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_ast::ast::{Attribute, LitFloatType, LitKind};
   6 use rustc_ast::walk_list;
   7 use rustc_data_structures::fx::FxHashMap;
   8 use rustc_hir as hir;
   9 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
  10 use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, Pat, PatKind, QPath, Stmt, StmtKind, TyKind};
  11 use rustc_lint::{LateContext, LateLintPass, LintContext};
  12 use rustc_middle::hir::map::Map;
  13 use rustc_session::Session;
  14 use rustc_session::{declare_lint_pass, declare_tool_lint};
  15
  16 declare_clippy_lint! {
  17     /// **What it does:** Generates clippy code that detects the offending pattern
  18     ///
  19     /// **Example:**
  20     /// ```rust,ignore
  21     /// // ./tests/ui/my_lint.rs
  22     /// fn foo() {
  23     ///     // detect the following pattern
  24     ///     #[clippy::author]
  25     ///     if x == 42 {
  26     ///         // but ignore everything from here on
  27     ///         #![clippy::author = "ignore"]
  28     ///     }
  29     ///     ()
  30     /// }
  31     /// ```
  32     ///
  33     /// Running `TESTNAME=ui/my_lint cargo uitest` will produce
  34     /// a `./tests/ui/new_lint.stdout` file with the generated code:
  35     ///
  36     /// ```rust,ignore
  37     /// // ./tests/ui/new_lint.stdout
  38     /// if_chain! {
  39     ///     if let ExprKind::If(ref cond, ref then, None) = item.kind,
  40     ///     if let ExprKind::Binary(BinOp::Eq, ref left, ref right) = cond.kind,
  41     ///     if let ExprKind::Path(ref path) = left.kind,
  42     ///     if let ExprKind::Lit(ref lit) = right.kind,
  43     ///     if let LitKind::Int(42, _) = lit.node,
  44     ///     then {
  45     ///         // report your lint here
  46     ///     }
  47     /// }
  48     /// ```
  49     pub LINT_AUTHOR,
  50     internal_warn,
  51     "helper for writing lints"
  52 }
  53
  54 declare_lint_pass!(Author => [LINT_AUTHOR]);
  55
  56 fn prelude() {
  57     println!("if_chain! {{");
  58 }
  59
  60 fn done() {
  61     println!("    then {{");
  62     println!("        // report your lint here");
  63     println!("    }}");
  64     println!("}}");
  65 }
  66
  67 impl<'tcx> LateLintPass<'tcx> for Author {
  68     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
  69         if !has_attr(cx.sess(), &item.attrs) {
  70             return;
  71         }
  72         prelude();
  73         PrintVisitor::new("item").visit_item(item);
  74         done();
  75     }
  76
  77     fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
  78         if !has_attr(cx.sess(), &item.attrs) {
  79             return;
  80         }
  81         prelude();
  82         PrintVisitor::new("item").visit_impl_item(item);
  83         done();
  84     }
  85
  86     fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
  87         if !has_attr(cx.sess(), &item.attrs) {
  88             return;
  89         }
  90         prelude();
  91         PrintVisitor::new("item").visit_trait_item(item);
  92         done();
  93     }
  94
  95     fn check_variant(&mut self, cx: &LateContext<'tcx>, var: &'tcx hir::Variant<'_>) {
  96         if !has_attr(cx.sess(), &var.attrs) {
  97             return;
  98         }
  99         prelude();
 100         let parent_hir_id = cx.tcx.hir().get_parent_node(var.id);
 101         PrintVisitor::new("var").visit_variant(var, &hir::Generics::empty(), parent_hir_id);
 102         done();
 103     }
 104
 105     fn check_struct_field(&mut self, cx: &LateContext<'tcx>, field: &'tcx hir::StructField<'_>) {
 106         if !has_attr(cx.sess(), &field.attrs) {
 107             return;
 108         }
 109         prelude();
 110         PrintVisitor::new("field").visit_struct_field(field);
 111         done();
 112     }
 113
 114     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 115         if !has_attr(cx.sess(), &expr.attrs) {
 116             return;
 117         }
 118         prelude();
 119         PrintVisitor::new("expr").visit_expr(expr);
 120         done();
 121     }
 122
 123     fn check_arm(&mut self, cx: &LateContext<'tcx>, arm: &'tcx hir::Arm<'_>) {
 124         if !has_attr(cx.sess(), &arm.attrs) {
 125             return;
 126         }
 127         prelude();
 128         PrintVisitor::new("arm").visit_arm(arm);
 129         done();
 130     }
 131
 132     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx hir::Stmt<'_>) {
 133         if !has_attr(cx.sess(), stmt.kind.attrs(|id| cx.tcx.hir().item(id.id))) {
 134             return;
 135         }
 136         prelude();
 137         PrintVisitor::new("stmt").visit_stmt(stmt);
 138         done();
 139     }
 140
 141     fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ForeignItem<'_>) {
 142         if !has_attr(cx.sess(), &item.attrs) {
 143             return;
 144         }
 145         prelude();
 146         PrintVisitor::new("item").visit_foreign_item(item);
 147         done();
 148     }
 149 }
 150
 151 impl PrintVisitor {
 152     #[must_use]
 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::{Occupied, Vacant};
 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         if let QPath::LangItem(lang_item, _) = *path {
 179             println!(
 180                 "    if matches!({}, QPath::LangItem(LangItem::{:?}, _));",
 181                 self.current, lang_item,
 182             );
 183         } else {
 184             print!("    if match_qpath({}, &[", self.current);
 185             print_path(path, &mut true);
 186             println!("]);");
 187         }
 188     }
 189 }
 190
 191 struct PrintVisitor {
 192     /// Fields are the current index that needs to be appended to pattern
 193     /// binding names
 194     ids: FxHashMap<&'static str, usize>,
 195     /// the name that needs to be destructured
 196     current: String,
 197 }
 198
 199 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 200     type Map = Map<'tcx>;
 201
 202     #[allow(clippy::too_many_lines)]
 203     fn visit_expr(&mut self, expr: &Expr<'_>) {
 204         print!("    if let ExprKind::");
 205         let current = format!("{}.kind", self.current);
 206         match expr.kind {
 207             ExprKind::Box(ref inner) => {
 208                 let inner_pat = self.next("inner");
 209                 println!("Box(ref {}) = {};", inner_pat, current);
 210                 self.current = inner_pat;
 211                 self.visit_expr(inner);
 212             },
 213             ExprKind::Array(ref elements) => {
 214                 let elements_pat = self.next("elements");
 215                 println!("Array(ref {}) = {};", elements_pat, current);
 216                 println!("    if {}.len() == {};", elements_pat, elements.len());
 217                 for (i, element) in elements.iter().enumerate() {
 218                     self.current = format!("{}[{}]", elements_pat, i);
 219                     self.visit_expr(element);
 220                 }
 221             },
 222             ExprKind::Call(ref func, ref args) => {
 223                 let func_pat = self.next("func");
 224                 let args_pat = self.next("args");
 225                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 226                 self.current = func_pat;
 227                 self.visit_expr(func);
 228                 println!("    if {}.len() == {};", args_pat, args.len());
 229                 for (i, arg) in args.iter().enumerate() {
 230                     self.current = format!("{}[{}]", args_pat, i);
 231                     self.visit_expr(arg);
 232                 }
 233             },
 234             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args, ref _fn_span) => {
 235                 println!(
 236                     "MethodCall(ref method_name, ref generics, ref args, ref fn_span) = {};",
 237                     current
 238                 );
 239                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 240             },
 241             ExprKind::Tup(ref elements) => {
 242                 let elements_pat = self.next("elements");
 243                 println!("Tup(ref {}) = {};", elements_pat, current);
 244                 println!("    if {}.len() == {};", elements_pat, elements.len());
 245                 for (i, element) in elements.iter().enumerate() {
 246                     self.current = format!("{}[{}]", elements_pat, i);
 247                     self.visit_expr(element);
 248                 }
 249             },
 250             ExprKind::Binary(ref op, ref left, ref right) => {
 251                 let op_pat = self.next("op");
 252                 let left_pat = self.next("left");
 253                 let right_pat = self.next("right");
 254                 println!(
 255                     "Binary(ref {}, ref {}, ref {}) = {};",
 256                     op_pat, left_pat, right_pat, current
 257                 );
 258                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 259                 self.current = left_pat;
 260                 self.visit_expr(left);
 261                 self.current = right_pat;
 262                 self.visit_expr(right);
 263             },
 264             ExprKind::Unary(ref op, ref inner) => {
 265                 let inner_pat = self.next("inner");
 266                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 267                 self.current = inner_pat;
 268                 self.visit_expr(inner);
 269             },
 270             ExprKind::Lit(ref lit) => {
 271                 let lit_pat = self.next("lit");
 272                 println!("Lit(ref {}) = {};", lit_pat, current);
 273                 match lit.node {
 274                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 275                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 276                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 277                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 278                     // FIXME: also check int type
 279                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 280                     LitKind::Float(_, LitFloatType::Suffixed(_)) => println!(
 281                         "    if let LitKind::Float(_, LitFloatType::Suffixed(_)) = {}.node;",
 282                         lit_pat
 283                     ),
 284                     LitKind::Float(_, LitFloatType::Unsuffixed) => println!(
 285                         "    if let LitKind::Float(_, LitFloatType::Unsuffixed) = {}.node;",
 286                         lit_pat
 287                     ),
 288                     LitKind::ByteStr(ref vec) => {
 289                         let vec_pat = self.next("vec");
 290                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 291                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 292                     },
 293                     LitKind::Str(ref text, _) => {
 294                         let str_pat = self.next("s");
 295                         println!("    if let LitKind::Str(ref {}, _) = {}.node;", str_pat, lit_pat);
 296                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 297                     },
 298                 }
 299             },
 300             ExprKind::Cast(ref expr, ref ty) => {
 301                 let cast_pat = self.next("expr");
 302                 let cast_ty = self.next("cast_ty");
 303                 let qp_label = self.next("qp");
 304
 305                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 306                 if let TyKind::Path(ref qp) = ty.kind {
 307                     println!("    if let TyKind::Path(ref {}) = {}.kind;", qp_label, cast_ty);
 308                     self.current = qp_label;
 309                     self.print_qpath(qp);
 310                 }
 311                 self.current = cast_pat;
 312                 self.visit_expr(expr);
 313             },
 314             ExprKind::Type(ref expr, ref _ty) => {
 315                 let cast_pat = self.next("expr");
 316                 println!("Type(ref {}, _) = {};", cast_pat, current);
 317                 self.current = cast_pat;
 318                 self.visit_expr(expr);
 319             },
 320             ExprKind::Loop(ref body, _, desugaring, _) => {
 321                 let body_pat = self.next("body");
 322                 let des = loop_desugaring_name(desugaring);
 323                 let label_pat = self.next("label");
 324                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 325                 self.current = body_pat;
 326                 self.visit_block(body);
 327             },
 328             ExprKind::If(ref cond, ref then, ref opt_else) => {
 329                 let cond_pat = self.next("cond");
 330                 let then_pat = self.next("then");
 331                 if let Some(ref else_) = *opt_else {
 332                     let else_pat = self.next("else_");
 333                     println!(
 334                         "If(ref {}, ref {}, Some(ref {})) = {};",
 335                         cond_pat, then_pat, else_pat, current
 336                     );
 337                     self.current = else_pat;
 338                     self.visit_expr(else_);
 339                 } else {
 340                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 341                 }
 342                 self.current = cond_pat;
 343                 self.visit_expr(cond);
 344                 self.current = then_pat;
 345                 self.visit_expr(then);
 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                             hir::Guard::IfLet(ref if_let_pat, ref if_let_expr) => {
 369                                 let if_let_pat_pat = self.next("pat");
 370                                 let if_let_expr_pat = self.next("expr");
 371                                 println!(
 372                                     "    if let Guard::IfLet(ref {}, ref {}) = {};",
 373                                     if_let_pat_pat, if_let_expr_pat, guard_pat
 374                                 );
 375                                 self.current = if_let_expr_pat;
 376                                 self.visit_expr(if_let_expr);
 377                                 self.current = if_let_pat_pat;
 378                                 self.visit_pat(if_let_pat);
 379                             },
 380                         }
 381                     }
 382                     self.current = format!("{}[{}].pat", arms_pat, i);
 383                     self.visit_pat(&arm.pat);
 384                 }
 385             },
 386             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 387                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 388                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 389             },
 390             ExprKind::Yield(ref sub, _) => {
 391                 let sub_pat = self.next("sub");
 392                 println!("Yield(ref sub) = {};", current);
 393                 self.current = sub_pat;
 394                 self.visit_expr(sub);
 395             },
 396             ExprKind::Block(ref block, _) => {
 397                 let block_pat = self.next("block");
 398                 println!("Block(ref {}) = {};", block_pat, current);
 399                 self.current = block_pat;
 400                 self.visit_block(block);
 401             },
 402             ExprKind::Assign(ref target, ref value, _) => {
 403                 let target_pat = self.next("target");
 404                 let value_pat = self.next("value");
 405                 println!(
 406                     "Assign(ref {}, ref {}, ref _span) = {};",
 407                     target_pat, value_pat, current
 408                 );
 409                 self.current = target_pat;
 410                 self.visit_expr(target);
 411                 self.current = value_pat;
 412                 self.visit_expr(value);
 413             },
 414             ExprKind::AssignOp(ref op, ref target, ref value) => {
 415                 let op_pat = self.next("op");
 416                 let target_pat = self.next("target");
 417                 let value_pat = self.next("value");
 418                 println!(
 419                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 420                     op_pat, target_pat, value_pat, current
 421                 );
 422                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 423                 self.current = target_pat;
 424                 self.visit_expr(target);
 425                 self.current = value_pat;
 426                 self.visit_expr(value);
 427             },
 428             ExprKind::Field(ref object, ref field_ident) => {
 429                 let obj_pat = self.next("object");
 430                 let field_name_pat = self.next("field_name");
 431                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 432                 println!("    if {}.as_str() == {:?}", field_name_pat, field_ident.as_str());
 433                 self.current = obj_pat;
 434                 self.visit_expr(object);
 435             },
 436             ExprKind::Index(ref object, ref index) => {
 437                 let object_pat = self.next("object");
 438                 let index_pat = self.next("index");
 439                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 440                 self.current = object_pat;
 441                 self.visit_expr(object);
 442                 self.current = index_pat;
 443                 self.visit_expr(index);
 444             },
 445             ExprKind::Path(ref path) => {
 446                 let path_pat = self.next("path");
 447                 println!("Path(ref {}) = {};", path_pat, current);
 448                 self.current = path_pat;
 449                 self.print_qpath(path);
 450             },
 451             ExprKind::AddrOf(kind, mutability, ref inner) => {
 452                 let inner_pat = self.next("inner");
 453                 println!(
 454                     "AddrOf(BorrowKind::{:?}, Mutability::{:?}, ref {}) = {};",
 455                     kind, mutability, inner_pat, current
 456                 );
 457                 self.current = inner_pat;
 458                 self.visit_expr(inner);
 459             },
 460             ExprKind::Break(ref _destination, ref opt_value) => {
 461                 let destination_pat = self.next("destination");
 462                 if let Some(ref value) = *opt_value {
 463                     let value_pat = self.next("value");
 464                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 465                     self.current = value_pat;
 466                     self.visit_expr(value);
 467                 } else {
 468                     println!("Break(ref {}, None) = {};", destination_pat, current);
 469                 }
 470                 // FIXME: implement label printing
 471             },
 472             ExprKind::Continue(ref _destination) => {
 473                 let destination_pat = self.next("destination");
 474                 println!("Again(ref {}) = {};", destination_pat, current);
 475                 // FIXME: implement label printing
 476             },
 477             ExprKind::Ret(ref opt_value) => {
 478                 if let Some(ref value) = *opt_value {
 479                     let value_pat = self.next("value");
 480                     println!("Ret(Some(ref {})) = {};", value_pat, current);
 481                     self.current = value_pat;
 482                     self.visit_expr(value);
 483                 } else {
 484                     println!("Ret(None) = {};", current);
 485                 }
 486             },
 487             ExprKind::InlineAsm(_) => {
 488                 println!("InlineAsm(_) = {};", current);
 489                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 490             },
 491             ExprKind::LlvmInlineAsm(_) => {
 492                 println!("LlvmInlineAsm(_) = {};", current);
 493                 println!("    // unimplemented: `ExprKind::LlvmInlineAsm` is not further destructured at the moment");
 494             },
 495             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 496                 let path_pat = self.next("path");
 497                 let fields_pat = self.next("fields");
 498                 if let Some(ref base) = *opt_base {
 499                     let base_pat = self.next("base");
 500                     println!(
 501                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 502                         path_pat, fields_pat, base_pat, current
 503                     );
 504                     self.current = base_pat;
 505                     self.visit_expr(base);
 506                 } else {
 507                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 508                 }
 509                 self.current = path_pat;
 510                 self.print_qpath(path);
 511                 println!("    if {}.len() == {};", fields_pat, fields.len());
 512                 println!("    // unimplemented: field checks");
 513             },
 514             ExprKind::ConstBlock(_) => {
 515                 let value_pat = self.next("value");
 516                 println!("Const({})", value_pat);
 517                 self.current = value_pat;
 518             },
 519             // FIXME: compute length (needs type info)
 520             ExprKind::Repeat(ref value, _) => {
 521                 let value_pat = self.next("value");
 522                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 523                 println!("// unimplemented: repeat count check");
 524                 self.current = value_pat;
 525                 self.visit_expr(value);
 526             },
 527             ExprKind::Err => {
 528                 println!("Err = {}", current);
 529             },
 530             ExprKind::DropTemps(ref expr) => {
 531                 let expr_pat = self.next("expr");
 532                 println!("DropTemps(ref {}) = {};", expr_pat, current);
 533                 self.current = expr_pat;
 534                 self.visit_expr(expr);
 535             },
 536         }
 537     }
 538
 539     fn visit_block(&mut self, block: &Block<'_>) {
 540         let trailing_pat = self.next("trailing_expr");
 541         println!("    if let Some({}) = &{}.expr;", trailing_pat, self.current);
 542         println!("    if {}.stmts.len() == {};", self.current, block.stmts.len());
 543         let current = self.current.clone();
 544         for (i, stmt) in block.stmts.iter().enumerate() {
 545             self.current = format!("{}.stmts[{}]", current, i);
 546             self.visit_stmt(stmt);
 547         }
 548     }
 549
 550     #[allow(clippy::too_many_lines)]
 551     fn visit_pat(&mut self, pat: &Pat<'_>) {
 552         print!("    if let PatKind::");
 553         let current = format!("{}.kind", self.current);
 554         match pat.kind {
 555             PatKind::Wild => println!("Wild = {};", current),
 556             PatKind::Binding(anno, .., ident, ref sub) => {
 557                 let anno_pat = match anno {
 558                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 559                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 560                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 561                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 562                 };
 563                 let name_pat = self.next("name");
 564                 if let Some(ref sub) = *sub {
 565                     let sub_pat = self.next("sub");
 566                     println!(
 567                         "Binding({}, _, {}, Some(ref {})) = {};",
 568                         anno_pat, name_pat, sub_pat, current
 569                     );
 570                     self.current = sub_pat;
 571                     self.visit_pat(sub);
 572                 } else {
 573                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 574                 }
 575                 println!("    if {}.as_str() == \"{}\";", name_pat, ident.as_str());
 576             },
 577             PatKind::Struct(ref path, ref fields, ignore) => {
 578                 let path_pat = self.next("path");
 579                 let fields_pat = self.next("fields");
 580                 println!(
 581                     "Struct(ref {}, ref {}, {}) = {};",
 582                     path_pat, fields_pat, ignore, current
 583                 );
 584                 self.current = path_pat;
 585                 self.print_qpath(path);
 586                 println!("    if {}.len() == {};", fields_pat, fields.len());
 587                 println!("    // unimplemented: field checks");
 588             },
 589             PatKind::Or(ref fields) => {
 590                 let fields_pat = self.next("fields");
 591                 println!("Or(ref {}) = {};", fields_pat, current);
 592                 println!("    if {}.len() == {};", fields_pat, fields.len());
 593                 println!("    // unimplemented: field checks");
 594             },
 595             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 596                 let path_pat = self.next("path");
 597                 let fields_pat = self.next("fields");
 598                 println!(
 599                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 600                     path_pat, fields_pat, skip_pos, current
 601                 );
 602                 self.current = path_pat;
 603                 self.print_qpath(path);
 604                 println!("    if {}.len() == {};", fields_pat, fields.len());
 605                 println!("    // unimplemented: field checks");
 606             },
 607             PatKind::Path(ref path) => {
 608                 let path_pat = self.next("path");
 609                 println!("Path(ref {}) = {};", path_pat, current);
 610                 self.current = path_pat;
 611                 self.print_qpath(path);
 612             },
 613             PatKind::Tuple(ref fields, skip_pos) => {
 614                 let fields_pat = self.next("fields");
 615                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 616                 println!("    if {}.len() == {};", fields_pat, fields.len());
 617                 println!("    // unimplemented: field checks");
 618             },
 619             PatKind::Box(ref pat) => {
 620                 let pat_pat = self.next("pat");
 621                 println!("Box(ref {}) = {};", pat_pat, current);
 622                 self.current = pat_pat;
 623                 self.visit_pat(pat);
 624             },
 625             PatKind::Ref(ref pat, muta) => {
 626                 let pat_pat = self.next("pat");
 627                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 628                 self.current = pat_pat;
 629                 self.visit_pat(pat);
 630             },
 631             PatKind::Lit(ref lit_expr) => {
 632                 let lit_expr_pat = self.next("lit_expr");
 633                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 634                 self.current = lit_expr_pat;
 635                 self.visit_expr(lit_expr);
 636             },
 637             PatKind::Range(ref start, ref end, end_kind) => {
 638                 let start_pat = self.next("start");
 639                 let end_pat = self.next("end");
 640                 println!(
 641                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 642                     start_pat, end_pat, end_kind, current
 643                 );
 644                 self.current = start_pat;
 645                 walk_list!(self, visit_expr, start);
 646                 self.current = end_pat;
 647                 walk_list!(self, visit_expr, end);
 648             },
 649             PatKind::Slice(ref start, ref middle, ref end) => {
 650                 let start_pat = self.next("start");
 651                 let end_pat = self.next("end");
 652                 if let Some(ref middle) = middle {
 653                     let middle_pat = self.next("middle");
 654                     println!(
 655                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 656                         start_pat, middle_pat, end_pat, current
 657                     );
 658                     self.current = middle_pat;
 659                     self.visit_pat(middle);
 660                 } else {
 661                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 662                 }
 663                 println!("    if {}.len() == {};", start_pat, start.len());
 664                 for (i, pat) in start.iter().enumerate() {
 665                     self.current = format!("{}[{}]", start_pat, i);
 666                     self.visit_pat(pat);
 667                 }
 668                 println!("    if {}.len() == {};", end_pat, end.len());
 669                 for (i, pat) in end.iter().enumerate() {
 670                     self.current = format!("{}[{}]", end_pat, i);
 671                     self.visit_pat(pat);
 672                 }
 673             },
 674         }
 675     }
 676
 677     fn visit_stmt(&mut self, s: &Stmt<'_>) {
 678         print!("    if let StmtKind::");
 679         let current = format!("{}.kind", self.current);
 680         match s.kind {
 681             // A local (let) binding:
 682             StmtKind::Local(ref local) => {
 683                 let local_pat = self.next("local");
 684                 println!("Local(ref {}) = {};", local_pat, current);
 685                 if let Some(ref init) = local.init {
 686                     let init_pat = self.next("init");
 687                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 688                     self.current = init_pat;
 689                     self.visit_expr(init);
 690                 }
 691                 self.current = format!("{}.pat", local_pat);
 692                 self.visit_pat(&local.pat);
 693             },
 694             // An item binding:
 695             StmtKind::Item(_) => {
 696                 println!("Item(item_id) = {};", current);
 697             },
 698
 699             // Expr without trailing semi-colon (must have unit type):
 700             StmtKind::Expr(ref e) => {
 701                 let e_pat = self.next("e");
 702                 println!("Expr(ref {}, _) = {}", e_pat, current);
 703                 self.current = e_pat;
 704                 self.visit_expr(e);
 705             },
 706
 707             // Expr with trailing semi-colon (may have any type):
 708             StmtKind::Semi(ref e) => {
 709                 let e_pat = self.next("e");
 710                 println!("Semi(ref {}, _) = {}", e_pat, current);
 711                 self.current = e_pat;
 712                 self.visit_expr(e);
 713             },
 714         }
 715     }
 716
 717     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 718         NestedVisitorMap::None
 719     }
 720 }
 721
 722 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 723     get_attr(sess, attrs, "author").count() > 0
 724 }
 725
 726 #[must_use]
 727 fn desugaring_name(des: hir::MatchSource) -> String {
 728     match des {
 729         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 730         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 731         hir::MatchSource::WhileDesugar => "MatchSource::WhileDesugar".to_string(),
 732         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 733         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 734         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 735             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 736             contains_else_clause
 737         ),
 738         hir::MatchSource::IfLetGuardDesugar => "MatchSource::IfLetGuardDesugar".to_string(),
 739         hir::MatchSource::AwaitDesugar => "MatchSource::AwaitDesugar".to_string(),
 740     }
 741 }
 742
 743 #[must_use]
 744 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 745     match des {
 746         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 747         hir::LoopSource::Loop => "LoopSource::Loop",
 748         hir::LoopSource::While => "LoopSource::While",
 749         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 750     }
 751 }
 752
 753 fn print_path(path: &QPath<'_>, first: &mut bool) {
 754     match *path {
 755         QPath::Resolved(_, ref path) => {
 756             for segment in path.segments {
 757                 if *first {
 758                     *first = false;
 759                 } else {
 760                     print!(", ");
 761                 }
 762                 print!("{:?}", segment.ident.as_str());
 763             }
 764         },
 765         QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
 766             hir::TyKind::Path(ref inner_path) => {
 767                 print_path(inner_path, first);
 768                 if *first {
 769                     *first = false;
 770                 } else {
 771                     print!(", ");
 772                 }
 773                 print!("{:?}", segment.ident.as_str());
 774             },
 775             ref other => print!("/* unimplemented: {:?}*/", other),
 776         },
 777         QPath::LangItem(..) => panic!("print_path: called for lang item qpath"),
 778     }
 779 }