Mark PYI025 fix as safe in more cases for stub files

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI025_3.py

@@ -0,0 +1,6 @@
+"""
+Tests for PYI025 where the import is marked as re-exported
+through usage of a "redundant" `import Set as Set` alias
+"""
+
+from collections.abc import Set as Set  # PYI025 triggered but fix is not marked as safe

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI025_3.pyi

@@ -0,0 +1,6 @@
+"""
+Tests for PYI025 where the import is marked as re-exported
+through usage of a "redundant" `import Set as Set` alias
+"""
+
+from collections.abc import Set as Set  # PYI025 triggered but fix is not marked as safe

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

@@ -83,6 +83,8 @@ mod tests {
     #[test_case(Rule::UnaliasedCollectionsAbcSetImport, Path::new("PYI025_1.pyi"))]
     #[test_case(Rule::UnaliasedCollectionsAbcSetImport, Path::new("PYI025_2.py"))]
     #[test_case(Rule::UnaliasedCollectionsAbcSetImport, Path::new("PYI025_2.pyi"))]
+    #[test_case(Rule::UnaliasedCollectionsAbcSetImport, Path::new("PYI025_3.py"))]
+    #[test_case(Rule::UnaliasedCollectionsAbcSetImport, Path::new("PYI025_3.pyi"))]
     #[test_case(Rule::UnannotatedAssignmentInStub, Path::new("PYI052.py"))]
     #[test_case(Rule::UnannotatedAssignmentInStub, Path::new("PYI052.pyi"))]
     #[test_case(Rule::UnassignedSpecialVariableInStub, Path::new("PYI035.py"))]

crates/ruff_linter/src/rules/flake8_pyi/rules/unaliased_collections_abc_set_import.rs

@@ -1,7 +1,7 @@
 use ruff_diagnostics::{Applicability, Diagnostic, Fix, FixAvailability, Violation};
 use ruff_macros::{derive_message_formats, violation};
 use ruff_python_semantic::Imported;
-use ruff_python_semantic::{Binding, BindingKind};
+use ruff_python_semantic::{Binding, BindingKind, Scope};
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
@@ -32,9 +32,14 @@ use crate::renamer::Renamer;
 ///
 /// ## Fix safety
 /// This rule's fix is marked as unsafe for `Set` imports defined at the
-/// top-level of a module. Top-level symbols are implicitly exported by the
+/// top-level of a `.py` module. Top-level symbols are implicitly exported by the
 /// module, and so renaming a top-level symbol may break downstream modules
 /// that import it.
+///
+/// The same is not true for `.pyi` files, where imported symbols are only
+/// re-exported if they are included in `__all__`, use a "redundant"
+/// `import foo as foo` alias, or are imported via a `*` import. As such, the
+/// fix is marked as safe in more cases for `.pyi` files.
 #[violation]
 pub struct UnaliasedCollectionsAbcSetImport;
 
@@ -76,24 +81,41 @@ pub(crate) fn unaliased_collections_abc_set_import(
     let mut diagnostic = Diagnostic::new(UnaliasedCollectionsAbcSetImport, binding.range());
     if checker.semantic().is_available("AbstractSet") {
         diagnostic.try_set_fix(|| {
-            let scope = &checker.semantic().scopes[binding.scope];
-            let (edit, rest) = Renamer::rename(
-                name,
-                "AbstractSet",
-                scope,
-                checker.semantic(),
-                checker.stylist(),
-            )?;
-            Ok(Fix::applicable_edits(
-                edit,
-                rest,
-                if scope.kind.is_module() {
-                    Applicability::Unsafe
-                } else {
-                    Applicability::Safe
-                },
-            ))
+            let semantic = checker.semantic();
+            let scope = &semantic.scopes[binding.scope];
+            let (edit, rest) =
+                Renamer::rename(name, "AbstractSet", scope, semantic, checker.stylist())?;
+            let applicability = determine_applicability(binding, scope, checker);
+            Ok(Fix::applicable_edits(edit, rest, applicability))
         });
     }
     Some(diagnostic)
 }
+
+fn determine_applicability(binding: &Binding, scope: &Scope, checker: &Checker) -> Applicability {
+    // If it's not in a module scope, the import can't be implicitly re-exported,
+    // so always mark it as safe
+    if !scope.kind.is_module() {
+        return Applicability::Safe;
+    }
+    // If it's not a stub and it's in the module scope, always mark the fix as unsafe
+    if !checker.source_type.is_stub() {
+        return Applicability::Unsafe;
+    }
+    // If the import was `from collections.abc import Set as Set`,
+    // it's being explicitly re-exported: mark the fix as unsafe
+    if binding.is_explicit_export() {
+        return Applicability::Unsafe;
+    }
+    // If it's included in `__all__`, mark the fix as unsafe
+    if binding.references().any(|reference| {
+        checker
+            .semantic()
+            .reference(reference)
+            .in_dunder_all_definition()
+    }) {
+        return Applicability::Unsafe;
+    }
+    // Anything else in a stub, and it's a safe fix:
+    Applicability::Safe
+}

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI025_PYI025_1.pyi.snap

@@ -87,7 +87,7 @@ PYI025_1.pyi:33:29: PYI025 [*] Use `from collections.abc import Set as AbstractS
    |
    = help: Alias `Set` to `AbstractSet`
 
-ℹ Unsafe fix
+ℹ Safe fix
 17 17 |     else:
 18 18 |         Set = 1
 19 19 | 

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI025_PYI025_3.py.snap

@@ -0,0 +1,18 @@
+---
+source: crates/ruff_linter/src/rules/flake8_pyi/mod.rs
+---
+PYI025_3.py:6:36: PYI025 [*] Use `from collections.abc import Set as AbstractSet` to avoid confusion with the `set` builtin
+  |
+4 | """
+5 | 
+6 | from collections.abc import Set as Set  # PYI025 triggered but fix is not marked as safe
+  |                                    ^^^ PYI025
+  |
+  = help: Alias `Set` to `AbstractSet`
+
+ℹ Unsafe fix
+3 3 | through usage of a "redundant" `import Set as Set` alias
+4 4 | """
+5 5 | 
+6   |-from collections.abc import Set as Set  # PYI025 triggered but fix is not marked as safe
+  6 |+from collections.abc import Set as AbstractSet  # PYI025 triggered but fix is not marked as safe

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI025_PYI025_3.pyi.snap

@@ -0,0 +1,18 @@
+---
+source: crates/ruff_linter/src/rules/flake8_pyi/mod.rs
+---
+PYI025_3.pyi:6:36: PYI025 [*] Use `from collections.abc import Set as AbstractSet` to avoid confusion with the `set` builtin
+  |
+4 | """
+5 | 
+6 | from collections.abc import Set as Set  # PYI025 triggered but fix is not marked as safe
+  |                                    ^^^ PYI025
+  |
+  = help: Alias `Set` to `AbstractSet`
+
+ℹ Unsafe fix
+3 3 | through usage of a "redundant" `import Set as Set` alias
+4 4 | """
+5 5 | 
+6   |-from collections.abc import Set as Set  # PYI025 triggered but fix is not marked as safe
+  6 |+from collections.abc import Set as AbstractSet  # PYI025 triggered but fix is not marked as safe