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;
   5 use rustc::hir;
   6 use rustc::hir::intravisit::{NestedVisitorMap, Visitor};
   7 use rustc::hir::{BindingAnnotation, 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         print!("    if let ExprKind::");
 191         let current = format!("{}.node", self.current);
 192         match expr.node {
 193             ExprKind::Box(ref inner) => {
 194                 let inner_pat = self.next("inner");
 195                 println!("Box(ref {}) = {};", inner_pat, current);
 196                 self.current = inner_pat;
 197                 self.visit_expr(inner);
 198             },
 199             ExprKind::Array(ref elements) => {
 200                 let elements_pat = self.next("elements");
 201                 println!("Array(ref {}) = {};", elements_pat, current);
 202                 println!("    if {}.len() == {};", elements_pat, elements.len());
 203                 for (i, element) in elements.iter().enumerate() {
 204                     self.current = format!("{}[{}]", elements_pat, i);
 205                     self.visit_expr(element);
 206                 }
 207             },
 208             ExprKind::Call(ref func, ref args) => {
 209                 let func_pat = self.next("func");
 210                 let args_pat = self.next("args");
 211                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 212                 self.current = func_pat;
 213                 self.visit_expr(func);
 214                 println!("    if {}.len() == {};", args_pat, args.len());
 215                 for (i, arg) in args.iter().enumerate() {
 216                     self.current = format!("{}[{}]", args_pat, i);
 217                     self.visit_expr(arg);
 218                 }
 219             },
 220             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args) => {
 221                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 222                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 223             },
 224             ExprKind::Tup(ref elements) => {
 225                 let elements_pat = self.next("elements");
 226                 println!("Tup(ref {}) = {};", elements_pat, current);
 227                 println!("    if {}.len() == {};", elements_pat, elements.len());
 228                 for (i, element) in elements.iter().enumerate() {
 229                     self.current = format!("{}[{}]", elements_pat, i);
 230                     self.visit_expr(element);
 231                 }
 232             },
 233             ExprKind::Binary(ref op, ref left, ref right) => {
 234                 let op_pat = self.next("op");
 235                 let left_pat = self.next("left");
 236                 let right_pat = self.next("right");
 237                 println!(
 238                     "Binary(ref {}, ref {}, ref {}) = {};",
 239                     op_pat, left_pat, right_pat, current
 240                 );
 241                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 242                 self.current = left_pat;
 243                 self.visit_expr(left);
 244                 self.current = right_pat;
 245                 self.visit_expr(right);
 246             },
 247             ExprKind::Unary(ref op, ref inner) => {
 248                 let inner_pat = self.next("inner");
 249                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 250                 self.current = inner_pat;
 251                 self.visit_expr(inner);
 252             },
 253             ExprKind::Lit(ref lit) => {
 254                 let lit_pat = self.next("lit");
 255                 println!("Lit(ref {}) = {};", lit_pat, current);
 256                 match lit.node {
 257                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 258                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 259                     LitKind::Err(val) => println!("    if let LitKind::Err({}) = {}.node;", val, lit_pat),
 260                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 261                     // FIXME: also check int type
 262                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 263                     LitKind::Float(..) => println!("    if let LitKind::Float(..) = {}.node;", lit_pat),
 264                     LitKind::FloatUnsuffixed(_) => {
 265                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 266                     },
 267                     LitKind::ByteStr(ref vec) => {
 268                         let vec_pat = self.next("vec");
 269                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 270                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 271                     },
 272                     LitKind::Str(ref text, _) => {
 273                         let str_pat = self.next("s");
 274                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 275                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 276                     },
 277                 }
 278             },
 279             ExprKind::Cast(ref expr, ref ty) => {
 280                 let cast_pat = self.next("expr");
 281                 let cast_ty = self.next("cast_ty");
 282                 let qp_label = self.next("qp");
 283
 284                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 285                 if let TyKind::Path(ref qp) = ty.node {
 286                     println!("    if let TyKind::Path(ref {}) = {}.node;", qp_label, cast_ty);
 287                     self.current = qp_label;
 288                     self.print_qpath(qp);
 289                 }
 290                 self.current = cast_pat;
 291                 self.visit_expr(expr);
 292             },
 293             ExprKind::Type(ref expr, ref _ty) => {
 294                 let cast_pat = self.next("expr");
 295                 println!("Type(ref {}, _) = {};", cast_pat, current);
 296                 self.current = cast_pat;
 297                 self.visit_expr(expr);
 298             },
 299             ExprKind::If(ref cond, ref then, ref opt_else) => {
 300                 let cond_pat = self.next("cond");
 301                 let then_pat = self.next("then");
 302                 if let Some(ref else_) = *opt_else {
 303                     let else_pat = self.next("else_");
 304                     println!(
 305                         "If(ref {}, ref {}, Some(ref {})) = {};",
 306                         cond_pat, then_pat, else_pat, current
 307                     );
 308                     self.current = else_pat;
 309                     self.visit_expr(else_);
 310                 } else {
 311                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 312                 }
 313                 self.current = cond_pat;
 314                 self.visit_expr(cond);
 315                 self.current = then_pat;
 316                 self.visit_expr(then);
 317             },
 318             ExprKind::While(ref cond, ref body, _) => {
 319                 let cond_pat = self.next("cond");
 320                 let body_pat = self.next("body");
 321                 let label_pat = self.next("label");
 322                 println!(
 323                     "While(ref {}, ref {}, ref {}) = {};",
 324                     cond_pat, body_pat, label_pat, current
 325                 );
 326                 self.current = cond_pat;
 327                 self.visit_expr(cond);
 328                 self.current = body_pat;
 329                 self.visit_block(body);
 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                     println!("    if {}[{}].pats.len() == {};", arms_pat, i, arm.pats.len());
 363                     for (j, pat) in arm.pats.iter().enumerate() {
 364                         self.current = format!("{}[{}].pats[{}]", arms_pat, i, j);
 365                         self.visit_pat(pat);
 366                     }
 367                 }
 368             },
 369             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 370                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 371                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 372             },
 373             ExprKind::Yield(ref sub) => {
 374                 let sub_pat = self.next("sub");
 375                 println!("Yield(ref sub) = {};", current);
 376                 self.current = sub_pat;
 377                 self.visit_expr(sub);
 378             },
 379             ExprKind::Block(ref block, _) => {
 380                 let block_pat = self.next("block");
 381                 println!("Block(ref {}) = {};", block_pat, current);
 382                 self.current = block_pat;
 383                 self.visit_block(block);
 384             },
 385             ExprKind::Assign(ref target, ref value) => {
 386                 let target_pat = self.next("target");
 387                 let value_pat = self.next("value");
 388                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 389                 self.current = target_pat;
 390                 self.visit_expr(target);
 391                 self.current = value_pat;
 392                 self.visit_expr(value);
 393             },
 394             ExprKind::AssignOp(ref op, ref target, ref value) => {
 395                 let op_pat = self.next("op");
 396                 let target_pat = self.next("target");
 397                 let value_pat = self.next("value");
 398                 println!(
 399                     "AssignOp(ref {}, ref {}, ref {}) = {};",
 400                     op_pat, target_pat, value_pat, current
 401                 );
 402                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 403                 self.current = target_pat;
 404                 self.visit_expr(target);
 405                 self.current = value_pat;
 406                 self.visit_expr(value);
 407             },
 408             ExprKind::Field(ref object, ref field_ident) => {
 409                 let obj_pat = self.next("object");
 410                 let field_name_pat = self.next("field_name");
 411                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 412                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_ident.as_str());
 413                 self.current = obj_pat;
 414                 self.visit_expr(object);
 415             },
 416             ExprKind::Index(ref object, ref index) => {
 417                 let object_pat = self.next("object");
 418                 let index_pat = self.next("index");
 419                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 420                 self.current = object_pat;
 421                 self.visit_expr(object);
 422                 self.current = index_pat;
 423                 self.visit_expr(index);
 424             },
 425             ExprKind::Path(ref path) => {
 426                 let path_pat = self.next("path");
 427                 println!("Path(ref {}) = {};", path_pat, current);
 428                 self.current = path_pat;
 429                 self.print_qpath(path);
 430             },
 431             ExprKind::AddrOf(mutability, ref inner) => {
 432                 let inner_pat = self.next("inner");
 433                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 434                 self.current = inner_pat;
 435                 self.visit_expr(inner);
 436             },
 437             ExprKind::Break(ref _destination, ref opt_value) => {
 438                 let destination_pat = self.next("destination");
 439                 if let Some(ref value) = *opt_value {
 440                     let value_pat = self.next("value");
 441                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 442                     self.current = value_pat;
 443                     self.visit_expr(value);
 444                 } else {
 445                     println!("Break(ref {}, None) = {};", destination_pat, current);
 446                 }
 447                 // FIXME: implement label printing
 448             },
 449             ExprKind::Continue(ref _destination) => {
 450                 let destination_pat = self.next("destination");
 451                 println!("Again(ref {}) = {};", destination_pat, current);
 452                 // FIXME: implement label printing
 453             },
 454             ExprKind::Ret(ref opt_value) => {
 455                 if let Some(ref value) = *opt_value {
 456                     let value_pat = self.next("value");
 457                     println!("Ret(Some(ref {})) = {};", value_pat, current);
 458                     self.current = value_pat;
 459                     self.visit_expr(value);
 460                 } else {
 461                     println!("Ret(None) = {};", current);
 462                 }
 463             },
 464             ExprKind::InlineAsm(_, ref _input, ref _output) => {
 465                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 466                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 467             },
 468             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 469                 let path_pat = self.next("path");
 470                 let fields_pat = self.next("fields");
 471                 if let Some(ref base) = *opt_base {
 472                     let base_pat = self.next("base");
 473                     println!(
 474                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 475                         path_pat, fields_pat, base_pat, current
 476                     );
 477                     self.current = base_pat;
 478                     self.visit_expr(base);
 479                 } else {
 480                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 481                 }
 482                 self.current = path_pat;
 483                 self.print_qpath(path);
 484                 println!("    if {}.len() == {};", fields_pat, fields.len());
 485                 println!("    // unimplemented: field checks");
 486             },
 487             // FIXME: compute length (needs type info)
 488             ExprKind::Repeat(ref value, _) => {
 489                 let value_pat = self.next("value");
 490                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 491                 println!("// unimplemented: repeat count check");
 492                 self.current = value_pat;
 493                 self.visit_expr(value);
 494             },
 495             ExprKind::Err => {
 496                 println!("Err = {}", current);
 497             },
 498             ExprKind::Use(ref expr) => {
 499                 let expr_pat = self.next("expr");
 500                 println!("Use(ref {}) = {};", expr_pat, current);
 501                 self.current = expr_pat;
 502                 self.visit_expr(expr);
 503             },
 504         }
 505     }
 506
 507     #[allow(clippy::too_many_lines)]
 508     fn visit_pat(&mut self, pat: &Pat) {
 509         print!("    if let PatKind::");
 510         let current = format!("{}.node", self.current);
 511         match pat.node {
 512             PatKind::Wild => println!("Wild = {};", current),
 513             PatKind::Binding(anno, .., ident, ref sub) => {
 514                 let anno_pat = match anno {
 515                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 516                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 517                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 518                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 519                 };
 520                 let name_pat = self.next("name");
 521                 if let Some(ref sub) = *sub {
 522                     let sub_pat = self.next("sub");
 523                     println!(
 524                         "Binding({}, _, {}, Some(ref {})) = {};",
 525                         anno_pat, name_pat, sub_pat, current
 526                     );
 527                     self.current = sub_pat;
 528                     self.visit_pat(sub);
 529                 } else {
 530                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 531                 }
 532                 println!("    if {}.node.as_str() == \"{}\";", name_pat, ident.as_str());
 533             },
 534             PatKind::Struct(ref path, ref fields, ignore) => {
 535                 let path_pat = self.next("path");
 536                 let fields_pat = self.next("fields");
 537                 println!(
 538                     "Struct(ref {}, ref {}, {}) = {};",
 539                     path_pat, fields_pat, ignore, current
 540                 );
 541                 self.current = path_pat;
 542                 self.print_qpath(path);
 543                 println!("    if {}.len() == {};", fields_pat, fields.len());
 544                 println!("    // unimplemented: field checks");
 545             },
 546             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 547                 let path_pat = self.next("path");
 548                 let fields_pat = self.next("fields");
 549                 println!(
 550                     "TupleStruct(ref {}, ref {}, {:?}) = {};",
 551                     path_pat, fields_pat, skip_pos, current
 552                 );
 553                 self.current = path_pat;
 554                 self.print_qpath(path);
 555                 println!("    if {}.len() == {};", fields_pat, fields.len());
 556                 println!("    // unimplemented: field checks");
 557             },
 558             PatKind::Path(ref path) => {
 559                 let path_pat = self.next("path");
 560                 println!("Path(ref {}) = {};", path_pat, current);
 561                 self.current = path_pat;
 562                 self.print_qpath(path);
 563             },
 564             PatKind::Tuple(ref fields, skip_pos) => {
 565                 let fields_pat = self.next("fields");
 566                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 567                 println!("    if {}.len() == {};", fields_pat, fields.len());
 568                 println!("    // unimplemented: field checks");
 569             },
 570             PatKind::Box(ref pat) => {
 571                 let pat_pat = self.next("pat");
 572                 println!("Box(ref {}) = {};", pat_pat, current);
 573                 self.current = pat_pat;
 574                 self.visit_pat(pat);
 575             },
 576             PatKind::Ref(ref pat, muta) => {
 577                 let pat_pat = self.next("pat");
 578                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 579                 self.current = pat_pat;
 580                 self.visit_pat(pat);
 581             },
 582             PatKind::Lit(ref lit_expr) => {
 583                 let lit_expr_pat = self.next("lit_expr");
 584                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 585                 self.current = lit_expr_pat;
 586                 self.visit_expr(lit_expr);
 587             },
 588             PatKind::Range(ref start, ref end, end_kind) => {
 589                 let start_pat = self.next("start");
 590                 let end_pat = self.next("end");
 591                 println!(
 592                     "Range(ref {}, ref {}, RangeEnd::{:?}) = {};",
 593                     start_pat, end_pat, end_kind, current
 594                 );
 595                 self.current = start_pat;
 596                 self.visit_expr(start);
 597                 self.current = end_pat;
 598                 self.visit_expr(end);
 599             },
 600             PatKind::Slice(ref start, ref middle, ref end) => {
 601                 let start_pat = self.next("start");
 602                 let end_pat = self.next("end");
 603                 if let Some(ref middle) = middle {
 604                     let middle_pat = self.next("middle");
 605                     println!(
 606                         "Slice(ref {}, Some(ref {}), ref {}) = {};",
 607                         start_pat, middle_pat, end_pat, current
 608                     );
 609                     self.current = middle_pat;
 610                     self.visit_pat(middle);
 611                 } else {
 612                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 613                 }
 614                 println!("    if {}.len() == {};", start_pat, start.len());
 615                 for (i, pat) in start.iter().enumerate() {
 616                     self.current = format!("{}[{}]", start_pat, i);
 617                     self.visit_pat(pat);
 618                 }
 619                 println!("    if {}.len() == {};", end_pat, end.len());
 620                 for (i, pat) in end.iter().enumerate() {
 621                     self.current = format!("{}[{}]", end_pat, i);
 622                     self.visit_pat(pat);
 623                 }
 624             },
 625         }
 626     }
 627
 628     fn visit_stmt(&mut self, s: &Stmt) {
 629         print!("    if let StmtKind::");
 630         let current = format!("{}.node", self.current);
 631         match s.node {
 632             // A local (let) binding:
 633             StmtKind::Local(ref local) => {
 634                 let local_pat = self.next("local");
 635                 println!("Local(ref {}) = {};", local_pat, current);
 636                 if let Some(ref init) = local.init {
 637                     let init_pat = self.next("init");
 638                     println!("    if let Some(ref {}) = {}.init;", init_pat, local_pat);
 639                     self.current = init_pat;
 640                     self.visit_expr(init);
 641                 }
 642                 self.current = format!("{}.pat", local_pat);
 643                 self.visit_pat(&local.pat);
 644             },
 645             // An item binding:
 646             StmtKind::Item(_) => {
 647                 println!("Item(item_id) = {};", current);
 648             },
 649
 650             // Expr without trailing semi-colon (must have unit type):
 651             StmtKind::Expr(ref e) => {
 652                 let e_pat = self.next("e");
 653                 println!("Expr(ref {}, _) = {}", e_pat, current);
 654                 self.current = e_pat;
 655                 self.visit_expr(e);
 656             },
 657
 658             // Expr with trailing semi-colon (may have any type):
 659             StmtKind::Semi(ref e) => {
 660                 let e_pat = self.next("e");
 661                 println!("Semi(ref {}, _) = {}", e_pat, current);
 662                 self.current = e_pat;
 663                 self.visit_expr(e);
 664             },
 665         }
 666     }
 667
 668     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 669         NestedVisitorMap::None
 670     }
 671 }
 672
 673 fn has_attr(sess: &Session, attrs: &[Attribute]) -> bool {
 674     get_attr(sess, attrs, "author").count() > 0
 675 }
 676
 677 fn desugaring_name(des: hir::MatchSource) -> String {
 678     match des {
 679         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 680         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 681         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 682         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 683         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!(
 684             "MatchSource::IfLetDesugar {{ contains_else_clause: {} }}",
 685             contains_else_clause
 686         ),
 687     }
 688 }
 689
 690 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 691     match des {
 692         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 693         hir::LoopSource::Loop => "LoopSource::Loop",
 694         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 695     }
 696 }
 697
 698 fn print_path(path: &QPath, first: &mut bool) {
 699     match *path {
 700         QPath::Resolved(_, ref path) => {
 701             for segment in &path.segments {
 702                 if *first {
 703                     *first = false;
 704                 } else {
 705                     print!(", ");
 706                 }
 707                 print!("{:?}", segment.ident.as_str());
 708             }
 709         },
 710         QPath::TypeRelative(ref ty, ref segment) => match ty.node {
 711             hir::TyKind::Path(ref inner_path) => {
 712                 print_path(inner_path, first);
 713                 if *first {
 714                     *first = false;
 715                 } else {
 716                     print!(", ");
 717                 }
 718                 print!("{:?}", segment.ident.as_str());
 719             },
 720             ref other => print!("/* unimplemented: {:?}*/", other),
 721         },
 722     }
 723 }