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