Battling allocator

.github/workflows/ci.yaml

@@ -2,16 +2,16 @@ name: CI
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
-    branches: [ main ]
+    branches: [main]
 
 jobs:
   cargo_build:
     name: "cargo build"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -33,7 +33,7 @@ jobs:
     name: "cargo fmt"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -55,7 +55,7 @@ jobs:
     name: "cargo clippy"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -77,7 +77,7 @@ jobs:
     name: "cargo test"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
@@ -99,13 +99,13 @@ jobs:
     name: "maturin build"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
       - uses: actions/setup-python@v4
         with:
-          python-version: '3.10'
+          python-version: "3.10"
       - run: pip install maturin
       - uses: actions/cache@v3
         env:

.github/workflows/release.yaml

@@ -227,9 +227,9 @@ jobs:
         os: [ubuntu-latest, macos-latest]
         target: [x86_64, aarch64]
         python-version:
-          - '3.7'
-          - '3.8'
-          - '3.9'
+          - "3.7"
+          - "3.8"
+          - "3.9"
         exclude:
           - os: macos-latest
             target: aarch64

.gitignore

@@ -1,5 +1,5 @@
 # Local cache
-.cache
+.ruff_cache
 resources/test/cpython
 
 ###

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+  - repo: https://github.com/charliermarsh/ruff
+    rev: v0.0.24
+    hooks:
+      - id: lint

.pre-commit-hooks.yaml

@@ -0,0 +1,7 @@
+- id: lint
+  name: ruff lint
+  description: Run ruff to lint Python files.
+  entry: ruff
+  language: python
+  types_or: [python]
+  pass_filenames: true

Cargo.toml

@@ -1,12 +1,13 @@
 [package]
 name = "ruff"
-version = "0.0.23"
+version = "0.0.24"
 edition = "2021"
 
 [lib]
 name = "ruff"
 
 [dependencies]
+libcst = { path = "../LibCST/native/libcst" }
 anyhow = { version = "1.0.60" }
 bincode = { version = "1.3.3" }
 cacache = { version = "10.0.1" }
@@ -21,6 +22,7 @@ filetime = { version = "0.2.17" }
 glob = { version = "0.3.0"}
 log = { version = "0.4.17" }
 notify = { version = "4.0.17" }
+once_cell = { version = "1.13.1" }
 rayon = { version = "1.5.3" }
 regex = { version = "1.6.0" }
 rustpython-parser = { features = ["lalrpop"], git = "https://github.com/charliermarsh/RustPython.git", rev = "1613f6c6990011a4bc559e79aaf28d715f9f729b" }
@@ -28,6 +30,8 @@ serde = { version = "1.0.143", features = ["derive"] }
 serde_json = { version = "1.0.83" }
 toml = { version = "0.5.9" }
 walkdir = { version = "2.3.2" }
+bumpalo = "3.11.0"
+bat = "0.21.0"
 
 [profile.release]
 panic = "abort"

README.md

@@ -51,6 +51,16 @@ You can run ruff in `--watch` mode to automatically re-run on-change:
 ruff path/to/code/ --watch
 ```
 
+ruff also works with [Pre-Commit](https://pre-commit.com) (requires Cargo on system):
+
+```yaml
+repos:
+- repo: https://github.com/charliermarsh/ruff
+  rev: v0.0.24
+  hooks:
+    - id: lint
+```
+
 ## Configuration
 
 ruff is configurable both via `pyproject.toml` and the command line.
@@ -215,6 +225,7 @@ hyperfine --ignore-failure --warmup 5 \
 ```
 
 In order, these evaluate:
+
 - ruff
 - Pylint
 - PyFlakes

remove_object_base.py

@@ -0,0 +1,10 @@
+class Foo(object):
+    pass
+
+
+class Bar(Foo, object):
+    pass
+
+
+class Baz(Foo, Bar, object):
+    pass

remove_redundant_fstring.py

@@ -0,0 +1 @@
+bad: str = f"bad" + "bad"

resources/test/src/F401.py

@@ -1,3 +1,4 @@
+from __future__ import all_feature_names
 import os
 import functools
 from collections import (
@@ -10,9 +11,15 @@ import multiprocessing.process
 import logging.config
 import logging.handlers
 
+from blah import ClassA, ClassB, ClassC
+
 
 class X:
     def a(self) -> "namedtuple":
         x = os.environ["1"]
         y = Counter()
         z = multiprocessing.pool.ThreadPool()
+
+
+__all__ = ["ClassA"] + ["ClassB"]
+__all__ += ["ClassC"]

resources/test/src/F634.py

@@ -6,3 +6,7 @@ for _ in range(5):
         pass
     elif (3, 4):
         pass
+
+
+class Foo(object):
+    pass

resources/test/src/F823.py

@@ -15,3 +15,13 @@ def baz():
     global my_var
     global my_dict
     my_dict[my_var] += 1
+
+
+def dec(x):
+    return x
+
+
+@dec
+def f():
+    dec = 1
+    return dec

resources/test/src/pyproject.toml

@@ -10,8 +10,8 @@ select = [
     "F704",
     "F706",
     "F821",
+    "F823",
     "F831",
-    "F832",
     "F841",
     "F901",
 ]

src/ast_ops.rs

@@ -0,0 +1,117 @@
+use std::collections::BTreeMap;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+use rustpython_parser::ast::{Constant, Expr, ExprKind, Location, Stmt, StmtKind};
+
+fn id() -> usize {
+    static COUNTER: AtomicUsize = AtomicUsize::new(1);
+    COUNTER.fetch_add(1, Ordering::Relaxed)
+}
+
+pub enum ScopeKind {
+    Class,
+    Function,
+    Generator,
+    Module,
+}
+
+pub struct Scope {
+    pub id: usize,
+    pub kind: ScopeKind,
+    pub values: BTreeMap<String, Binding>,
+}
+
+impl Scope {
+    pub fn new(kind: ScopeKind) -> Self {
+        Scope {
+            id: id(),
+            kind,
+            values: BTreeMap::new(),
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum BindingKind {
+    Argument,
+    Assignment,
+    Builtin,
+    ClassDefinition,
+    Definition,
+    Export(Vec<String>),
+    FutureImportation,
+    Importation(String),
+    StarImportation,
+    SubmoduleImportation(String),
+}
+
+#[derive(Clone, Debug)]
+pub struct Binding {
+    pub kind: BindingKind,
+    pub location: Location,
+    pub used: Option<usize>,
+}
+
+/// Extract the names bound to a given __all__ assignment.
+pub fn extract_all_names(stmt: &Stmt, scope: &Scope) -> Vec<String> {
+    let mut names: Vec<String> = vec![];
+
+    fn add_to_names(names: &mut Vec<String>, elts: &[Expr]) {
+        for elt in elts {
+            if let ExprKind::Constant {
+                value: Constant::Str(value),
+                ..
+            } = &elt.node
+            {
+                names.push(value.to_string())
+            }
+        }
+    }
+
+    // Grab the existing bound __all__ values.
+    if let StmtKind::AugAssign { .. } = &stmt.node {
+        if let Some(binding) = scope.values.get("__all__") {
+            if let BindingKind::Export(existing) = &binding.kind {
+                names.extend(existing.clone());
+            }
+        }
+    }
+
+    if let Some(value) = match &stmt.node {
+        StmtKind::Assign { value, .. } => Some(value),
+        StmtKind::AnnAssign { value, .. } => value.as_ref(),
+        StmtKind::AugAssign { value, .. } => Some(value),
+        _ => None,
+    } {
+        match &value.node {
+            ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                add_to_names(&mut names, elts)
+            }
+            ExprKind::BinOp { left, right, .. } => {
+                let mut current_left = left;
+                let mut current_right = right;
+                while let Some(elts) = match &current_right.node {
+                    ExprKind::List { elts, .. } => Some(elts),
+                    ExprKind::Tuple { elts, .. } => Some(elts),
+                    _ => None,
+                } {
+                    add_to_names(&mut names, elts);
+                    match &current_left.node {
+                        ExprKind::BinOp { left, right, .. } => {
+                            current_left = left;
+                            current_right = right;
+                        }
+                        ExprKind::List { elts, .. } | ExprKind::Tuple { elts, .. } => {
+                            add_to_names(&mut names, elts);
+                            break;
+                        }
+                        _ => break,
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+
+    names
+}

src/ast_visitor.rs

@@ -4,14 +4,14 @@ use rustpython_parser::ast::{
     PatternKind, Stmt, StmtKind, Unaryop, Withitem,
 };
 
-pub trait Visitor {
+pub trait ASTVisitor {
     fn visit_stmt(&mut self, stmt: &Stmt) {
         walk_stmt(self, stmt);
     }
     fn visit_annotation(&mut self, expr: &Expr) {
         walk_expr(self, expr);
     }
-    fn visit_expr(&mut self, expr: &Expr) {
+    fn visit_expr(&mut self, expr: &Expr, _parent: Option<&Stmt>) {
         walk_expr(self, expr);
     }
     fn visit_constant(&mut self, constant: &Constant) {
@@ -61,84 +61,45 @@ pub trait Visitor {
     }
 }
 
-pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
+pub fn walk_stmt<V: ASTVisitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
     match &stmt.node {
-        StmtKind::FunctionDef {
-            args,
-            body,
-            decorator_list,
-            returns,
-            ..
-        } => {
+        StmtKind::FunctionDef { args, body, .. } => {
             visitor.visit_arguments(args);
-            for expr in decorator_list {
-                visitor.visit_expr(expr)
-            }
-            for expr in returns {
-                visitor.visit_annotation(expr);
-            }
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
         }
-        StmtKind::AsyncFunctionDef {
-            args,
-            body,
-            decorator_list,
-            returns,
-            ..
-        } => {
+        StmtKind::AsyncFunctionDef { args, body, .. } => {
             visitor.visit_arguments(args);
-            for expr in decorator_list {
-                visitor.visit_expr(expr)
-            }
-            for expr in returns {
-                visitor.visit_annotation(expr);
-            }
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
         }
-        StmtKind::ClassDef {
-            bases,
-            keywords,
-            body,
-            decorator_list,
-            ..
-        } => {
-            for expr in bases {
-                visitor.visit_expr(expr)
-            }
-            for keyword in keywords {
-                visitor.visit_keyword(keyword)
-            }
+        StmtKind::ClassDef { body, .. } => {
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
-            for expr in decorator_list {
-                visitor.visit_expr(expr)
-            }
         }
         StmtKind::Return { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             }
         }
         StmtKind::Delete { targets } => {
             for expr in targets {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             }
         }
         StmtKind::Assign { targets, value, .. } => {
             for expr in targets {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             }
-            visitor.visit_expr(value)
+            visitor.visit_expr(value, Some(stmt))
         }
         StmtKind::AugAssign { target, op, value } => {
-            visitor.visit_expr(target);
+            visitor.visit_expr(target, Some(stmt));
             visitor.visit_operator(op);
-            visitor.visit_expr(value);
+            visitor.visit_expr(value, Some(stmt));
         }
         StmtKind::AnnAssign {
             target,
@@ -146,10 +107,10 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             value,
             ..
         } => {
-            visitor.visit_expr(target);
+            visitor.visit_expr(target, Some(stmt));
             visitor.visit_annotation(annotation);
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             }
         }
         StmtKind::For {
@@ -159,8 +120,8 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             orelse,
             ..
         } => {
-            visitor.visit_expr(target);
-            visitor.visit_expr(iter);
+            visitor.visit_expr(target, Some(stmt));
+            visitor.visit_expr(iter, Some(stmt));
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
@@ -175,8 +136,8 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             orelse,
             ..
         } => {
-            visitor.visit_expr(target);
-            visitor.visit_expr(iter);
+            visitor.visit_expr(target, Some(stmt));
+            visitor.visit_expr(iter, Some(stmt));
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
@@ -185,7 +146,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             }
         }
         StmtKind::While { test, body, orelse } => {
-            visitor.visit_expr(test);
+            visitor.visit_expr(test, Some(stmt));
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
@@ -194,7 +155,7 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             }
         }
         StmtKind::If { test, body, orelse } => {
-            visitor.visit_expr(test);
+            visitor.visit_expr(test, Some(stmt));
             for stmt in body {
                 visitor.visit_stmt(stmt)
             }
@@ -220,17 +181,17 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         }
         StmtKind::Match { subject, cases } => {
             // TODO(charlie): Handle `cases`.
-            visitor.visit_expr(subject);
+            visitor.visit_expr(subject, Some(stmt));
             for match_case in cases {
                 visitor.visit_match_case(match_case);
             }
         }
         StmtKind::Raise { exc, cause } => {
             if let Some(expr) = exc {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             };
             if let Some(expr) = cause {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             };
         }
         StmtKind::Try {
@@ -253,9 +214,9 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
             }
         }
         StmtKind::Assert { test, msg } => {
-            visitor.visit_expr(test);
+            visitor.visit_expr(test, None);
             if let Some(expr) = msg {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, Some(stmt))
             }
         }
         StmtKind::Import { names } => {
@@ -270,67 +231,67 @@ pub fn walk_stmt<V: Visitor + ?Sized>(visitor: &mut V, stmt: &Stmt) {
         }
         StmtKind::Global { .. } => {}
         StmtKind::Nonlocal { .. } => {}
-        StmtKind::Expr { value } => visitor.visit_expr(value),
+        StmtKind::Expr { value } => visitor.visit_expr(value, Some(stmt)),
         StmtKind::Pass => {}
         StmtKind::Break => {}
         StmtKind::Continue => {}
     }
 }
 
-pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
+pub fn walk_expr<V: ASTVisitor + ?Sized>(visitor: &mut V, expr: &Expr) {
     match &expr.node {
         ExprKind::BoolOp { op, values } => {
             visitor.visit_boolop(op);
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
         ExprKind::NamedExpr { target, value } => {
-            visitor.visit_expr(target);
-            visitor.visit_expr(value);
+            visitor.visit_expr(target, None);
+            visitor.visit_expr(value, None);
         }
         ExprKind::BinOp { left, op, right } => {
-            visitor.visit_expr(left);
+            visitor.visit_expr(left, None);
             visitor.visit_operator(op);
-            visitor.visit_expr(right);
+            visitor.visit_expr(right, None);
         }
         ExprKind::UnaryOp { op, operand } => {
             visitor.visit_unaryop(op);
-            visitor.visit_expr(operand);
+            visitor.visit_expr(operand, None);
         }
         ExprKind::Lambda { args, body } => {
             visitor.visit_arguments(args);
-            visitor.visit_expr(body);
+            visitor.visit_expr(body, None);
         }
         ExprKind::IfExp { test, body, orelse } => {
-            visitor.visit_expr(test);
-            visitor.visit_expr(body);
-            visitor.visit_expr(orelse);
+            visitor.visit_expr(test, None);
+            visitor.visit_expr(body, None);
+            visitor.visit_expr(orelse, None);
         }
         ExprKind::Dict { keys, values } => {
             for expr in keys {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
         ExprKind::Set { elts } => {
             for expr in elts {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
         ExprKind::ListComp { elt, generators } => {
             for comprehension in generators {
                 visitor.visit_comprehension(comprehension)
             }
-            visitor.visit_expr(elt);
+            visitor.visit_expr(elt, None);
         }
         ExprKind::SetComp { elt, generators } => {
             for comprehension in generators {
                 visitor.visit_comprehension(comprehension)
             }
-            visitor.visit_expr(elt);
+            visitor.visit_expr(elt, None);
         }
         ExprKind::DictComp {
             key,
@@ -340,33 +301,33 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
             for comprehension in generators {
                 visitor.visit_comprehension(comprehension)
             }
-            visitor.visit_expr(key);
-            visitor.visit_expr(value);
+            visitor.visit_expr(key, None);
+            visitor.visit_expr(value, None);
         }
         ExprKind::GeneratorExp { elt, generators } => {
             for comprehension in generators {
                 visitor.visit_comprehension(comprehension)
             }
-            visitor.visit_expr(elt);
+            visitor.visit_expr(elt, None);
         }
-        ExprKind::Await { value } => visitor.visit_expr(value),
+        ExprKind::Await { value } => visitor.visit_expr(value, None),
         ExprKind::Yield { value } => {
             if let Some(expr) = value {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
-        ExprKind::YieldFrom { value } => visitor.visit_expr(value),
+        ExprKind::YieldFrom { value } => visitor.visit_expr(value, None),
         ExprKind::Compare {
             left,
             ops,
             comparators,
         } => {
-            visitor.visit_expr(left);
+            visitor.visit_expr(left, None);
             for cmpop in ops {
                 visitor.visit_cmpop(cmpop);
             }
             for expr in comparators {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
         ExprKind::Call {
@@ -374,9 +335,9 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
             args,
             keywords,
         } => {
-            visitor.visit_expr(func);
+            visitor.visit_expr(func, None);
             for expr in args {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             for keyword in keywords {
                 visitor.visit_keyword(keyword);
@@ -385,28 +346,28 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         ExprKind::FormattedValue {
             value, format_spec, ..
         } => {
-            visitor.visit_expr(value);
+            visitor.visit_expr(value, None);
             if let Some(expr) = format_spec {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
         ExprKind::JoinedStr { values } => {
             for expr in values {
-                visitor.visit_expr(expr)
+                visitor.visit_expr(expr, None)
             }
         }
         ExprKind::Constant { value, .. } => visitor.visit_constant(value),
         ExprKind::Attribute { value, ctx, .. } => {
-            visitor.visit_expr(value);
+            visitor.visit_expr(value, None);
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Subscript { value, slice, ctx } => {
-            visitor.visit_expr(value);
-            visitor.visit_expr(slice);
+            visitor.visit_expr(value, None);
+            visitor.visit_expr(slice, None);
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Starred { value, ctx } => {
-            visitor.visit_expr(value);
+            visitor.visit_expr(value, None);
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Name { ctx, .. } => {
@@ -414,31 +375,31 @@ pub fn walk_expr<V: Visitor + ?Sized>(visitor: &mut V, expr: &Expr) {
         }
         ExprKind::List { elts, ctx } => {
             for expr in elts {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Tuple { elts, ctx } => {
             for expr in elts {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             visitor.visit_expr_context(ctx);
         }
         ExprKind::Slice { lower, upper, step } => {
             if let Some(expr) = lower {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             if let Some(expr) = upper {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             if let Some(expr) = step {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
         }
     }
 }
 
-pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant) {
+pub fn walk_constant<V: ASTVisitor + ?Sized>(visitor: &mut V, constant: &Constant) {
     if let Constant::Tuple(constants) = constant {
         for constant in constants {
             visitor.visit_constant(constant)
@@ -446,19 +407,19 @@ pub fn walk_constant<V: Visitor + ?Sized>(visitor: &mut V, constant: &Constant)
     }
 }
 
-pub fn walk_comprehension<V: Visitor + ?Sized>(visitor: &mut V, comprehension: &Comprehension) {
-    visitor.visit_expr(&comprehension.target);
-    visitor.visit_expr(&comprehension.iter);
+pub fn walk_comprehension<V: ASTVisitor + ?Sized>(visitor: &mut V, comprehension: &Comprehension) {
+    visitor.visit_expr(&comprehension.target, None);
+    visitor.visit_expr(&comprehension.iter, None);
     for expr in &comprehension.ifs {
-        visitor.visit_expr(expr);
+        visitor.visit_expr(expr, None);
     }
 }
 
-pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &Excepthandler) {
+pub fn walk_excepthandler<V: ASTVisitor + ?Sized>(visitor: &mut V, excepthandler: &Excepthandler) {
     match &excepthandler.node {
         ExcepthandlerKind::ExceptHandler { type_, body, .. } => {
             if let Some(expr) = type_ {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             for stmt in body {
                 visitor.visit_stmt(stmt);
@@ -467,7 +428,7 @@ pub fn walk_excepthandler<V: Visitor + ?Sized>(visitor: &mut V, excepthandler: &
     }
 }
 
-pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Arguments) {
+pub fn walk_arguments<V: ASTVisitor + ?Sized>(visitor: &mut V, arguments: &Arguments) {
     for arg in &arguments.posonlyargs {
         visitor.visit_arg(arg);
     }
@@ -481,46 +442,46 @@ pub fn walk_arguments<V: Visitor + ?Sized>(visitor: &mut V, arguments: &Argument
         visitor.visit_arg(arg);
     }
     for expr in &arguments.kw_defaults {
-        visitor.visit_expr(expr)
+        visitor.visit_expr(expr, None)
     }
     if let Some(arg) = &arguments.kwarg {
         visitor.visit_arg(arg)
     }
     for expr in &arguments.defaults {
-        visitor.visit_expr(expr)
+        visitor.visit_expr(expr, None)
     }
 }
 
-pub fn walk_arg<V: Visitor + ?Sized>(visitor: &mut V, arg: &Arg) {
+pub fn walk_arg<V: ASTVisitor + ?Sized>(visitor: &mut V, arg: &Arg) {
     if let Some(expr) = &arg.node.annotation {
         visitor.visit_annotation(expr)
     }
 }
 
-pub fn walk_keyword<V: Visitor + ?Sized>(visitor: &mut V, keyword: &Keyword) {
-    visitor.visit_expr(&keyword.node.value);
+pub fn walk_keyword<V: ASTVisitor + ?Sized>(visitor: &mut V, keyword: &Keyword) {
+    visitor.visit_expr(&keyword.node.value, None);
 }
 
-pub fn walk_withitem<V: Visitor + ?Sized>(visitor: &mut V, withitem: &Withitem) {
-    visitor.visit_expr(&withitem.context_expr);
+pub fn walk_withitem<V: ASTVisitor + ?Sized>(visitor: &mut V, withitem: &Withitem) {
+    visitor.visit_expr(&withitem.context_expr, None);
     if let Some(expr) = &withitem.optional_vars {
-        visitor.visit_expr(expr);
+        visitor.visit_expr(expr, None);
     }
 }
 
-pub fn walk_match_case<V: Visitor + ?Sized>(visitor: &mut V, match_case: &MatchCase) {
+pub fn walk_match_case<V: ASTVisitor + ?Sized>(visitor: &mut V, match_case: &MatchCase) {
     visitor.visit_pattern(&match_case.pattern);
     if let Some(expr) = &match_case.guard {
-        visitor.visit_expr(expr);
+        visitor.visit_expr(expr, None);
     }
     for stmt in &match_case.body {
         visitor.visit_stmt(stmt);
     }
 }
 
-pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
+pub fn walk_pattern<V: ASTVisitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
     match &pattern.node {
-        PatternKind::MatchValue { value } => visitor.visit_expr(value),
+        PatternKind::MatchValue { value } => visitor.visit_expr(value, None),
         PatternKind::MatchSingleton { value } => visitor.visit_constant(value),
         PatternKind::MatchSequence { patterns } => {
             for pattern in patterns {
@@ -529,7 +490,7 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
         }
         PatternKind::MatchMapping { keys, patterns, .. } => {
             for expr in keys {
-                visitor.visit_expr(expr);
+                visitor.visit_expr(expr, None);
             }
             for pattern in patterns {
                 visitor.visit_pattern(pattern);
@@ -541,7 +502,7 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
             kwd_patterns,
             ..
         } => {
-            visitor.visit_expr(cls);
+            visitor.visit_expr(cls, None);
             for pattern in patterns {
                 visitor.visit_pattern(pattern);
             }
@@ -566,24 +527,24 @@ pub fn walk_pattern<V: Visitor + ?Sized>(visitor: &mut V, pattern: &Pattern) {
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_expr_context<V: Visitor + ?Sized>(visitor: &mut V, expr_context: &ExprContext) {}
+pub fn walk_expr_context<V: ASTVisitor + ?Sized>(visitor: &mut V, expr_context: &ExprContext) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_boolop<V: Visitor + ?Sized>(visitor: &mut V, boolop: &Boolop) {}
+pub fn walk_boolop<V: ASTVisitor + ?Sized>(visitor: &mut V, boolop: &Boolop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_operator<V: Visitor + ?Sized>(visitor: &mut V, operator: &Operator) {}
+pub fn walk_operator<V: ASTVisitor + ?Sized>(visitor: &mut V, operator: &Operator) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_unaryop<V: Visitor + ?Sized>(visitor: &mut V, unaryop: &Unaryop) {}
+pub fn walk_unaryop<V: ASTVisitor + ?Sized>(visitor: &mut V, unaryop: &Unaryop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_cmpop<V: Visitor + ?Sized>(visitor: &mut V, cmpop: &Cmpop) {}
+pub fn walk_cmpop<V: ASTVisitor + ?Sized>(visitor: &mut V, cmpop: &Cmpop) {}
 
 #[allow(unused_variables)]
 #[inline(always)]
-pub fn walk_alias<V: Visitor + ?Sized>(visitor: &mut V, alias: &Alias) {}
+pub fn walk_alias<V: ASTVisitor + ?Sized>(visitor: &mut V, alias: &Alias) {}

src/check_ast.rs

@@ -1,66 +1,17 @@
-use std::collections::{BTreeMap, BTreeSet};
-use std::sync::atomic::{AtomicUsize, Ordering};
+use std::collections::BTreeSet;
 
 use rustpython_parser::ast::{
-    Arg, Arguments, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind,
-    Location, Stmt, StmtKind, Suite,
+    Arg, Arguments, Constant, Excepthandler, ExcepthandlerKind, Expr, ExprContext, ExprKind, Stmt,
+    StmtKind, Suite,
 };
 use rustpython_parser::parser;
 
+use crate::ast_ops::{extract_all_names, Binding, BindingKind, Scope, ScopeKind};
+use crate::ast_visitor;
+use crate::ast_visitor::{walk_excepthandler, ASTVisitor};
 use crate::builtins::{BUILTINS, MAGIC_GLOBALS};
-use crate::check_ast::ScopeKind::{Class, Function, Generator, Module};
 use crate::checks::{Check, CheckCode, CheckKind};
 use crate::settings::Settings;
-use crate::visitor;
-use crate::visitor::{walk_excepthandler, Visitor};
-
-fn id() -> usize {
-    static COUNTER: AtomicUsize = AtomicUsize::new(1);
-    COUNTER.fetch_add(1, Ordering::Relaxed)
-}
-
-enum ScopeKind {
-    Class,
-    Function,
-    Generator,
-    Module,
-}
-
-struct Scope {
-    id: usize,
-    kind: ScopeKind,
-    values: BTreeMap<String, Binding>,
-}
-
-impl Scope {
-    fn new(kind: ScopeKind) -> Self {
-        Scope {
-            id: id(),
-            kind,
-            values: BTreeMap::new(),
-        }
-    }
-}
-
-#[derive(Clone)]
-enum BindingKind {
-    Argument,
-    Assignment,
-    Definition,
-    ClassDefinition,
-    Builtin,
-    FutureImportation,
-    Importation(String),
-    StarImportation,
-    SubmoduleImportation(String),
-}
-
-#[derive(Clone)]
-struct Binding {
-    kind: BindingKind,
-    location: Location,
-    used: Option<usize>,
-}
 
 struct Checker<'a> {
     settings: &'a Settings,
@@ -86,7 +37,7 @@ impl Checker<'_> {
     }
 }
 
-impl Visitor for Checker<'_> {
+impl ASTVisitor for Checker<'_> {
     fn visit_stmt(&mut self, stmt: &Stmt) {
         match &stmt.node {
             StmtKind::Global { names } | StmtKind::Nonlocal { names } => {
@@ -109,18 +60,24 @@ impl Visitor for Checker<'_> {
                     }
                 }
             }
-            StmtKind::FunctionDef { name, .. } => {
-                self.add_binding(
-                    name.to_string(),
-                    Binding {
-                        kind: BindingKind::Definition,
-                        used: None,
-                        location: stmt.location,
-                    },
-                );
-                self.push_scope(Scope::new(Function));
+            StmtKind::FunctionDef {
+                name,
+                decorator_list,
+                returns,
+                ..
             }
-            StmtKind::AsyncFunctionDef { name, .. } => {
+            | StmtKind::AsyncFunctionDef {
+                name,
+                decorator_list,
+                returns,
+                ..
+            } => {
+                for expr in decorator_list {
+                    self.visit_expr(expr, Some(stmt));
+                }
+                for expr in returns {
+                    self.visit_annotation(expr);
+                }
                 self.add_binding(
                     name.to_string(),
                     Binding {
@@ -129,7 +86,7 @@ impl Visitor for Checker<'_> {
                         location: stmt.location,
                     },
                 );
-                self.push_scope(Scope::new(Function));
+                self.push_scope(Scope::new(ScopeKind::Function));
             }
             StmtKind::Return { .. } => {
                 if self
@@ -139,7 +96,7 @@ impl Visitor for Checker<'_> {
                 {
                     if let Some(scope) = self.scopes.last() {
                         match scope.kind {
-                            Class | Module => {
+                            ScopeKind::Class | ScopeKind::Module => {
                                 self.checks.push(Check {
                                     kind: CheckKind::ReturnOutsideFunction,
                                     location: stmt.location,
@@ -150,7 +107,23 @@ impl Visitor for Checker<'_> {
                     }
                 }
             }
-            StmtKind::ClassDef { .. } => self.push_scope(Scope::new(Class)),
+            StmtKind::ClassDef {
+                bases,
+                keywords,
+                decorator_list,
+                ..
+            } => {
+                for expr in bases {
+                    self.visit_expr(expr, Some(stmt))
+                }
+                for keyword in keywords {
+                    self.visit_keyword(keyword)
+                }
+                for expr in decorator_list {
+                    self.visit_expr(expr, Some(stmt))
+                }
+                self.push_scope(Scope::new(ScopeKind::Class))
+            }
             StmtKind::Import { names } => {
                 for alias in names {
                     if alias.node.name.contains('.') && alias.node.asname.is_none() {
@@ -195,12 +168,11 @@ impl Visitor for Checker<'_> {
                         .asname
                         .clone()
                         .unwrap_or_else(|| alias.node.name.clone());
-                    if let Some("future") = module.as_deref() {
+                    if let Some("__future__") = module.as_deref() {
                         self.add_binding(
                             name,
                             Binding {
                                 kind: BindingKind::FutureImportation,
-
                                 used: Some(self.scopes.last().expect("No current scope found.").id),
                                 location: stmt.location,
                             },
@@ -210,7 +182,6 @@ impl Visitor for Checker<'_> {
                             name,
                             Binding {
                                 kind: BindingKind::StarImportation,
-
                                 used: None,
                                 location: stmt.location,
                             },
@@ -284,7 +255,7 @@ impl Visitor for Checker<'_> {
             _ => {}
         }
 
-        visitor::walk_stmt(self, stmt);
+        ast_visitor::walk_stmt(self, stmt);
 
         match &stmt.node {
             StmtKind::ClassDef { .. } => {
@@ -332,23 +303,23 @@ impl Visitor for Checker<'_> {
     fn visit_annotation(&mut self, expr: &Expr) {
         let initial = self.in_annotation;
         self.in_annotation = true;
-        self.visit_expr(expr);
+        self.visit_expr(expr, None);
         self.in_annotation = initial;
     }
 
-    fn visit_expr(&mut self, expr: &Expr) {
+    fn visit_expr(&mut self, expr: &Expr, parent: Option<&Stmt>) {
         let initial = self.in_f_string;
         match &expr.node {
             ExprKind::Name { ctx, .. } => match ctx {
                 ExprContext::Load => self.handle_node_load(expr),
-                ExprContext::Store => self.handle_node_store(expr),
+                ExprContext::Store => self.handle_node_store(expr, parent),
                 ExprContext::Del => self.handle_node_delete(expr),
             },
             ExprKind::GeneratorExp { .. }
             | ExprKind::ListComp { .. }
             | ExprKind::DictComp { .. }
-            | ExprKind::SetComp { .. } => self.push_scope(Scope::new(Generator)),
-            ExprKind::Lambda { .. } => self.push_scope(Scope::new(Function)),
+            | ExprKind::SetComp { .. } => self.push_scope(Scope::new(ScopeKind::Generator)),
+            ExprKind::Lambda { .. } => self.push_scope(Scope::new(ScopeKind::Function)),
             ExprKind::Yield { .. } | ExprKind::YieldFrom { .. } => {
                 let scope = self.scopes.last().expect("No current scope found.");
                 if self
@@ -388,7 +359,7 @@ impl Visitor for Checker<'_> {
             _ => {}
         };
 
-        visitor::walk_expr(self, expr);
+        ast_visitor::walk_expr(self, expr);
 
         match &expr.node {
             ExprKind::GeneratorExp { .. }
@@ -413,24 +384,30 @@ impl Visitor for Checker<'_> {
                 Some(name) => {
                     let scope = self.scopes.last().expect("No current scope found.");
                     if scope.values.contains_key(name) {
-                        self.handle_node_store(&Expr::new(
+                        self.handle_node_store(
+                            &Expr::new(
+                                excepthandler.location,
+                                ExprKind::Name {
+                                    id: name.to_string(),
+                                    ctx: ExprContext::Store,
+                                },
+                            ),
+                            None,
+                        );
+                    }
+
+                    let scope = self.scopes.last().expect("No current scope found.");
+                    let prev_definition = scope.values.get(name).cloned();
+                    self.handle_node_store(
+                        &Expr::new(
                             excepthandler.location,
                             ExprKind::Name {
                                 id: name.to_string(),
                                 ctx: ExprContext::Store,
                             },
-                        ));
-                    }
-
-                    let scope = self.scopes.last().expect("No current scope found.");
-                    let prev_definition = scope.values.get(name).cloned();
-                    self.handle_node_store(&Expr::new(
-                        excepthandler.location,
-                        ExprKind::Name {
-                            id: name.to_string(),
-                            ctx: ExprContext::Store,
-                        },
-                    ));
+                        ),
+                        None,
+                    );
 
                     walk_excepthandler(self, excepthandler);
 
@@ -489,7 +466,7 @@ impl Visitor for Checker<'_> {
             }
         }
 
-        visitor::walk_arguments(self, arguments);
+        ast_visitor::walk_arguments(self, arguments);
     }
 
     fn visit_arg(&mut self, arg: &Arg) {
@@ -501,7 +478,7 @@ impl Visitor for Checker<'_> {
                 location: arg.location,
             },
         );
-        visitor::walk_arg(self, arg);
+        ast_visitor::walk_arg(self, arg);
     }
 }
 
@@ -559,7 +536,7 @@ impl Checker<'_> {
             let mut first_iter = true;
             let mut in_generators = false;
             for scope in self.scopes.iter_mut().rev() {
-                if matches!(scope.kind, Class) {
+                if matches!(scope.kind, ScopeKind::Class) {
                     if id == "__class__" {
                         return;
                     } else if !first_iter && !in_generators {
@@ -572,7 +549,7 @@ impl Checker<'_> {
                 }
 
                 first_iter = false;
-                in_generators = matches!(scope.kind, Generator);
+                in_generators = matches!(scope.kind, ScopeKind::Generator);
             }
 
             if self.settings.select.contains(&CheckCode::F821) {
@@ -584,26 +561,29 @@ impl Checker<'_> {
         }
     }
 
-    fn handle_node_store(&mut self, expr: &Expr) {
+    fn handle_node_store(&mut self, expr: &Expr, parent: Option<&Stmt>) {
         if let ExprKind::Name { id, .. } = &expr.node {
-            if self.settings.select.contains(&CheckCode::F832) {
-                let current = self.scopes.last().expect("No current scope found.");
-                if matches!(current.kind, ScopeKind::Function) && !current.values.contains_key(id) {
-                    for scope in self.scopes.iter().rev().skip(1) {
-                        if matches!(scope.kind, ScopeKind::Function) || matches!(scope.kind, Module)
-                        {
-                            let used = scope
-                                .values
-                                .get(id)
-                                .map(|binding| binding.used)
-                                .unwrap_or_default();
-                            if let Some(scope_id) = used {
-                                if scope_id == current.id {
-                                    self.checks.push(Check {
-                                        kind: CheckKind::UndefinedLocal(id.clone()),
-                                        location: expr.location,
-                                    });
-                                }
+            let current = self.scopes.last().expect("No current scope found.");
+
+            if self.settings.select.contains(&CheckCode::F823)
+                && matches!(current.kind, ScopeKind::Function)
+                && !current.values.contains_key(id)
+            {
+                for scope in self.scopes.iter().rev().skip(1) {
+                    if matches!(scope.kind, ScopeKind::Function)
+                        || matches!(scope.kind, ScopeKind::Module)
+                    {
+                        let used = scope
+                            .values
+                            .get(id)
+                            .map(|binding| binding.used)
+                            .unwrap_or_default();
+                        if let Some(scope_id) = used {
+                            if scope_id == current.id {
+                                self.checks.push(Check {
+                                    kind: CheckKind::UndefinedLocal(id.clone()),
+                                    location: expr.location,
+                                });
                             }
                         }
                     }
@@ -611,14 +591,36 @@ impl Checker<'_> {
             }
 
             // TODO(charlie): Handle alternate binding types (like `Annotation`).
-            self.add_binding(
-                id.to_string(),
-                Binding {
-                    kind: BindingKind::Assignment,
-                    used: None,
-                    location: expr.location,
-                },
-            );
+            if id == "__all__"
+                && matches!(current.kind, ScopeKind::Module)
+                && match parent {
+                    None => false,
+                    Some(stmt) => {
+                        matches!(stmt.node, StmtKind::Assign { .. })
+                            || matches!(stmt.node, StmtKind::AugAssign { .. })
+                            || matches!(stmt.node, StmtKind::AnnAssign { .. })
+                    }
+                }
+            {
+                // Really need parent here.
+                self.add_binding(
+                    id.to_string(),
+                    Binding {
+                        kind: BindingKind::Export(extract_all_names(parent.unwrap(), current)),
+                        used: None,
+                        location: expr.location,
+                    },
+                );
+            } else {
+                self.add_binding(
+                    id.to_string(),
+                    Binding {
+                        kind: BindingKind::Assignment,
+                        used: None,
+                        location: expr.location,
+                    },
+                );
+            }
         }
     }
 
@@ -639,17 +641,29 @@ impl Checker<'_> {
     fn check_deferred(&mut self, path: &str) {
         for value in self.deferred.clone() {
             if let Ok(expr) = &parser::parse_expression(&value, path) {
-                self.visit_expr(expr);
+                self.visit_expr(expr, None);
             }
         }
     }
 
     fn check_dead_scopes(&mut self) {
         if self.settings.select.contains(&CheckCode::F401) {
-            // TODO(charlie): Handle `__all__`.
             for scope in &self.dead_scopes {
-                for (_, binding) in scope.values.iter().rev() {
-                    if binding.used.is_none() {
+                let all_binding = match scope.values.get("__all__") {
+                    Some(binding) => match &binding.kind {
+                        BindingKind::Export(names) => Some(names),
+                        _ => None,
+                    },
+                    _ => None,
+                };
+
+                for (name, binding) in scope.values.iter().rev() {
+                    let used = binding.used.is_some()
+                        || all_binding
+                            .map(|names| names.contains(name))
+                            .unwrap_or_default();
+
+                    if !used {
                         match &binding.kind {
                             BindingKind::Importation(full_name)
                             | BindingKind::SubmoduleImportation(full_name) => {
@@ -669,7 +683,7 @@ impl Checker<'_> {
 
 pub fn check_ast(python_ast: &Suite, settings: &Settings, path: &str) -> Vec<Check> {
     let mut checker = Checker::new(settings);
-    checker.push_scope(Scope::new(Module));
+    checker.push_scope(Scope::new(ScopeKind::Module));
     checker.bind_builtins();
 
     for stmt in python_ast {

src/check_cst.rs

@@ -0,0 +1,164 @@
+use std::borrow::Borrow;
+use std::collections::BTreeMap;
+use std::sync::Arc;
+
+use bat::PrettyPrinter;
+use bumpalo::Bump;
+use libcst_native::{
+    Arg, ClassDef, Codegen, Expression, FormattedStringContent, If, Module, SimpleString,
+};
+use rustpython_parser::ast::Location;
+
+use crate::checks::{Check, CheckKind};
+use crate::cst_visitor;
+use crate::cst_visitor::CSTVisitor;
+use crate::settings::Settings;
+
+enum ScopeKind {
+    Class,
+    Function,
+    Generator,
+    Module,
+}
+
+struct Scope {
+    kind: ScopeKind,
+    values: BTreeMap<String, Binding>,
+}
+
+enum BindingKind {
+    Argument,
+    Assignment,
+    ClassDefinition,
+    Definition,
+    FutureImportation,
+    Importation,
+    StarImportation,
+    SubmoduleImportation,
+}
+
+struct Binding {
+    kind: BindingKind,
+    name: String,
+    location: Location,
+    used: bool,
+}
+
+struct Checker<'a> {
+    settings: &'a Settings,
+    checks: Vec<Check>,
+    arena: Vec<String>,
+}
+
+impl Checker<'_> {
+    pub fn new(settings: &Settings) -> Checker {
+        Checker {
+            settings,
+            checks: vec![],
+            arena: vec![],
+        }
+    }
+}
+
+const QUOTE: &str = "\"";
+
+impl<'b> CSTVisitor for Checker<'_> {
+    fn visit_Expression<'a>(&mut self, node: &'a Expression<'a>) -> Expression<'a> {
+        match node {
+            Expression::FormattedString(node) => match &node.parts[..] {
+                [node] => match node {
+                    FormattedStringContent::Text(node) => {
+                        self.arena.push(format!("\"{}\"", node.value));
+                        return Expression::SimpleString(Box::new(SimpleString {
+                            value: node.value,
+                            lpar: vec![],
+                            rpar: vec![],
+                        }));
+                    }
+                    _ => {}
+                },
+                _ => {}
+            },
+            _ => {}
+        }
+
+        cst_visitor::walk_Expression(self, node)
+    }
+
+    fn visit_ClassDef<'a>(&mut self, node: &'a ClassDef<'a>) -> ClassDef<'a> {
+        let mut bases: Vec<Arg<'a>> = node
+            .bases
+            .clone()
+            .into_iter()
+            .filter(|node| {
+                if let Expression::Name(node) = &node.value {
+                    node.value != "object"
+                } else {
+                    true
+                }
+            })
+            .collect();
+
+        let mut transformed: ClassDef<'a> = node.clone();
+        if bases.is_empty() {
+            transformed.lpar = None;
+            transformed.rpar = None;
+        } else {
+            let node = bases.last_mut().unwrap();
+            node.comma = None;
+        }
+        transformed.bases = bases;
+        transformed
+    }
+
+    fn visit_If(&mut self, node: &If) {
+        if let Expression::Tuple { .. } = node.test {
+            self.checks.push(Check {
+                kind: CheckKind::IfTuple,
+                location: Default::default(),
+            });
+        }
+        cst_visitor::walk_If(self, node);
+    }
+}
+
+pub fn check_cst<'a>(python_cst: &'a Module<'a>, settings: &Settings) -> Vec<Check> {
+    // // Create a new arena to bump allocate into.
+    // let bump = Bump::new();
+    //
+    // // Allocate values into the arena.
+    // let scooter = bump.alloc(python_cst.clone());
+
+    let mut x = python_cst.clone();
+    let mut s = Default::default();
+    x.codegen(&mut s);
+
+    println!("Starting from source:");
+    println!("```");
+    let source = s.to_string().into_bytes();
+    PrettyPrinter::new()
+        .input_from_bytes(&source)
+        .language("python")
+        .print()
+        .unwrap();
+    println!("```");
+
+    let mut checker = Checker::new(settings);
+    let mut transformed = checker.visit_Module(python_cst);
+
+    let mut state = Default::default();
+    transformed.codegen(&mut state);
+
+    println!("");
+    println!("Generated output:");
+    println!("```");
+    let source = state.to_string().into_bytes();
+    PrettyPrinter::new()
+        .input_from_bytes(&source)
+        .language("python")
+        .print()
+        .unwrap();
+    println!("```");
+
+    checker.checks
+}

src/checks.rs

@@ -1,6 +1,7 @@
 use std::str::FromStr;
 
 use anyhow::Result;
+use once_cell::sync::Lazy;
 use regex::Regex;
 use rustpython_parser::ast::Location;
 use serde::{Deserialize, Serialize};
@@ -15,8 +16,8 @@ pub enum CheckCode {
     F704,
     F706,
     F821,
+    F823,
     F831,
-    F832,
     F841,
     F901,
 }
@@ -34,8 +35,8 @@ impl FromStr for CheckCode {
             "F704" => Ok(CheckCode::F704),
             "F706" => Ok(CheckCode::F706),
             "F821" => Ok(CheckCode::F821),
+            "F823" => Ok(CheckCode::F823),
             "F831" => Ok(CheckCode::F831),
-            "F832" => Ok(CheckCode::F832),
             "F841" => Ok(CheckCode::F841),
             "F901" => Ok(CheckCode::F901),
             _ => Err(anyhow::anyhow!("Unknown check code: {s}")),
@@ -54,8 +55,8 @@ impl CheckCode {
             CheckCode::F704 => "F704",
             CheckCode::F706 => "F706",
             CheckCode::F821 => "F821",
+            CheckCode::F823 => "F823",
             CheckCode::F831 => "F831",
-            CheckCode::F832 => "F832",
             CheckCode::F841 => "F841",
             CheckCode::F901 => "F901",
         }
@@ -72,8 +73,8 @@ impl CheckCode {
             CheckCode::F704 => &LintSource::AST,
             CheckCode::F706 => &LintSource::AST,
             CheckCode::F821 => &LintSource::AST,
+            CheckCode::F823 => &LintSource::AST,
             CheckCode::F831 => &LintSource::AST,
-            CheckCode::F832 => &LintSource::AST,
             CheckCode::F841 => &LintSource::AST,
             CheckCode::F901 => &LintSource::AST,
         }
@@ -94,12 +95,12 @@ pub enum CheckKind {
     ImportStarUsage,
     LineTooLong,
     RaiseNotImplemented,
-    YieldOutsideFunction,
     ReturnOutsideFunction,
-    UndefinedName(String),
     UndefinedLocal(String),
-    UnusedVariable(String),
+    UndefinedName(String),
     UnusedImport(String),
+    UnusedVariable(String),
+    YieldOutsideFunction,
 }
 
 impl CheckKind {
@@ -112,12 +113,12 @@ impl CheckKind {
             CheckKind::ImportStarUsage => &CheckCode::F403,
             CheckKind::LineTooLong => &CheckCode::E501,
             CheckKind::RaiseNotImplemented => &CheckCode::F901,
-            CheckKind::YieldOutsideFunction => &CheckCode::F704,
             CheckKind::ReturnOutsideFunction => &CheckCode::F706,
+            CheckKind::UndefinedLocal(_) => &CheckCode::F823,
             CheckKind::UndefinedName(_) => &CheckCode::F821,
-            CheckKind::UndefinedLocal(_) => &CheckCode::F832,
-            CheckKind::UnusedVariable(_) => &CheckCode::F841,
             CheckKind::UnusedImport(_) => &CheckCode::F401,
+            CheckKind::UnusedVariable(_) => &CheckCode::F841,
+            CheckKind::YieldOutsideFunction => &CheckCode::F704,
         }
     }
 
@@ -136,22 +137,22 @@ impl CheckKind {
             CheckKind::RaiseNotImplemented => {
                 "'raise NotImplemented' should be 'raise NotImplementedError".to_string()
             }
-            CheckKind::YieldOutsideFunction => {
-                "a `yield` or `yield from` statement outside of a function/method".to_string()
-            }
             CheckKind::ReturnOutsideFunction => {
                 "a `return` statement outside of a function/method".to_string()
             }
             CheckKind::UndefinedName(name) => {
                 format!("Undefined name `{name}`")
             }
-            CheckKind::UnusedVariable(name) => {
-                format!("Local variable `{name}` is assigned to but never used")
-            }
             CheckKind::UndefinedLocal(name) => {
                 format!("Local variable `{name}` referenced before assignment")
             }
             CheckKind::UnusedImport(name) => format!("`{name}` imported but unused"),
+            CheckKind::UnusedVariable(name) => {
+                format!("Local variable `{name}` is assigned to but never used")
+            }
+            CheckKind::YieldOutsideFunction => {
+                "a `yield` or `yield from` statement outside of a function/method".to_string()
+            }
         }
     }
 }
@@ -162,14 +163,17 @@ pub struct Check {
     pub location: Location,
 }
 
+static NO_QA_REGEX: Lazy<Regex> = Lazy::new(|| {
+    Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").expect("Invalid regex")
+});
+static SPLIT_COMMA_REGEX: Lazy<Regex> = Lazy::new(|| Regex::new(r"[,\s]").expect("Invalid regex"));
+
 impl Check {
     pub fn is_inline_ignored(&self, line: &str) -> bool {
-        let re = Regex::new(r"(?i)# noqa(?::\s?(?P<codes>([A-Z]+[0-9]+(?:[,\s]+)?)+))?").unwrap();
-        match re.captures(line) {
+        match NO_QA_REGEX.captures(line) {
             Some(caps) => match caps.name("codes") {
                 Some(codes) => {
-                    let re = Regex::new(r"[,\s]").unwrap();
-                    for code in re
+                    for code in SPLIT_COMMA_REGEX
                         .split(codes.as_str())
                         .map(|code| code.trim())
                         .filter(|code| !code.is_empty())

src/lib.rs

@@ -1,12 +1,15 @@
+mod ast_ops;
+mod ast_visitor;
 mod builtins;
 mod cache;
 pub mod check_ast;
+mod check_cst;
 mod check_lines;
 pub mod checks;
+mod cst_visitor;
 pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
 mod pyproject;
 pub mod settings;
-mod visitor;

src/linter.rs

@@ -2,21 +2,19 @@ use std::path::Path;
 
 use anyhow::Result;
 use log::debug;
-use rustpython_parser::parser;
 
-use crate::check_ast::check_ast;
-use crate::check_lines::check_lines;
-use crate::checks::{Check, LintSource};
+use crate::check_cst::check_cst;
+use crate::checks::Check;
 use crate::message::Message;
 use crate::settings::Settings;
 use crate::{cache, fs};
 
 pub fn check_path(path: &Path, settings: &Settings, mode: &cache::Mode) -> Result<Vec<Message>> {
-    // Check the cache.
-    if let Some(messages) = cache::get(path, settings, mode) {
-        debug!("Cache hit for: {}", path.to_string_lossy());
-        return Ok(messages);
-    }
+    // // Check the cache.
+    // if let Some(messages) = cache::get(path, settings, mode) {
+    //     debug!("Cache hit for: {}", path.to_string_lossy());
+    //     return Ok(messages);
+    // }
 
     // Read the file from disk.
     let contents = fs::read_file(path)?;
@@ -24,32 +22,44 @@ pub fn check_path(path: &Path, settings: &Settings, mode: &cache::Mode) -> Resul
     // Aggregate all checks.
     let mut checks: Vec<Check> = vec![];
 
-    // Run the AST-based checks.
-    if settings
-        .select
-        .iter()
-        .any(|check_code| matches!(check_code.lint_source(), LintSource::AST))
-    {
-        let path = path.to_string_lossy();
-        let python_ast = parser::parse_program(&contents, &path)?;
-        checks.extend(check_ast(&python_ast, settings, &path));
-    }
+    // Run the CST-based checks.
+    let _ = match libcst_native::parse_module(&contents, None) {
+        Ok(m) => m,
+        Err(e) => {
+            return Err(anyhow::anyhow!("Failed to parse"));
+        }
+    };
 
-    // Run the lines-based checks.
-    check_lines(&mut checks, &contents, settings);
+    Ok(vec![])
+    // checks.extend(check_cst(&python_cst, settings));
 
-    // Convert to messages.
-    let messages: Vec<Message> = checks
-        .into_iter()
-        .map(|check| Message {
-            kind: check.kind,
-            location: check.location,
-            filename: path.to_string_lossy().to_string(),
-        })
-        .collect();
-    cache::set(path, settings, &messages, mode);
-
-    Ok(messages)
+    // // Run the AST-based checks.
+    // if settings
+    //     .select
+    //     .iter()
+    //     .any(|check_code| matches!(check_code.lint_source(), LintSource::AST))
+    // {
+    //     let path = path.to_string_lossy();
+    //     let python_ast = parser::parse_program(&contents, &path)?;
+    //     checks.extend(check_ast(&python_ast, settings, &path));
+    // }
+    //
+    // // Run the lines-based checks.
+    // check_lines(&mut checks, &contents, settings);
+    //
+    // // Convert to messages.
+    // let messages: Vec<Message> = checks
+    //     .into_iter()
+    //     .map(|check| Message {
+    //         kind: check.kind,
+    //         location: check.location,
+    //         filename: path.to_string_lossy().to_string(),
+    //     })
+    //     .collect();
+    //
+    // cache::set(path, settings, &messages, mode);
+    //
+    // Ok(messages)
 }
 
 #[cfg(test)]
@@ -103,17 +113,17 @@ mod tests {
         let expected = vec![
             Message {
                 kind: CheckKind::UnusedImport("logging.handlers".to_string()),
-                location: Location::new(11, 1),
+                location: Location::new(12, 1),
                 filename: "./resources/test/src/F401.py".to_string(),
             },
             Message {
                 kind: CheckKind::UnusedImport("functools".to_string()),
-                location: Location::new(2, 1),
+                location: Location::new(3, 1),
                 filename: "./resources/test/src/F401.py".to_string(),
             },
             Message {
                 kind: CheckKind::UnusedImport("collections.OrderedDict".to_string()),
-                location: Location::new(3, 1),
+                location: Location::new(4, 1),
                 filename: "./resources/test/src/F401.py".to_string(),
             },
         ];
@@ -367,20 +377,20 @@ mod tests {
     }
 
     #[test]
-    fn f832() -> Result<()> {
+    fn f823() -> Result<()> {
         let actual = check_path(
-            &Path::new("./resources/test/src/F832.py"),
+            &Path::new("./resources/test/src/F823.py"),
             &settings::Settings {
                 line_length: 88,
                 exclude: vec![],
-                select: BTreeSet::from([CheckCode::F832]),
+                select: BTreeSet::from([CheckCode::F823]),
             },
             &cache::Mode::None,
         )?;
         let expected = vec![Message {
             kind: CheckKind::UndefinedLocal("my_var".to_string()),
             location: Location::new(6, 5),
-            filename: "./resources/test/src/F832.py".to_string(),
+            filename: "./resources/test/src/F823.py".to_string(),
         }];
         assert_eq!(actual.len(), expected.len());
         for i in 0..actual.len() {

src/main.rs

@@ -77,7 +77,7 @@ fn run_once(files: &[PathBuf], settings: &Settings, cache: bool) -> Result<Vec<M
 }
 
 fn report_once(messages: &[Message]) -> Result<()> {
-    println!("Found {} error(s).", messages.len());
+    // println!("Found {} error(s).", messages.len());
 
     if !messages.is_empty() {
         println!();

src/pyproject.rs

@@ -246,8 +246,8 @@ other-attribute = 1
                     CheckCode::F704,
                     CheckCode::F706,
                     CheckCode::F821,
+                    CheckCode::F823,
                     CheckCode::F831,
-                    CheckCode::F832,
                     CheckCode::F841,
                     CheckCode::F901,
                 ])),

src/settings.rs

@@ -51,7 +51,7 @@ impl Settings {
                     CheckCode::F634,
                     CheckCode::F706,
                     CheckCode::F831,
-                    CheckCode::F832,
+                    CheckCode::F823,
                     CheckCode::F901,
                 ])
             }),