Exempt parameters with immutable annotations from B006

resources/test/fixtures/B006_B008.py

@@ -185,3 +185,23 @@ def nested_b008(a=random.randint(0, dt.datetime.now().year)):
 # Ignore lambda contents since they are evaluated at call time.
 def foo(f=lambda x: print(x)):
     f(1)
+
+
+from collections import abc
+from typing import Annotated, Dict, Optional, Sequence, Union, Set
+
+
+def immutable_annotations(
+    a: Sequence[int] | None = [],
+    b: Optional[abc.Mapping[int, int]] = {},
+    c: Annotated[Union[abc.Set[str], abc.Sized], "annotation"] = set(),
+):
+    pass
+
+
+def mutable_annotations(
+    a: list[int] | None = [],
+    b: Optional[Dict[int, int]] = {},
+    c: Annotated[Union[Set[str], abc.Sized], "annotation"] = set(),
+):
+    pass

src/flake8_bugbear/plugins/mutable_argument_default.rs

@@ -1,12 +1,12 @@
 use fnv::{FnvHashMap, FnvHashSet};
-use rustpython_ast::{Arguments, Expr, ExprKind};
+use rustpython_ast::{Arguments, Constant, Expr, ExprKind, Operator};
 
 use crate::ast::helpers::{collect_call_paths, dealias_call_path, match_call_path};
 use crate::ast::types::Range;
 use crate::check_ast::Checker;
 use crate::checks::{Check, CheckKind};
 
-const MUTABLE_FUNCS: [(&str, &str); 7] = [
+const MUTABLE_FUNCS: &[(&str, &str)] = &[
     ("", "dict"),
     ("", "list"),
     ("", "set"),
@@ -16,6 +16,47 @@ const MUTABLE_FUNCS: [(&str, &str); 7] = [
     ("collections", "deque"),
 ];
 
+const IMMUTABLE_TYPES: &[(&str, &str)] = &[
+    ("", "bool"),
+    ("", "bytes"),
+    ("", "complex"),
+    ("", "float"),
+    ("", "frozenset"),
+    ("", "int"),
+    ("", "object"),
+    ("", "range"),
+    ("", "str"),
+    ("collections.abc", "Sized"),
+    ("typing", "LiteralString"),
+    ("typing", "Sized"),
+];
+
+const IMMUTABLE_GENERIC_TYPES: &[(&str, &str)] = &[
+    ("", "tuple"),
+    ("collections.abc", "ByteString"),
+    ("collections.abc", "Collection"),
+    ("collections.abc", "Container"),
+    ("collections.abc", "Iterable"),
+    ("collections.abc", "Mapping"),
+    ("collections.abc", "Reversible"),
+    ("collections.abc", "Sequence"),
+    ("collections.abc", "Set"),
+    ("typing", "AbstractSet"),
+    ("typing", "ByteString"),
+    ("typing", "Callable"),
+    ("typing", "Collection"),
+    ("typing", "Container"),
+    ("typing", "FrozenSet"),
+    ("typing", "Iterable"),
+    ("typing", "Literal"),
+    ("typing", "Mapping"),
+    ("typing", "Never"),
+    ("typing", "NoReturn"),
+    ("typing", "Reversible"),
+    ("typing", "Sequence"),
+    ("typing", "Tuple"),
+];
+
 pub fn is_mutable_func(
     expr: &Expr,
     from_imports: &FnvHashMap<&str, FnvHashSet<&str>>,
@@ -27,34 +68,106 @@ pub fn is_mutable_func(
         .any(|(module, member)| match_call_path(&call_path, module, member, from_imports))
 }
 
+fn is_mutable_expr(
+    expr: &Expr,
+    from_imports: &FnvHashMap<&str, FnvHashSet<&str>>,
+    import_aliases: &FnvHashMap<&str, &str>,
+) -> bool {
+    match &expr.node {
+        ExprKind::List { .. }
+        | ExprKind::Dict { .. }
+        | ExprKind::Set { .. }
+        | ExprKind::ListComp { .. }
+        | ExprKind::DictComp { .. }
+        | ExprKind::SetComp { .. } => true,
+        ExprKind::Call { func, .. } => is_mutable_func(func, from_imports, import_aliases),
+        _ => false,
+    }
+}
+
+fn is_immutable_annotation(
+    expr: &Expr,
+    from_imports: &FnvHashMap<&str, FnvHashSet<&str>>,
+    import_aliases: &FnvHashMap<&str, &str>,
+) -> bool {
+    match &expr.node {
+        ExprKind::Name { .. } | ExprKind::Attribute { .. } => {
+            let call_path = dealias_call_path(collect_call_paths(expr), import_aliases);
+            IMMUTABLE_TYPES
+                .iter()
+                .chain(IMMUTABLE_GENERIC_TYPES)
+                .any(|(module, member)| match_call_path(&call_path, module, member, from_imports))
+        }
+        ExprKind::Subscript { value, slice, .. } => {
+            let call_path = dealias_call_path(collect_call_paths(value), import_aliases);
+            if IMMUTABLE_GENERIC_TYPES
+                .iter()
+                .any(|(module, member)| match_call_path(&call_path, module, member, from_imports))
+            {
+                true
+            } else if match_call_path(&call_path, "typing", "Union", from_imports) {
+                if let ExprKind::Tuple { elts, .. } = &slice.node {
+                    elts.iter()
+                        .all(|elt| is_immutable_annotation(elt, from_imports, import_aliases))
+                } else {
+                    false
+                }
+            } else if match_call_path(&call_path, "typing", "Optional", from_imports) {
+                is_immutable_annotation(slice, from_imports, import_aliases)
+            } else if match_call_path(&call_path, "typing", "Annotated", from_imports) {
+                if let ExprKind::Tuple { elts, .. } = &slice.node {
+                    elts.first().map_or(false, |elt| {
+                        is_immutable_annotation(elt, from_imports, import_aliases)
+                    })
+                } else {
+                    false
+                }
+            } else {
+                false
+            }
+        }
+        ExprKind::BinOp {
+            left,
+            op: Operator::BitOr,
+            right,
+        } => {
+            is_immutable_annotation(left, from_imports, import_aliases)
+                && is_immutable_annotation(right, from_imports, import_aliases)
+        }
+        ExprKind::Constant {
+            value: Constant::None,
+            ..
+        } => true,
+        _ => false,
+    }
+}
+
 /// B006
 pub fn mutable_argument_default(checker: &mut Checker, arguments: &Arguments) {
-    for expr in arguments
-        .defaults
+    // Scan in reverse order to right-align zip()
+    for (arg, default) in arguments
+        .kwonlyargs
         .iter()
-        .chain(arguments.kw_defaults.iter())
+        .rev()
+        .zip(arguments.kw_defaults.iter().rev())
+        .chain(
+            arguments
+                .args
+                .iter()
+                .rev()
+                .chain(arguments.posonlyargs.iter().rev())
+                .zip(arguments.defaults.iter().rev()),
+        )
     {
-        match &expr.node {
-            ExprKind::List { .. }
-            | ExprKind::Dict { .. }
-            | ExprKind::Set { .. }
-            | ExprKind::ListComp { .. }
-            | ExprKind::DictComp { .. }
-            | ExprKind::SetComp { .. } => {
-                checker.add_check(Check::new(
-                    CheckKind::MutableArgumentDefault,
-                    Range::from_located(expr),
-                ));
-            }
-            ExprKind::Call { func, .. } => {
-                if is_mutable_func(func, &checker.from_imports, &checker.import_aliases) {
-                    checker.add_check(Check::new(
-                        CheckKind::MutableArgumentDefault,
-                        Range::from_located(expr),
-                    ));
-                }
-            }
-            _ => {}
+        if is_mutable_expr(default, &checker.from_imports, &checker.import_aliases)
+            && arg.node.annotation.as_ref().map_or(true, |expr| {
+                !is_immutable_annotation(expr, &checker.from_imports, &checker.import_aliases)
+            })
+        {
+            checker.add_check(Check::new(
+                CheckKind::MutableArgumentDefault,
+                Range::from_located(default),
+            ));
         }
     }
 }

src/snapshots/ruff__linter__tests__B006_B006_B008.py.snap

@@ -90,4 +90,28 @@ expression: checks
     row: 170
     column: 48
   fix: ~
+- kind: MutableArgumentDefault
+  location:
+    row: 203
+    column: 26
+  end_location:
+    row: 203
+    column: 28
+  fix: ~
+- kind: MutableArgumentDefault
+  location:
+    row: 204
+    column: 34
+  end_location:
+    row: 204
+    column: 36
+  fix: ~
+- kind: MutableArgumentDefault
+  location:
+    row: 205
+    column: 61
+  end_location:
+    row: 205
+    column: 66
+  fix: ~