[syntax-errors] Detect single starred expression assignment x = *y (#17624)

## Summary

Part of #17412

Starred expressions cannot be used as values in assignment expressions.
Add a new semantic syntax error to catch such instances.
Note that we already have
`ParseErrorType::InvalidStarredExpressionUsage` to catch some starred
expression errors during parsing, but that does not cover top level
assignment expressions.

## Test Plan

- Added new inline tests for the new rule
- Found some examples marked as "valid" in existing tests (`_ = *data`),
which are not really valid (per this new rule) and updated them
- There was an existing inline test - `assign_stmt_invalid_value_expr`
which had instances of `*` expression which would be deemed invalid by
this new rule. Converted these to tuples, so that they do not trigger
this new rule.
This commit is contained in:
Abhijeet Prasad Bodas 2025-05-01 00:34:00 +05:30 committed by GitHub
parent f31b1c695c
commit 0eeb02c0c1
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GPG key ID: B5690EEEBB952194
10 changed files with 661 additions and 217 deletions

View file

@ -1,18 +1,17 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/err/assign_stmt_invalid_value_expr.py
snapshot_kind: text
---
## AST
```
Module(
ModModule {
range: 0..72,
range: 0..90,
body: [
Assign(
StmtAssign {
range: 0..12,
range: 0..15,
targets: [
Name(
ExprName {
@ -22,164 +21,216 @@ Module(
},
),
],
value: Starred(
ExprStarred {
range: 4..12,
value: BoolOp(
ExprBoolOp {
range: 5..12,
op: And,
values: [
Name(
ExprName {
range: 5..6,
id: Name("a"),
ctx: Load,
},
),
Name(
ExprName {
range: 11..12,
id: Name("b"),
ctx: Load,
},
),
],
},
),
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 13..25,
targets: [
Name(
ExprName {
range: 13..14,
id: Name("x"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 17..25,
value: Yield(
ExprYield {
range: 18..25,
value: Some(
Name(
ExprName {
range: 24..25,
id: Name("x"),
ctx: Load,
},
),
),
},
),
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 26..43,
targets: [
Name(
ExprName {
range: 26..27,
id: Name("x"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 30..43,
value: YieldFrom(
ExprYieldFrom {
range: 31..43,
value: Name(
ExprName {
range: 42..43,
id: Name("x"),
ctx: Load,
},
),
},
),
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 44..60,
targets: [
Name(
ExprName {
range: 44..45,
id: Name("x"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 48..60,
value: Lambda(
ExprLambda {
range: 49..60,
parameters: Some(
Parameters {
range: 56..57,
posonlyargs: [],
args: [
ParameterWithDefault {
range: 56..57,
parameter: Parameter {
range: 56..57,
name: Identifier {
id: Name("x"),
range: 56..57,
value: Tuple(
ExprTuple {
range: 4..15,
elts: [
Starred(
ExprStarred {
range: 5..13,
value: BoolOp(
ExprBoolOp {
range: 6..13,
op: And,
values: [
Name(
ExprName {
range: 6..7,
id: Name("a"),
ctx: Load,
},
annotation: None,
},
default: None,
},
],
vararg: None,
kwonlyargs: [],
kwarg: None,
},
),
body: Name(
ExprName {
range: 59..60,
id: Name("x"),
ctx: Load,
},
),
},
),
),
Name(
ExprName {
range: 12..13,
id: Name("b"),
ctx: Load,
},
),
],
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 61..66,
range: 16..34,
targets: [
Name(
ExprName {
range: 61..62,
range: 16..17,
id: Name("x"),
ctx: Store,
},
),
],
value: Tuple(
ExprTuple {
range: 20..34,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 21..23,
value: Int(
42,
),
},
),
Starred(
ExprStarred {
range: 25..33,
value: Yield(
ExprYield {
range: 26..33,
value: Some(
Name(
ExprName {
range: 32..33,
id: Name("x"),
ctx: Load,
},
),
),
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 35..58,
targets: [
Name(
ExprName {
range: 35..36,
id: Name("x"),
ctx: Store,
},
),
],
value: Tuple(
ExprTuple {
range: 39..58,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 40..42,
value: Int(
42,
),
},
),
Starred(
ExprStarred {
range: 44..57,
value: YieldFrom(
ExprYieldFrom {
range: 45..57,
value: Name(
ExprName {
range: 56..57,
id: Name("x"),
ctx: Load,
},
),
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 59..78,
targets: [
Name(
ExprName {
range: 59..60,
id: Name("x"),
ctx: Store,
},
),
],
value: Tuple(
ExprTuple {
range: 63..78,
elts: [
Starred(
ExprStarred {
range: 64..76,
value: Lambda(
ExprLambda {
range: 65..76,
parameters: Some(
Parameters {
range: 72..73,
posonlyargs: [],
args: [
ParameterWithDefault {
range: 72..73,
parameter: Parameter {
range: 72..73,
name: Identifier {
id: Name("x"),
range: 72..73,
},
annotation: None,
},
default: None,
},
],
vararg: None,
kwonlyargs: [],
kwarg: None,
},
),
body: Name(
ExprName {
range: 75..76,
id: Name("x"),
ctx: Load,
},
),
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 79..84,
targets: [
Name(
ExprName {
range: 79..80,
id: Name("x"),
ctx: Store,
},
@ -187,7 +238,7 @@ Module(
],
value: Name(
ExprName {
range: 65..66,
range: 83..84,
id: Name("x"),
ctx: Load,
},
@ -196,10 +247,10 @@ Module(
),
Expr(
StmtExpr {
range: 70..71,
range: 88..89,
value: NumberLiteral(
ExprNumberLiteral {
range: 70..71,
range: 88..89,
value: Int(
1,
),
@ -214,44 +265,44 @@ Module(
## Errors
|
1 | x = *a and b
| ^^^^^^^ Syntax Error: Boolean expression cannot be used here
2 | x = *yield x
3 | x = *yield from x
1 | x = (*a and b,)
| ^^^^^^^ Syntax Error: Boolean expression cannot be used here
2 | x = (42, *yield x)
3 | x = (42, *yield from x)
|
|
1 | x = *a and b
2 | x = *yield x
| ^^^^^^^ Syntax Error: Yield expression cannot be used here
3 | x = *yield from x
4 | x = *lambda x: x
1 | x = (*a and b,)
2 | x = (42, *yield x)
| ^^^^^^^ Syntax Error: Yield expression cannot be used here
3 | x = (42, *yield from x)
4 | x = (*lambda x: x,)
|
|
1 | x = *a and b
2 | x = *yield x
3 | x = *yield from x
| ^^^^^^^^^^^^ Syntax Error: Yield expression cannot be used here
4 | x = *lambda x: x
1 | x = (*a and b,)
2 | x = (42, *yield x)
3 | x = (42, *yield from x)
| ^^^^^^^^^^^^ Syntax Error: Yield expression cannot be used here
4 | x = (*lambda x: x,)
5 | x = x := 1
|
|
2 | x = *yield x
3 | x = *yield from x
4 | x = *lambda x: x
| ^^^^^^^^^^^ Syntax Error: Lambda expression cannot be used here
2 | x = (42, *yield x)
3 | x = (42, *yield from x)
4 | x = (*lambda x: x,)
| ^^^^^^^^^^^ Syntax Error: Lambda expression cannot be used here
5 | x = x := 1
|
|
3 | x = *yield from x
4 | x = *lambda x: x
3 | x = (42, *yield from x)
4 | x = (*lambda x: x,)
5 | x = x := 1
| ^^ Syntax Error: Expected a statement
|

View file

@ -0,0 +1,197 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/err/assign_stmt_starred_expr_value.py
---
## AST
```
Module(
ModModule {
range: 0..45,
body: [
Assign(
StmtAssign {
range: 0..9,
targets: [
Name(
ExprName {
range: 0..1,
id: Name("_"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 4..9,
value: List(
ExprList {
range: 5..9,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 6..8,
value: Int(
42,
),
},
),
],
ctx: Load,
},
),
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 10..19,
targets: [
Name(
ExprName {
range: 10..11,
id: Name("_"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 14..19,
value: Set(
ExprSet {
range: 15..19,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 16..18,
value: Int(
42,
),
},
),
],
},
),
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 20..31,
targets: [
Name(
ExprName {
range: 20..21,
id: Name("_"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 24..31,
value: Call(
ExprCall {
range: 25..31,
func: Name(
ExprName {
range: 25..29,
id: Name("list"),
ctx: Load,
},
),
arguments: Arguments {
range: 29..31,
args: [],
keywords: [],
},
},
),
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 32..44,
targets: [
Name(
ExprName {
range: 32..33,
id: Name("_"),
ctx: Store,
},
),
],
value: Starred(
ExprStarred {
range: 36..44,
value: BinOp(
ExprBinOp {
range: 38..43,
left: Name(
ExprName {
range: 38..39,
id: Name("p"),
ctx: Load,
},
),
op: Add,
right: Name(
ExprName {
range: 42..43,
id: Name("q"),
ctx: Load,
},
),
},
),
ctx: Load,
},
),
},
),
],
},
)
```
## Semantic Syntax Errors
|
1 | _ = *[42]
| ^^^^^ Syntax Error: can't use starred expression here
2 | _ = *{42}
3 | _ = *list()
|
|
1 | _ = *[42]
2 | _ = *{42}
| ^^^^^ Syntax Error: can't use starred expression here
3 | _ = *list()
4 | _ = *(p + q)
|
|
1 | _ = *[42]
2 | _ = *{42}
3 | _ = *list()
| ^^^^^^^ Syntax Error: can't use starred expression here
4 | _ = *(p + q)
|
|
2 | _ = *{42}
3 | _ = *list()
4 | _ = *(p + q)
| ^^^^^^^^ Syntax Error: can't use starred expression here
|

View file

@ -0,0 +1,157 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/ok/assign_stmt_starred_expr_value.py
---
## AST
```
Module(
ModModule {
range: 0..36,
body: [
Assign(
StmtAssign {
range: 0..5,
targets: [
Name(
ExprName {
range: 0..1,
id: Name("_"),
ctx: Store,
},
),
],
value: NumberLiteral(
ExprNumberLiteral {
range: 4..5,
value: Int(
4,
),
},
),
},
),
Assign(
StmtAssign {
range: 6..13,
targets: [
Name(
ExprName {
range: 6..7,
id: Name("_"),
ctx: Store,
},
),
],
value: List(
ExprList {
range: 10..13,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 11..12,
value: Int(
4,
),
},
),
],
ctx: Load,
},
),
},
),
Assign(
StmtAssign {
range: 14..25,
targets: [
Name(
ExprName {
range: 14..15,
id: Name("_"),
ctx: Store,
},
),
],
value: Tuple(
ExprTuple {
range: 18..25,
elts: [
Starred(
ExprStarred {
range: 19..23,
value: List(
ExprList {
range: 20..23,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 21..22,
value: Int(
1,
),
},
),
],
ctx: Load,
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 26..35,
targets: [
Name(
ExprName {
range: 26..27,
id: Name("_"),
ctx: Store,
},
),
],
value: Tuple(
ExprTuple {
range: 30..35,
elts: [
Starred(
ExprStarred {
range: 30..34,
value: List(
ExprList {
range: 31..34,
elts: [
NumberLiteral(
ExprNumberLiteral {
range: 32..33,
value: Int(
1,
),
},
),
],
ctx: Load,
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: false,
},
),
},
),
],
},
)
```

View file

@ -7,7 +7,7 @@ input_file: crates/ruff_python_parser/resources/valid/statement/assignment.py
```
Module(
ModModule {
range: 0..723,
range: 0..729,
body: [
Assign(
StmtAssign {
@ -802,7 +802,7 @@ Module(
),
Assign(
StmtAssign {
range: 682..692,
range: 682..695,
targets: [
List(
ExprList {
@ -812,67 +812,85 @@ Module(
},
),
],
value: Starred(
ExprStarred {
range: 687..692,
value: Name(
ExprName {
range: 688..692,
id: Name("data"),
ctx: Load,
},
),
value: Tuple(
ExprTuple {
range: 687..695,
elts: [
Starred(
ExprStarred {
range: 688..693,
value: Name(
ExprName {
range: 689..693,
id: Name("data"),
ctx: Load,
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 693..703,
range: 696..709,
targets: [
Tuple(
ExprTuple {
range: 693..695,
range: 696..698,
elts: [],
ctx: Store,
parenthesized: true,
},
),
],
value: Starred(
ExprStarred {
range: 698..703,
value: Name(
ExprName {
range: 699..703,
id: Name("data"),
ctx: Load,
},
),
value: Tuple(
ExprTuple {
range: 701..709,
elts: [
Starred(
ExprStarred {
range: 702..707,
value: Name(
ExprName {
range: 703..707,
id: Name("data"),
ctx: Load,
},
),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
},
),
Assign(
StmtAssign {
range: 704..713,
range: 710..719,
targets: [
Tuple(
ExprTuple {
range: 704..708,
range: 710..714,
elts: [
Name(
ExprName {
range: 704..705,
range: 710..711,
id: Name("a"),
ctx: Store,
},
),
Name(
ExprName {
range: 707..708,
range: 713..714,
id: Name("b"),
ctx: Store,
},
@ -885,7 +903,7 @@ Module(
],
value: Name(
ExprName {
range: 711..713,
range: 717..719,
id: Name("ab"),
ctx: Load,
},
@ -894,18 +912,18 @@ Module(
),
Assign(
StmtAssign {
range: 714..723,
range: 720..729,
targets: [
Name(
ExprName {
range: 714..715,
range: 720..721,
id: Name("a"),
ctx: Store,
},
),
Name(
ExprName {
range: 718..719,
range: 724..725,
id: Name("b"),
ctx: Store,
},
@ -913,7 +931,7 @@ Module(
],
value: Name(
ExprName {
range: 722..723,
range: 728..729,
id: Name("c"),
ctx: Load,
},