src/tools/clippy/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, higher};
   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         // handle if desugarings
 205         // TODO add more desugarings here
 206         if let Some((cond, then, opt_else)) = higher::if_block(&expr) {
 207             let cond_pat = self.next("cond");
 208             let then_pat = self.next("then");
 209             if let Some(else_) = opt_else {
 210                 let else_pat = self.next("else_");
 211                 println!(
 212                     "    if let Some((ref {}, ref {}, Some({}))) = higher::if_block(&{});",
 213                     cond_pat, then_pat, else_pat, self.current
 214                 );
 215                 self.current = else_pat;
 216                 self.visit_expr(else_);
 217             } else {
 218                 println!(
 219                     "    if let Some((ref {}, ref {}, None)) = higher::if_block(&{});",
 220                     cond_pat, then_pat, self.current
 221                 );
 222             }
 223             self.current = cond_pat;
 224             self.visit_expr(cond);
 225             self.current = then_pat;
 226             self.visit_expr(then);
 227             return;
 228         }
 229
 230         print!("    if let ExprKind::");
 231         let current = format!("{}.kind", self.current);
 232         match expr.kind {
 233             ExprKind::Box(ref inner) => {
 234                 let inner_pat = self.next("inner");
 235                 println!("Box(ref {}) = {};", inner_pat, current);
 236                 self.current = inner_pat;
 237                 self.visit_expr(inner);
 238             },
 239             ExprKind::Array(ref elements) => {
 240                 let elements_pat = self.next("elements");
 241                 println!("Array(ref {}) = {};", elements_pat, current);
 242                 println!("    if {}.len() == {};", elements_pat, elements.len());
 243                 for (i, element) in elements.iter().enumerate() {
 244                     self.current = format!("{}[{}]", elements_pat, i);
 245                     self.visit_expr(element);
 246                 }
 247             },
 248             ExprKind::Call(ref func, ref args) => {
 249                 let func_pat = self.next("func");
 250                 let args_pat = self.next("args");
 251                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 252                 self.current = func_pat;
 253                 self.visit_expr(func);
 254                 println!("    if {}.len() == {};", args_pat, args.len());
 255                 for (i, arg) in args.iter().enumerate() {
 256                     self.current = format!("{}[{}]", args_pat, i);
 257                     self.visit_expr(arg);
 258                 }
 259             },
 260             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args, ref _fn_span) => {
 261                 println!(
 262                     "MethodCall(ref method_name, ref generics, ref args, ref fn_span) = {};",
 263                     current
 264                 );
 265                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 266             },
 267             ExprKind::Tup(ref elements) => {
 268                 let elements_pat = self.next("elements");
 269                 println!("Tup(ref {}) = {};", elements_pat, current);
 270                 println!("    if {}.len() == {};", elements_pat, elements.len());
 271                 for (i, element) in elements.iter().enumerate() {
 272                     self.current = format!("{}[{}]", elements_pat, i);
 273                     self.visit_expr(element);
 274                 }
 275             },
 276             ExprKind::Binary(ref op, ref left, ref right) => {
 277                 let op_pat = self.next("op");
 278                 let left_pat = self.next("left");
 279                 let right_pat = self.next("right");
 280                 println!(
 281                     "Binary(ref {}, ref {}, ref {}) = {};",
 282                     op_pat, left_pat, right_pat, current
 283                 );
 284                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 285                 self.current = left_pat;
 286                 self.visit_expr(left);
 287                 self.current = right_pat;
 288                 self.visit_expr(right);
 289             },
 290             ExprKind::Unary(ref op, ref inner) => {
 291                 let inner_pat = self.next("inner");
 292                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 293                 self.current = inner_pat;
 294                 self.visit_expr(inner);
 295             },
 296             ExprKind::Lit(ref lit) => {
 297                 let lit_pat = self.next("lit");
 298                 println!("Lit(ref {}) = {};", lit_pat, current);
 299                 match lit.node {
 300                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 301                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 302                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 303                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 304                     // FIXME: also check int type
 305                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 306                     LitKind::Float(_, LitFloatType::Suffixed(_)) => println!(
 307                         "    if let LitKind::Float(_, LitFloatType::Suffixed(_)) = {}.node;",
 308                         lit_pat
 309                     ),
 310                     LitKind::Float(_, LitFloatType::Unsuffixed) => println!(
 311                         "    if let LitKind::Float(_, LitFloatType::Unsuffixed) = {}.node;",
 312                         lit_pat
 313                     ),
 314                     LitKind::ByteStr(ref vec) => {
 315                         let vec_pat = self.next("vec");
 316                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 317                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 318                     },
 319                     LitKind::Str(ref text, _) => {
 320                         let str_pat = self.next("s");
 321                         println!("    if let LitKind::Str(ref {}, _) = {}.node;", str_pat, lit_pat);
 322                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 323                     },
 324                 }
 325             },
 326             ExprKind::Cast(ref expr, ref ty) => {
 327                 let cast_pat = self.next("expr");
 328                 let cast_ty = self.next("cast_ty");
 329                 let qp_label = self.next("qp");
 330
 331                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 332                 if let TyKind::Path(ref qp) = ty.kind {
 333                     println!("    if let TyKind::Path(ref {}) = {}.kind;", qp_label, cast_ty);
 334                     self.current = qp_label;
 335                     self.print_qpath(qp);
 336                 }
 337                 self.current = cast_pat;
 338                 self.visit_expr(expr);
 339             },
 340             ExprKind::Type(ref expr, ref _ty) => {
 341                 let cast_pat = self.next("expr");
 342                 println!("Type(ref {}, _) = {};", cast_pat, current);
 343                 self.current = cast_pat;
 344                 self.visit_expr(expr);
 345             },
 346             ExprKind::Loop(ref body, _, desugaring) => {
 347                 let body_pat = self.next("body");
 348                 let des = loop_desugaring_name(desugaring);
 349                 let label_pat = self.next("label");
 350                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 351                 self.current = body_pat;
 352                 self.visit_block(body);
 353             },
 354             ExprKind::Match(ref expr, ref arms, desugaring) => {
 355                 let des = desugaring_name(desugaring);
 356                 let expr_pat = self.next("expr");
 357                 let arms_pat = self.next("arms");
 358                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 359                 self.current = expr_pat;
 360                 self.visit_expr(expr);
 361                 println!("    if {}.len() == {};", arms_pat, arms.len());
 362                 for (i, arm) in arms.iter().enumerate() {
 363                     self.current = format!("{}[{}].body", arms_pat, i);
 364                     self.visit_expr(&arm.body);
 365                     if let Some(ref guard) = arm.guard {
 366                         let guard_pat = self.next("guard");
 367                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 368                         match guard {
 369                             hir::Guard::If(ref if_expr) => {
 370                                 let if_expr_pat = self.next("expr");
 371                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 372                                 self.current = if_expr_pat;
 373                                 self.visit_expr(if_expr);
 374                             },
 375                         }
 376                     }
 377                     self.current = format!("{}[{}].pat", arms_pat, i);
 378                     self.visit_pat(&arm.pat);
 379                 }
 380             },
 381             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 382                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 383                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 384             },
 385             ExprKind::Yield(ref sub, _) => {
 386                 let sub_pat = self.next("sub");
 387                 println!("Yield(ref sub) = {};", current);
 388                 self.current = sub_pat;
 389                 self.visit_expr(sub);
 390             },
 391             ExprKind::Block(ref block, _) => {
 392                 let block_pat = self.next("block");
 393                 println!("Block(ref {}) = {};", block_pat, current);
 394                 self.current = block_pat;
 395                 self.visit_block(block);
 396             },
 397             ExprKind::Assign(ref target, ref value, _) => {
 398                 let target_pat = self.next("target");
 399                 let value_pat = self.next("value");
 400                 println!(
 401                     "Assign(ref {}, ref {}, ref _span) = {};",
 402                     target_pat, value_pat, current
 403                 );
 404                 self.current = target_pat;
 405                 self.visit_expr(target);
 406                 self.current = value_pat;
 407                 self.visit_expr(value);
 408             },
 409             ExprKind::AssignOp(ref op, ref target, ref value) => {
 410                 let op_pat = self.next("op");
 411                 let target_pat = self.next("target");
 412                 let value_pat = self.next("value");
 413                 println!(
 414                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 415                     op_pat, target_pat, value_pat, current
 416                 );
 417                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 418                 self.current = target_pat;
 419                 self.visit_expr(target);
 420                 self.current = value_pat;
 421                 self.visit_expr(value);
 422             },
 423             ExprKind::Field(ref object, ref field_ident) => {
 424                 let obj_pat = self.next("object");
 425                 let field_name_pat = self.next("field_name");
 426                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 427                 println!("    if {}.as_str() == {:?}", field_name_pat, field_ident.as_str());
 428                 self.current = obj_pat;
 429                 self.visit_expr(object);
 430             },
 431             ExprKind::Index(ref object, ref index) => {
 432                 let object_pat = self.next("object");
 433                 let index_pat = self.next("index");
 434                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 435                 self.current = object_pat;
 436                 self.visit_expr(object);
 437                 self.current = index_pat;
 438                 self.visit_expr(index);
 439             },
 440             ExprKind::Path(ref path) => {
 441                 let path_pat = self.next("path");
 442                 println!("Path(ref {}) = {};", path_pat, current);
 443                 self.current = path_pat;
 444                 self.print_qpath(path);
 445             },
 446             ExprKind::AddrOf(kind, mutability, ref inner) => {
 447                 let inner_pat = self.next("inner");
 448                 println!(
 449                     "AddrOf(BorrowKind::{:?}, Mutability::{:?}, ref {}) = {};",
 450                     kind, mutability, inner_pat, current
 451                 );
 452                 self.current = inner_pat;
 453                 self.visit_expr(inner);
 454             },
 455             ExprKind::Break(ref _destination, ref opt_value) => {
 456                 let destination_pat = self.next("destination");
 457                 if let Some(ref value) = *opt_value {
 458                     let value_pat = self.next("value");
 459                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 460                     self.current = value_pat;
 461                     self.visit_expr(value);
 462                 } else {
 463                     println!("Break(ref {}, None) = {};", destination_pat, current);
 464                 }
 465                 // FIXME: implement label printing
 466             },
 467             ExprKind::Continue(ref _destination) => {
 468                 let destination_pat = self.next("destination");
 469                 println!("Again(ref {}) = {};", destination_pat, current);
 470                 // FIXME: implement label printing
 471             },
 472             ExprKind::Ret(ref opt_value) => {
 473                 if let Some(ref value) = *opt_value {
 474                     let value_pat = self.next("value");
 475                     println!("Ret(Some(ref {})) = {};", value_pat, current);
 476                     self.current = value_pat;
 477                     self.visit_expr(value);
 478                 } else {
 479                     println!("Ret(None) = {};", current);
 480                 }
 481             },
 482             ExprKind::InlineAsm(_) => {
 483                 println!("InlineAsm(_) = {};", current);
 484                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 485             },
 486             ExprKind::LlvmInlineAsm(_) => {
 487                 println!("LlvmInlineAsm(_) = {};", current);
 488                 println!("    // unimplemented: `ExprKind::LlvmInlineAsm` is not further destructured at the moment");
 489             },
 490             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 491                 let path_pat = self.next("path");
 492                 let fields_pat = self.next("fields");
 493                 if let Some(ref base) = *opt_base {
 494                     let base_pat = self.next("base");
 495                     println!(
 496                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 497                         path_pat, fields_pat, base_pat, current
 498                     );
 499                     self.current = base_pat;
 500                     self.visit_expr(base);
 501                 } else {
 502                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 503                 }
 504                 self.current = path_pat;
 505                 self.print_qpath(path);
 506                 println!("    if {}.len() == {};", fields_pat, fields.len());
 507                 println!("    // unimplemented: field checks");
 508             },
 509             ExprKind::ConstBlock(_) => {
 510                 let value_pat = self.next("value");
 511                 println!("Const({})", value_pat);
 512                 self.current = value_pat;
 513             },
 514             // FIXME: compute length (needs type info)
 515             ExprKind::Repeat(ref value, _) => {
 516                 let value_pat = self.next("value");
 517                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 518                 println!("// unimplemented: repeat count check");
 519                 self.current = value_pat;
 520                 self.visit_expr(value);
 521             },
 522             ExprKind::Err => {
 523                 println!("Err = {}", current);
 524             },
 525             ExprKind::DropTemps(ref expr) => {
 526                 let expr_pat = self.next("expr");
 527                 println!("DropTemps(ref {}) = {};", expr_pat, current);
 528                 self.current = expr_pat;
 529                 self.visit_expr(expr);
 530             },
 531         }
 532     }
 533
 534     fn visit_block(&mut self, block: &Block<'_>) {
 535         let trailing_pat = self.next("trailing_expr");
 536         println!("    if let Some({}) = &{}.expr;", trailing_pat, self.current);
 537         println!("    if {}.stmts.len() == {};", self.current, block.stmts.len());
 538         let current = self.current.clone();
 539         for (i, stmt) in block.stmts.iter().enumerate() {
 540             self.current = format!("{}.stmts[{}]", current, i);
 541             self.visit_stmt(stmt);
 542         }
 543     }
 544
 545     #[allow(clippy::too_many_lines)]
 546     fn visit_pat(&mut self, pat: &Pat<'_>) {
 547         print!("    if let PatKind::");
 548         let current = format!("{}.kind", self.current);
 549         match pat.kind {
 550             PatKind::Wild => println!("Wild = {};", current),
 551             PatKind::Binding(anno, .., ident, ref sub) => {
 552                 let anno_pat = match anno {
 553                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 554                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 555                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 556                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 557                 };
 558                 let name_pat = self.next("name");
 559                 if let Some(ref sub) = *sub {
 560                     let sub_pat = self.next("sub");
 561                     println!(
 562                         "Binding({}, _, {}, Some(ref {})) = {};",
 563                         anno_pat, name_pat, sub_pat, current
 564                     );
 565                     self.current = sub_pat;
 566                     self.visit_pat(sub);
 567                 } else {
 568                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 569                 }
 570                 println!("    if {}.as_str() == \"{}\";", name_pat, ident.as_str());
 571             },
 572             PatKind::Struct(ref path, ref fields, ignore) => {
 573                 let path_pat = self.next("path");
 574                 let fields_pat = self.next("fields");
 575                 println!(
 576                     "Struct(ref {}, ref {}, {}) = {};",
 577                     path_pat, fields_pat, ignore, current
 578                 );
 579                 self.current = path_pat;
 580                 self.print_qpath(path);
 581                 println!("    if {}.len() == {};", fields_pat, fields.len());
 582                 println!("    // unimplemented: field checks");
 583             },
 584             PatKind::Or(ref fields) => {
 585                 let fields_pat = self.next("fields");
 586                 println!("Or(ref {}) = {};", fields_pat, current);
 587                 println!("    if {}.len() == {};", fields_pat, fields.len());
 588                 println!("    // unimplemented: field checks");
 589             },
 590             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 591                 let path_pat = self.next("path");
 592                 let fields_pat = self.next("fields");
 593                 println!(
 594                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 595                     path_pat, fields_pat, skip_pos, current
 596                 );
 597                 self.current = path_pat;
 598                 self.print_qpath(path);
 599                 println!("    if {}.len() == {};", fields_pat, fields.len());
 600                 println!("    // unimplemented: field checks");
 601             },
 602             PatKind::Path(ref path) => {
 603                 let path_pat = self.next("path");
 604                 println!("Path(ref {}) = {};", path_pat, current);
 605                 self.current = path_pat;
 606                 self.print_qpath(path);
 607             },
 608             PatKind::Tuple(ref fields, skip_pos) => {
 609                 let fields_pat = self.next("fields");
 610                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 611                 println!("    if {}.len() == {};", fields_pat, fields.len());
 612                 println!("    // unimplemented: field checks");
 613             },
 614             PatKind::Box(ref pat) => {
 615                 let pat_pat = self.next("pat");
 616                 println!("Box(ref {}) = {};", pat_pat, current);
 617                 self.current = pat_pat;
 618                 self.visit_pat(pat);
 619             },
 620             PatKind::Ref(ref pat, muta) => {
 621                 let pat_pat = self.next("pat");
 622                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 623                 self.current = pat_pat;
 624                 self.visit_pat(pat);
 625             },
 626             PatKind::Lit(ref lit_expr) => {
 627                 let lit_expr_pat = self.next("lit_expr");
 628                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 629                 self.current = lit_expr_pat;
 630                 self.visit_expr(lit_expr);
 631             },
 632             PatKind::Range(ref start, ref end, end_kind) => {
 633                 let start_pat = self.next("start");
 634                 let end_pat = self.next("end");
 635                 println!(
 636                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 637                     start_pat, end_pat, end_kind, current
 638                 );
 639                 self.current = start_pat;
 640                 walk_list!(self, visit_expr, start);
 641                 self.current = end_pat;
 642                 walk_list!(self, visit_expr, end);
 643             },
 644             PatKind::Slice(ref start, ref middle, ref end) => {
 645                 let start_pat = self.next("start");
 646                 let end_pat = self.next("end");
 647                 if let Some(ref middle) = middle {
 648                     let middle_pat = self.next("middle");
 649                     println!(
 650                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 651                         start_pat, middle_pat, end_pat, current
 652                     );
 653                     self.current = middle_pat;
 654                     self.visit_pat(middle);
 655                 } else {
 656                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 657                 }
 658                 println!("    if {}.len() == {};", start_pat, start.len());
 659                 for (i, pat) in start.iter().enumerate() {
 660                     self.current = format!("{}[{}]", start_pat, i);
 661                     self.visit_pat(pat);
 662                 }
 663                 println!("    if {}.len() == {};", end_pat, end.len());
 664                 for (i, pat) in end.iter().enumerate() {
 665                     self.current = format!("{}[{}]", end_pat, i);
 666                     self.visit_pat(pat);
 667                 }
 668             },
 669         }
 670     }
 671
 672     fn visit_stmt(&mut self, s: &Stmt<'_>) {
 673         print!("    if let StmtKind::");
 674         let current = format!("{}.kind", self.current);
 675         match s.kind {
 676             // A local (let) binding:
 677             StmtKind::Local(ref local) => {
 678                 let local_pat = self.next("local");
 679                 println!("Local(ref {}) = {};", local_pat, current);
 680                 if let Some(ref init) = local.init {
 681                     let init_pat = self.next("init");
 682                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 683                     self.current = init_pat;
 684                     self.visit_expr(init);
 685                 }
 686                 self.current = format!("{}.pat", local_pat);
 687                 self.visit_pat(&local.pat);
 688             },
 689             // An item binding:
 690             StmtKind::Item(_) => {
 691                 println!("Item(item_id) = {};", current);
 692             },
 693
 694             // Expr without trailing semi-colon (must have unit type):
 695             StmtKind::Expr(ref e) => {
 696                 let e_pat = self.next("e");
 697                 println!("Expr(ref {}, _) = {}", e_pat, current);
 698                 self.current = e_pat;
 699                 self.visit_expr(e);
 700             },
 701
 702             // Expr with trailing semi-colon (may have any type):
 703             StmtKind::Semi(ref e) => {
 704                 let e_pat = self.next("e");
 705                 println!("Semi(ref {}, _) = {}", e_pat, current);
 706                 self.current = e_pat;
 707                 self.visit_expr(e);
 708             },
 709         }
 710     }
 711
 712     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 713         NestedVisitorMap::None
 714     }
 715 }
 716
 717 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 718     get_attr(sess, attrs, "author").count() > 0
 719 }
 720
 721 #[must_use]
 722 fn desugaring_name(des: hir::MatchSource) -> String {
 723     match des {
 724         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 725         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 726         hir::MatchSource::WhileDesugar => "MatchSource::WhileDesugar".to_string(),
 727         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 728         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 729         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 730             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 731             contains_else_clause
 732         ),
 733         hir::MatchSource::IfLetGuardDesugar => "MatchSource::IfLetGuardDesugar".to_string(),
 734         hir::MatchSource::IfDesugar { contains_else_clause } => format!(
 735             "MatchSource::IfDesugar {{ contains_else_clause: {} }}",
 736             contains_else_clause
 737         ),
 738         hir::MatchSource::AwaitDesugar => "MatchSource::AwaitDesugar".to_string(),
 739     }
 740 }
 741
 742 #[must_use]
 743 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 744     match des {
 745         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 746         hir::LoopSource::Loop => "LoopSource::Loop",
 747         hir::LoopSource::While => "LoopSource::While",
 748         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 749     }
 750 }
 751
 752 fn print_path(path: &QPath<'_>, first: &mut bool) {
 753     match *path {
 754         QPath::Resolved(_, ref path) => {
 755             for segment in path.segments {
 756                 if *first {
 757                     *first = false;
 758                 } else {
 759                     print!(", ");
 760                 }
 761                 print!("{:?}", segment.ident.as_str());
 762             }
 763         },
 764         QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
 765             hir::TyKind::Path(ref inner_path) => {
 766                 print_path(inner_path, first);
 767                 if *first {
 768                     *first = false;
 769                 } else {
 770                     print!(", ");
 771                 }
 772                 print!("{:?}", segment.ident.as_str());
 773             },
 774             ref other => print!("/* unimplemented: {:?}*/", other),
 775         },
 776         QPath::LangItem(..) => panic!("print_path: called for lang item qpath"),
 777     }
 778 }