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dylwil3 merged 3 commits into from
Apr 2, 2026
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Disallow starred expressions as values of starred expressions #24280

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e2e89bb
disallow starred expressions as value of starred expression
dylwil3 Mar 29, 2026
60b780e
add test
dylwil3 Apr 2, 2026
f3a8a22
add another test
dylwil3 Apr 2, 2026
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3 changes: 3 additions & 0 deletions crates/ruff_python_parser/resources/inline/err/starred_starred_expression.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
print(*
*[])
print(* *[])
16 changes: 13 additions & 3 deletions crates/ruff_python_parser/src/parser/expression.rs
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Expand Up @@ -2545,9 +2545,14 @@ impl<'src> Parser<'src> {
self.bump(TokenKind::Star);

let parsed_expr = match context.starred_expression_precedence() {
StarredExpressionPrecedence::Conditional => {
self.parse_conditional_expression_or_higher_impl(context)
}
StarredExpressionPrecedence::Conditional => self
.parse_conditional_expression_or_higher_impl(
// test_err starred_starred_expression
// print(*
// *[])
// print(* *[])
context.disallow_starred_expressions(),
),
StarredExpressionPrecedence::BitwiseOr => {
Comment on lines 2547 to 2556
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@dhruvmanila dhruvmanila Apr 2, 2026

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I initially thought this might not be the correct place but then I realize that this is actually correct given that if we're parsing an expression followed by the * token, then that expression cannot itself be a starred expression unless it's a keyword-variadic argument which is actually a different token (**).

I think we should add this example as well:

print(* *[])

For posterity, I thought the issue must be in parse_arguments instead. The lexer emits [..., Star, Star, ...] for the above code and [..., Star, NonLogicalNewline, Star, ...] for the one in the test. So, I thought we'd need to special case this order of two consecutive Star tokens that could contain a NonLogicalNewline token in between and check whether they're actually consecutive or not.

self.parse_expression_with_bitwise_or_precedence()
}
Expand Down Expand Up @@ -2999,6 +3004,11 @@ impl ExpressionContext {
ExpressionContext::starred_bitwise_or().with_yield_expression_allowed()
}

pub(super) fn disallow_starred_expressions(self) -> Self {
let flags = self.0 & !ExpressionContextFlags::ALLOW_STARRED_EXPRESSION;
ExpressionContext(flags)
}

/// Returns a new [`ExpressionContext`] which allows starred expression with the given
/// precedence.
fn with_starred_expression_allowed(self, precedence: StarredExpressionPrecedence) -> Self {
Expand Down
129 changes: 129 additions & 0 deletions crates/ruff_python_parser/tests/snapshots/invalid_syntax@starred_starred_expression.py.snap
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@@ -0,0 +1,129 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
---
## AST

```
Module(
ModModule {
node_index: NodeIndex(None),
range: 0..26,
body: [
Expr(
StmtExpr {
node_index: NodeIndex(None),
range: 0..12,
value: Call(
ExprCall {
node_index: NodeIndex(None),
range: 0..12,
func: Name(
ExprName {
node_index: NodeIndex(None),
range: 0..5,
id: Name("print"),
ctx: Load,
},
),
arguments: Arguments {
range: 5..12,
node_index: NodeIndex(None),
args: [
Starred(
ExprStarred {
node_index: NodeIndex(None),
range: 6..11,
value: Starred(
ExprStarred {
node_index: NodeIndex(None),
range: 8..11,
value: List(
ExprList {
node_index: NodeIndex(None),
range: 9..11,
elts: [],
ctx: Load,
},
),
ctx: Load,
},
),
ctx: Load,
},
),
],
keywords: [],
},
},
),
},
),
Expr(
StmtExpr {
node_index: NodeIndex(None),
range: 13..25,
value: Call(
ExprCall {
node_index: NodeIndex(None),
range: 13..25,
func: Name(
ExprName {
node_index: NodeIndex(None),
range: 13..18,
id: Name("print"),
ctx: Load,
},
),
arguments: Arguments {
range: 18..25,
node_index: NodeIndex(None),
args: [
Starred(
ExprStarred {
node_index: NodeIndex(None),
range: 19..24,
value: Starred(
ExprStarred {
node_index: NodeIndex(None),
range: 21..24,
value: List(
ExprList {
node_index: NodeIndex(None),
range: 22..24,
elts: [],
ctx: Load,
},
),
ctx: Load,
},
),
ctx: Load,
},
),
],
keywords: [],
},
},
),
},
),
],
},
)
```
## Errors

|
1 | print(*
2 | *[])
| ^^^ Syntax Error: Starred expression cannot be used here
3 | print(* *[])
|


|
1 | print(*
2 | *[])
3 | print(* *[])
| ^^^ Syntax Error: Starred expression cannot be used here
|
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