Address review comments in catalog, frontend and pofile

- catalog: use _key_for(id, context) in add_conflict/get_conflicts to
  correctly handle messages with msgctxt; add docstrings to both methods
- frontend: tighten type hints (Counter[_MessageID], dict[_MessageID, ...]);
  remove redundant early-return guard in _get_messages_from_compendiums;
  initialize self.compendium as empty list
- pofile: replace .startswith() calls with slice comparisons for consistency

Author: soft-suroleb

babel/messages/catalog.py

@@ -790,17 +790,35 @@ def __setitem__(self, id: _MessageID, message: Message) -> None:
                 )
             self._messages[key] = message
 
-    def add_conflict(self, message: Message, filename: str, project: str, version: str):
-        key = message.id
+    def add_conflict(self, message: Message, filename: str, project: str, version: str) -> None:
+        """Record a conflicting translation for a message.
+
+        When the same message ID has different translations across input files,
+        the conflicting entry is stored and the message is marked as fuzzy in
+        the output catalog.
+
+        :param message: the conflicting :class:`Message` object
+        :param filename: the basename of the file where the conflict originates
+        :param project: the project name of the conflicting file
+        :param version: the project version of the conflicting file
+        """
+        key = self._key_for(message.id, message.context)
         self._conflicts[key].append({
             'message': message,
             'filename': filename,
             'project': project,
             'version': version,
         })
 
-    def get_conflicts(self, id: _MessageID) -> list[ConflictInfo]:
-        return self._conflicts.get(id, [])
+    def get_conflicts(self, id: _MessageID, context: str | None = None) -> list[ConflictInfo]:
+        """Return all recorded conflicts for a message ID.
+
+        :param id: the message ID to look up conflicts for
+        :param context: optional message context (msgctxt)
+        :return: list of :class:`ConflictInfo` dicts, or an empty list if none
+        """
+        key = self._key_for(id, context)
+        return self._conflicts.get(key, [])
 
     def add(
         self,

babel/messages/frontend.py

@@ -24,7 +24,10 @@
 from collections import Counter, defaultdict
 from configparser import RawConfigParser
 from io import StringIO
-from typing import Any, BinaryIO, Iterable, Literal
+from typing import TYPE_CHECKING, Any, BinaryIO, Iterable, Literal
+
+if TYPE_CHECKING:
+    from babel.messages.catalog import _MessageID
 
 from babel import Locale, localedata
 from babel import __version__ as VERSION
@@ -960,8 +963,8 @@ def finalize_options(self):
 
     def _collect_message_info(self):
         templates: list[tuple[str, Catalog]] = []
-        message_counts: Counter = Counter()
-        message_strings: dict[object, set] = defaultdict(set)
+        message_counts: Counter[_MessageID] = Counter()
+        message_strings: dict[_MessageID, set[str | tuple[str, ...]]] = defaultdict(set)
 
         for filename in self.input_files:
             with open(filename, 'r') as pofile:
@@ -1095,8 +1098,6 @@ def finalize_options(self):
             self.width = int(self.width)
 
     def _get_messages_from_compendiums(self, compendium_paths):
-        if not compendium_paths:
-            return
         for file_path in compendium_paths:
             with open(file_path, 'r') as pofile:
                 catalog = read_po(pofile)

babel/messages/pofile.py

@@ -351,11 +351,11 @@ def parse(self, fileobj: IO[AnyStr] | Iterable[AnyStr]) -> None:
                 continue
             if needs_decode:
                 line = line.decode(self.catalog.charset)
-            if line.startswith('#'):
-                if line[1:].startswith('-'):
+            if line[:1] == '#':
+                if line[1:2] == '-':
                     self._invalid_pofile(line, lineno, 'cannot parse po file with conflicts')
 
-                if line[1:].startswith('~'):
+                if line[1:2] == '~':
                     self._process_message_line(lineno, line[2:].lstrip(), obsolete=True)
                 else:
                     try: