Don't drop comments inside __all__, and only read markers from comments

[hakancelikdev]

From the core-dev review of the integration branch.

Problems

1. Comments inside a multi-line __all__ were deleted on rewrite, because the literal is rebuilt from scratch. This also happens on main.

   __all__ = [
       "A",  # the main entry point
       # "Old",
   ]

2. Misleading message. When the refactor left __all__ unchanged, the message always said it "is built from several statements". That was wrong for a single ["A"] + ["B"].
3. Markers inside strings counted. # unexport: not-public / public were matched against the whole physical line, so X = "# unexport: not-public" marked X. This also happens on main.

Fix

• refactor._has_comments tokenizes the source and returns the source unchanged when a comment lies inside the literal's span. It converts the AST's UTF-8 byte column to a character column for the closing line. A comment after the literal (__all__ = [...] # public API) is still kept by the normal rewrite.
• The message now lists every reason: built from several statements, not a plain list/tuple/set, or has comments inside.
• set_extra_attr only looks at COMMENT tokens.
• A changelog entry is added.

Tests

• Two new test_refactor cases: comments inside the literal leave it untouched, and a trailing comment survives a rewrite.
• test_marker_inside_a_string_is_not_a_comment.
• The first and third fail before this change.
• 3.10 / 3.12 / 3.14, pre-commit, mypy and the self-check all pass.

🤖 Generated with Claude Code

https://claude.ai/code/session_019P9bvuGwAyVCNUdsAYPB1V

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