ci: extract-maintainers-meta tweaks (#7434)

Simplify extraction and generation of file. We dont need the comments
and can leverage the appropriate lib.generator function.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>

lib/python/generate-all-maintainers.py

@@ -9,13 +9,37 @@ reliable than parsing files with regex.
 """
 
 import argparse
+import inspect
 import json
 import subprocess
 import sys
 from pathlib import Path
-from typing import Dict
 
 
+def get_project_root() -> Path:
+    """
+    Find the project root directory.
+
+    Tries to find the git repository root. If that fails, falls back to
+    locating it relative to this script file.
+    """
+    try:
+        # Ask git for the top-level directory of the current repository.
+        git_root_bytes = subprocess.check_output(
+            ["git", "rev-parse", "--show-toplevel"], stderr=subprocess.DEVNULL
+        )
+        return Path(git_root_bytes.decode("utf-8").strip())
+    except (subprocess.CalledProcessError, FileNotFoundError):
+        # Fallback for when not in a git repo or git is not installed.
+        print(
+            "Warning: 'git rev-parse --show-toplevel' failed.",
+            "Falling back to script location to determine root.",
+            "This may not work correctly with flakes.",
+            file=sys.stderr,
+        )
+        # Assumes this script is at: <root>/flake/dev/generate-all-maintainers/
+        return Path(__file__).parent.parent.parent.parent.resolve()
+
 class MetaMaintainerGenerator:
     """Generates maintainers list using meta.maintainers from Home Manager evaluation."""
 
@@ -25,13 +49,13 @@ class MetaMaintainerGenerator:
         self.output_file = hm_root / "all-maintainers.nix"
         self.extractor_script = hm_root / "lib" / "nix" / "extract-maintainers-meta.nix"
 
-    def extract_maintainers_from_meta(self) -> Dict:
+    def extract_maintainers_from_meta(self) -> dict:
         """Extract maintainer information using meta.maintainers."""
         print("🔍 Extracting maintainers using meta.maintainers...")
 
         try:
             result = subprocess.run([
-                "nix", "eval", "--impure", "--file", str(self.extractor_script), "--json"
+                "nix", "eval", "--file", str(self.extractor_script), "--json"
             ], capture_output=True, text=True, timeout=60)
 
             if result.returncode == 0:
@@ -49,7 +73,7 @@ class MetaMaintainerGenerator:
             print(f"❌ Error extracting maintainers: {e}")
             sys.exit(1)
 
-    def format_maintainer_entry(self, name: str, info: Dict, source: str) -> str:
+    def format_maintainer_entry(self, name: str, info: dict, source: str) -> str:
         """Format a single maintainer entry with nix fmt compatible formatting."""
         lines = [f"  # {source}"]
         lines.append(f"  {name} = {{")
@@ -116,26 +140,26 @@ class MetaMaintainerGenerator:
         print(f"📦 Nixpkgs maintainers: {len(nixpkgs_maintainers)}")
 
         with open(self.output_file, 'w') as f:
-            f.write('''# Home Manager all maintainers list.
-#
-# This file lists all referenced maintainers in Home Manager.
-#
-# This file is automatically generated using meta.maintainers from Home Manager evaluation
-# DO NOT EDIT MANUALLY
-#
-# To regenerate: ./lib/python/generate-all-maintainers.py
-#
-{
-''')
+            f.write(
+                inspect.cleandoc("""
+              # Home Manager all maintainers list.
+              #
+              # This file lists all referenced maintainers in Home Manager.
+              #
+              # This file is automatically generated using meta.maintainers from Home Manager evaluation
+              # DO NOT EDIT MANUALLY
+              #
+              # To regenerate: ./lib/python/generate-all-maintainers.py
+              #
+            """)
+            )
 
             # Use the formatted maintainers from Nix evaluation
             print("✨ Adding formatted maintainers using lib.generators.toPretty...")
+            f.write("\n")
             f.write(formatted_maintainers)
             f.write("\n")
 
-            f.write('''}
-''')
-
         self.validate_generated_file()
         self.print_statistics(maintainer_data)
 
@@ -143,7 +167,7 @@ class MetaMaintainerGenerator:
         """Validate the generated Nix file syntax."""
         try:
             result = subprocess.run([
-                'nix', 'eval', '--file', str(self.output_file), '--json'
+                'nix-instantiate', '--eval', str(self.output_file), '--strict'
             ], capture_output=True, text=True, timeout=10)
 
             if result.returncode == 0:
@@ -157,7 +181,7 @@ class MetaMaintainerGenerator:
             print(f"Warning: Could not validate file: {e}")
             return False
 
-    def print_statistics(self, maintainer_data: Dict) -> None:
+    def print_statistics(self, maintainer_data: dict) -> None:
         """Print generation statistics."""
         stats = maintainer_data["stats"]
 
@@ -193,8 +217,7 @@ def main():
     if args.root:
         hm_root = args.root
     else:
-        script_dir = Path(__file__).parent
-        hm_root = script_dir.parent.parent
+        hm_root = get_project_root()
 
     if not (hm_root / "modules" / "lib" / "maintainers.nix").exists():
         print(f"Error: Could not find maintainers.nix in {hm_root}")