[syntax-errors] Type parameter lists before Python 3.12 (#16479)

Summary
--

Another simple one, just detect type parameter lists in functions
and classes. Like pyright, we don't emit a second diagnostic for
`type` alias statements, which were also introduced in 3.12.

Test Plan
--
Inline tests.
This commit is contained in:
Brent Westbrook 2025-03-05 08:19:09 -05:00 committed by GitHub
parent d94a78a134
commit 81bcdcebd3
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10 changed files with 557 additions and 0 deletions

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@ -0,0 +1,3 @@
# parse_options: {"target-version": "3.11"}
class Foo[S: (str, bytes), T: float, *Ts, **P]: ...
class Foo[]: ...

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@ -0,0 +1,3 @@
# parse_options: {"target-version": "3.11"}
def foo[T](): ...
def foo[](): ...

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@ -0,0 +1,2 @@
# parse_options: {"target-version": "3.12"}
class Foo[S: (str, bytes), T: float, *Ts, **P]: ...

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@ -0,0 +1,2 @@
# parse_options: {"target-version": "3.12"}
def foo[T](): ...

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@ -449,6 +449,34 @@ pub enum UnsupportedSyntaxErrorKind {
Match,
Walrus,
ExceptStar,
/// Represents the use of a [type parameter list] before Python 3.12.
///
/// ## Examples
///
/// Before Python 3.12, generic parameters had to be declared separately using a class like
/// [`typing.TypeVar`], which could then be used in a function or class definition:
///
/// ```python
/// from typing import Generic, TypeVar
///
/// T = TypeVar("T")
///
/// def f(t: T): ...
/// class C(Generic[T]): ...
/// ```
///
/// [PEP 695], included in Python 3.12, introduced the new type parameter syntax, which allows
/// these to be written more compactly and without a separate type variable:
///
/// ```python
/// def f[T](t: T): ...
/// class C[T]: ...
/// ```
///
/// [type parameter list]: https://docs.python.org/3/reference/compound_stmts.html#type-parameter-lists
/// [PEP 695]: https://peps.python.org/pep-0695/
/// [`typing.TypeVar`]: https://docs.python.org/3/library/typing.html#typevar
TypeParameterList,
TypeAliasStatement,
TypeParamDefault,
}
@ -459,6 +487,7 @@ impl Display for UnsupportedSyntaxError {
UnsupportedSyntaxErrorKind::Match => "Cannot use `match` statement",
UnsupportedSyntaxErrorKind::Walrus => "Cannot use named assignment expression (`:=`)",
UnsupportedSyntaxErrorKind::ExceptStar => "Cannot use `except*`",
UnsupportedSyntaxErrorKind::TypeParameterList => "Cannot use type parameter lists",
UnsupportedSyntaxErrorKind::TypeAliasStatement => "Cannot use `type` alias statement",
UnsupportedSyntaxErrorKind::TypeParamDefault => {
"Cannot set default type for a type parameter"
@ -480,6 +509,7 @@ impl UnsupportedSyntaxErrorKind {
UnsupportedSyntaxErrorKind::Match => PythonVersion::PY310,
UnsupportedSyntaxErrorKind::Walrus => PythonVersion::PY38,
UnsupportedSyntaxErrorKind::ExceptStar => PythonVersion::PY311,
UnsupportedSyntaxErrorKind::TypeParameterList => PythonVersion::PY312,
UnsupportedSyntaxErrorKind::TypeAliasStatement => PythonVersion::PY312,
UnsupportedSyntaxErrorKind::TypeParamDefault => PythonVersion::PY313,
}

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@ -1786,6 +1786,21 @@ impl<'src> Parser<'src> {
// x = 10
let type_params = self.try_parse_type_params();
// test_ok function_type_params_py312
// # parse_options: {"target-version": "3.12"}
// def foo[T](): ...
// test_err function_type_params_py311
// # parse_options: {"target-version": "3.11"}
// def foo[T](): ...
// def foo[](): ...
if let Some(ast::TypeParams { range, .. }) = &type_params {
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::TypeParameterList,
*range,
);
}
// test_ok function_def_parameter_range
// def foo(
// first: int,
@ -1900,6 +1915,21 @@ impl<'src> Parser<'src> {
// x = 10
let type_params = self.try_parse_type_params();
// test_ok class_type_params_py312
// # parse_options: {"target-version": "3.12"}
// class Foo[S: (str, bytes), T: float, *Ts, **P]: ...
// test_err class_type_params_py311
// # parse_options: {"target-version": "3.11"}
// class Foo[S: (str, bytes), T: float, *Ts, **P]: ...
// class Foo[]: ...
if let Some(ast::TypeParams { range, .. }) = &type_params {
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::TypeParameterList,
*range,
);
}
// test_ok class_def_arguments
// class Foo: ...
// class Foo(): ...

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@ -0,0 +1,174 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/err/class_type_params_py311.py
---
## AST
```
Module(
ModModule {
range: 0..113,
body: [
ClassDef(
StmtClassDef {
range: 44..95,
decorator_list: [],
name: Identifier {
id: Name("Foo"),
range: 50..53,
},
type_params: Some(
TypeParams {
range: 53..90,
type_params: [
TypeVar(
TypeParamTypeVar {
range: 54..69,
name: Identifier {
id: Name("S"),
range: 54..55,
},
bound: Some(
Tuple(
ExprTuple {
range: 57..69,
elts: [
Name(
ExprName {
range: 58..61,
id: Name("str"),
ctx: Load,
},
),
Name(
ExprName {
range: 63..68,
id: Name("bytes"),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
),
default: None,
},
),
TypeVar(
TypeParamTypeVar {
range: 71..79,
name: Identifier {
id: Name("T"),
range: 71..72,
},
bound: Some(
Name(
ExprName {
range: 74..79,
id: Name("float"),
ctx: Load,
},
),
),
default: None,
},
),
TypeVarTuple(
TypeParamTypeVarTuple {
range: 81..84,
name: Identifier {
id: Name("Ts"),
range: 82..84,
},
default: None,
},
),
ParamSpec(
TypeParamParamSpec {
range: 86..89,
name: Identifier {
id: Name("P"),
range: 88..89,
},
default: None,
},
),
],
},
),
arguments: None,
body: [
Expr(
StmtExpr {
range: 92..95,
value: EllipsisLiteral(
ExprEllipsisLiteral {
range: 92..95,
},
),
},
),
],
},
),
ClassDef(
StmtClassDef {
range: 96..112,
decorator_list: [],
name: Identifier {
id: Name("Foo"),
range: 102..105,
},
type_params: Some(
TypeParams {
range: 105..107,
type_params: [],
},
),
arguments: None,
body: [
Expr(
StmtExpr {
range: 109..112,
value: EllipsisLiteral(
ExprEllipsisLiteral {
range: 109..112,
},
),
},
),
],
},
),
],
},
)
```
## Errors
|
1 | # parse_options: {"target-version": "3.11"}
2 | class Foo[S: (str, bytes), T: float, *Ts, **P]: ...
3 | class Foo[]: ...
| ^ Syntax Error: Type parameter list cannot be empty
|
## Unsupported Syntax Errors
|
1 | # parse_options: {"target-version": "3.11"}
2 | class Foo[S: (str, bytes), T: float, *Ts, **P]: ...
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Syntax Error: Cannot use type parameter lists on Python 3.11 (syntax was added in Python 3.12)
3 | class Foo[]: ...
|
|
1 | # parse_options: {"target-version": "3.11"}
2 | class Foo[S: (str, bytes), T: float, *Ts, **P]: ...
3 | class Foo[]: ...
| ^^ Syntax Error: Cannot use type parameter lists on Python 3.11 (syntax was added in Python 3.12)
|

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@ -0,0 +1,129 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/err/function_type_params_py311.py
---
## AST
```
Module(
ModModule {
range: 0..79,
body: [
FunctionDef(
StmtFunctionDef {
range: 44..61,
is_async: false,
decorator_list: [],
name: Identifier {
id: Name("foo"),
range: 48..51,
},
type_params: Some(
TypeParams {
range: 51..54,
type_params: [
TypeVar(
TypeParamTypeVar {
range: 52..53,
name: Identifier {
id: Name("T"),
range: 52..53,
},
bound: None,
default: None,
},
),
],
},
),
parameters: Parameters {
range: 54..56,
posonlyargs: [],
args: [],
vararg: None,
kwonlyargs: [],
kwarg: None,
},
returns: None,
body: [
Expr(
StmtExpr {
range: 58..61,
value: EllipsisLiteral(
ExprEllipsisLiteral {
range: 58..61,
},
),
},
),
],
},
),
FunctionDef(
StmtFunctionDef {
range: 62..78,
is_async: false,
decorator_list: [],
name: Identifier {
id: Name("foo"),
range: 66..69,
},
type_params: Some(
TypeParams {
range: 69..71,
type_params: [],
},
),
parameters: Parameters {
range: 71..73,
posonlyargs: [],
args: [],
vararg: None,
kwonlyargs: [],
kwarg: None,
},
returns: None,
body: [
Expr(
StmtExpr {
range: 75..78,
value: EllipsisLiteral(
ExprEllipsisLiteral {
range: 75..78,
},
),
},
),
],
},
),
],
},
)
```
## Errors
|
1 | # parse_options: {"target-version": "3.11"}
2 | def foo[T](): ...
3 | def foo[](): ...
| ^ Syntax Error: Type parameter list cannot be empty
|
## Unsupported Syntax Errors
|
1 | # parse_options: {"target-version": "3.11"}
2 | def foo[T](): ...
| ^^^ Syntax Error: Cannot use type parameter lists on Python 3.11 (syntax was added in Python 3.12)
3 | def foo[](): ...
|
|
1 | # parse_options: {"target-version": "3.11"}
2 | def foo[T](): ...
3 | def foo[](): ...
| ^^ Syntax Error: Cannot use type parameter lists on Python 3.11 (syntax was added in Python 3.12)
|

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@ -0,0 +1,119 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/ok/class_type_params_py312.py
---
## AST
```
Module(
ModModule {
range: 0..96,
body: [
ClassDef(
StmtClassDef {
range: 44..95,
decorator_list: [],
name: Identifier {
id: Name("Foo"),
range: 50..53,
},
type_params: Some(
TypeParams {
range: 53..90,
type_params: [
TypeVar(
TypeParamTypeVar {
range: 54..69,
name: Identifier {
id: Name("S"),
range: 54..55,
},
bound: Some(
Tuple(
ExprTuple {
range: 57..69,
elts: [
Name(
ExprName {
range: 58..61,
id: Name("str"),
ctx: Load,
},
),
Name(
ExprName {
range: 63..68,
id: Name("bytes"),
ctx: Load,
},
),
],
ctx: Load,
parenthesized: true,
},
),
),
default: None,
},
),
TypeVar(
TypeParamTypeVar {
range: 71..79,
name: Identifier {
id: Name("T"),
range: 71..72,
},
bound: Some(
Name(
ExprName {
range: 74..79,
id: Name("float"),
ctx: Load,
},
),
),
default: None,
},
),
TypeVarTuple(
TypeParamTypeVarTuple {
range: 81..84,
name: Identifier {
id: Name("Ts"),
range: 82..84,
},
default: None,
},
),
ParamSpec(
TypeParamParamSpec {
range: 86..89,
name: Identifier {
id: Name("P"),
range: 88..89,
},
default: None,
},
),
],
},
),
arguments: None,
body: [
Expr(
StmtExpr {
range: 92..95,
value: EllipsisLiteral(
ExprEllipsisLiteral {
range: 92..95,
},
),
},
),
],
},
),
],
},
)
```

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@ -0,0 +1,65 @@
---
source: crates/ruff_python_parser/tests/fixtures.rs
input_file: crates/ruff_python_parser/resources/inline/ok/function_type_params_py312.py
---
## AST
```
Module(
ModModule {
range: 0..62,
body: [
FunctionDef(
StmtFunctionDef {
range: 44..61,
is_async: false,
decorator_list: [],
name: Identifier {
id: Name("foo"),
range: 48..51,
},
type_params: Some(
TypeParams {
range: 51..54,
type_params: [
TypeVar(
TypeParamTypeVar {
range: 52..53,
name: Identifier {
id: Name("T"),
range: 52..53,
},
bound: None,
default: None,
},
),
],
},
),
parameters: Parameters {
range: 54..56,
posonlyargs: [],
args: [],
vararg: None,
kwonlyargs: [],
kwarg: None,
},
returns: None,
body: [
Expr(
StmtExpr {
range: 58..61,
value: EllipsisLiteral(
ExprEllipsisLiteral {
range: 58..61,
},
),
},
),
],
},
),
],
},
)
```