fix: strip inline config comments the way git does

A `#` or `;` outside quotes starts a comment in git, with or without a
space before it and whether or not the value is quoted. The parser only
cut a `;` that was preceded by whitespace in an unquoted value, so
`name = Alice # work` read back with the comment attached, and
`k = "quoted" # after` was mistaken for an unterminated multi-line quote
and returned `quoted" # after`.

`parse_value` already implements git's rule, but it only ran when a
backslash continuation had been joined. Cut the comment before the
quote-structure branches, using the same quote- and escape-aware scan
that `is_line_continuation` uses, and let `parse_value` handle every
unquoted value rather than only continued ones.

That last part corrects one expectation in test_backslash_line_continuation:
`k = val\\` ends in an even number of backslashes, so it is an escaped
backslash rather than a continuation and the escape resolves.
`git config --get a.k` prints `val\`, where the test expected `val\\`.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: rawsun007

git/config.py

@@ -511,6 +511,24 @@ def is_line_continuation(value: str) -> bool:
                     return False
             return escaped
 
+        def strip_inline_comment(value: str) -> str:
+            """Cut an unquoted ``#`` or ``;`` comment, as git's ``parse_value`` does.
+
+            Quoting and backslash escapes are honoured, so a ``#`` inside a quoted
+            value is literal and an unterminated quote swallows the rest of the line.
+            """
+            quoted = escaped = False
+            for index, char in enumerate(value):
+                if escaped:
+                    escaped = False
+                elif char == "\\":
+                    escaped = True
+                elif char == '"':
+                    quoted = not quoted
+                elif char in "#;" and not quoted:
+                    return value[:index]
+            return value
+
         def parse_value(value: str) -> str:
             parsed: List[str] = []
             whitespace: List[str] = []
@@ -575,11 +593,7 @@ def parse_value(value: str) -> str:
                     optname, vi, optval = mo.group("option", "vi", "value")
                     optname = self.optionxform(optname.rstrip())
 
-                    if vi in ("=", ":") and ";" in optval and not optval.strip().startswith('"'):
-                        pos = optval.find(";")
-                        if pos != -1 and optval[pos - 1].isspace():
-                            optval = optval[:pos]
-                    optval = optval.strip()
+                    optval = strip_inline_comment(optval).strip()
 
                     if len(optval) < 2 or optval[0] != '"':
                         # Does not open quoting.
@@ -589,7 +603,6 @@ def parse_value(value: str) -> str:
                         # next line is appended before the complete value is
                         # parsed. An even number means the last backslash is
                         # escaped and the value ends there.
-                        continued = False
                         while True:
                             if not is_line_continuation(optval):
                                 break
@@ -603,9 +616,7 @@ def parse_value(value: str) -> str:
                             while joined.endswith("\n") or joined.endswith("\r"):
                                 joined = joined[:-1]
                             optval = optval[:-1] + joined
-                            continued = True
-                        if continued:
-                            optval = parse_value(optval)
+                        optval = parse_value(optval)
                     elif optval[-1] != '"':
                         # Opens quoting and does not close: appears to start multi-line quoting.
                         is_multi_line = True

test/test_config.py

@@ -239,6 +239,29 @@ def test_multi_line_config(self):
             )
             self.assertEqual(len(config.sections()), 23)
 
+    def test_inline_comments_are_stripped_like_git(self):
+        """A `#` or `;` outside quotes starts a comment, with or without a space
+        before it, and whether or not the value is quoted. Expectations are what
+        `git config -f <file> --get a.k` prints on git 2.50.1."""
+        cases = [
+            (b"[a]\n\tk = value # comment\n", "value"),
+            (b"[a]\n\tk = value ; comment\n", "value"),
+            (b"[a]\n\tk = value#nospace\n", "value"),
+            (b"[a]\n\tk = value;nospace\n", "value"),
+            (b"[a]\n\tk = a # b ; c\n", "a"),
+            (b'[a]\n\tk = "quoted" # after\n', "quoted"),
+            # A comment character inside quotes is literal.
+            (b'[a]\n\tk = "has # inside"\n', "has # inside"),
+            (b'[a]\n\tk = "has ; inside"\n', "has ; inside"),
+        ]
+        for content, expected in cases:
+            config_file = io.BytesIO(content)
+            config_file.name = "inline_comment.config"
+            config = GitConfigParser(config_file)
+            config.read()
+            with self.subTest(content=content):
+                self.assertEqual(config.get_value("a", "k"), expected)
+
     def test_backslash_line_continuation(self):
         """An unquoted value ending in a backslash continues on the next line,
         exactly as git config parses it: the final backslash and the newline
@@ -250,7 +273,10 @@ def test_backslash_line_continuation(self):
             (b"[a]\n\tk = one\\\n two ; ignored\n", "one two"),
             (b'[a]\n\tk = one\\\n "two"\n', "one two"),
             (b"[a]\n\tk = one\\\n two\\tthree\n", "one two\tthree"),
-            (b"[a]\n\tk = val\\\\\n next\n", "val\\\\"),
+            # An even number of trailing backslashes is an escaped backslash, not a
+            # continuation, so the value ends here and the escape resolves:
+            # `git config --get a.k` prints `val\\`.
+            (b"[a]\n\tk = val\\\\\n next\n", "val\\"),
             (b"[a]\n\tk = end\\\n", "end"),
             (b"[alias]\n\tco = checkout \\\n\t\t-v\n", "checkout \t\t-v"),
         ]