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<'a, 'tcx> LateLintPass<'a, 'tcx> for Author {
  68     fn check_item(&mut self, cx: &LateContext<'a, '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<'a, '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<'a, '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<'a, '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<'a, '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<'a, '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<'a, '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<'a, 'tcx>, stmt: &'tcx hir::Stmt<'_>) {
 133         if !has_attr(cx.sess(), stmt.kind.attrs()) {
 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<'a, '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         print!("    if match_qpath({}, &[", self.current);
 179         print_path(path, &mut true);
 180         println!("]);");
 181     }
 182 }
 183
 184 struct PrintVisitor {
 185     /// Fields are the current index that needs to be appended to pattern
 186     /// binding names
 187     ids: FxHashMap<&'static str, usize>,
 188     /// the name that needs to be destructured
 189     current: String,
 190 }
 191
 192 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 193     type Map = Map<'tcx>;
 194
 195     #[allow(clippy::too_many_lines)]
 196     fn visit_expr(&mut self, expr: &Expr<'_>) {
 197         // handle if desugarings
 198         // TODO add more desugarings here
 199         if let Some((cond, then, opt_else)) = higher::if_block(&expr) {
 200             let cond_pat = self.next("cond");
 201             let then_pat = self.next("then");
 202             if let Some(else_) = opt_else {
 203                 let else_pat = self.next("else_");
 204                 println!(
 205                     "    if let Some((ref {}, ref {}, Some({}))) = higher::if_block(&{});",
 206                     cond_pat, then_pat, else_pat, self.current
 207                 );
 208                 self.current = else_pat;
 209                 self.visit_expr(else_);
 210             } else {
 211                 println!(
 212                     "    if let Some((ref {}, ref {}, None)) = higher::if_block(&{});",
 213                     cond_pat, then_pat, self.current
 214                 );
 215             }
 216             self.current = cond_pat;
 217             self.visit_expr(cond);
 218             self.current = then_pat;
 219             self.visit_expr(then);
 220             return;
 221         }
 222
 223         print!("    if let ExprKind::");
 224         let current = format!("{}.kind", self.current);
 225         match expr.kind {
 226             ExprKind::Box(ref inner) => {
 227                 let inner_pat = self.next("inner");
 228                 println!("Box(ref {}) = {};", inner_pat, current);
 229                 self.current = inner_pat;
 230                 self.visit_expr(inner);
 231             },
 232             ExprKind::Array(ref elements) => {
 233                 let elements_pat = self.next("elements");
 234                 println!("Array(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::Call(ref func, ref args) => {
 242                 let func_pat = self.next("func");
 243                 let args_pat = self.next("args");
 244                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 245                 self.current = func_pat;
 246                 self.visit_expr(func);
 247                 println!("    if {}.len() == {};", args_pat, args.len());
 248                 for (i, arg) in args.iter().enumerate() {
 249                     self.current = format!("{}[{}]", args_pat, i);
 250                     self.visit_expr(arg);
 251                 }
 252             },
 253             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args, ref _fn_span) => {
 254                 println!("MethodCall(ref method_name, ref generics, ref args, ref fn_span) = {};", current);
 255                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 256             },
 257             ExprKind::Tup(ref elements) => {
 258                 let elements_pat = self.next("elements");
 259                 println!("Tup(ref {}) = {};", elements_pat, current);
 260                 println!("    if {}.len() == {};", elements_pat, elements.len());
 261                 for (i, element) in elements.iter().enumerate() {
 262                     self.current = format!("{}[{}]", elements_pat, i);
 263                     self.visit_expr(element);
 264                 }
 265             },
 266             ExprKind::Binary(ref op, ref left, ref right) => {
 267                 let op_pat = self.next("op");
 268                 let left_pat = self.next("left");
 269                 let right_pat = self.next("right");
 270                 println!(
 271                     "Binary(ref {}, ref {}, ref {}) = {};",
 272                     op_pat, left_pat, right_pat, current
 273                 );
 274                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 275                 self.current = left_pat;
 276                 self.visit_expr(left);
 277                 self.current = right_pat;
 278                 self.visit_expr(right);
 279             },
 280             ExprKind::Unary(ref op, ref inner) => {
 281                 let inner_pat = self.next("inner");
 282                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 283                 self.current = inner_pat;
 284                 self.visit_expr(inner);
 285             },
 286             ExprKind::Lit(ref lit) => {
 287                 let lit_pat = self.next("lit");
 288                 println!("Lit(ref {}) = {};", lit_pat, current);
 289                 match lit.node {
 290                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 291                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 292                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 293                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 294                     // FIXME: also check int type
 295                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 296                     LitKind::Float(_, LitFloatType::Suffixed(_)) => println!(
 297                         "    if let LitKind::Float(_, LitFloatType::Suffixed(_)) = {}.node;",
 298                         lit_pat
 299                     ),
 300                     LitKind::Float(_, LitFloatType::Unsuffixed) => println!(
 301                         "    if let LitKind::Float(_, LitFloatType::Unsuffixed) = {}.node;",
 302                         lit_pat
 303                     ),
 304                     LitKind::ByteStr(ref vec) => {
 305                         let vec_pat = self.next("vec");
 306                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 307                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 308                     },
 309                     LitKind::Str(ref text, _) => {
 310                         let str_pat = self.next("s");
 311                         println!("    if let LitKind::Str(ref {}, _) = {}.node;", str_pat, lit_pat);
 312                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 313                     },
 314                 }
 315             },
 316             ExprKind::Cast(ref expr, ref ty) => {
 317                 let cast_pat = self.next("expr");
 318                 let cast_ty = self.next("cast_ty");
 319                 let qp_label = self.next("qp");
 320
 321                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 322                 if let TyKind::Path(ref qp) = ty.kind {
 323                     println!("    if let TyKind::Path(ref {}) = {}.kind;", qp_label, cast_ty);
 324                     self.current = qp_label;
 325                     self.print_qpath(qp);
 326                 }
 327                 self.current = cast_pat;
 328                 self.visit_expr(expr);
 329             },
 330             ExprKind::Type(ref expr, ref _ty) => {
 331                 let cast_pat = self.next("expr");
 332                 println!("Type(ref {}, _) = {};", cast_pat, current);
 333                 self.current = cast_pat;
 334                 self.visit_expr(expr);
 335             },
 336             ExprKind::Loop(ref body, _, desugaring) => {
 337                 let body_pat = self.next("body");
 338                 let des = loop_desugaring_name(desugaring);
 339                 let label_pat = self.next("label");
 340                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 341                 self.current = body_pat;
 342                 self.visit_block(body);
 343             },
 344             ExprKind::Match(ref expr, ref arms, desugaring) => {
 345                 let des = desugaring_name(desugaring);
 346                 let expr_pat = self.next("expr");
 347                 let arms_pat = self.next("arms");
 348                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 349                 self.current = expr_pat;
 350                 self.visit_expr(expr);
 351                 println!("    if {}.len() == {};", arms_pat, arms.len());
 352                 for (i, arm) in arms.iter().enumerate() {
 353                     self.current = format!("{}[{}].body", arms_pat, i);
 354                     self.visit_expr(&arm.body);
 355                     if let Some(ref guard) = arm.guard {
 356                         let guard_pat = self.next("guard");
 357                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 358                         match guard {
 359                             hir::Guard::If(ref if_expr) => {
 360                                 let if_expr_pat = self.next("expr");
 361                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 362                                 self.current = if_expr_pat;
 363                                 self.visit_expr(if_expr);
 364                             },
 365                         }
 366                     }
 367                     self.current = format!("{}[{}].pat", arms_pat, i);
 368                     self.visit_pat(&arm.pat);
 369                 }
 370             },
 371             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 372                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 373                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 374             },
 375             ExprKind::Yield(ref sub, _) => {
 376                 let sub_pat = self.next("sub");
 377                 println!("Yield(ref sub) = {};", current);
 378                 self.current = sub_pat;
 379                 self.visit_expr(sub);
 380             },
 381             ExprKind::Block(ref block, _) => {
 382                 let block_pat = self.next("block");
 383                 println!("Block(ref {}) = {};", block_pat, current);
 384                 self.current = block_pat;
 385                 self.visit_block(block);
 386             },
 387             ExprKind::Assign(ref target, ref value, _) => {
 388                 let target_pat = self.next("target");
 389                 let value_pat = self.next("value");
 390                 println!(
 391                     "Assign(ref {}, ref {}, ref _span) = {};",
 392                     target_pat, value_pat, current
 393                 );
 394                 self.current = target_pat;
 395                 self.visit_expr(target);
 396                 self.current = value_pat;
 397                 self.visit_expr(value);
 398             },
 399             ExprKind::AssignOp(ref op, ref target, ref value) => {
 400                 let op_pat = self.next("op");
 401                 let target_pat = self.next("target");
 402                 let value_pat = self.next("value");
 403                 println!(
 404                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 405                     op_pat, target_pat, value_pat, current
 406                 );
 407                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 408                 self.current = target_pat;
 409                 self.visit_expr(target);
 410                 self.current = value_pat;
 411                 self.visit_expr(value);
 412             },
 413             ExprKind::Field(ref object, ref field_ident) => {
 414                 let obj_pat = self.next("object");
 415                 let field_name_pat = self.next("field_name");
 416                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 417                 println!("    if {}.as_str() == {:?}", field_name_pat, field_ident.as_str());
 418                 self.current = obj_pat;
 419                 self.visit_expr(object);
 420             },
 421             ExprKind::Index(ref object, ref index) => {
 422                 let object_pat = self.next("object");
 423                 let index_pat = self.next("index");
 424                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 425                 self.current = object_pat;
 426                 self.visit_expr(object);
 427                 self.current = index_pat;
 428                 self.visit_expr(index);
 429             },
 430             ExprKind::Path(ref path) => {
 431                 let path_pat = self.next("path");
 432                 println!("Path(ref {}) = {};", path_pat, current);
 433                 self.current = path_pat;
 434                 self.print_qpath(path);
 435             },
 436             ExprKind::AddrOf(kind, mutability, ref inner) => {
 437                 let inner_pat = self.next("inner");
 438                 println!(
 439                     "AddrOf(BorrowKind::{:?}, Mutability::{:?}, ref {}) = {};",
 440                     kind, mutability, inner_pat, current
 441                 );
 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(_) => {
 473                 println!("InlineAsm(_) = {};", current);
 474                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 475             },
 476             ExprKind::LlvmInlineAsm(_) => {
 477                 println!("LlvmInlineAsm(_) = {};", current);
 478                 println!("    // unimplemented: `ExprKind::LlvmInlineAsm` is not further destructured at the moment");
 479             },
 480             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 481                 let path_pat = self.next("path");
 482                 let fields_pat = self.next("fields");
 483                 if let Some(ref base) = *opt_base {
 484                     let base_pat = self.next("base");
 485                     println!(
 486                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 487                         path_pat, fields_pat, base_pat, current
 488                     );
 489                     self.current = base_pat;
 490                     self.visit_expr(base);
 491                 } else {
 492                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 493                 }
 494                 self.current = path_pat;
 495                 self.print_qpath(path);
 496                 println!("    if {}.len() == {};", fields_pat, fields.len());
 497                 println!("    // unimplemented: field checks");
 498             },
 499             // FIXME: compute length (needs type info)
 500             ExprKind::Repeat(ref value, _) => {
 501                 let value_pat = self.next("value");
 502                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 503                 println!("// unimplemented: repeat count check");
 504                 self.current = value_pat;
 505                 self.visit_expr(value);
 506             },
 507             ExprKind::Err => {
 508                 println!("Err = {}", current);
 509             },
 510             ExprKind::DropTemps(ref expr) => {
 511                 let expr_pat = self.next("expr");
 512                 println!("DropTemps(ref {}) = {};", expr_pat, current);
 513                 self.current = expr_pat;
 514                 self.visit_expr(expr);
 515             },
 516         }
 517     }
 518
 519     fn visit_block(&mut self, block: &Block<'_>) {
 520         let trailing_pat = self.next("trailing_expr");
 521         println!("    if let Some({}) = &{}.expr;", trailing_pat, self.current);
 522         println!("    if {}.stmts.len() == {};", self.current, block.stmts.len());
 523         let current = self.current.clone();
 524         for (i, stmt) in block.stmts.iter().enumerate() {
 525             self.current = format!("{}.stmts[{}]", current, i);
 526             self.visit_stmt(stmt);
 527         }
 528     }
 529
 530     #[allow(clippy::too_many_lines)]
 531     fn visit_pat(&mut self, pat: &Pat<'_>) {
 532         print!("    if let PatKind::");
 533         let current = format!("{}.kind", self.current);
 534         match pat.kind {
 535             PatKind::Wild => println!("Wild = {};", current),
 536             PatKind::Binding(anno, .., ident, ref sub) => {
 537                 let anno_pat = match anno {
 538                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 539                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 540                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 541                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 542                 };
 543                 let name_pat = self.next("name");
 544                 if let Some(ref sub) = *sub {
 545                     let sub_pat = self.next("sub");
 546                     println!(
 547                         "Binding({}, _, {}, Some(ref {})) = {};",
 548                         anno_pat, name_pat, sub_pat, current
 549                     );
 550                     self.current = sub_pat;
 551                     self.visit_pat(sub);
 552                 } else {
 553                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 554                 }
 555                 println!("    if {}.as_str() == \"{}\";", name_pat, ident.as_str());
 556             },
 557             PatKind::Struct(ref path, ref fields, ignore) => {
 558                 let path_pat = self.next("path");
 559                 let fields_pat = self.next("fields");
 560                 println!(
 561                     "Struct(ref {}, ref {}, {}) = {};",
 562                     path_pat, fields_pat, ignore, current
 563                 );
 564                 self.current = path_pat;
 565                 self.print_qpath(path);
 566                 println!("    if {}.len() == {};", fields_pat, fields.len());
 567                 println!("    // unimplemented: field checks");
 568             },
 569             PatKind::Or(ref fields) => {
 570                 let fields_pat = self.next("fields");
 571                 println!("Or(ref {}) = {};", fields_pat, current);
 572                 println!("    if {}.len() == {};", fields_pat, fields.len());
 573                 println!("    // unimplemented: field checks");
 574             },
 575             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 576                 let path_pat = self.next("path");
 577                 let fields_pat = self.next("fields");
 578                 println!(
 579                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 580                     path_pat, fields_pat, skip_pos, current
 581                 );
 582                 self.current = path_pat;
 583                 self.print_qpath(path);
 584                 println!("    if {}.len() == {};", fields_pat, fields.len());
 585                 println!("    // unimplemented: field checks");
 586             },
 587             PatKind::Path(ref path) => {
 588                 let path_pat = self.next("path");
 589                 println!("Path(ref {}) = {};", path_pat, current);
 590                 self.current = path_pat;
 591                 self.print_qpath(path);
 592             },
 593             PatKind::Tuple(ref fields, skip_pos) => {
 594                 let fields_pat = self.next("fields");
 595                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 596                 println!("    if {}.len() == {};", fields_pat, fields.len());
 597                 println!("    // unimplemented: field checks");
 598             },
 599             PatKind::Box(ref pat) => {
 600                 let pat_pat = self.next("pat");
 601                 println!("Box(ref {}) = {};", pat_pat, current);
 602                 self.current = pat_pat;
 603                 self.visit_pat(pat);
 604             },
 605             PatKind::Ref(ref pat, muta) => {
 606                 let pat_pat = self.next("pat");
 607                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 608                 self.current = pat_pat;
 609                 self.visit_pat(pat);
 610             },
 611             PatKind::Lit(ref lit_expr) => {
 612                 let lit_expr_pat = self.next("lit_expr");
 613                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 614                 self.current = lit_expr_pat;
 615                 self.visit_expr(lit_expr);
 616             },
 617             PatKind::Range(ref start, ref end, end_kind) => {
 618                 let start_pat = self.next("start");
 619                 let end_pat = self.next("end");
 620                 println!(
 621                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 622                     start_pat, end_pat, end_kind, current
 623                 );
 624                 self.current = start_pat;
 625                 walk_list!(self, visit_expr, start);
 626                 self.current = end_pat;
 627                 walk_list!(self, visit_expr, end);
 628             },
 629             PatKind::Slice(ref start, ref middle, ref end) => {
 630                 let start_pat = self.next("start");
 631                 let end_pat = self.next("end");
 632                 if let Some(ref middle) = middle {
 633                     let middle_pat = self.next("middle");
 634                     println!(
 635                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 636                         start_pat, middle_pat, end_pat, current
 637                     );
 638                     self.current = middle_pat;
 639                     self.visit_pat(middle);
 640                 } else {
 641                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 642                 }
 643                 println!("    if {}.len() == {};", start_pat, start.len());
 644                 for (i, pat) in start.iter().enumerate() {
 645                     self.current = format!("{}[{}]", start_pat, i);
 646                     self.visit_pat(pat);
 647                 }
 648                 println!("    if {}.len() == {};", end_pat, end.len());
 649                 for (i, pat) in end.iter().enumerate() {
 650                     self.current = format!("{}[{}]", end_pat, i);
 651                     self.visit_pat(pat);
 652                 }
 653             },
 654         }
 655     }
 656
 657     fn visit_stmt(&mut self, s: &Stmt<'_>) {
 658         print!("    if let StmtKind::");
 659         let current = format!("{}.kind", self.current);
 660         match s.kind {
 661             // A local (let) binding:
 662             StmtKind::Local(ref local) => {
 663                 let local_pat = self.next("local");
 664                 println!("Local(ref {}) = {};", local_pat, current);
 665                 if let Some(ref init) = local.init {
 666                     let init_pat = self.next("init");
 667                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 668                     self.current = init_pat;
 669                     self.visit_expr(init);
 670                 }
 671                 self.current = format!("{}.pat", local_pat);
 672                 self.visit_pat(&local.pat);
 673             },
 674             // An item binding:
 675             StmtKind::Item(_) => {
 676                 println!("Item(item_id) = {};", current);
 677             },
 678
 679             // Expr without trailing semi-colon (must have unit type):
 680             StmtKind::Expr(ref e) => {
 681                 let e_pat = self.next("e");
 682                 println!("Expr(ref {}, _) = {}", e_pat, current);
 683                 self.current = e_pat;
 684                 self.visit_expr(e);
 685             },
 686
 687             // Expr with trailing semi-colon (may have any type):
 688             StmtKind::Semi(ref e) => {
 689                 let e_pat = self.next("e");
 690                 println!("Semi(ref {}, _) = {}", e_pat, current);
 691                 self.current = e_pat;
 692                 self.visit_expr(e);
 693             },
 694         }
 695     }
 696
 697     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 698         NestedVisitorMap::None
 699     }
 700 }
 701
 702 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 703     get_attr(sess, attrs, "author").count() > 0
 704 }
 705
 706 #[must_use]
 707 fn desugaring_name(des: hir::MatchSource) -> String {
 708     match des {
 709         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 710         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 711         hir::MatchSource::WhileDesugar => "MatchSource::WhileDesugar".to_string(),
 712         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 713         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 714         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 715             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 716             contains_else_clause
 717         ),
 718         hir::MatchSource::IfDesugar { contains_else_clause } => format!(
 719             "MatchSource::IfDesugar {{ contains_else_clause: {} }}",
 720             contains_else_clause
 721         ),
 722         hir::MatchSource::AwaitDesugar => "MatchSource::AwaitDesugar".to_string(),
 723     }
 724 }
 725
 726 #[must_use]
 727 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 728     match des {
 729         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 730         hir::LoopSource::Loop => "LoopSource::Loop",
 731         hir::LoopSource::While => "LoopSource::While",
 732         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 733     }
 734 }
 735
 736 fn print_path(path: &QPath<'_>, first: &mut bool) {
 737     match *path {
 738         QPath::Resolved(_, ref path) => {
 739             for segment in path.segments {
 740                 if *first {
 741                     *first = false;
 742                 } else {
 743                     print!(", ");
 744                 }
 745                 print!("{:?}", segment.ident.as_str());
 746             }
 747         },
 748         QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
 749             hir::TyKind::Path(ref inner_path) => {
 750                 print_path(inner_path, first);
 751                 if *first {
 752                     *first = false;
 753                 } else {
 754                     print!(", ");
 755                 }
 756                 print!("{:?}", segment.ident.as_str());
 757             },
 758             ref other => print!("/* unimplemented: {:?}*/", other),
 759         },
 760     }
 761 }