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