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::hir::map::Map;
   6 use rustc::session::Session;
   7 use rustc_ast::ast::{Attribute, LitFloatType, LitKind};
   8 use rustc_ast::walk_list;
   9 use rustc_data_structures::fx::FxHashMap;
  10 use rustc_hir as hir;
  11 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
  12 use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, Pat, PatKind, QPath, Stmt, StmtKind, TyKind};
  13 use rustc_lint::{LateContext, LateLintPass, LintContext};
  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         PrintVisitor::new("var").visit_variant(var, &hir::Generics::empty(), hir::DUMMY_HIR_ID);
 101         done();
 102     }
 103
 104     fn check_struct_field(&mut self, cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField<'_>) {
 105         if !has_attr(cx.sess(), &field.attrs) {
 106             return;
 107         }
 108         prelude();
 109         PrintVisitor::new("field").visit_struct_field(field);
 110         done();
 111     }
 112
 113     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) {
 114         if !has_attr(cx.sess(), &expr.attrs) {
 115             return;
 116         }
 117         prelude();
 118         PrintVisitor::new("expr").visit_expr(expr);
 119         done();
 120     }
 121
 122     fn check_arm(&mut self, cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm<'_>) {
 123         if !has_attr(cx.sess(), &arm.attrs) {
 124             return;
 125         }
 126         prelude();
 127         PrintVisitor::new("arm").visit_arm(arm);
 128         done();
 129     }
 130
 131     fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt<'_>) {
 132         if !has_attr(cx.sess(), stmt.kind.attrs()) {
 133             return;
 134         }
 135         prelude();
 136         PrintVisitor::new("stmt").visit_stmt(stmt);
 137         done();
 138     }
 139
 140     fn check_foreign_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem<'_>) {
 141         if !has_attr(cx.sess(), &item.attrs) {
 142             return;
 143         }
 144         prelude();
 145         PrintVisitor::new("item").visit_foreign_item(item);
 146         done();
 147     }
 148 }
 149
 150 impl PrintVisitor {
 151     #[must_use]
 152     fn new(s: &'static str) -> Self {
 153         Self {
 154             ids: FxHashMap::default(),
 155             current: s.to_owned(),
 156         }
 157     }
 158
 159     fn next(&mut self, s: &'static str) -> String {
 160         use std::collections::hash_map::Entry::{Occupied, Vacant};
 161         match self.ids.entry(s) {
 162             // already there: start numbering from `1`
 163             Occupied(mut occ) => {
 164                 let val = occ.get_mut();
 165                 *val += 1;
 166                 format!("{}{}", s, *val)
 167             },
 168             // not there: insert and return name as given
 169             Vacant(vac) => {
 170                 vac.insert(0);
 171                 s.to_owned()
 172             },
 173         }
 174     }
 175
 176     fn print_qpath(&mut self, path: &QPath<'_>) {
 177         print!("    if match_qpath({}, &[", self.current);
 178         print_path(path, &mut true);
 179         println!("]);");
 180     }
 181 }
 182
 183 struct PrintVisitor {
 184     /// Fields are the current index that needs to be appended to pattern
 185     /// binding names
 186     ids: FxHashMap<&'static str, usize>,
 187     /// the name that needs to be destructured
 188     current: String,
 189 }
 190
 191 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 192     type Map = Map<'tcx>;
 193
 194     #[allow(clippy::too_many_lines)]
 195     fn visit_expr(&mut self, expr: &Expr<'_>) {
 196         // handle if desugarings
 197         // TODO add more desugarings here
 198         if let Some((cond, then, opt_else)) = higher::if_block(&expr) {
 199             let cond_pat = self.next("cond");
 200             let then_pat = self.next("then");
 201             if let Some(else_) = opt_else {
 202                 let else_pat = self.next("else_");
 203                 println!(
 204                     "    if let Some((ref {}, ref {}, Some({}))) = higher::if_block(&{});",
 205                     cond_pat, then_pat, else_pat, self.current
 206                 );
 207                 self.current = else_pat;
 208                 self.visit_expr(else_);
 209             } else {
 210                 println!(
 211                     "    if let Some((ref {}, ref {}, None)) = higher::if_block(&{});",
 212                     cond_pat, then_pat, self.current
 213                 );
 214             }
 215             self.current = cond_pat;
 216             self.visit_expr(cond);
 217             self.current = then_pat;
 218             self.visit_expr(then);
 219             return;
 220         }
 221
 222         print!("    if let ExprKind::");
 223         let current = format!("{}.kind", self.current);
 224         match expr.kind {
 225             ExprKind::Box(ref inner) => {
 226                 let inner_pat = self.next("inner");
 227                 println!("Box(ref {}) = {};", inner_pat, current);
 228                 self.current = inner_pat;
 229                 self.visit_expr(inner);
 230             },
 231             ExprKind::Array(ref elements) => {
 232                 let elements_pat = self.next("elements");
 233                 println!("Array(ref {}) = {};", elements_pat, current);
 234                 println!("    if {}.len() == {};", elements_pat, elements.len());
 235                 for (i, element) in elements.iter().enumerate() {
 236                     self.current = format!("{}[{}]", elements_pat, i);
 237                     self.visit_expr(element);
 238                 }
 239             },
 240             ExprKind::Call(ref func, ref args) => {
 241                 let func_pat = self.next("func");
 242                 let args_pat = self.next("args");
 243                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 244                 self.current = func_pat;
 245                 self.visit_expr(func);
 246                 println!("    if {}.len() == {};", args_pat, args.len());
 247                 for (i, arg) in args.iter().enumerate() {
 248                     self.current = format!("{}[{}]", args_pat, i);
 249                     self.visit_expr(arg);
 250                 }
 251             },
 252             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args) => {
 253                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 254                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 255             },
 256             ExprKind::Tup(ref elements) => {
 257                 let elements_pat = self.next("elements");
 258                 println!("Tup(ref {}) = {};", elements_pat, current);
 259                 println!("    if {}.len() == {};", elements_pat, elements.len());
 260                 for (i, element) in elements.iter().enumerate() {
 261                     self.current = format!("{}[{}]", elements_pat, i);
 262                     self.visit_expr(element);
 263                 }
 264             },
 265             ExprKind::Binary(ref op, ref left, ref right) => {
 266                 let op_pat = self.next("op");
 267                 let left_pat = self.next("left");
 268                 let right_pat = self.next("right");
 269                 println!(
 270                     "Binary(ref {}, ref {}, ref {}) = {};",
 271                     op_pat, left_pat, right_pat, current
 272                 );
 273                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 274                 self.current = left_pat;
 275                 self.visit_expr(left);
 276                 self.current = right_pat;
 277                 self.visit_expr(right);
 278             },
 279             ExprKind::Unary(ref op, ref inner) => {
 280                 let inner_pat = self.next("inner");
 281                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 282                 self.current = inner_pat;
 283                 self.visit_expr(inner);
 284             },
 285             ExprKind::Lit(ref lit) => {
 286                 let lit_pat = self.next("lit");
 287                 println!("Lit(ref {}) = {};", lit_pat, current);
 288                 match lit.node {
 289                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 290                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 291                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 292                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 293                     // FIXME: also check int type
 294                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 295                     LitKind::Float(_, LitFloatType::Suffixed(_)) => println!(
 296                         "    if let LitKind::Float(_, LitFloatType::Suffixed(_)) = {}.node;",
 297                         lit_pat
 298                     ),
 299                     LitKind::Float(_, LitFloatType::Unsuffixed) => println!(
 300                         "    if let LitKind::Float(_, LitFloatType::Unsuffixed) = {}.node;",
 301                         lit_pat
 302                     ),
 303                     LitKind::ByteStr(ref vec) => {
 304                         let vec_pat = self.next("vec");
 305                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 306                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 307                     },
 308                     LitKind::Str(ref text, _) => {
 309                         let str_pat = self.next("s");
 310                         println!("    if let LitKind::Str(ref {}, _) = {}.node;", str_pat, lit_pat);
 311                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 312                     },
 313                 }
 314             },
 315             ExprKind::Cast(ref expr, ref ty) => {
 316                 let cast_pat = self.next("expr");
 317                 let cast_ty = self.next("cast_ty");
 318                 let qp_label = self.next("qp");
 319
 320                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 321                 if let TyKind::Path(ref qp) = ty.kind {
 322                     println!("    if let TyKind::Path(ref {}) = {}.kind;", qp_label, cast_ty);
 323                     self.current = qp_label;
 324                     self.print_qpath(qp);
 325                 }
 326                 self.current = cast_pat;
 327                 self.visit_expr(expr);
 328             },
 329             ExprKind::Type(ref expr, ref _ty) => {
 330                 let cast_pat = self.next("expr");
 331                 println!("Type(ref {}, _) = {};", cast_pat, current);
 332                 self.current = cast_pat;
 333                 self.visit_expr(expr);
 334             },
 335             ExprKind::Loop(ref body, _, desugaring) => {
 336                 let body_pat = self.next("body");
 337                 let des = loop_desugaring_name(desugaring);
 338                 let label_pat = self.next("label");
 339                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 340                 self.current = body_pat;
 341                 self.visit_block(body);
 342             },
 343             ExprKind::Match(ref expr, ref arms, desugaring) => {
 344                 let des = desugaring_name(desugaring);
 345                 let expr_pat = self.next("expr");
 346                 let arms_pat = self.next("arms");
 347                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 348                 self.current = expr_pat;
 349                 self.visit_expr(expr);
 350                 println!("    if {}.len() == {};", arms_pat, arms.len());
 351                 for (i, arm) in arms.iter().enumerate() {
 352                     self.current = format!("{}[{}].body", arms_pat, i);
 353                     self.visit_expr(&arm.body);
 354                     if let Some(ref guard) = arm.guard {
 355                         let guard_pat = self.next("guard");
 356                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 357                         match guard {
 358                             hir::Guard::If(ref if_expr) => {
 359                                 let if_expr_pat = self.next("expr");
 360                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 361                                 self.current = if_expr_pat;
 362                                 self.visit_expr(if_expr);
 363                             },
 364                         }
 365                     }
 366                     self.current = format!("{}[{}].pat", arms_pat, i);
 367                     self.visit_pat(&arm.pat);
 368                 }
 369             },
 370             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 371                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 372                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 373             },
 374             ExprKind::Yield(ref sub, _) => {
 375                 let sub_pat = self.next("sub");
 376                 println!("Yield(ref sub) = {};", current);
 377                 self.current = sub_pat;
 378                 self.visit_expr(sub);
 379             },
 380             ExprKind::Block(ref block, _) => {
 381                 let block_pat = self.next("block");
 382                 println!("Block(ref {}) = {};", block_pat, current);
 383                 self.current = block_pat;
 384                 self.visit_block(block);
 385             },
 386             ExprKind::Assign(ref target, ref value, _) => {
 387                 let target_pat = self.next("target");
 388                 let value_pat = self.next("value");
 389                 println!(
 390                     "Assign(ref {}, ref {}, ref _span) = {};",
 391                     target_pat, value_pat, current
 392                 );
 393                 self.current = target_pat;
 394                 self.visit_expr(target);
 395                 self.current = value_pat;
 396                 self.visit_expr(value);
 397             },
 398             ExprKind::AssignOp(ref op, ref target, ref value) => {
 399                 let op_pat = self.next("op");
 400                 let target_pat = self.next("target");
 401                 let value_pat = self.next("value");
 402                 println!(
 403                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 404                     op_pat, target_pat, value_pat, current
 405                 );
 406                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 407                 self.current = target_pat;
 408                 self.visit_expr(target);
 409                 self.current = value_pat;
 410                 self.visit_expr(value);
 411             },
 412             ExprKind::Field(ref object, ref field_ident) => {
 413                 let obj_pat = self.next("object");
 414                 let field_name_pat = self.next("field_name");
 415                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 416                 println!("    if {}.as_str() == {:?}", field_name_pat, field_ident.as_str());
 417                 self.current = obj_pat;
 418                 self.visit_expr(object);
 419             },
 420             ExprKind::Index(ref object, ref index) => {
 421                 let object_pat = self.next("object");
 422                 let index_pat = self.next("index");
 423                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 424                 self.current = object_pat;
 425                 self.visit_expr(object);
 426                 self.current = index_pat;
 427                 self.visit_expr(index);
 428             },
 429             ExprKind::Path(ref path) => {
 430                 let path_pat = self.next("path");
 431                 println!("Path(ref {}) = {};", path_pat, current);
 432                 self.current = path_pat;
 433                 self.print_qpath(path);
 434             },
 435             ExprKind::AddrOf(kind, mutability, ref inner) => {
 436                 let inner_pat = self.next("inner");
 437                 println!(
 438                     "AddrOf(BorrowKind::{:?}, Mutability::{:?}, ref {}) = {};",
 439                     kind, mutability, inner_pat, current
 440                 );
 441                 self.current = inner_pat;
 442                 self.visit_expr(inner);
 443             },
 444             ExprKind::Break(ref _destination, ref opt_value) => {
 445                 let destination_pat = self.next("destination");
 446                 if let Some(ref value) = *opt_value {
 447                     let value_pat = self.next("value");
 448                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 449                     self.current = value_pat;
 450                     self.visit_expr(value);
 451                 } else {
 452                     println!("Break(ref {}, None) = {};", destination_pat, current);
 453                 }
 454                 // FIXME: implement label printing
 455             },
 456             ExprKind::Continue(ref _destination) => {
 457                 let destination_pat = self.next("destination");
 458                 println!("Again(ref {}) = {};", destination_pat, current);
 459                 // FIXME: implement label printing
 460             },
 461             ExprKind::Ret(ref opt_value) => {
 462                 if let Some(ref value) = *opt_value {
 463                     let value_pat = self.next("value");
 464                     println!("Ret(Some(ref {})) = {};", value_pat, current);
 465                     self.current = value_pat;
 466                     self.visit_expr(value);
 467                 } else {
 468                     println!("Ret(None) = {};", current);
 469                 }
 470             },
 471             ExprKind::InlineAsm(_) => {
 472                 println!("InlineAsm(_) = {};", current);
 473                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 474             },
 475             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 476                 let path_pat = self.next("path");
 477                 let fields_pat = self.next("fields");
 478                 if let Some(ref base) = *opt_base {
 479                     let base_pat = self.next("base");
 480                     println!(
 481                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 482                         path_pat, fields_pat, base_pat, current
 483                     );
 484                     self.current = base_pat;
 485                     self.visit_expr(base);
 486                 } else {
 487                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 488                 }
 489                 self.current = path_pat;
 490                 self.print_qpath(path);
 491                 println!("    if {}.len() == {};", fields_pat, fields.len());
 492                 println!("    // unimplemented: field checks");
 493             },
 494             // FIXME: compute length (needs type info)
 495             ExprKind::Repeat(ref value, _) => {
 496                 let value_pat = self.next("value");
 497                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 498                 println!("// unimplemented: repeat count check");
 499                 self.current = value_pat;
 500                 self.visit_expr(value);
 501             },
 502             ExprKind::Err => {
 503                 println!("Err = {}", current);
 504             },
 505             ExprKind::DropTemps(ref expr) => {
 506                 let expr_pat = self.next("expr");
 507                 println!("DropTemps(ref {}) = {};", expr_pat, current);
 508                 self.current = expr_pat;
 509                 self.visit_expr(expr);
 510             },
 511         }
 512     }
 513
 514     fn visit_block(&mut self, block: &Block<'_>) {
 515         let trailing_pat = self.next("trailing_expr");
 516         println!("    if let Some({}) = &{}.expr;", trailing_pat, self.current);
 517         println!("    if {}.stmts.len() == {};", self.current, block.stmts.len());
 518         let current = self.current.clone();
 519         for (i, stmt) in block.stmts.iter().enumerate() {
 520             self.current = format!("{}.stmts[{}]", current, i);
 521             self.visit_stmt(stmt);
 522         }
 523     }
 524
 525     #[allow(clippy::too_many_lines)]
 526     fn visit_pat(&mut self, pat: &Pat<'_>) {
 527         print!("    if let PatKind::");
 528         let current = format!("{}.kind", self.current);
 529         match pat.kind {
 530             PatKind::Wild => println!("Wild = {};", current),
 531             PatKind::Binding(anno, .., ident, ref sub) => {
 532                 let anno_pat = match anno {
 533                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 534                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 535                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 536                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 537                 };
 538                 let name_pat = self.next("name");
 539                 if let Some(ref sub) = *sub {
 540                     let sub_pat = self.next("sub");
 541                     println!(
 542                         "Binding({}, _, {}, Some(ref {})) = {};",
 543                         anno_pat, name_pat, sub_pat, current
 544                     );
 545                     self.current = sub_pat;
 546                     self.visit_pat(sub);
 547                 } else {
 548                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 549                 }
 550                 println!("    if {}.as_str() == \"{}\";", name_pat, ident.as_str());
 551             },
 552             PatKind::Struct(ref path, ref fields, ignore) => {
 553                 let path_pat = self.next("path");
 554                 let fields_pat = self.next("fields");
 555                 println!(
 556                     "Struct(ref {}, ref {}, {}) = {};",
 557                     path_pat, fields_pat, ignore, current
 558                 );
 559                 self.current = path_pat;
 560                 self.print_qpath(path);
 561                 println!("    if {}.len() == {};", fields_pat, fields.len());
 562                 println!("    // unimplemented: field checks");
 563             },
 564             PatKind::Or(ref fields) => {
 565                 let fields_pat = self.next("fields");
 566                 println!("Or(ref {}) = {};", fields_pat, current);
 567                 println!("    if {}.len() == {};", fields_pat, fields.len());
 568                 println!("    // unimplemented: field checks");
 569             },
 570             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 571                 let path_pat = self.next("path");
 572                 let fields_pat = self.next("fields");
 573                 println!(
 574                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 575                     path_pat, fields_pat, skip_pos, current
 576                 );
 577                 self.current = path_pat;
 578                 self.print_qpath(path);
 579                 println!("    if {}.len() == {};", fields_pat, fields.len());
 580                 println!("    // unimplemented: field checks");
 581             },
 582             PatKind::Path(ref path) => {
 583                 let path_pat = self.next("path");
 584                 println!("Path(ref {}) = {};", path_pat, current);
 585                 self.current = path_pat;
 586                 self.print_qpath(path);
 587             },
 588             PatKind::Tuple(ref fields, skip_pos) => {
 589                 let fields_pat = self.next("fields");
 590                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 591                 println!("    if {}.len() == {};", fields_pat, fields.len());
 592                 println!("    // unimplemented: field checks");
 593             },
 594             PatKind::Box(ref pat) => {
 595                 let pat_pat = self.next("pat");
 596                 println!("Box(ref {}) = {};", pat_pat, current);
 597                 self.current = pat_pat;
 598                 self.visit_pat(pat);
 599             },
 600             PatKind::Ref(ref pat, muta) => {
 601                 let pat_pat = self.next("pat");
 602                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 603                 self.current = pat_pat;
 604                 self.visit_pat(pat);
 605             },
 606             PatKind::Lit(ref lit_expr) => {
 607                 let lit_expr_pat = self.next("lit_expr");
 608                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 609                 self.current = lit_expr_pat;
 610                 self.visit_expr(lit_expr);
 611             },
 612             PatKind::Range(ref start, ref end, end_kind) => {
 613                 let start_pat = self.next("start");
 614                 let end_pat = self.next("end");
 615                 println!(
 616                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 617                     start_pat, end_pat, end_kind, current
 618                 );
 619                 self.current = start_pat;
 620                 walk_list!(self, visit_expr, start);
 621                 self.current = end_pat;
 622                 walk_list!(self, visit_expr, end);
 623             },
 624             PatKind::Slice(ref start, ref middle, ref end) => {
 625                 let start_pat = self.next("start");
 626                 let end_pat = self.next("end");
 627                 if let Some(ref middle) = middle {
 628                     let middle_pat = self.next("middle");
 629                     println!(
 630                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 631                         start_pat, middle_pat, end_pat, current
 632                     );
 633                     self.current = middle_pat;
 634                     self.visit_pat(middle);
 635                 } else {
 636                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 637                 }
 638                 println!("    if {}.len() == {};", start_pat, start.len());
 639                 for (i, pat) in start.iter().enumerate() {
 640                     self.current = format!("{}[{}]", start_pat, i);
 641                     self.visit_pat(pat);
 642                 }
 643                 println!("    if {}.len() == {};", end_pat, end.len());
 644                 for (i, pat) in end.iter().enumerate() {
 645                     self.current = format!("{}[{}]", end_pat, i);
 646                     self.visit_pat(pat);
 647                 }
 648             },
 649         }
 650     }
 651
 652     fn visit_stmt(&mut self, s: &Stmt<'_>) {
 653         print!("    if let StmtKind::");
 654         let current = format!("{}.kind", self.current);
 655         match s.kind {
 656             // A local (let) binding:
 657             StmtKind::Local(ref local) => {
 658                 let local_pat = self.next("local");
 659                 println!("Local(ref {}) = {};", local_pat, current);
 660                 if let Some(ref init) = local.init {
 661                     let init_pat = self.next("init");
 662                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 663                     self.current = init_pat;
 664                     self.visit_expr(init);
 665                 }
 666                 self.current = format!("{}.pat", local_pat);
 667                 self.visit_pat(&local.pat);
 668             },
 669             // An item binding:
 670             StmtKind::Item(_) => {
 671                 println!("Item(item_id) = {};", current);
 672             },
 673
 674             // Expr without trailing semi-colon (must have unit type):
 675             StmtKind::Expr(ref e) => {
 676                 let e_pat = self.next("e");
 677                 println!("Expr(ref {}, _) = {}", e_pat, current);
 678                 self.current = e_pat;
 679                 self.visit_expr(e);
 680             },
 681
 682             // Expr with trailing semi-colon (may have any type):
 683             StmtKind::Semi(ref e) => {
 684                 let e_pat = self.next("e");
 685                 println!("Semi(ref {}, _) = {}", e_pat, current);
 686                 self.current = e_pat;
 687                 self.visit_expr(e);
 688             },
 689         }
 690     }
 691
 692     fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
 693         NestedVisitorMap::None
 694     }
 695 }
 696
 697 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 698     get_attr(sess, attrs, "author").count() > 0
 699 }
 700
 701 #[must_use]
 702 fn desugaring_name(des: hir::MatchSource) -> String {
 703     match des {
 704         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 705         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 706         hir::MatchSource::WhileDesugar => "MatchSource::WhileDesugar".to_string(),
 707         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 708         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 709         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 710             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 711             contains_else_clause
 712         ),
 713         hir::MatchSource::IfDesugar { contains_else_clause } => format!(
 714             "MatchSource::IfDesugar {{ contains_else_clause: {} }}",
 715             contains_else_clause
 716         ),
 717         hir::MatchSource::AwaitDesugar => "MatchSource::AwaitDesugar".to_string(),
 718     }
 719 }
 720
 721 #[must_use]
 722 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 723     match des {
 724         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 725         hir::LoopSource::Loop => "LoopSource::Loop",
 726         hir::LoopSource::While => "LoopSource::While",
 727         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 728     }
 729 }
 730
 731 fn print_path(path: &QPath<'_>, first: &mut bool) {
 732     match *path {
 733         QPath::Resolved(_, ref path) => {
 734             for segment in path.segments {
 735                 if *first {
 736                     *first = false;
 737                 } else {
 738                     print!(", ");
 739                 }
 740                 print!("{:?}", segment.ident.as_str());
 741             }
 742         },
 743         QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
 744             hir::TyKind::Path(ref inner_path) => {
 745                 print_path(inner_path, first);
 746                 if *first {
 747                     *first = false;
 748                 } else {
 749                     print!(", ");
 750                 }
 751                 print!("{:?}", segment.ident.as_str());
 752             },
 753             ref other => print!("/* unimplemented: {:?}*/", other),
 754         },
 755     }
 756 }