Add FA102 (using new-style annotation without annotations import)

Refs #3072

Refs #4553

crates/ruff/src/checkers/ast/mod.rs

@@ -2206,6 +2206,19 @@ where
                         }
                     }
                 }
+                // PEP585 list[...], dict[...] without future when required by Python version
+                if self.enabled(Rule::MissingFutureAnnotationsImportNewStyle)
+                    && self.settings.target_version < PythonVersion::Py39
+                    && !self.semantic_model.future_annotations()
+                    && self.semantic_model.in_annotation()
+                    && analyze::typing::is_pep585_generic(value, &self.semantic_model)
+                {
+                    flake8_future_annotations::rules::missing_future_annotations_new_style(
+                        self,
+                        "PEP585 collection",
+                        expr,
+                    );
+                }
 
                 if self.semantic_model.match_typing_expr(value, "Literal") {
                     self.semantic_model.flags |= SemanticModelFlags::LITERAL;
@@ -3190,6 +3203,18 @@ where
                 op: Operator::BitOr,
                 ..
             }) => {
+                // Target version < 3.10, but using a PEP604 `|` operator.
+                if self.enabled(Rule::MissingFutureAnnotationsImportNewStyle)
+                    && self.settings.target_version < PythonVersion::Py310
+                    && self.semantic_model.in_annotation()
+                {
+                    flake8_future_annotations::rules::missing_future_annotations_new_style(
+                        self,
+                        "PEP604 union",
+                        expr,
+                    );
+                }
+
                 if self.is_stub {
                     if self.enabled(Rule::DuplicateUnionMember)
                         && self.semantic_model.in_type_definition()

crates/ruff/src/codes.rs

@@ -319,6 +319,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
 
         // flake8-future-annotations
         (Flake8FutureAnnotations, "100") => (RuleGroup::Unspecified, Rule::MissingFutureAnnotationsImportOldStyle),
+        (Flake8FutureAnnotations, "102") => (RuleGroup::Unspecified, Rule::MissingFutureAnnotationsImportNewStyle),
 
         // flake8-2020
         (Flake82020, "101") => (RuleGroup::Unspecified, Rule::SysVersionSlice3),

crates/ruff/src/registry.rs

@@ -268,6 +268,7 @@ ruff_macros::register_rules!(
     rules::flake8_annotations::rules::AnyType,
     // flake8-future-annotations
     rules::flake8_future_annotations::rules::MissingFutureAnnotationsImportOldStyle,
+    rules::flake8_future_annotations::rules::MissingFutureAnnotationsImportNewStyle,
     // flake8-2020
     rules::flake8_2020::rules::SysVersionSlice3,
     rules::flake8_2020::rules::SysVersion2,

crates/ruff/src/rules/flake8_future_annotations/mod.rs

@@ -37,4 +37,22 @@ mod tests {
         assert_messages!(snapshot, diagnostics);
         Ok(())
     }
+
+    #[test_case(Path::new("no_future_import_uses_lowercase.py"); "no_future_import_uses_lowercase")]
+    #[test_case(Path::new("no_future_import_uses_union.py"); "no_future_import_uses_union")]
+    #[test_case(Path::new("no_future_import_uses_union_inner.py"); "no_future_import_uses_union_inner")]
+    #[test_case(Path::new("ok_no_types.py"); "ok_no_types")]
+    #[test_case(Path::new("ok_uses_future.py"); "ok_uses_future")]
+    fn fa102(path: &Path) -> Result<()> {
+        let snapshot = format!("fa102_{}", path.to_string_lossy());
+        let diagnostics = test_path(
+            Path::new("flake8_future_annotations").join(path).as_path(),
+            &settings::Settings {
+                target_version: PythonVersion::Py37,
+                ..settings::Settings::for_rule(Rule::MissingFutureAnnotationsImportNewStyle)
+            },
+        )?;
+        assert_messages!(snapshot, diagnostics);
+        Ok(())
+    }
 }

crates/ruff/src/rules/flake8_future_annotations/rules/missing_future_annotations_new_style.rs

@@ -0,0 +1,44 @@
+use rustpython_parser::ast::{Expr, Ranged};
+
+use ruff_diagnostics::{Diagnostic, Violation};
+use ruff_macros::{derive_message_formats, violation};
+
+use crate::checkers::ast::Checker;
+
+/// ## What it does
+/// Checks for missing `from __future__ import annotations` imports upon
+/// detecting type annotations that are written in PEP 585 or PEP 604 style but
+/// the target Python version doesn't support them without the import.
+///
+/// ## Example
+///
+/// ```python
+/// def function(a_dict: dict[str, int | None]) -> None:
+///     a_list: list[str] = []
+///     a_list.append("hello")
+/// ```
+/// would raise an exception at runtime before Python 3.9 and Python 3.10.
+#[violation]
+pub struct MissingFutureAnnotationsImportNewStyle {
+    kind: String,
+    expr: String,
+}
+
+impl Violation for MissingFutureAnnotationsImportNewStyle {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        let MissingFutureAnnotationsImportNewStyle { kind, expr } = self;
+        format!("Missing `from __future__ import annotations`, but uses {kind} `{expr}`")
+    }
+}
+
+/// FA102
+pub(crate) fn missing_future_annotations_new_style(checker: &mut Checker, kind: &str, expr: &Expr) {
+    checker.diagnostics.push(Diagnostic::new(
+        MissingFutureAnnotationsImportNewStyle {
+            kind: kind.to_string(),
+            expr: checker.locator.slice(expr.range()).to_string(),
+        },
+        expr.range(),
+    ));
+}

crates/ruff/src/rules/flake8_future_annotations/rules/mod.rs

@@ -1,5 +1,9 @@
+pub(crate) use missing_future_annotations_new_style::{
+    missing_future_annotations_new_style, MissingFutureAnnotationsImportNewStyle,
+};
 pub(crate) use missing_future_annotations_old_style::{
     missing_future_annotations_old_style, MissingFutureAnnotationsImportOldStyle,
 };
 
+mod missing_future_annotations_new_style;
 mod missing_future_annotations_old_style;

crates/ruff/src/rules/flake8_future_annotations/snapshots/ruff__rules__flake8_future_annotations__tests__fa102_no_future_import_uses_lowercase.py.snap

@@ -0,0 +1,12 @@
+---
+source: crates/ruff/src/rules/flake8_future_annotations/mod.rs
+---
+no_future_import_uses_lowercase.py:2:13: FA102 Missing `from __future__ import annotations`, but uses PEP585 collection `list[str]`
+  |
+2 | def main() -> None:
+3 |     a_list: list[str] = []
+  |             ^^^^^^^^^ FA102
+4 |     a_list.append("hello")
+  |
+
+

crates/ruff/src/rules/flake8_future_annotations/snapshots/ruff__rules__flake8_future_annotations__tests__fa102_no_future_import_uses_union.py.snap

@@ -0,0 +1,20 @@
+---
+source: crates/ruff/src/rules/flake8_future_annotations/mod.rs
+---
+no_future_import_uses_union.py:2:13: FA102 Missing `from __future__ import annotations`, but uses PEP604 union `list[str] | None`
+  |
+2 | def main() -> None:
+3 |     a_list: list[str] | None = []
+  |             ^^^^^^^^^^^^^^^^ FA102
+4 |     a_list.append("hello")
+  |
+
+no_future_import_uses_union.py:2:13: FA102 Missing `from __future__ import annotations`, but uses PEP585 collection `list[str]`
+  |
+2 | def main() -> None:
+3 |     a_list: list[str] | None = []
+  |             ^^^^^^^^^ FA102
+4 |     a_list.append("hello")
+  |
+
+

crates/ruff/src/rules/flake8_future_annotations/snapshots/ruff__rules__flake8_future_annotations__tests__fa102_no_future_import_uses_union_inner.py.snap

@@ -0,0 +1,36 @@
+---
+source: crates/ruff/src/rules/flake8_future_annotations/mod.rs
+---
+no_future_import_uses_union_inner.py:2:13: FA102 Missing `from __future__ import annotations`, but uses PEP585 collection `list[str | None]`
+  |
+2 | def main() -> None:
+3 |     a_list: list[str | None] = []
+  |             ^^^^^^^^^^^^^^^^ FA102
+4 |     a_list.append("hello")
+  |
+
+no_future_import_uses_union_inner.py:2:18: FA102 Missing `from __future__ import annotations`, but uses PEP604 union `str | None`
+  |
+2 | def main() -> None:
+3 |     a_list: list[str | None] = []
+  |                  ^^^^^^^^^^ FA102
+4 |     a_list.append("hello")
+  |
+
+no_future_import_uses_union_inner.py:7:8: FA102 Missing `from __future__ import annotations`, but uses PEP585 collection `tuple[str, str | None, str]`
+  |
+7 | def hello(y: dict[str | None, int]) -> None:
+8 |     z: tuple[str, str | None, str] = tuple(y)
+  |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ FA102
+9 |     del z
+  |
+
+no_future_import_uses_union_inner.py:7:19: FA102 Missing `from __future__ import annotations`, but uses PEP604 union `str | None`
+  |
+7 | def hello(y: dict[str | None, int]) -> None:
+8 |     z: tuple[str, str | None, str] = tuple(y)
+  |                   ^^^^^^^^^^ FA102
+9 |     del z
+  |
+
+

crates/ruff/src/rules/flake8_future_annotations/snapshots/ruff__rules__flake8_future_annotations__tests__fa102_ok_no_types.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff/src/rules/flake8_future_annotations/mod.rs
+---
+

crates/ruff/src/rules/flake8_future_annotations/snapshots/ruff__rules__flake8_future_annotations__tests__fa102_ok_uses_future.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff/src/rules/flake8_future_annotations/mod.rs
+---
+