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