fix: render empty-tuple subscript annotation as tuple[()] not tuple[]#474
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fix: render empty-tuple subscript annotation as tuple[()] not tuple[]#474gaoflow wants to merge 1 commit into
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An empty `ExprTuple` with `implicit=True` (produced when parsing a subscript like `tuple[()]`) previously yielded nothing in `iterate()`, resulting in the invalid string `tuple[]`. An empty tuple has no implicit form—it must always be written as `()`—so treat an empty implicit tuple the same as an explicit one. Before: `str(returns)` of `def f() -> tuple[()]` gave `"tuple[]"`, which is a `SyntaxError` when re-parsed. After: correctly yields `"tuple[()]"`.
pawamoy
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Jun 25, 2026
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Please follow our PR template.
| """Whether the tuple is implicit (e.g. without parentheses in a subscript's slice).""" | ||
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| def iterate(self, *, flat: bool = True) -> Iterator[str | Expr]: | ||
| if self.implicit and not self.elements: |
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An empty tuple is always written as
()
So we don't need to check self.implicit, right?
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Updated the PR description to follow the template, including the AI disclosure checkbox. |
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Description of the change
Fix rendering for empty-tuple subscript annotations so
tuple[()]andTuple[()]stringify as valid Python instead oftuple[]/Tuple[].tuple[()]is a valid annotation for a zero-element tuple. Griffe parses it as anExprSubscriptwhose slice is an implicit, emptyExprTuple. BecauseExprTuple.iterate()suppressed parentheses whenimplicit=Trueand yielded no elements for an empty tuple, the outer subscript rendered empty brackets.An empty tuple has no omitted source form; it must be written as
(). This adds a focused early return for the empty implicit tuple case and covers both builtintupleandtyping.Tuplewithtest_empty_tuple_annotation_str.Validation:
test_empty_tuple_annotation_str.Relevant resources