home-assistant: Add error output for missing deps

Print missing dependencies to the console when running the parse
requirements script. This allows to spot missing packages that could be
added to nixpkgs

pkgs/servers/home-assistant/parse-requirements.py

@@ -105,7 +105,9 @@ components = parse_components(version=version)
 build_inputs = {}
 for component in sorted(components.keys()):
     attr_paths = []
-    for req in sorted(get_reqs(components, component)):
+    missing_reqs = []
+    reqs = sorted(get_reqs(components, component))
+    for req in reqs:
         # Some requirements are specified by url, e.g. https://example.org/foobar#xyz==1.0.0
         # Therefore, if there's a "#" in the line, only take the part after it
         req = req[req.find('#') + 1:]
@@ -114,8 +116,14 @@ for component in sorted(components.keys()):
         if attr_path is not None:
             # Add attribute path without "python3Packages." prefix
             attr_paths.append(attr_path[len(PKG_SET + '.'):])
+        else:
+            missing_reqs.append(name)
     else:
         build_inputs[component] = attr_paths
+    n_diff = len(reqs) > len(build_inputs[component])
+    if n_diff > 0:
+        print("Component {} is missing {} dependencies".format(component, n_diff))
+        print("missing requirements: {}".format(missing_reqs))
 
 with open(os.path.dirname(sys.argv[0]) + '/component-packages.nix', 'w') as f:
     f.write('# Generated by parse-requirements.py\n')