update-scripts: move out of flake

See the explanation in the new update-scripts/README.md file.

update-scripts/generate.nix

@@ -0,0 +1,79 @@
+{
+  writeShellApplication,
+  rust-analyzer-options,
+  efmls-configs-sources,
+  none-ls-builtins,
+  nixfmt-rfc-style,
+}:
+writeShellApplication {
+  name = "generate";
+
+  runtimeInputs = [ nixfmt-rfc-style ];
+
+  text = ''
+    repo_root=$(git rev-parse --show-toplevel)
+    generated_dir=$repo_root/generated
+
+    commit=
+    while [ $# -gt 0 ]; do
+      case "$1" in
+      --commit) commit=1
+        ;;
+      --*) echo "unknown option $1"
+        ;;
+      *) echo "unexpected argument $1"
+        ;;
+      esac
+      shift
+    done
+
+    generate() {
+      echo "$2"
+      cp "$1" "$generated_dir/$2.nix"
+      nixfmt "$generated_dir/$2.nix"
+    }
+
+    mkdir -p "$generated_dir"
+    generate "${rust-analyzer-options}" "rust-analyzer"
+    generate "${efmls-configs-sources}" "efmls-configs"
+    generate "${none-ls-builtins}" "none-ls"
+
+    if [ -n "$commit" ]; then
+      cd "$generated_dir"
+      git add .
+
+      # Construct a msg body from `git status -- .`
+      body=$(
+        git status \
+          --short \
+          --ignored=no \
+          --untracked-files=no \
+          --no-ahead-behind \
+          -- . \
+        | sed \
+          -e 's/^\s*\([A-Z]\)\s*/\1 /' \
+          -e 's/^A/Added/' \
+          -e 's/^M/Updated/' \
+          -e 's/^R/Renamed/' \
+          -e 's/^D/Removed/' \
+          -e 's/^/- /'
+      )
+
+      # Construct the commit message based on the body
+      # NOTE: Can't use `wc -l` due to how `echo` pipes its output
+      count=$(echo -n "$body" | awk 'END {print NR}')
+      if [ "$count" -gt 1 ] || [ ''${#body} -gt 50 ]; then
+        msg=$(echo -e "generated: Update\n\n$body")
+      else
+        msg="generated:''${body:1}"
+      fi
+
+      # Commit if there are changes
+      if [ "$count" -gt 0 ]; then
+        echo "Committing $count changes..."
+        echo "$msg"
+        git commit -m "$msg" --no-verify
+      fi
+    fi
+  '';
+}