Allow private accesses on current class (#2929)

crates/ruff/resources/test/fixtures/flake8_self/SLF001.py

@@ -35,6 +35,13 @@ class Foo(metaclass=BazMeta):
             return None
         if self.bar()._private:  # SLF001
             return None
+        if Bar._private_thing:  # SLF001
+            return None
+        if Foo._private_thing:
+            return None
+        Foo = Bar()
+        if Foo._private_thing:  # SLF001
+            return None
         return self.bar
 
     def public_func(self):
@@ -61,3 +68,4 @@ print(foo._private_func())  # SLF001
 print(foo.__really_private_func(1))  # SLF001
 print(foo.bar._private)  # SLF001
 print(foo()._private_thing)  # SLF001
+print(foo()._private_thing__)  # SLF001

crates/ruff/src/rules/flake8_self/rules/private_member_access.rs

@@ -3,7 +3,7 @@ use rustpython_parser::ast::{Expr, ExprKind};
 use ruff_macros::{define_violation, derive_message_formats};
 
 use crate::ast::helpers::collect_call_path;
-use crate::ast::types::Range;
+use crate::ast::types::{BindingKind, Range, ScopeKind};
 use crate::checkers::ast::Checker;
 use crate::registry::Diagnostic;
 use crate::violation::Violation;
@@ -60,13 +60,17 @@ impl Violation for PrivateMemberAccess {
 /// SLF001
 pub fn private_member_access(checker: &mut Checker, expr: &Expr) {
     if let ExprKind::Attribute { value, attr, .. } = &expr.node {
-        if !attr.ends_with("__") && (attr.starts_with('_') || attr.starts_with("__")) {
+        if (attr.starts_with("__") && !attr.ends_with("__"))
+            || (attr.starts_with('_') && !attr.starts_with("__"))
+        {
             if let ExprKind::Call { func, .. } = &value.node {
+                // Ignore `super()` calls.
                 let call_path = collect_call_path(func);
                 if call_path.as_slice() == ["super"] {
                     return;
                 }
             } else {
+                // Ignore `self` and `cls` accesses.
                 let call_path = collect_call_path(value);
                 if call_path.as_slice() == ["self"]
                     || call_path.as_slice() == ["cls"]
@@ -74,6 +78,32 @@ pub fn private_member_access(checker: &mut Checker, expr: &Expr) {
                 {
                     return;
                 }
+
+                // Ignore accesses on class members from _within_ the class.
+                if checker
+                    .scopes
+                    .iter()
+                    .rev()
+                    .find_map(|scope| match &scope.kind {
+                        ScopeKind::Class(class_def) => Some(class_def),
+                        _ => None,
+                    })
+                    .map_or(false, |class_def| {
+                        if call_path.as_slice() == [class_def.name] {
+                            checker
+                                .find_binding(class_def.name)
+                                .map_or(false, |binding| {
+                                    // TODO(charlie): Could the name ever be bound to a _different_
+                                    // class here?
+                                    matches!(binding.kind, BindingKind::ClassDefinition)
+                                })
+                        } else {
+                            false
+                        }
+                    })
+                {
+                    return;
+                }
             }
 
             checker.diagnostics.push(Diagnostic::new(

crates/ruff/src/rules/flake8_self/snapshots/ruff__rules__flake8_self__tests__private-member-access_SLF001.py.snap

@@ -28,10 +28,32 @@ expression: diagnostics
     PrivateMemberAccess:
       access: _private_thing
   location:
-    row: 58
+    row: 38
+    column: 11
+  end_location:
+    row: 38
+    column: 29
+  fix: ~
+  parent: ~
+- kind:
+    PrivateMemberAccess:
+      access: _private_thing
+  location:
+    row: 43
+    column: 11
+  end_location:
+    row: 43
+    column: 29
+  fix: ~
+  parent: ~
+- kind:
+    PrivateMemberAccess:
+      access: _private_thing
+  location:
+    row: 65
     column: 6
   end_location:
-    row: 58
+    row: 65
     column: 24
   fix: ~
   parent: ~
@@ -39,10 +61,10 @@ expression: diagnostics
     PrivateMemberAccess:
       access: __really_private_thing
   location:
-    row: 59
+    row: 66
     column: 6
   end_location:
-    row: 59
+    row: 66
     column: 32
   fix: ~
   parent: ~
@@ -50,10 +72,10 @@ expression: diagnostics
     PrivateMemberAccess:
       access: _private_func
   location:
-    row: 60
+    row: 67
     column: 6
   end_location:
-    row: 60
+    row: 67
     column: 23
   fix: ~
   parent: ~
@@ -61,10 +83,10 @@ expression: diagnostics
     PrivateMemberAccess:
       access: __really_private_func
   location:
-    row: 61
+    row: 68
     column: 6
   end_location:
-    row: 61
+    row: 68
     column: 31
   fix: ~
   parent: ~
@@ -72,10 +94,10 @@ expression: diagnostics
     PrivateMemberAccess:
       access: _private
   location:
-    row: 62
+    row: 69
     column: 6
   end_location:
-    row: 62
+    row: 69
     column: 22
   fix: ~
   parent: ~
@@ -83,11 +105,22 @@ expression: diagnostics
     PrivateMemberAccess:
       access: _private_thing
   location:
-    row: 63
+    row: 70
     column: 6
   end_location:
-    row: 63
+    row: 70
     column: 26
   fix: ~
   parent: ~
+- kind:
+    PrivateMemberAccess:
+      access: _private_thing__
+  location:
+    row: 71
+    column: 6
+  end_location:
+    row: 71
+    column: 28
+  fix: ~
+  parent: ~