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