Python: Fix tuple parsing for parenthesized element with trailing comma#6811
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knutwannheden merged 1 commit intomainfrom Feb 25, 2026
Merged
Python: Fix tuple parsing for parenthesized element with trailing comma#6811knutwannheden merged 1 commit intomainfrom
knutwannheden merged 1 commit intomainfrom
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…ma outside
The parser incorrectly identified `(` as the tuple's opening paren in
expressions like `("a"),` where the parentheses wrap the element and the
trailing comma outside creates an implicit single-element tuple. This caused
the token index to fall behind the AST position, eventually crashing with
`'NoneType' object has no attribute 'value_source'` when parsing string
literals in type annotations like `Literal["..."]` later in the file.
macsux
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Feb 27, 2026
…ma outside (#6811) The parser incorrectly identified `(` as the tuple's opening paren in expressions like `("a"),` where the parentheses wrap the element and the trailing comma outside creates an implicit single-element tuple. This caused the token index to fall behind the AST position, eventually crashing with `'NoneType' object has no attribute 'value_source'` when parsing string literals in type annotations like `Literal["..."]` later in the file.
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Summary
'NoneType' object has no attribute 'value_source') when parsing files containing single-element tuples where parentheses wrap the element and the trailing comma is outside, e.g.("a"),(as the tuple's opening paren in such expressions, causing the token index to progressively fall behind the AST position, eventually crashing when encountering string literals in type annotations likeLiteral["..."])is followed by,with no,inside the parens, distinguishing("a"),(grouping parens + implicit tuple) from("a",)(tuple parens)Test plan
test_literal_string_type_hint_with_assignment— minimal reproduction of the original crashtest_single_element_tuple_with_trailing_comma_outside_parens— inline casetest_single_element_tuple_with_trailing_comma_outside_parens_multiline— multi-line string concatenation casepreview_long_strings.py) parses successfully