolu = import ./fourmolu.nix {};
+  inherit (default) pkgs;
+  inherit (pkgs) fd;
+in
+
+pkgs.mkShell {
+  buildInputs = [ fourmolu fd ];
+}

nix/shell.hpack.nix

@@ -0,0 +1,8 @@
+let
+  default = import ../default.nix {};
+  hpack = import ./hpack.nix {};
+in
+
+default.pkgs.mkShell {
+  buildInputs = [ hpack ];
+}

shell.nix

@@ -12,9 +12,7 @@ let
   inherit (pkgs) cabal-install ghcid stack;
   inherit (pkgs) fd gnumake yq z3;
 
-  # Change the compiler when updating our own resolver.
-  compiler-nix-name = "ghc8104";
-  index-state = "2021-02-09T00:00:00Z";
+  inherit (default) compiler-nix-name index-state;
 
   hls-project = import sources."nix-haskell-hls" {
     ghcVersion = compiler-nix-name;
@@ -35,19 +33,9 @@ let
   };
   inherit (stylish-haskell-project.stylish-haskell.components.exes) stylish-haskell;
 
-  fourmolu-project = default.pkgs.haskell-nix.cabalProject {
-    src = sources."fourmolu";
-    inherit checkMaterialization compiler-nix-name index-state;
-    materialized = ./nix/fourmolu.nix.d;
-  };
-  inherit (fourmolu-project.fourmolu.components.exes) fourmolu;
+  fourmolu = import ./nix/fourmolu.nix { inherit default checkMaterialization; };
 
-  hpack-project = default.pkgs.haskell-nix.cabalProject {
-    src = sources."hpack";
-    inherit checkMaterialization compiler-nix-name index-state;
-    materialized = ./nix/hpack.nix.d;
-  };
-  inherit (hpack-project.hpack.components.exes) hpack;
+  hpack = import ./nix/hpack.nix { inherit default checkMaterialization; };
 
 in
 
@@ -63,6 +51,7 @@ shellFor {
     #!/bin/sh
     ${hlint-project.plan-nix.passthru.updateMaterialized}
     ${stylish-haskell-project.plan-nix.passthru.updateMaterialized}
-    ${hpack-project.plan-nix.passthru.updateMaterialized}
+    ${fourmolu.passthru.updateMaterialized}
+    ${hpack.passthru.updateMaterialized}
   '';
 }