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;
   6 use rustc::hir::intravisit::{NestedVisitorMap, Visitor};
   7 use rustc::hir::{BindingAnnotation, Block, Expr, ExprKind, Pat, PatKind, QPath, Stmt, StmtKind, TyKind};
   8 use rustc::lint::{LateContext, LateLintPass, LintArray, LintContext, LintPass};
   9 use rustc::session::Session;
  10 use rustc::{declare_lint_pass, declare_tool_lint};
  11 use rustc_data_structures::fx::FxHashMap;
  12 use syntax::ast::{Attribute, LitFloatType, LitKind};
  13
  14 declare_clippy_lint! {
  15     /// **What it does:** Generates clippy code that detects the offending pattern
  16     ///
  17     /// **Example:**
  18     /// ```rust,ignore
  19     /// // ./tests/ui/my_lint.rs
  20     /// fn foo() {
  21     ///     // detect the following pattern
  22     ///     #[clippy::author]
  23     ///     if x == 42 {
  24     ///         // but ignore everything from here on
  25     ///         #![clippy::author = "ignore"]
  26     ///     }
  27     ///     ()
  28     /// }
  29     /// ```
  30     ///
  31     /// Running `TESTNAME=ui/my_lint cargo uitest` will produce
  32     /// a `./tests/ui/new_lint.stdout` file with the generated code:
  33     ///
  34     /// ```rust,ignore
  35     /// // ./tests/ui/new_lint.stdout
  36     /// if_chain! {
  37     ///     if let ExprKind::If(ref cond, ref then, None) = item.kind,
  38     ///     if let ExprKind::Binary(BinOp::Eq, ref left, ref right) = cond.kind,
  39     ///     if let ExprKind::Path(ref path) = left.kind,
  40     ///     if let ExprKind::Lit(ref lit) = right.kind,
  41     ///     if let LitKind::Int(42, _) = lit.node,
  42     ///     then {
  43     ///         // report your lint here
  44     ///     }
  45     /// }
  46     /// ```
  47     pub LINT_AUTHOR,
  48     internal_warn,
  49     "helper for writing lints"
  50 }
  51
  52 declare_lint_pass!(Author => [LINT_AUTHOR]);
  53
  54 fn prelude() {
  55     println!("if_chain! {{");
  56 }
  57
  58 fn done() {
  59     println!("    then {{");
  60     println!("        // report your lint here");
  61     println!("    }}");
  62     println!("}}");
  63 }
  64
  65 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Author {
  66     fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
  67         if !has_attr(cx.sess(), &item.attrs) {
  68             return;
  69         }
  70         prelude();
  71         PrintVisitor::new("item").visit_item(item);
  72         done();
  73     }
  74
  75     fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
  76         if !has_attr(cx.sess(), &item.attrs) {
  77             return;
  78         }
  79         prelude();
  80         PrintVisitor::new("item").visit_impl_item(item);
  81         done();
  82     }
  83
  84     fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
  85         if !has_attr(cx.sess(), &item.attrs) {
  86             return;
  87         }
  88         prelude();
  89         PrintVisitor::new("item").visit_trait_item(item);
  90         done();
  91     }
  92
  93     fn check_variant(&mut self, cx: &LateContext<'a, 'tcx>, var: &'tcx hir::Variant) {
  94         if !has_attr(cx.sess(), &var.attrs) {
  95             return;
  96         }
  97         prelude();
  98         PrintVisitor::new("var").visit_variant(var, &hir::Generics::empty(), hir::DUMMY_HIR_ID);
  99         done();
 100     }
 101
 102     fn check_struct_field(&mut self, cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
 103         if !has_attr(cx.sess(), &field.attrs) {
 104             return;
 105         }
 106         prelude();
 107         PrintVisitor::new("field").visit_struct_field(field);
 108         done();
 109     }
 110
 111     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
 112         if !has_attr(cx.sess(), &expr.attrs) {
 113             return;
 114         }
 115         prelude();
 116         PrintVisitor::new("expr").visit_expr(expr);
 117         done();
 118     }
 119
 120     fn check_arm(&mut self, cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm) {
 121         if !has_attr(cx.sess(), &arm.attrs) {
 122             return;
 123         }
 124         prelude();
 125         PrintVisitor::new("arm").visit_arm(arm);
 126         done();
 127     }
 128
 129     fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt) {
 130         if !has_attr(cx.sess(), stmt.kind.attrs()) {
 131             return;
 132         }
 133         prelude();
 134         PrintVisitor::new("stmt").visit_stmt(stmt);
 135         done();
 136     }
 137
 138     fn check_foreign_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem) {
 139         if !has_attr(cx.sess(), &item.attrs) {
 140             return;
 141         }
 142         prelude();
 143         PrintVisitor::new("item").visit_foreign_item(item);
 144         done();
 145     }
 146 }
 147
 148 impl PrintVisitor {
 149     #[must_use]
 150     fn new(s: &'static str) -> Self {
 151         Self {
 152             ids: FxHashMap::default(),
 153             current: s.to_owned(),
 154         }
 155     }
 156
 157     fn next(&mut self, s: &'static str) -> String {
 158         use std::collections::hash_map::Entry::*;
 159         match self.ids.entry(s) {
 160             // already there: start numbering from `1`
 161             Occupied(mut occ) => {
 162                 let val = occ.get_mut();
 163                 *val += 1;
 164                 format!("{}{}", s, *val)
 165             },
 166             // not there: insert and return name as given
 167             Vacant(vac) => {
 168                 vac.insert(0);
 169                 s.to_owned()
 170             },
 171         }
 172     }
 173
 174     fn print_qpath(&mut self, path: &QPath) {
 175         print!("    if match_qpath({}, &[", self.current);
 176         print_path(path, &mut true);
 177         println!("]);");
 178     }
 179 }
 180
 181 struct PrintVisitor {
 182     /// Fields are the current index that needs to be appended to pattern
 183     /// binding names
 184     ids: FxHashMap<&'static str, usize>,
 185     /// the name that needs to be destructured
 186     current: String,
 187 }
 188
 189 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 190     #[allow(clippy::too_many_lines)]
 191     fn visit_expr(&mut self, expr: &Expr) {
 192         // handle if desugarings
 193         // TODO add more desugarings here
 194         if let Some((cond, then, opt_else)) = higher::if_block(&expr) {
 195             let cond_pat = self.next("cond");
 196             let then_pat = self.next("then");
 197             if let Some(else_) = opt_else {
 198                 let else_pat = self.next("else_");
 199                 println!(
 200                     "    if let Some((ref {}, ref {}, Some({}))) = higher::if_block(&{});",
 201                     cond_pat, then_pat, else_pat, self.current
 202                 );
 203                 self.current = else_pat;
 204                 self.visit_expr(else_);
 205             } else {
 206                 println!(
 207                     "    if let Some((ref {}, ref {}, None)) = higher::if_block(&{});",
 208                     cond_pat, then_pat, self.current
 209                 );
 210             }
 211             self.current = cond_pat;
 212             self.visit_expr(cond);
 213             self.current = then_pat;
 214             self.visit_expr(then);
 215             return;
 216         }
 217
 218         print!("    if let ExprKind::");
 219         let current = format!("{}.kind", self.current);
 220         match expr.kind {
 221             ExprKind::Box(ref inner) => {
 222                 let inner_pat = self.next("inner");
 223                 println!("Box(ref {}) = {};", inner_pat, current);
 224                 self.current = inner_pat;
 225                 self.visit_expr(inner);
 226             },
 227             ExprKind::Array(ref elements) => {
 228                 let elements_pat = self.next("elements");
 229                 println!("Array(ref {}) = {};", elements_pat, current);
 230                 println!("    if {}.len() == {};", elements_pat, elements.len());
 231                 for (i, element) in elements.iter().enumerate() {
 232                     self.current = format!("{}[{}]", elements_pat, i);
 233                     self.visit_expr(element);
 234                 }
 235             },
 236             ExprKind::Call(ref func, ref args) => {
 237                 let func_pat = self.next("func");
 238                 let args_pat = self.next("args");
 239                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 240                 self.current = func_pat;
 241                 self.visit_expr(func);
 242                 println!("    if {}.len() == {};", args_pat, args.len());
 243                 for (i, arg) in args.iter().enumerate() {
 244                     self.current = format!("{}[{}]", args_pat, i);
 245                     self.visit_expr(arg);
 246                 }
 247             },
 248             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args) => {
 249                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 250                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 251             },
 252             ExprKind::Tup(ref elements) => {
 253                 let elements_pat = self.next("elements");
 254                 println!("Tup(ref {}) = {};", elements_pat, current);
 255                 println!("    if {}.len() == {};", elements_pat, elements.len());
 256                 for (i, element) in elements.iter().enumerate() {
 257                     self.current = format!("{}[{}]", elements_pat, i);
 258                     self.visit_expr(element);
 259                 }
 260             },
 261             ExprKind::Binary(ref op, ref left, ref right) => {
 262                 let op_pat = self.next("op");
 263                 let left_pat = self.next("left");
 264                 let right_pat = self.next("right");
 265                 println!(
 266                     "Binary(ref {}, ref {}, ref {}) = {};",
 267                     op_pat, left_pat, right_pat, current
 268                 );
 269                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 270                 self.current = left_pat;
 271                 self.visit_expr(left);
 272                 self.current = right_pat;
 273                 self.visit_expr(right);
 274             },
 275             ExprKind::Unary(ref op, ref inner) => {
 276                 let inner_pat = self.next("inner");
 277                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 278                 self.current = inner_pat;
 279                 self.visit_expr(inner);
 280             },
 281             ExprKind::Lit(ref lit) => {
 282                 let lit_pat = self.next("lit");
 283                 println!("Lit(ref {}) = {};", lit_pat, current);
 284                 match lit.node {
 285                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 286                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 287                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 288                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 289                     // FIXME: also check int type
 290                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 291                     LitKind::Float(_, LitFloatType::Suffixed(_)) => println!(
 292                         "    if let LitKind::Float(_, LitFloatType::Suffixed(_)) = {}.node;",
 293                         lit_pat
 294                     ),
 295                     LitKind::Float(_, LitFloatType::Unsuffixed) => println!(
 296                         "    if let LitKind::Float(_, LitFloatType::Unsuffixed) = {}.node;",
 297                         lit_pat
 298                     ),
 299                     LitKind::ByteStr(ref vec) => {
 300                         let vec_pat = self.next("vec");
 301                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 302                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 303                     },
 304                     LitKind::Str(ref text, _) => {
 305                         let str_pat = self.next("s");
 306                         println!("    if let LitKind::Str(ref {}, _) = {}.node;", str_pat, lit_pat);
 307                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 308                     },
 309                 }
 310             },
 311             ExprKind::Cast(ref expr, ref ty) => {
 312                 let cast_pat = self.next("expr");
 313                 let cast_ty = self.next("cast_ty");
 314                 let qp_label = self.next("qp");
 315
 316                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 317                 if let TyKind::Path(ref qp) = ty.kind {
 318                     println!("    if let TyKind::Path(ref {}) = {}.kind;", qp_label, cast_ty);
 319                     self.current = qp_label;
 320                     self.print_qpath(qp);
 321                 }
 322                 self.current = cast_pat;
 323                 self.visit_expr(expr);
 324             },
 325             ExprKind::Type(ref expr, ref _ty) => {
 326                 let cast_pat = self.next("expr");
 327                 println!("Type(ref {}, _) = {};", cast_pat, current);
 328                 self.current = cast_pat;
 329                 self.visit_expr(expr);
 330             },
 331             ExprKind::Loop(ref body, _, desugaring) => {
 332                 let body_pat = self.next("body");
 333                 let des = loop_desugaring_name(desugaring);
 334                 let label_pat = self.next("label");
 335                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 336                 self.current = body_pat;
 337                 self.visit_block(body);
 338             },
 339             ExprKind::Match(ref expr, ref arms, desugaring) => {
 340                 let des = desugaring_name(desugaring);
 341                 let expr_pat = self.next("expr");
 342                 let arms_pat = self.next("arms");
 343                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 344                 self.current = expr_pat;
 345                 self.visit_expr(expr);
 346                 println!("    if {}.len() == {};", arms_pat, arms.len());
 347                 for (i, arm) in arms.iter().enumerate() {
 348                     self.current = format!("{}[{}].body", arms_pat, i);
 349                     self.visit_expr(&arm.body);
 350                     if let Some(ref guard) = arm.guard {
 351                         let guard_pat = self.next("guard");
 352                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 353                         match guard {
 354                             hir::Guard::If(ref if_expr) => {
 355                                 let if_expr_pat = self.next("expr");
 356                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 357                                 self.current = if_expr_pat;
 358                                 self.visit_expr(if_expr);
 359                             },
 360                         }
 361                     }
 362                     self.current = format!("{}[{}].pat", arms_pat, i);
 363                     self.visit_pat(&arm.pat);
 364                 }
 365             },
 366             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 367                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 368                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 369             },
 370             ExprKind::Yield(ref sub, _) => {
 371                 let sub_pat = self.next("sub");
 372                 println!("Yield(ref sub) = {};", current);
 373                 self.current = sub_pat;
 374                 self.visit_expr(sub);
 375             },
 376             ExprKind::Block(ref block, _) => {
 377                 let block_pat = self.next("block");
 378                 println!("Block(ref {}) = {};", block_pat, current);
 379                 self.current = block_pat;
 380                 self.visit_block(block);
 381             },
 382             ExprKind::Assign(ref target, ref value) => {
 383                 let target_pat = self.next("target");
 384                 let value_pat = self.next("value");
 385                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 386                 self.current = target_pat;
 387                 self.visit_expr(target);
 388                 self.current = value_pat;
 389                 self.visit_expr(value);
 390             },
 391             ExprKind::AssignOp(ref op, ref target, ref value) => {
 392                 let op_pat = self.next("op");
 393                 let target_pat = self.next("target");
 394                 let value_pat = self.next("value");
 395                 println!(
 396                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 397                     op_pat, target_pat, value_pat, current
 398                 );
 399                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 400                 self.current = target_pat;
 401                 self.visit_expr(target);
 402                 self.current = value_pat;
 403                 self.visit_expr(value);
 404             },
 405             ExprKind::Field(ref object, ref field_ident) => {
 406                 let obj_pat = self.next("object");
 407                 let field_name_pat = self.next("field_name");
 408                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 409                 println!("    if {}.as_str() == {:?}", field_name_pat, field_ident.as_str());
 410                 self.current = obj_pat;
 411                 self.visit_expr(object);
 412             },
 413             ExprKind::Index(ref object, ref index) => {
 414                 let object_pat = self.next("object");
 415                 let index_pat = self.next("index");
 416                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 417                 self.current = object_pat;
 418                 self.visit_expr(object);
 419                 self.current = index_pat;
 420                 self.visit_expr(index);
 421             },
 422             ExprKind::Path(ref path) => {
 423                 let path_pat = self.next("path");
 424                 println!("Path(ref {}) = {};", path_pat, current);
 425                 self.current = path_pat;
 426                 self.print_qpath(path);
 427             },
 428             ExprKind::AddrOf(mutability, ref inner) => {
 429                 let inner_pat = self.next("inner");
 430                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 431                 self.current = inner_pat;
 432                 self.visit_expr(inner);
 433             },
 434             ExprKind::Break(ref _destination, ref opt_value) => {
 435                 let destination_pat = self.next("destination");
 436                 if let Some(ref value) = *opt_value {
 437                     let value_pat = self.next("value");
 438                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 439                     self.current = value_pat;
 440                     self.visit_expr(value);
 441                 } else {
 442                     println!("Break(ref {}, None) = {};", destination_pat, current);
 443                 }
 444                 // FIXME: implement label printing
 445             },
 446             ExprKind::Continue(ref _destination) => {
 447                 let destination_pat = self.next("destination");
 448                 println!("Again(ref {}) = {};", destination_pat, current);
 449                 // FIXME: implement label printing
 450             },
 451             ExprKind::Ret(ref opt_value) => {
 452                 if let Some(ref value) = *opt_value {
 453                     let value_pat = self.next("value");
 454                     println!("Ret(Some(ref {})) = {};", value_pat, current);
 455                     self.current = value_pat;
 456                     self.visit_expr(value);
 457                 } else {
 458                     println!("Ret(None) = {};", current);
 459                 }
 460             },
 461             ExprKind::InlineAsm(_, ref _input, ref _output) => {
 462                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 463                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 464             },
 465             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 466                 let path_pat = self.next("path");
 467                 let fields_pat = self.next("fields");
 468                 if let Some(ref base) = *opt_base {
 469                     let base_pat = self.next("base");
 470                     println!(
 471                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 472                         path_pat, fields_pat, base_pat, current
 473                     );
 474                     self.current = base_pat;
 475                     self.visit_expr(base);
 476                 } else {
 477                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 478                 }
 479                 self.current = path_pat;
 480                 self.print_qpath(path);
 481                 println!("    if {}.len() == {};", fields_pat, fields.len());
 482                 println!("    // unimplemented: field checks");
 483             },
 484             // FIXME: compute length (needs type info)
 485             ExprKind::Repeat(ref value, _) => {
 486                 let value_pat = self.next("value");
 487                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 488                 println!("// unimplemented: repeat count check");
 489                 self.current = value_pat;
 490                 self.visit_expr(value);
 491             },
 492             ExprKind::Err => {
 493                 println!("Err = {}", current);
 494             },
 495             ExprKind::DropTemps(ref expr) => {
 496                 let expr_pat = self.next("expr");
 497                 println!("DropTemps(ref {}) = {};", expr_pat, current);
 498                 self.current = expr_pat;
 499                 self.visit_expr(expr);
 500             },
 501         }
 502     }
 503
 504     fn visit_block(&mut self, block: &Block) {
 505         let trailing_pat = self.next("trailing_expr");
 506         println!("    if let Some({}) = &{}.expr;", trailing_pat, self.current);
 507         println!("    if {}.stmts.len() == {};", self.current, block.stmts.len());
 508         let current = self.current.clone();
 509         for (i, stmt) in block.stmts.iter().enumerate() {
 510             self.current = format!("{}.stmts[{}]", current, i);
 511             self.visit_stmt(stmt);
 512         }
 513     }
 514
 515     #[allow(clippy::too_many_lines)]
 516     fn visit_pat(&mut self, pat: &Pat) {
 517         print!("    if let PatKind::");
 518         let current = format!("{}.kind", self.current);
 519         match pat.kind {
 520             PatKind::Wild => println!("Wild = {};", current),
 521             PatKind::Binding(anno, .., ident, ref sub) => {
 522                 let anno_pat = match anno {
 523                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 524                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 525                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 526                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 527                 };
 528                 let name_pat = self.next("name");
 529                 if let Some(ref sub) = *sub {
 530                     let sub_pat = self.next("sub");
 531                     println!(
 532                         "Binding({}, _, {}, Some(ref {})) = {};",
 533                         anno_pat, name_pat, sub_pat, current
 534                     );
 535                     self.current = sub_pat;
 536                     self.visit_pat(sub);
 537                 } else {
 538                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 539                 }
 540                 println!("    if {}.as_str() == \"{}\";", name_pat, ident.as_str());
 541             },
 542             PatKind::Struct(ref path, ref fields, ignore) => {
 543                 let path_pat = self.next("path");
 544                 let fields_pat = self.next("fields");
 545                 println!(
 546                     "Struct(ref {}, ref {}, {}) = {};",
 547                     path_pat, fields_pat, ignore, current
 548                 );
 549                 self.current = path_pat;
 550                 self.print_qpath(path);
 551                 println!("    if {}.len() == {};", fields_pat, fields.len());
 552                 println!("    // unimplemented: field checks");
 553             },
 554             PatKind::Or(ref fields) => {
 555                 let fields_pat = self.next("fields");
 556                 println!("Or(ref {}) = {};", fields_pat, current);
 557                 println!("    if {}.len() == {};", fields_pat, fields.len());
 558                 println!("    // unimplemented: field checks");
 559             },
 560             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 561                 let path_pat = self.next("path");
 562                 let fields_pat = self.next("fields");
 563                 println!(
 564                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 565                     path_pat, fields_pat, skip_pos, current
 566                 );
 567                 self.current = path_pat;
 568                 self.print_qpath(path);
 569                 println!("    if {}.len() == {};", fields_pat, fields.len());
 570                 println!("    // unimplemented: field checks");
 571             },
 572             PatKind::Path(ref path) => {
 573                 let path_pat = self.next("path");
 574                 println!("Path(ref {}) = {};", path_pat, current);
 575                 self.current = path_pat;
 576                 self.print_qpath(path);
 577             },
 578             PatKind::Tuple(ref fields, skip_pos) => {
 579                 let fields_pat = self.next("fields");
 580                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 581                 println!("    if {}.len() == {};", fields_pat, fields.len());
 582                 println!("    // unimplemented: field checks");
 583             },
 584             PatKind::Box(ref pat) => {
 585                 let pat_pat = self.next("pat");
 586                 println!("Box(ref {}) = {};", pat_pat, current);
 587                 self.current = pat_pat;
 588                 self.visit_pat(pat);
 589             },
 590             PatKind::Ref(ref pat, muta) => {
 591                 let pat_pat = self.next("pat");
 592                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 593                 self.current = pat_pat;
 594                 self.visit_pat(pat);
 595             },
 596             PatKind::Lit(ref lit_expr) => {
 597                 let lit_expr_pat = self.next("lit_expr");
 598                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 599                 self.current = lit_expr_pat;
 600                 self.visit_expr(lit_expr);
 601             },
 602             PatKind::Range(ref start, ref end, end_kind) => {
 603                 let start_pat = self.next("start");
 604                 let end_pat = self.next("end");
 605                 println!(
 606                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 607                     start_pat, end_pat, end_kind, current
 608                 );
 609                 self.current = start_pat;
 610                 self.visit_expr(start);
 611                 self.current = end_pat;
 612                 self.visit_expr(end);
 613             },
 614             PatKind::Slice(ref start, ref middle, ref end) => {
 615                 let start_pat = self.next("start");
 616                 let end_pat = self.next("end");
 617                 if let Some(ref middle) = middle {
 618                     let middle_pat = self.next("middle");
 619                     println!(
 620                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 621                         start_pat, middle_pat, end_pat, current
 622                     );
 623                     self.current = middle_pat;
 624                     self.visit_pat(middle);
 625                 } else {
 626                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 627                 }
 628                 println!("    if {}.len() == {};", start_pat, start.len());
 629                 for (i, pat) in start.iter().enumerate() {
 630                     self.current = format!("{}[{}]", start_pat, i);
 631                     self.visit_pat(pat);
 632                 }
 633                 println!("    if {}.len() == {};", end_pat, end.len());
 634                 for (i, pat) in end.iter().enumerate() {
 635                     self.current = format!("{}[{}]", end_pat, i);
 636                     self.visit_pat(pat);
 637                 }
 638             },
 639         }
 640     }
 641
 642     fn visit_stmt(&mut self, s: &Stmt) {
 643         print!("    if let StmtKind::");
 644         let current = format!("{}.kind", self.current);
 645         match s.kind {
 646             // A local (let) binding:
 647             StmtKind::Local(ref local) => {
 648                 let local_pat = self.next("local");
 649                 println!("Local(ref {}) = {};", local_pat, current);
 650                 if let Some(ref init) = local.init {
 651                     let init_pat = self.next("init");
 652                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 653                     self.current = init_pat;
 654                     self.visit_expr(init);
 655                 }
 656                 self.current = format!("{}.pat", local_pat);
 657                 self.visit_pat(&local.pat);
 658             },
 659             // An item binding:
 660             StmtKind::Item(_) => {
 661                 println!("Item(item_id) = {};", current);
 662             },
 663
 664             // Expr without trailing semi-colon (must have unit type):
 665             StmtKind::Expr(ref e) => {
 666                 let e_pat = self.next("e");
 667                 println!("Expr(ref {}, _) = {}", e_pat, current);
 668                 self.current = e_pat;
 669                 self.visit_expr(e);
 670             },
 671
 672             // Expr with trailing semi-colon (may have any type):
 673             StmtKind::Semi(ref e) => {
 674                 let e_pat = self.next("e");
 675                 println!("Semi(ref {}, _) = {}", e_pat, current);
 676                 self.current = e_pat;
 677                 self.visit_expr(e);
 678             },
 679         }
 680     }
 681
 682     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 683         NestedVisitorMap::None
 684     }
 685 }
 686
 687 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 688     get_attr(sess, attrs, "author").count() > 0
 689 }
 690
 691 #[must_use]
 692 fn desugaring_name(des: hir::MatchSource) -> String {
 693     match des {
 694         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 695         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 696         hir::MatchSource::WhileDesugar => "MatchSource::WhileDesugar".to_string(),
 697         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 698         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 699         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 700             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 701             contains_else_clause
 702         ),
 703         hir::MatchSource::IfDesugar { contains_else_clause } => format!(
 704             "MatchSource::IfDesugar {{ contains_else_clause: {} }}",
 705             contains_else_clause
 706         ),
 707         hir::MatchSource::AwaitDesugar => "MatchSource::AwaitDesugar".to_string(),
 708     }
 709 }
 710
 711 #[must_use]
 712 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 713     match des {
 714         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 715         hir::LoopSource::Loop => "LoopSource::Loop",
 716         hir::LoopSource::While => "LoopSource::While",
 717         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 718     }
 719 }
 720
 721 fn print_path(path: &QPath, first: &mut bool) {
 722     match *path {
 723         QPath::Resolved(_, ref path) => {
 724             for segment in &path.segments {
 725                 if *first {
 726                     *first = false;
 727                 } else {
 728                     print!(", ");
 729                 }
 730                 print!("{:?}", segment.ident.as_str());
 731             }
 732         },
 733         QPath::TypeRelative(ref ty, ref segment) => match ty.kind {
 734             hir::TyKind::Path(ref inner_path) => {
 735                 print_path(inner_path, first);
 736                 if *first {
 737                     *first = false;
 738                 } else {
 739                     print!(", ");
 740                 }
 741                 print!("{:?}", segment.ident.as_str());
 742             },
 743             ref other => print!("/* unimplemented: {:?}*/", other),
 744         },
 745     }
 746 }