[flake8-pyi] Implement PYI056

crates/ruff/resources/test/fixtures/flake8_pyi/PYI056.py

@@ -0,0 +1,12 @@
+__all__ = ["A", "B", "C"]
+
+# Errors
+__all__.append("D")
+__all__.extend(["E", "Foo"])
+__all__.remove("A")
+
+# OK
+__all__ += ["D"]
+foo = ["Hello"]
+foo.append("World")
+foo.bar.append("World")

crates/ruff/resources/test/fixtures/flake8_pyi/PYI056.pyi

@@ -0,0 +1,12 @@
+__all__ = ["A", "B", "C"]
+
+# Errors
+__all__.append("D")
+__all__.extend(["E", "Foo"])
+__all__.remove("A")
+
+# OK
+__all__ += ["D"]
+foo = ["Hello"]
+foo.append("World")
+foo.bar.append("World")

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

@@ -3037,6 +3037,9 @@ where
                 if self.enabled(Rule::DjangoLocalsInRenderFunction) {
                     flake8_django::rules::locals_in_render_function(self, func, args, keywords);
                 }
+                if self.is_stub && self.enabled(Rule::UnsupportedMethodCallOnAll) {
+                    flake8_pyi::rules::unsupported_method_call_on_all(self, func);
+                }
             }
             Expr::Dict(ast::ExprDict {
                 keys,

crates/ruff/src/codes.rs

@@ -652,6 +652,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Flake8Pyi, "052") => (RuleGroup::Unspecified, rules::flake8_pyi::rules::UnannotatedAssignmentInStub),
         (Flake8Pyi, "054") => (RuleGroup::Unspecified, rules::flake8_pyi::rules::NumericLiteralTooLong),
         (Flake8Pyi, "053") => (RuleGroup::Unspecified, rules::flake8_pyi::rules::StringOrBytesTooLong),
+        (Flake8Pyi, "056") => (RuleGroup::Unspecified, rules::flake8_pyi::rules::UnsupportedMethodCallOnAll),
 
         // flake8-pytest-style
         (Flake8PytestStyle, "001") => (RuleGroup::Unspecified, rules::flake8_pytest_style::rules::PytestFixtureIncorrectParenthesesStyle),

crates/ruff/src/rules/flake8_pyi/mod.rs

@@ -91,6 +91,8 @@ mod tests {
     #[test_case(Rule::WrongTupleLengthVersionComparison, Path::new("PYI005.pyi"))]
     #[test_case(Rule::TypeAliasWithoutAnnotation, Path::new("PYI026.py"))]
     #[test_case(Rule::TypeAliasWithoutAnnotation, Path::new("PYI026.pyi"))]
+    #[test_case(Rule::UnsupportedMethodCallOnAll, Path::new("PYI056.py"))]
+    #[test_case(Rule::UnsupportedMethodCallOnAll, Path::new("PYI056.pyi"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());
         let diagnostics = test_path(

crates/ruff/src/rules/flake8_pyi/rules/mod.rs

@@ -28,6 +28,7 @@ pub(crate) use unaliased_collections_abc_set_import::*;
 pub(crate) use unnecessary_literal_union::*;
 pub(crate) use unrecognized_platform::*;
 pub(crate) use unrecognized_version_info::*;
+pub(crate) use unsupported_method_call_on_all::*;
 
 mod any_eq_ne_annotation;
 mod bad_version_info_comparison;
@@ -59,3 +60,4 @@ mod unaliased_collections_abc_set_import;
 mod unnecessary_literal_union;
 mod unrecognized_platform;
 mod unrecognized_version_info;
+mod unsupported_method_call_on_all;

crates/ruff/src/rules/flake8_pyi/rules/unsupported_method_call_on_all.rs

@@ -0,0 +1,65 @@
+use rustpython_parser::ast::{self, Expr, Ranged};
+
+use ruff_diagnostics::{Diagnostic, Violation};
+use ruff_macros::{derive_message_formats, violation};
+
+use crate::checkers::ast::Checker;
+
+/// ## What it does
+/// Checks that `append`, `extend` and `remove` methods are not called on
+/// `__all__`.
+///
+/// ## Why is this bad?
+/// Different type checkers have varying levels of support for calling these
+/// methods on `__all__`. Instead, use the `+=` operator to add items to
+/// `__all__`, which is known to be supported by all major type checkers.
+///
+/// ## Example
+/// ```python
+/// __all__ = ["A"]
+/// __all__.append("B")
+/// ```
+///
+/// Use instead:
+/// ```python
+/// __all__ = ["A"]
+/// __all__ += "B"
+/// ```
+#[violation]
+pub struct UnsupportedMethodCallOnAll {
+    name: String,
+}
+
+impl Violation for UnsupportedMethodCallOnAll {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        let UnsupportedMethodCallOnAll { name } = self;
+        format!("Calling `.{name}()` on `__all__` may not be supported by all type checkers (use `+=` instead)")
+    }
+}
+
+/// PYI056
+pub(crate) fn unsupported_method_call_on_all(checker: &mut Checker, func: &Expr) {
+    let Expr::Attribute(ast::ExprAttribute { value, attr, .. }) = func else {
+        return;
+    };
+    let Expr::Name(ast::ExprName { id, .. }) = value.as_ref() else {
+        return;
+    };
+    if id.as_str() != "__all__" {
+        return;
+    }
+    if !is_unsupported_method(attr.as_str()) {
+        return;
+    }
+    checker.diagnostics.push(Diagnostic::new(
+        UnsupportedMethodCallOnAll {
+            name: attr.to_string(),
+        },
+        func.range(),
+    ));
+}
+
+fn is_unsupported_method(name: &str) -> bool {
+    matches!(name, "append" | "extend" | "remove")
+}

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI056_PYI056.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff/src/rules/flake8_pyi/mod.rs
+---
+

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI056_PYI056.pyi.snap

@@ -0,0 +1,32 @@
+---
+source: crates/ruff/src/rules/flake8_pyi/mod.rs
+---
+PYI056.pyi:4:1: PYI056 Calling `.append()` on `__all__` may not be supported by all type checkers (use `+=` instead)
+  |
+3 | # Errors
+4 | __all__.append("D")
+  | ^^^^^^^^^^^^^^ PYI056
+5 | __all__.extend(["E", "Foo"])
+6 | __all__.remove("A")
+  |
+
+PYI056.pyi:5:1: PYI056 Calling `.extend()` on `__all__` may not be supported by all type checkers (use `+=` instead)
+  |
+3 | # Errors
+4 | __all__.append("D")
+5 | __all__.extend(["E", "Foo"])
+  | ^^^^^^^^^^^^^^ PYI056
+6 | __all__.remove("A")
+  |
+
+PYI056.pyi:6:1: PYI056 Calling `.remove()` on `__all__` may not be supported by all type checkers (use `+=` instead)
+  |
+4 | __all__.append("D")
+5 | __all__.extend(["E", "Foo"])
+6 | __all__.remove("A")
+  | ^^^^^^^^^^^^^^ PYI056
+7 | 
+8 | # OK
+  |
+
+