clippy_lints/src/utils/author.rs

   1 //! A group of attributes that can be attached to Rust code in order
   2 //! to generate a clippy lint detecting said code automatically.
   3
   4 use crate::utils::get_attr;
   5 use rustc::hir;
   6 use rustc::hir::intravisit::{NestedVisitorMap, Visitor};
   7 use rustc::hir::{BindingAnnotation, Expr, ExprKind, Pat, PatKind, QPath, Stmt, StmtKind, TyKind};
   8 use rustc::lint::{LateContext, LateLintPass, LintArray, LintContext, LintPass};
   9 use rustc::session::Session;
  10 use rustc::{declare_tool_lint, lint_array};
  11 use rustc_data_structures::fx::FxHashMap;
  12 use syntax::ast::{Attribute, LitKind};
  13
  14 declare_clippy_lint! {
  15     /// **What it does:** Generates clippy code that detects the offending pattern
  16     ///
  17     /// **Example:**
  18     /// ```rust
  19     /// // ./tests/ui/my_lint.rs
  20     /// fn foo() {
  21     ///     // detect the following pattern
  22     ///     #[clippy::author]
  23     ///     if x == 42 {
  24     ///         // but ignore everything from here on
  25     ///         #![clippy::author = "ignore"]
  26     ///     }
  27     /// }
  28     /// ```
  29     ///
  30     /// Running `TESTNAME=ui/my_lint cargo uitest` will produce
  31     /// a `./tests/ui/new_lint.stdout` file with the generated code:
  32     ///
  33     /// ```rust
  34     /// // ./tests/ui/new_lint.stdout
  35     /// if_chain! {
  36     ///     if let ExprKind::If(ref cond, ref then, None) = item.node,
  37     ///     if let ExprKind::Binary(BinOp::Eq, ref left, ref right) = cond.node,
  38     ///     if let ExprKind::Path(ref path) = left.node,
  39     ///     if let ExprKind::Lit(ref lit) = right.node,
  40     ///     if let LitKind::Int(42, _) = lit.node,
  41     ///     then {
  42     ///         // report your lint here
  43     ///     }
  44     /// }
  45     /// ```
  46     pub LINT_AUTHOR,
  47     internal_warn,
  48     "helper for writing lints"
  49 }
  50
  51 pub struct Pass;
  52
  53 impl LintPass for Pass {
  54     fn get_lints(&self) -> LintArray {
  55         lint_array!(LINT_AUTHOR)
  56     }
  57
  58     fn name(&self) -> &'static str {
  59         "Author"
  60     }
  61 }
  62
  63 fn prelude() {
  64     println!("if_chain! {{");
  65 }
  66
  67 fn done() {
  68     println!("    then {{");
  69     println!("        // report your lint here");
  70     println!("    }}");
  71     println!("}}");
  72 }
  73
  74 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
  75     fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
  76         if !has_attr(cx.sess(), &item.attrs) {
  77             return;
  78         }
  79         prelude();
  80         PrintVisitor::new("item").visit_item(item);
  81         done();
  82     }
  83
  84     fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
  85         if !has_attr(cx.sess(), &item.attrs) {
  86             return;
  87         }
  88         prelude();
  89         PrintVisitor::new("item").visit_impl_item(item);
  90         done();
  91     }
  92
  93     fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
  94         if !has_attr(cx.sess(), &item.attrs) {
  95             return;
  96         }
  97         prelude();
  98         PrintVisitor::new("item").visit_trait_item(item);
  99         done();
 100     }
 101
 102     fn check_variant(&mut self, cx: &LateContext<'a, 'tcx>, var: &'tcx hir::Variant, generics: &hir::Generics) {
 103         if !has_attr(cx.sess(), &var.node.attrs) {
 104             return;
 105         }
 106         prelude();
 107         PrintVisitor::new("var").visit_variant(var, generics, hir::DUMMY_HIR_ID);
 108         done();
 109     }
 110
 111     fn check_struct_field(&mut self, cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
 112         if !has_attr(cx.sess(), &field.attrs) {
 113             return;
 114         }
 115         prelude();
 116         PrintVisitor::new("field").visit_struct_field(field);
 117         done();
 118     }
 119
 120     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
 121         if !has_attr(cx.sess(), &expr.attrs) {
 122             return;
 123         }
 124         prelude();
 125         PrintVisitor::new("expr").visit_expr(expr);
 126         done();
 127     }
 128
 129     fn check_arm(&mut self, cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm) {
 130         if !has_attr(cx.sess(), &arm.attrs) {
 131             return;
 132         }
 133         prelude();
 134         PrintVisitor::new("arm").visit_arm(arm);
 135         done();
 136     }
 137
 138     fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt) {
 139         if !has_attr(cx.sess(), stmt.node.attrs()) {
 140             return;
 141         }
 142         prelude();
 143         PrintVisitor::new("stmt").visit_stmt(stmt);
 144         done();
 145     }
 146
 147     fn check_foreign_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem) {
 148         if !has_attr(cx.sess(), &item.attrs) {
 149             return;
 150         }
 151         prelude();
 152         PrintVisitor::new("item").visit_foreign_item(item);
 153         done();
 154     }
 155 }
 156
 157 impl PrintVisitor {
 158     fn new(s: &'static str) -> Self {
 159         Self {
 160             ids: FxHashMap::default(),
 161             current: s.to_owned(),
 162         }
 163     }
 164
 165     fn next(&mut self, s: &'static str) -> String {
 166         use std::collections::hash_map::Entry::*;
 167         match self.ids.entry(s) {
 168             // already there: start numbering from `1`
 169             Occupied(mut occ) => {
 170                 let val = occ.get_mut();
 171                 *val += 1;
 172                 format!("{}{}", s, *val)
 173             },
 174             // not there: insert and return name as given
 175             Vacant(vac) => {
 176                 vac.insert(0);
 177                 s.to_owned()
 178             },
 179         }
 180     }
 181
 182     fn print_qpath(&mut self, path: &QPath) {
 183         print!("    if match_qpath({}, &[", self.current);
 184         print_path(path, &mut true);
 185         println!("]);");
 186     }
 187 }
 188
 189 struct PrintVisitor {
 190     /// Fields are the current index that needs to be appended to pattern
 191     /// binding names
 192     ids: FxHashMap<&'static str, usize>,
 193     /// the name that needs to be destructured
 194     current: String,
 195 }
 196
 197 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 198     #[allow(clippy::too_many_lines)]
 199     fn visit_expr(&mut self, expr: &Expr) {
 200         print!("    if let ExprKind::");
 201         let current = format!("{}.node", self.current);
 202         match expr.node {
 203             ExprKind::Box(ref inner) => {
 204                 let inner_pat = self.next("inner");
 205                 println!("Box(ref {}) = {};", inner_pat, current);
 206                 self.current = inner_pat;
 207                 self.visit_expr(inner);
 208             },
 209             ExprKind::Array(ref elements) => {
 210                 let elements_pat = self.next("elements");
 211                 println!("Array(ref {}) = {};", elements_pat, current);
 212                 println!("    if {}.len() == {};", elements_pat, elements.len());
 213                 for (i, element) in elements.iter().enumerate() {
 214                     self.current = format!("{}[{}]", elements_pat, i);
 215                     self.visit_expr(element);
 216                 }
 217             },
 218             ExprKind::Call(ref func, ref args) => {
 219                 let func_pat = self.next("func");
 220                 let args_pat = self.next("args");
 221                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 222                 self.current = func_pat;
 223                 self.visit_expr(func);
 224                 println!("    if {}.len() == {};", args_pat, args.len());
 225                 for (i, arg) in args.iter().enumerate() {
 226                     self.current = format!("{}[{}]", args_pat, i);
 227                     self.visit_expr(arg);
 228                 }
 229             },
 230             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args) => {
 231                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 232                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 233             },
 234             ExprKind::Tup(ref elements) => {
 235                 let elements_pat = self.next("elements");
 236                 println!("Tup(ref {}) = {};", elements_pat, current);
 237                 println!("    if {}.len() == {};", elements_pat, elements.len());
 238                 for (i, element) in elements.iter().enumerate() {
 239                     self.current = format!("{}[{}]", elements_pat, i);
 240                     self.visit_expr(element);
 241                 }
 242             },
 243             ExprKind::Binary(ref op, ref left, ref right) => {
 244                 let op_pat = self.next("op");
 245                 let left_pat = self.next("left");
 246                 let right_pat = self.next("right");
 247                 println!(
 248                     "Binary(ref {}, ref {}, ref {}) = {};",
 249                     op_pat, left_pat, right_pat, current
 250                 );
 251                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 252                 self.current = left_pat;
 253                 self.visit_expr(left);
 254                 self.current = right_pat;
 255                 self.visit_expr(right);
 256             },
 257             ExprKind::Unary(ref op, ref inner) => {
 258                 let inner_pat = self.next("inner");
 259                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 260                 self.current = inner_pat;
 261                 self.visit_expr(inner);
 262             },
 263             ExprKind::Lit(ref lit) => {
 264                 let lit_pat = self.next("lit");
 265                 println!("Lit(ref {}) = {};", lit_pat, current);
 266                 match lit.node {
 267                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 268                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 269                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 270                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 271                     // FIXME: also check int type
 272                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 273                     LitKind::Float(..) => println!("    if let LitKind::Float(..) = {}.node;", lit_pat),
 274                     LitKind::FloatUnsuffixed(_) => {
 275                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 276                     },
 277                     LitKind::ByteStr(ref vec) => {
 278                         let vec_pat = self.next("vec");
 279                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 280                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 281                     },
 282                     LitKind::Str(ref text, _) => {
 283                         let str_pat = self.next("s");
 284                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 285                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 286                     },
 287                 }
 288             },
 289             ExprKind::Cast(ref expr, ref ty) => {
 290                 let cast_pat = self.next("expr");
 291                 let cast_ty = self.next("cast_ty");
 292                 let qp_label = self.next("qp");
 293
 294                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 295                 if let TyKind::Path(ref qp) = ty.node {
 296                     println!("    if let TyKind::Path(ref {}) = {}.node;", qp_label, cast_ty);
 297                     self.current = qp_label;
 298                     self.print_qpath(qp);
 299                 }
 300                 self.current = cast_pat;
 301                 self.visit_expr(expr);
 302             },
 303             ExprKind::Type(ref expr, ref _ty) => {
 304                 let cast_pat = self.next("expr");
 305                 println!("Type(ref {}, _) = {};", cast_pat, current);
 306                 self.current = cast_pat;
 307                 self.visit_expr(expr);
 308             },
 309             ExprKind::If(ref cond, ref then, ref opt_else) => {
 310                 let cond_pat = self.next("cond");
 311                 let then_pat = self.next("then");
 312                 if let Some(ref else_) = *opt_else {
 313                     let else_pat = self.next("else_");
 314                     println!(
 315                         "If(ref {}, ref {}, Some(ref {})) = {};",
 316                         cond_pat, then_pat, else_pat, current
 317                     );
 318                     self.current = else_pat;
 319                     self.visit_expr(else_);
 320                 } else {
 321                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 322                 }
 323                 self.current = cond_pat;
 324                 self.visit_expr(cond);
 325                 self.current = then_pat;
 326                 self.visit_expr(then);
 327             },
 328             ExprKind::While(ref cond, ref body, _) => {
 329                 let cond_pat = self.next("cond");
 330                 let body_pat = self.next("body");
 331                 let label_pat = self.next("label");
 332                 println!(
 333                     "While(ref {}, ref {}, ref {}) = {};",
 334                     cond_pat, body_pat, label_pat, current
 335                 );
 336                 self.current = cond_pat;
 337                 self.visit_expr(cond);
 338                 self.current = body_pat;
 339                 self.visit_block(body);
 340             },
 341             ExprKind::Loop(ref body, _, desugaring) => {
 342                 let body_pat = self.next("body");
 343                 let des = loop_desugaring_name(desugaring);
 344                 let label_pat = self.next("label");
 345                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 346                 self.current = body_pat;
 347                 self.visit_block(body);
 348             },
 349             ExprKind::Match(ref expr, ref arms, desugaring) => {
 350                 let des = desugaring_name(desugaring);
 351                 let expr_pat = self.next("expr");
 352                 let arms_pat = self.next("arms");
 353                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 354                 self.current = expr_pat;
 355                 self.visit_expr(expr);
 356                 println!("    if {}.len() == {};", arms_pat, arms.len());
 357                 for (i, arm) in arms.iter().enumerate() {
 358                     self.current = format!("{}[{}].body", arms_pat, i);
 359                     self.visit_expr(&arm.body);
 360                     if let Some(ref guard) = arm.guard {
 361                         let guard_pat = self.next("guard");
 362                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 363                         match guard {
 364                             hir::Guard::If(ref if_expr) => {
 365                                 let if_expr_pat = self.next("expr");
 366                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 367                                 self.current = if_expr_pat;
 368                                 self.visit_expr(if_expr);
 369                             },
 370                         }
 371                     }
 372                     println!("    if {}[{}].pats.len() == {};", arms_pat, i, arm.pats.len());
 373                     for (j, pat) in arm.pats.iter().enumerate() {
 374                         self.current = format!("{}[{}].pats[{}]", arms_pat, i, j);
 375                         self.visit_pat(pat);
 376                     }
 377                 }
 378             },
 379             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 380                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 381                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 382             },
 383             ExprKind::Yield(ref sub) => {
 384                 let sub_pat = self.next("sub");
 385                 println!("Yield(ref sub) = {};", current);
 386                 self.current = sub_pat;
 387                 self.visit_expr(sub);
 388             },
 389             ExprKind::Block(ref block, _) => {
 390                 let block_pat = self.next("block");
 391                 println!("Block(ref {}) = {};", block_pat, current);
 392                 self.current = block_pat;
 393                 self.visit_block(block);
 394             },
 395             ExprKind::Assign(ref target, ref value) => {
 396                 let target_pat = self.next("target");
 397                 let value_pat = self.next("value");
 398                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 399                 self.current = target_pat;
 400                 self.visit_expr(target);
 401                 self.current = value_pat;
 402                 self.visit_expr(value);
 403             },
 404             ExprKind::AssignOp(ref op, ref target, ref value) => {
 405                 let op_pat = self.next("op");
 406                 let target_pat = self.next("target");
 407                 let value_pat = self.next("value");
 408                 println!(
 409                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 410                     op_pat, target_pat, value_pat, current
 411                 );
 412                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 413                 self.current = target_pat;
 414                 self.visit_expr(target);
 415                 self.current = value_pat;
 416                 self.visit_expr(value);
 417             },
 418             ExprKind::Field(ref object, ref field_ident) => {
 419                 let obj_pat = self.next("object");
 420                 let field_name_pat = self.next("field_name");
 421                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 422                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_ident.as_str());
 423                 self.current = obj_pat;
 424                 self.visit_expr(object);
 425             },
 426             ExprKind::Index(ref object, ref index) => {
 427                 let object_pat = self.next("object");
 428                 let index_pat = self.next("index");
 429                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 430                 self.current = object_pat;
 431                 self.visit_expr(object);
 432                 self.current = index_pat;
 433                 self.visit_expr(index);
 434             },
 435             ExprKind::Path(ref path) => {
 436                 let path_pat = self.next("path");
 437                 println!("Path(ref {}) = {};", path_pat, current);
 438                 self.current = path_pat;
 439                 self.print_qpath(path);
 440             },
 441             ExprKind::AddrOf(mutability, ref inner) => {
 442                 let inner_pat = self.next("inner");
 443                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 444                 self.current = inner_pat;
 445                 self.visit_expr(inner);
 446             },
 447             ExprKind::Break(ref _destination, ref opt_value) => {
 448                 let destination_pat = self.next("destination");
 449                 if let Some(ref value) = *opt_value {
 450                     let value_pat = self.next("value");
 451                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 452                     self.current = value_pat;
 453                     self.visit_expr(value);
 454                 } else {
 455                     println!("Break(ref {}, None) = {};", destination_pat, current);
 456                 }
 457                 // FIXME: implement label printing
 458             },
 459             ExprKind::Continue(ref _destination) => {
 460                 let destination_pat = self.next("destination");
 461                 println!("Again(ref {}) = {};", destination_pat, current);
 462                 // FIXME: implement label printing
 463             },
 464             ExprKind::Ret(ref opt_value) => {
 465                 if let Some(ref value) = *opt_value {
 466                     let value_pat = self.next("value");
 467                     println!("Ret(Some(ref {})) = {};", value_pat, current);
 468                     self.current = value_pat;
 469                     self.visit_expr(value);
 470                 } else {
 471                     println!("Ret(None) = {};", current);
 472                 }
 473             },
 474             ExprKind::InlineAsm(_, ref _input, ref _output) => {
 475                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 476                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 477             },
 478             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 479                 let path_pat = self.next("path");
 480                 let fields_pat = self.next("fields");
 481                 if let Some(ref base) = *opt_base {
 482                     let base_pat = self.next("base");
 483                     println!(
 484                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 485                         path_pat, fields_pat, base_pat, current
 486                     );
 487                     self.current = base_pat;
 488                     self.visit_expr(base);
 489                 } else {
 490                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 491                 }
 492                 self.current = path_pat;
 493                 self.print_qpath(path);
 494                 println!("    if {}.len() == {};", fields_pat, fields.len());
 495                 println!("    // unimplemented: field checks");
 496             },
 497             // FIXME: compute length (needs type info)
 498             ExprKind::Repeat(ref value, _) => {
 499                 let value_pat = self.next("value");
 500                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 501                 println!("// unimplemented: repeat count check");
 502                 self.current = value_pat;
 503                 self.visit_expr(value);
 504             },
 505             ExprKind::Err => {
 506                 println!("Err = {}", current);
 507             },
 508         }
 509     }
 510
 511     #[allow(clippy::too_many_lines)]
 512     fn visit_pat(&mut self, pat: &Pat) {
 513         print!("    if let PatKind::");
 514         let current = format!("{}.node", self.current);
 515         match pat.node {
 516             PatKind::Wild => println!("Wild = {};", current),
 517             PatKind::Binding(anno, .., ident, ref sub) => {
 518                 let anno_pat = match anno {
 519                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 520                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 521                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 522                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 523                 };
 524                 let name_pat = self.next("name");
 525                 if let Some(ref sub) = *sub {
 526                     let sub_pat = self.next("sub");
 527                     println!(
 528                         "Binding({}, _, {}, Some(ref {})) = {};",
 529                         anno_pat, name_pat, sub_pat, current
 530                     );
 531                     self.current = sub_pat;
 532                     self.visit_pat(sub);
 533                 } else {
 534                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 535                 }
 536                 println!("    if {}.node.as_str() == \"{}\";", name_pat, ident.as_str());
 537             },
 538             PatKind::Struct(ref path, ref fields, ignore) => {
 539                 let path_pat = self.next("path");
 540                 let fields_pat = self.next("fields");
 541                 println!(
 542                     "Struct(ref {}, ref {}, {}) = {};",
 543                     path_pat, fields_pat, ignore, current
 544                 );
 545                 self.current = path_pat;
 546                 self.print_qpath(path);
 547                 println!("    if {}.len() == {};", fields_pat, fields.len());
 548                 println!("    // unimplemented: field checks");
 549             },
 550             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 551                 let path_pat = self.next("path");
 552                 let fields_pat = self.next("fields");
 553                 println!(
 554                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 555                     path_pat, fields_pat, skip_pos, current
 556                 );
 557                 self.current = path_pat;
 558                 self.print_qpath(path);
 559                 println!("    if {}.len() == {};", fields_pat, fields.len());
 560                 println!("    // unimplemented: field checks");
 561             },
 562             PatKind::Path(ref path) => {
 563                 let path_pat = self.next("path");
 564                 println!("Path(ref {}) = {};", path_pat, current);
 565                 self.current = path_pat;
 566                 self.print_qpath(path);
 567             },
 568             PatKind::Tuple(ref fields, skip_pos) => {
 569                 let fields_pat = self.next("fields");
 570                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 571                 println!("    if {}.len() == {};", fields_pat, fields.len());
 572                 println!("    // unimplemented: field checks");
 573             },
 574             PatKind::Box(ref pat) => {
 575                 let pat_pat = self.next("pat");
 576                 println!("Box(ref {}) = {};", pat_pat, current);
 577                 self.current = pat_pat;
 578                 self.visit_pat(pat);
 579             },
 580             PatKind::Ref(ref pat, muta) => {
 581                 let pat_pat = self.next("pat");
 582                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 583                 self.current = pat_pat;
 584                 self.visit_pat(pat);
 585             },
 586             PatKind::Lit(ref lit_expr) => {
 587                 let lit_expr_pat = self.next("lit_expr");
 588                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 589                 self.current = lit_expr_pat;
 590                 self.visit_expr(lit_expr);
 591             },
 592             PatKind::Range(ref start, ref end, end_kind) => {
 593                 let start_pat = self.next("start");
 594                 let end_pat = self.next("end");
 595                 println!(
 596                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 597                     start_pat, end_pat, end_kind, current
 598                 );
 599                 self.current = start_pat;
 600                 self.visit_expr(start);
 601                 self.current = end_pat;
 602                 self.visit_expr(end);
 603             },
 604             PatKind::Slice(ref start, ref middle, ref end) => {
 605                 let start_pat = self.next("start");
 606                 let end_pat = self.next("end");
 607                 if let Some(ref middle) = middle {
 608                     let middle_pat = self.next("middle");
 609                     println!(
 610                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 611                         start_pat, middle_pat, end_pat, current
 612                     );
 613                     self.current = middle_pat;
 614                     self.visit_pat(middle);
 615                 } else {
 616                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 617                 }
 618                 println!("    if {}.len() == {};", start_pat, start.len());
 619                 for (i, pat) in start.iter().enumerate() {
 620                     self.current = format!("{}[{}]", start_pat, i);
 621                     self.visit_pat(pat);
 622                 }
 623                 println!("    if {}.len() == {};", end_pat, end.len());
 624                 for (i, pat) in end.iter().enumerate() {
 625                     self.current = format!("{}[{}]", end_pat, i);
 626                     self.visit_pat(pat);
 627                 }
 628             },
 629         }
 630     }
 631
 632     fn visit_stmt(&mut self, s: &Stmt) {
 633         print!("    if let StmtKind::");
 634         let current = format!("{}.node", self.current);
 635         match s.node {
 636             // A local (let) binding:
 637             StmtKind::Local(ref local) => {
 638                 let local_pat = self.next("local");
 639                 println!("Local(ref {}) = {};", local_pat, current);
 640                 if let Some(ref init) = local.init {
 641                     let init_pat = self.next("init");
 642                     println!("    if let Some(ref {}) = {}.init", init_pat, local_pat);
 643                     self.current = init_pat;
 644                     self.visit_expr(init);
 645                 }
 646                 self.current = format!("{}.pat", local_pat);
 647                 self.visit_pat(&local.pat);
 648             },
 649             // An item binding:
 650             StmtKind::Item(_) => {
 651                 println!("Item(item_id) = {};", current);
 652             },
 653
 654             // Expr without trailing semi-colon (must have unit type):
 655             StmtKind::Expr(ref e) => {
 656                 let e_pat = self.next("e");
 657                 println!("Expr(ref {}, _) = {}", e_pat, current);
 658                 self.current = e_pat;
 659                 self.visit_expr(e);
 660             },
 661
 662             // Expr with trailing semi-colon (may have any type):
 663             StmtKind::Semi(ref e) => {
 664                 let e_pat = self.next("e");
 665                 println!("Semi(ref {}, _) = {}", e_pat, current);
 666                 self.current = e_pat;
 667                 self.visit_expr(e);
 668             },
 669         }
 670     }
 671
 672     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 673         NestedVisitorMap::None
 674     }
 675 }
 676
 677 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 678     get_attr(sess, attrs, "author").count() > 0
 679 }
 680
 681 fn desugaring_name(des: hir::MatchSource) -> String {
 682     match des {
 683         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 684         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 685         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 686         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 687         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 688             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 689             contains_else_clause
 690         ),
 691     }
 692 }
 693
 694 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 695     match des {
 696         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 697         hir::LoopSource::Loop => "LoopSource::Loop",
 698         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 699     }
 700 }
 701
 702 fn print_path(path: &QPath, first: &mut bool) {
 703     match *path {
 704         QPath::Resolved(_, ref path) => {
 705             for segment in &path.segments {
 706                 if *first {
 707                     *first = false;
 708                 } else {
 709                     print!(", ");
 710                 }
 711                 print!("{:?}", segment.ident.as_str());
 712             }
 713         },
 714         QPath::TypeRelative(ref ty, ref segment) => match ty.node {
 715             hir::TyKind::Path(ref inner_path) => {
 716                 print_path(inner_path, first);
 717                 if *first {
 718                     *first = false;
 719                 } else {
 720                     print!(", ");
 721                 }
 722                 print!("{:?}", segment.ident.as_str());
 723             },
 724             ref other => print!("/* unimplemented: {:?}*/", other),
 725         },
 726     }
 727 }