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, LitKind};
  13
  14 declare_clippy_lint! {
  15     /// **What it does:** Generates clippy code that detects the offending pattern
  16     ///
  17     /// **Example:**
  18     /// ```rust
  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     /// Running `TESTNAME=ui/my_lint cargo uitest` will produce
  31     /// a `./tests/ui/new_lint.stdout` file with the generated code:
  32     ///
  33     /// ```rust
  34     /// // ./tests/ui/new_lint.stdout
  35     /// if_chain! {
  36     ///     if let ExprKind::If(ref cond, ref then, None) = item.node,
  37     ///     if let ExprKind::Binary(BinOp::Eq, ref left, ref right) = cond.node,
  38     ///     if let ExprKind::Path(ref path) = left.node,
  39     ///     if let ExprKind::Lit(ref lit) = right.node,
  40     ///     if let LitKind::Int(42, _) = lit.node,
  41     ///     then {
  42     ///         // report your lint here
  43     ///     }
  44     /// }
  45     /// ```
  46     pub LINT_AUTHOR,
  47     internal_warn,
  48     "helper for writing lints"
  49 }
  50
  51 declare_lint_pass!(Author => [LINT_AUTHOR]);
  52
  53 fn prelude() {
  54     println!("if_chain! {{");
  55 }
  56
  57 fn done() {
  58     println!("    then {{");
  59     println!("        // report your lint here");
  60     println!("    }}");
  61     println!("}}");
  62 }
  63
  64 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Author {
  65     fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
  66         if !has_attr(cx.sess(), &item.attrs) {
  67             return;
  68         }
  69         prelude();
  70         PrintVisitor::new("item").visit_item(item);
  71         done();
  72     }
  73
  74     fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
  75         if !has_attr(cx.sess(), &item.attrs) {
  76             return;
  77         }
  78         prelude();
  79         PrintVisitor::new("item").visit_impl_item(item);
  80         done();
  81     }
  82
  83     fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
  84         if !has_attr(cx.sess(), &item.attrs) {
  85             return;
  86         }
  87         prelude();
  88         PrintVisitor::new("item").visit_trait_item(item);
  89         done();
  90     }
  91
  92     fn check_variant(&mut self, cx: &LateContext<'a, 'tcx>, var: &'tcx hir::Variant, generics: &hir::Generics) {
  93         if !has_attr(cx.sess(), &var.node.attrs) {
  94             return;
  95         }
  96         prelude();
  97         PrintVisitor::new("var").visit_variant(var, generics, hir::DUMMY_HIR_ID);
  98         done();
  99     }
 100
 101     fn check_struct_field(&mut self, cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
 102         if !has_attr(cx.sess(), &field.attrs) {
 103             return;
 104         }
 105         prelude();
 106         PrintVisitor::new("field").visit_struct_field(field);
 107         done();
 108     }
 109
 110     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
 111         if !has_attr(cx.sess(), &expr.attrs) {
 112             return;
 113         }
 114         prelude();
 115         PrintVisitor::new("expr").visit_expr(expr);
 116         done();
 117     }
 118
 119     fn check_arm(&mut self, cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm) {
 120         if !has_attr(cx.sess(), &arm.attrs) {
 121             return;
 122         }
 123         prelude();
 124         PrintVisitor::new("arm").visit_arm(arm);
 125         done();
 126     }
 127
 128     fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt) {
 129         if !has_attr(cx.sess(), stmt.node.attrs()) {
 130             return;
 131         }
 132         prelude();
 133         PrintVisitor::new("stmt").visit_stmt(stmt);
 134         done();
 135     }
 136
 137     fn check_foreign_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem) {
 138         if !has_attr(cx.sess(), &item.attrs) {
 139             return;
 140         }
 141         prelude();
 142         PrintVisitor::new("item").visit_foreign_item(item);
 143         done();
 144     }
 145 }
 146
 147 impl PrintVisitor {
 148     fn new(s: &'static str) -> Self {
 149         Self {
 150             ids: FxHashMap::default(),
 151             current: s.to_owned(),
 152         }
 153     }
 154
 155     fn next(&mut self, s: &'static str) -> String {
 156         use std::collections::hash_map::Entry::*;
 157         match self.ids.entry(s) {
 158             // already there: start numbering from `1`
 159             Occupied(mut occ) => {
 160                 let val = occ.get_mut();
 161                 *val += 1;
 162                 format!("{}{}", s, *val)
 163             },
 164             // not there: insert and return name as given
 165             Vacant(vac) => {
 166                 vac.insert(0);
 167                 s.to_owned()
 168             },
 169         }
 170     }
 171
 172     fn print_qpath(&mut self, path: &QPath) {
 173         print!("    if match_qpath({}, &[", self.current);
 174         print_path(path, &mut true);
 175         println!("]);");
 176     }
 177 }
 178
 179 struct PrintVisitor {
 180     /// Fields are the current index that needs to be appended to pattern
 181     /// binding names
 182     ids: FxHashMap<&'static str, usize>,
 183     /// the name that needs to be destructured
 184     current: String,
 185 }
 186
 187 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 188     #[allow(clippy::too_many_lines)]
 189     fn visit_expr(&mut self, expr: &Expr) {
 190         // handle if desugarings
 191         // TODO add more desugarings here
 192         if let Some((cond, then, opt_else)) = higher::if_block(&expr) {
 193             let cond_pat = self.next("cond");
 194             let then_pat = self.next("then");
 195             if let Some(else_) = opt_else {
 196                 let else_pat = self.next("else_");
 197                 println!(
 198                     "    if let Some((ref {}, ref {}, Some({}))) = higher::if_block(&{});",
 199                     cond_pat, then_pat, else_pat, self.current
 200                 );
 201                 self.current = else_pat;
 202                 self.visit_expr(else_);
 203             } else {
 204                 println!(
 205                     "    if let Some((ref {}, ref {}, None)) = higher::if_block(&{});",
 206                     cond_pat, then_pat, self.current
 207                 );
 208             }
 209             self.current = cond_pat;
 210             self.visit_expr(cond);
 211             self.current = then_pat;
 212             self.visit_expr(then);
 213             return;
 214         }
 215
 216         print!("    if let ExprKind::");
 217         let current = format!("{}.node", self.current);
 218         match expr.node {
 219             ExprKind::Box(ref inner) => {
 220                 let inner_pat = self.next("inner");
 221                 println!("Box(ref {}) = {};", inner_pat, current);
 222                 self.current = inner_pat;
 223                 self.visit_expr(inner);
 224             },
 225             ExprKind::Array(ref elements) => {
 226                 let elements_pat = self.next("elements");
 227                 println!("Array(ref {}) = {};", elements_pat, current);
 228                 println!("    if {}.len() == {};", elements_pat, elements.len());
 229                 for (i, element) in elements.iter().enumerate() {
 230                     self.current = format!("{}[{}]", elements_pat, i);
 231                     self.visit_expr(element);
 232                 }
 233             },
 234             ExprKind::Call(ref func, ref args) => {
 235                 let func_pat = self.next("func");
 236                 let args_pat = self.next("args");
 237                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 238                 self.current = func_pat;
 239                 self.visit_expr(func);
 240                 println!("    if {}.len() == {};", args_pat, args.len());
 241                 for (i, arg) in args.iter().enumerate() {
 242                     self.current = format!("{}[{}]", args_pat, i);
 243                     self.visit_expr(arg);
 244                 }
 245             },
 246             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args) => {
 247                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 248                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 249             },
 250             ExprKind::Tup(ref elements) => {
 251                 let elements_pat = self.next("elements");
 252                 println!("Tup(ref {}) = {};", elements_pat, current);
 253                 println!("    if {}.len() == {};", elements_pat, elements.len());
 254                 for (i, element) in elements.iter().enumerate() {
 255                     self.current = format!("{}[{}]", elements_pat, i);
 256                     self.visit_expr(element);
 257                 }
 258             },
 259             ExprKind::Binary(ref op, ref left, ref right) => {
 260                 let op_pat = self.next("op");
 261                 let left_pat = self.next("left");
 262                 let right_pat = self.next("right");
 263                 println!(
 264                     "Binary(ref {}, ref {}, ref {}) = {};",
 265                     op_pat, left_pat, right_pat, current
 266                 );
 267                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 268                 self.current = left_pat;
 269                 self.visit_expr(left);
 270                 self.current = right_pat;
 271                 self.visit_expr(right);
 272             },
 273             ExprKind::Unary(ref op, ref inner) => {
 274                 let inner_pat = self.next("inner");
 275                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 276                 self.current = inner_pat;
 277                 self.visit_expr(inner);
 278             },
 279             ExprKind::Lit(ref lit) => {
 280                 let lit_pat = self.next("lit");
 281                 println!("Lit(ref {}) = {};", lit_pat, current);
 282                 match lit.node {
 283                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 284                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 285                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 286                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 287                     // FIXME: also check int type
 288                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 289                     LitKind::Float(..) => println!("    if let LitKind::Float(..) = {}.node;", lit_pat),
 290                     LitKind::FloatUnsuffixed(_) => {
 291                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 292                     },
 293                     LitKind::ByteStr(ref vec) => {
 294                         let vec_pat = self.next("vec");
 295                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 296                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 297                     },
 298                     LitKind::Str(ref text, _) => {
 299                         let str_pat = self.next("s");
 300                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 301                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 302                     },
 303                 }
 304             },
 305             ExprKind::Cast(ref expr, ref ty) => {
 306                 let cast_pat = self.next("expr");
 307                 let cast_ty = self.next("cast_ty");
 308                 let qp_label = self.next("qp");
 309
 310                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 311                 if let TyKind::Path(ref qp) = ty.node {
 312                     println!("    if let TyKind::Path(ref {}) = {}.node;", qp_label, cast_ty);
 313                     self.current = qp_label;
 314                     self.print_qpath(qp);
 315                 }
 316                 self.current = cast_pat;
 317                 self.visit_expr(expr);
 318             },
 319             ExprKind::Type(ref expr, ref _ty) => {
 320                 let cast_pat = self.next("expr");
 321                 println!("Type(ref {}, _) = {};", cast_pat, current);
 322                 self.current = cast_pat;
 323                 self.visit_expr(expr);
 324             },
 325             ExprKind::While(ref cond, ref body, _) => {
 326                 let cond_pat = self.next("cond");
 327                 let body_pat = self.next("body");
 328                 let label_pat = self.next("label");
 329                 println!(
 330                     "While(ref {}, ref {}, ref {}) = {};",
 331                     cond_pat, body_pat, label_pat, current
 332                 );
 333                 self.current = cond_pat;
 334                 self.visit_expr(cond);
 335                 self.current = body_pat;
 336                 self.visit_block(body);
 337             },
 338             ExprKind::Loop(ref body, _, desugaring) => {
 339                 let body_pat = self.next("body");
 340                 let des = loop_desugaring_name(desugaring);
 341                 let label_pat = self.next("label");
 342                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 343                 self.current = body_pat;
 344                 self.visit_block(body);
 345             },
 346             ExprKind::Match(ref expr, ref arms, desugaring) => {
 347                 let des = desugaring_name(desugaring);
 348                 let expr_pat = self.next("expr");
 349                 let arms_pat = self.next("arms");
 350                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 351                 self.current = expr_pat;
 352                 self.visit_expr(expr);
 353                 println!("    if {}.len() == {};", arms_pat, arms.len());
 354                 for (i, arm) in arms.iter().enumerate() {
 355                     self.current = format!("{}[{}].body", arms_pat, i);
 356                     self.visit_expr(&arm.body);
 357                     if let Some(ref guard) = arm.guard {
 358                         let guard_pat = self.next("guard");
 359                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 360                         match guard {
 361                             hir::Guard::If(ref if_expr) => {
 362                                 let if_expr_pat = self.next("expr");
 363                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 364                                 self.current = if_expr_pat;
 365                                 self.visit_expr(if_expr);
 366                             },
 367                         }
 368                     }
 369                     println!("    if {}[{}].pats.len() == {};", arms_pat, i, arm.pats.len());
 370                     for (j, pat) in arm.pats.iter().enumerate() {
 371                         self.current = format!("{}[{}].pats[{}]", arms_pat, i, j);
 372                         self.visit_pat(pat);
 373                     }
 374                 }
 375             },
 376             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 377                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 378                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 379             },
 380             ExprKind::Yield(ref sub, _) => {
 381                 let sub_pat = self.next("sub");
 382                 println!("Yield(ref sub) = {};", current);
 383                 self.current = sub_pat;
 384                 self.visit_expr(sub);
 385             },
 386             ExprKind::Block(ref block, _) => {
 387                 let block_pat = self.next("block");
 388                 println!("Block(ref {}) = {};", block_pat, current);
 389                 self.current = block_pat;
 390                 self.visit_block(block);
 391             },
 392             ExprKind::Assign(ref target, ref value) => {
 393                 let target_pat = self.next("target");
 394                 let value_pat = self.next("value");
 395                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 396                 self.current = target_pat;
 397                 self.visit_expr(target);
 398                 self.current = value_pat;
 399                 self.visit_expr(value);
 400             },
 401             ExprKind::AssignOp(ref op, ref target, ref value) => {
 402                 let op_pat = self.next("op");
 403                 let target_pat = self.next("target");
 404                 let value_pat = self.next("value");
 405                 println!(
 406                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 407                     op_pat, target_pat, value_pat, current
 408                 );
 409                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 410                 self.current = target_pat;
 411                 self.visit_expr(target);
 412                 self.current = value_pat;
 413                 self.visit_expr(value);
 414             },
 415             ExprKind::Field(ref object, ref field_ident) => {
 416                 let obj_pat = self.next("object");
 417                 let field_name_pat = self.next("field_name");
 418                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 419                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_ident.as_str());
 420                 self.current = obj_pat;
 421                 self.visit_expr(object);
 422             },
 423             ExprKind::Index(ref object, ref index) => {
 424                 let object_pat = self.next("object");
 425                 let index_pat = self.next("index");
 426                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 427                 self.current = object_pat;
 428                 self.visit_expr(object);
 429                 self.current = index_pat;
 430                 self.visit_expr(index);
 431             },
 432             ExprKind::Path(ref path) => {
 433                 let path_pat = self.next("path");
 434                 println!("Path(ref {}) = {};", path_pat, current);
 435                 self.current = path_pat;
 436                 self.print_qpath(path);
 437             },
 438             ExprKind::AddrOf(mutability, ref inner) => {
 439                 let inner_pat = self.next("inner");
 440                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 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(_, ref _input, ref _output) => {
 472                 println!("InlineAsm(_, ref input, ref output) = {};", 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!("{}.node", self.current);
 529         match pat.node {
 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 {}.node.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::TupleStruct(ref path, ref fields, skip_pos) => {
 565                 let path_pat = self.next("path");
 566                 let fields_pat = self.next("fields");
 567                 println!(
 568                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 569                     path_pat, fields_pat, skip_pos, current
 570                 );
 571                 self.current = path_pat;
 572                 self.print_qpath(path);
 573                 println!("    if {}.len() == {};", fields_pat, fields.len());
 574                 println!("    // unimplemented: field checks");
 575             },
 576             PatKind::Path(ref path) => {
 577                 let path_pat = self.next("path");
 578                 println!("Path(ref {}) = {};", path_pat, current);
 579                 self.current = path_pat;
 580                 self.print_qpath(path);
 581             },
 582             PatKind::Tuple(ref fields, skip_pos) => {
 583                 let fields_pat = self.next("fields");
 584                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 585                 println!("    if {}.len() == {};", fields_pat, fields.len());
 586                 println!("    // unimplemented: field checks");
 587             },
 588             PatKind::Box(ref pat) => {
 589                 let pat_pat = self.next("pat");
 590                 println!("Box(ref {}) = {};", pat_pat, current);
 591                 self.current = pat_pat;
 592                 self.visit_pat(pat);
 593             },
 594             PatKind::Ref(ref pat, muta) => {
 595                 let pat_pat = self.next("pat");
 596                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 597                 self.current = pat_pat;
 598                 self.visit_pat(pat);
 599             },
 600             PatKind::Lit(ref lit_expr) => {
 601                 let lit_expr_pat = self.next("lit_expr");
 602                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 603                 self.current = lit_expr_pat;
 604                 self.visit_expr(lit_expr);
 605             },
 606             PatKind::Range(ref start, ref end, end_kind) => {
 607                 let start_pat = self.next("start");
 608                 let end_pat = self.next("end");
 609                 println!(
 610                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 611                     start_pat, end_pat, end_kind, current
 612                 );
 613                 self.current = start_pat;
 614                 self.visit_expr(start);
 615                 self.current = end_pat;
 616                 self.visit_expr(end);
 617             },
 618             PatKind::Slice(ref start, ref middle, ref end) => {
 619                 let start_pat = self.next("start");
 620                 let end_pat = self.next("end");
 621                 if let Some(ref middle) = middle {
 622                     let middle_pat = self.next("middle");
 623                     println!(
 624                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 625                         start_pat, middle_pat, end_pat, current
 626                     );
 627                     self.current = middle_pat;
 628                     self.visit_pat(middle);
 629                 } else {
 630                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 631                 }
 632                 println!("    if {}.len() == {};", start_pat, start.len());
 633                 for (i, pat) in start.iter().enumerate() {
 634                     self.current = format!("{}[{}]", start_pat, i);
 635                     self.visit_pat(pat);
 636                 }
 637                 println!("    if {}.len() == {};", end_pat, end.len());
 638                 for (i, pat) in end.iter().enumerate() {
 639                     self.current = format!("{}[{}]", end_pat, i);
 640                     self.visit_pat(pat);
 641                 }
 642             },
 643         }
 644     }
 645
 646     fn visit_stmt(&mut self, s: &Stmt) {
 647         print!("    if let StmtKind::");
 648         let current = format!("{}.node", self.current);
 649         match s.node {
 650             // A local (let) binding:
 651             StmtKind::Local(ref local) => {
 652                 let local_pat = self.next("local");
 653                 println!("Local(ref {}) = {};", local_pat, current);
 654                 if let Some(ref init) = local.init {
 655                     let init_pat = self.next("init");
 656                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 657                     self.current = init_pat;
 658                     self.visit_expr(init);
 659                 }
 660                 self.current = format!("{}.pat", local_pat);
 661                 self.visit_pat(&local.pat);
 662             },
 663             // An item binding:
 664             StmtKind::Item(_) => {
 665                 println!("Item(item_id) = {};", current);
 666             },
 667
 668             // Expr without trailing semi-colon (must have unit type):
 669             StmtKind::Expr(ref e) => {
 670                 let e_pat = self.next("e");
 671                 println!("Expr(ref {}, _) = {}", e_pat, current);
 672                 self.current = e_pat;
 673                 self.visit_expr(e);
 674             },
 675
 676             // Expr with trailing semi-colon (may have any type):
 677             StmtKind::Semi(ref e) => {
 678                 let e_pat = self.next("e");
 679                 println!("Semi(ref {}, _) = {}", e_pat, current);
 680                 self.current = e_pat;
 681                 self.visit_expr(e);
 682             },
 683         }
 684     }
 685
 686     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 687         NestedVisitorMap::None
 688     }
 689 }
 690
 691 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 692     get_attr(sess, attrs, "author").count() > 0
 693 }
 694
 695 fn desugaring_name(des: hir::MatchSource) -> String {
 696     match des {
 697         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 698         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 699         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 700         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 701         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 702             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 703             contains_else_clause
 704         ),
 705         hir::MatchSource::IfDesugar { contains_else_clause } => format!(
 706             "MatchSource::IfDesugar {{ contains_else_clause: {} }}",
 707             contains_else_clause
 708         ),
 709         hir::MatchSource::AwaitDesugar => "MatchSource::AwaitDesugar".to_string(),
 710     }
 711 }
 712
 713 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 714     match des {
 715         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 716         hir::LoopSource::Loop => "LoopSource::Loop",
 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.node {
 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 }