clippy_lints/src/utils/author.rs

   1 // Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution.
   3 //
   4 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   5 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   7 // option. This file may not be copied, modified, or distributed
   8 // except according to those terms.
   9
  10
  11 //! A group of attributes that can be attached to Rust code in order
  12 //! to generate a clippy lint detecting said code automatically.
  13
  14 use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
  15 use crate::rustc::{declare_tool_lint, lint_array};
  16 use crate::rustc::hir;
  17 use crate::rustc::hir::{Expr, ExprKind, QPath, TyKind, Pat, PatKind, BindingAnnotation, StmtKind, DeclKind, Stmt};
  18 use crate::rustc::hir::intravisit::{NestedVisitorMap, Visitor};
  19 use crate::rustc_data_structures::fx::FxHashMap;
  20 use crate::syntax::ast::{Attribute, LitKind, DUMMY_NODE_ID};
  21 use crate::utils::get_attr;
  22
  23 /// **What it does:** Generates clippy code that detects the offending pattern
  24 ///
  25 /// **Example:**
  26 /// ```rust
  27 /// // ./tests/ui/my_lint.rs
  28 /// fn foo() {
  29 ///     // detect the following pattern
  30 ///     #[clippy::author]
  31 ///     if x == 42 {
  32 ///         // but ignore everything from here on
  33 ///         #![clippy::author = "ignore"]
  34 ///     }
  35 /// }
  36 /// ```
  37 ///
  38 /// Running `TESTNAME=ui/my_lint cargo test --test compile-test` will produce
  39 /// a `./tests/ui/new_lint.stdout` file with the generated code:
  40 ///
  41 /// ```rust
  42 /// // ./tests/ui/new_lint.stdout
  43 /// if_chain!{
  44 ///     if let ExprKind::If(ref cond, ref then, None) = item.node,
  45 ///     if let ExprKind::Binary(BinOp::Eq, ref left, ref right) = cond.node,
  46 ///     if let ExprKind::Path(ref path) = left.node,
  47 ///     if let ExprKind::Lit(ref lit) = right.node,
  48 ///     if let LitKind::Int(42, _) = lit.node,
  49 ///     then {
  50 ///         // report your lint here
  51 ///     }
  52 /// }
  53 /// ```
  54 declare_clippy_lint! {
  55     pub LINT_AUTHOR,
  56     internal_warn,
  57     "helper for writing lints"
  58 }
  59
  60 pub struct Pass;
  61
  62 impl LintPass for Pass {
  63     fn get_lints(&self) -> LintArray {
  64         lint_array!(LINT_AUTHOR)
  65     }
  66 }
  67
  68 fn prelude() {
  69     println!("if_chain! {{");
  70 }
  71
  72 fn done() {
  73     println!("    then {{");
  74     println!("        // report your lint here");
  75     println!("    }}");
  76     println!("}}");
  77 }
  78
  79 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
  80     fn check_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
  81         if !has_attr(&item.attrs) {
  82             return;
  83         }
  84         prelude();
  85         PrintVisitor::new("item").visit_item(item);
  86         done();
  87     }
  88
  89     fn check_impl_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
  90         if !has_attr(&item.attrs) {
  91             return;
  92         }
  93         prelude();
  94         PrintVisitor::new("item").visit_impl_item(item);
  95         done();
  96     }
  97
  98     fn check_trait_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
  99         if !has_attr(&item.attrs) {
 100             return;
 101         }
 102         prelude();
 103         PrintVisitor::new("item").visit_trait_item(item);
 104         done();
 105     }
 106
 107     fn check_variant(&mut self, _cx: &LateContext<'a, 'tcx>, var: &'tcx hir::Variant, generics: &hir::Generics) {
 108         if !has_attr(&var.node.attrs) {
 109             return;
 110         }
 111         prelude();
 112         PrintVisitor::new("var").visit_variant(var, generics, DUMMY_NODE_ID);
 113         done();
 114     }
 115
 116     fn check_struct_field(&mut self, _cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
 117         if !has_attr(&field.attrs) {
 118             return;
 119         }
 120         prelude();
 121         PrintVisitor::new("field").visit_struct_field(field);
 122         done();
 123     }
 124
 125     fn check_expr(&mut self, _cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
 126         if !has_attr(&expr.attrs) {
 127             return;
 128         }
 129         prelude();
 130         PrintVisitor::new("expr").visit_expr(expr);
 131         done();
 132     }
 133
 134     fn check_arm(&mut self, _cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm) {
 135         if !has_attr(&arm.attrs) {
 136             return;
 137         }
 138         prelude();
 139         PrintVisitor::new("arm").visit_arm(arm);
 140         done();
 141     }
 142
 143     fn check_stmt(&mut self, _cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt) {
 144         if !has_attr(stmt.node.attrs()) {
 145             return;
 146         }
 147         prelude();
 148         PrintVisitor::new("stmt").visit_stmt(stmt);
 149         done();
 150     }
 151
 152     fn check_foreign_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem) {
 153         if !has_attr(&item.attrs) {
 154             return;
 155         }
 156         prelude();
 157         PrintVisitor::new("item").visit_foreign_item(item);
 158         done();
 159     }
 160 }
 161
 162 impl PrintVisitor {
 163     fn new(s: &'static str) -> Self {
 164         Self {
 165             ids: FxHashMap::default(),
 166             current: s.to_owned(),
 167         }
 168     }
 169
 170     fn next(&mut self, s: &'static str) -> String {
 171         use std::collections::hash_map::Entry::*;
 172         match self.ids.entry(s) {
 173             // already there: start numbering from `1`
 174             Occupied(mut occ) => {
 175                 let val = occ.get_mut();
 176                 *val += 1;
 177                 format!("{}{}", s, *val)
 178             },
 179             // not there: insert and return name as given
 180             Vacant(vac) => {
 181                 vac.insert(0);
 182                 s.to_owned()
 183             },
 184         }
 185     }
 186
 187     fn print_qpath(&mut self, path: &QPath) {
 188         print!("    if match_qpath({}, &[", self.current);
 189         print_path(path, &mut true);
 190         println!("]);");
 191     }
 192 }
 193
 194 struct PrintVisitor {
 195     /// Fields are the current index that needs to be appended to pattern
 196     /// binding names
 197     ids: FxHashMap<&'static str, usize>,
 198     /// the name that needs to be destructured
 199     current: String,
 200 }
 201
 202 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 203     fn visit_expr(&mut self, expr: &Expr) {
 204         print!("    if let ExprKind::");
 205         let current = format!("{}.node", self.current);
 206         match expr.node {
 207             ExprKind::Box(ref inner) => {
 208                 let inner_pat = self.next("inner");
 209                 println!("Box(ref {}) = {};", inner_pat, current);
 210                 self.current = inner_pat;
 211                 self.visit_expr(inner);
 212             },
 213             ExprKind::Array(ref elements) => {
 214                 let elements_pat = self.next("elements");
 215                 println!("Array(ref {}) = {};", elements_pat, current);
 216                 println!("    if {}.len() == {};", elements_pat, elements.len());
 217                 for (i, element) in elements.iter().enumerate() {
 218                     self.current = format!("{}[{}]", elements_pat, i);
 219                     self.visit_expr(element);
 220                 }
 221             },
 222             ExprKind::Call(ref func, ref args) => {
 223                 let func_pat = self.next("func");
 224                 let args_pat = self.next("args");
 225                 println!("Call(ref {}, ref {}) = {};", func_pat, args_pat, current);
 226                 self.current = func_pat;
 227                 self.visit_expr(func);
 228                 println!("    if {}.len() == {};", args_pat, args.len());
 229                 for (i, arg) in args.iter().enumerate() {
 230                     self.current = format!("{}[{}]", args_pat, i);
 231                     self.visit_expr(arg);
 232                 }
 233             },
 234             ExprKind::MethodCall(ref _method_name, ref _generics, ref _args) => {
 235                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 236                 println!("    // unimplemented: `ExprKind::MethodCall` is not further destructured at the moment");
 237             },
 238             ExprKind::Tup(ref elements) => {
 239                 let elements_pat = self.next("elements");
 240                 println!("Tup(ref {}) = {};", elements_pat, current);
 241                 println!("    if {}.len() == {};", elements_pat, elements.len());
 242                 for (i, element) in elements.iter().enumerate() {
 243                     self.current = format!("{}[{}]", elements_pat, i);
 244                     self.visit_expr(element);
 245                 }
 246             },
 247             ExprKind::Binary(ref op, ref left, ref right) => {
 248                 let op_pat = self.next("op");
 249                 let left_pat = self.next("left");
 250                 let right_pat = self.next("right");
 251                 println!("Binary(ref {}, ref {}, ref {}) = {};", op_pat, left_pat, right_pat, current);
 252                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 253                 self.current = left_pat;
 254                 self.visit_expr(left);
 255                 self.current = right_pat;
 256                 self.visit_expr(right);
 257             },
 258             ExprKind::Unary(ref op, ref inner) => {
 259                 let inner_pat = self.next("inner");
 260                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 261                 self.current = inner_pat;
 262                 self.visit_expr(inner);
 263             },
 264             ExprKind::Lit(ref lit) => {
 265                 let lit_pat = self.next("lit");
 266                 println!("Lit(ref {}) = {};", lit_pat, current);
 267                 match lit.node {
 268                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 269                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 270                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 271                     // FIXME: also check int type
 272                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 273                     LitKind::Float(..) => println!("    if let LitKind::Float(..) = {}.node;", lit_pat),
 274                     LitKind::FloatUnsuffixed(_) => {
 275                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 276                     },
 277                     LitKind::ByteStr(ref vec) => {
 278                         let vec_pat = self.next("vec");
 279                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 280                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 281                     },
 282                     LitKind::Str(ref text, _) => {
 283                         let str_pat = self.next("s");
 284                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 285                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 286                     },
 287                 }
 288             },
 289             ExprKind::Cast(ref expr, ref ty) => {
 290                 let cast_pat = self.next("expr");
 291                 let cast_ty = self.next("cast_ty");
 292                 let qp_label = self.next("qp");
 293
 294                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 295                 if let TyKind::Path(ref qp) = ty.node {
 296                     println!("    if let TyKind::Path(ref {}) = {}.node;", qp_label, cast_ty);
 297                     self.current = qp_label;
 298                     self.print_qpath(qp);
 299                 }
 300                 self.current = cast_pat;
 301                 self.visit_expr(expr);
 302             },
 303             ExprKind::Type(ref expr, ref _ty) => {
 304                 let cast_pat = self.next("expr");
 305                 println!("Type(ref {}, _) = {};", cast_pat, current);
 306                 self.current = cast_pat;
 307                 self.visit_expr(expr);
 308             },
 309             ExprKind::If(ref cond, ref then, ref opt_else) => {
 310                 let cond_pat = self.next("cond");
 311                 let then_pat = self.next("then");
 312                 if let Some(ref else_) = *opt_else {
 313                     let else_pat = self.next("else_");
 314                     println!("If(ref {}, ref {}, Some(ref {})) = {};", cond_pat, then_pat, else_pat, current);
 315                     self.current = else_pat;
 316                     self.visit_expr(else_);
 317                 } else {
 318                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 319                 }
 320                 self.current = cond_pat;
 321                 self.visit_expr(cond);
 322                 self.current = then_pat;
 323                 self.visit_expr(then);
 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!("While(ref {}, ref {}, ref {}) = {};", cond_pat, body_pat, label_pat, current);
 330                 self.current = cond_pat;
 331                 self.visit_expr(cond);
 332                 self.current = body_pat;
 333                 self.visit_block(body);
 334             },
 335             ExprKind::Loop(ref body, _, desugaring) => {
 336                 let body_pat = self.next("body");
 337                 let des = loop_desugaring_name(desugaring);
 338                 let label_pat = self.next("label");
 339                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 340                 self.current = body_pat;
 341                 self.visit_block(body);
 342             },
 343             ExprKind::Match(ref expr, ref arms, desugaring) => {
 344                 let des = desugaring_name(desugaring);
 345                 let expr_pat = self.next("expr");
 346                 let arms_pat = self.next("arms");
 347                 println!("Match(ref {}, ref {}, {}) = {};", expr_pat, arms_pat, des, current);
 348                 self.current = expr_pat;
 349                 self.visit_expr(expr);
 350                 println!("    if {}.len() == {};", arms_pat, arms.len());
 351                 for (i, arm) in arms.iter().enumerate() {
 352                     self.current = format!("{}[{}].body", arms_pat, i);
 353                     self.visit_expr(&arm.body);
 354                     if let Some(ref guard) = arm.guard {
 355                         let guard_pat = self.next("guard");
 356                         println!("    if let Some(ref {}) = {}[{}].guard;", guard_pat, arms_pat, i);
 357                         match guard {
 358                             hir::Guard::If(ref if_expr) => {
 359                                 let if_expr_pat = self.next("expr");
 360                                 println!("    if let Guard::If(ref {}) = {};", if_expr_pat, guard_pat);
 361                                 self.current = if_expr_pat;
 362                                 self.visit_expr(if_expr);
 363                             }
 364                         }
 365                     }
 366                     println!("    if {}[{}].pats.len() == {};", arms_pat, i, arm.pats.len());
 367                     for (j, pat) in arm.pats.iter().enumerate() {
 368                         self.current = format!("{}[{}].pats[{}]", arms_pat, i, j);
 369                         self.visit_pat(pat);
 370                     }
 371                 }
 372             },
 373             ExprKind::Closure(ref _capture_clause, ref _func, _, _, _) => {
 374                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 375                 println!("    // unimplemented: `ExprKind::Closure` is not further destructured at the moment");
 376             },
 377             ExprKind::Yield(ref sub) => {
 378                 let sub_pat = self.next("sub");
 379                 println!("Yield(ref sub) = {};", current);
 380                 self.current = sub_pat;
 381                 self.visit_expr(sub);
 382             },
 383             ExprKind::Block(ref block, _) => {
 384                 let block_pat = self.next("block");
 385                 println!("Block(ref {}) = {};", block_pat, current);
 386                 self.current = block_pat;
 387                 self.visit_block(block);
 388             },
 389             ExprKind::Assign(ref target, ref value) => {
 390                 let target_pat = self.next("target");
 391                 let value_pat = self.next("value");
 392                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 393                 self.current = target_pat;
 394                 self.visit_expr(target);
 395                 self.current = value_pat;
 396                 self.visit_expr(value);
 397             },
 398             ExprKind::AssignOp(ref op, ref target, ref value) => {
 399                 let op_pat = self.next("op");
 400                 let target_pat = self.next("target");
 401                 let value_pat = self.next("value");
 402                 println!("AssignOp(ref {}, ref {}, ref {}) = {};", op_pat, target_pat, value_pat, current);
 403                 println!("    if BinOpKind::{:?} == {}.node;", op.node, op_pat);
 404                 self.current = target_pat;
 405                 self.visit_expr(target);
 406                 self.current = value_pat;
 407                 self.visit_expr(value);
 408             },
 409             ExprKind::Field(ref object, ref field_ident) => {
 410                 let obj_pat = self.next("object");
 411                 let field_name_pat = self.next("field_name");
 412                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 413                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_ident.as_str());
 414                 self.current = obj_pat;
 415                 self.visit_expr(object);
 416             },
 417             ExprKind::Index(ref object, ref index) => {
 418                 let object_pat = self.next("object");
 419                 let index_pat = self.next("index");
 420                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 421                 self.current = object_pat;
 422                 self.visit_expr(object);
 423                 self.current = index_pat;
 424                 self.visit_expr(index);
 425             },
 426             ExprKind::Path(ref path) => {
 427                 let path_pat = self.next("path");
 428                 println!("Path(ref {}) = {};", path_pat, current);
 429                 self.current = path_pat;
 430                 self.print_qpath(path);
 431             },
 432             ExprKind::AddrOf(mutability, ref inner) => {
 433                 let inner_pat = self.next("inner");
 434                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 435                 self.current = inner_pat;
 436                 self.visit_expr(inner);
 437             },
 438             ExprKind::Break(ref _destination, ref opt_value) => {
 439                 let destination_pat = self.next("destination");
 440                 if let Some(ref value) = *opt_value {
 441                     let value_pat = self.next("value");
 442                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 443                     self.current = value_pat;
 444                     self.visit_expr(value);
 445                 } else {
 446                     println!("Break(ref {}, None) = {};", destination_pat, current);
 447                 }
 448                 // FIXME: implement label printing
 449             },
 450             ExprKind::Continue(ref _destination) => {
 451                 let destination_pat = self.next("destination");
 452                 println!("Again(ref {}) = {};", destination_pat, current);
 453                 // FIXME: implement label printing
 454             },
 455             ExprKind::Ret(ref opt_value) => 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             ExprKind::InlineAsm(_, ref _input, ref _output) => {
 464                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 465                 println!("    // unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
 466             },
 467             ExprKind::Struct(ref path, ref fields, ref opt_base) => {
 468                 let path_pat = self.next("path");
 469                 let fields_pat = self.next("fields");
 470                 if let Some(ref base) = *opt_base {
 471                     let base_pat = self.next("base");
 472                     println!(
 473                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 474                         path_pat,
 475                         fields_pat,
 476                         base_pat,
 477                         current
 478                     );
 479                     self.current = base_pat;
 480                     self.visit_expr(base);
 481                 } else {
 482                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 483                 }
 484                 self.current = path_pat;
 485                 self.print_qpath(path);
 486                 println!("    if {}.len() == {};", fields_pat, fields.len());
 487                 println!("    // unimplemented: field checks");
 488             },
 489             // FIXME: compute length (needs type info)
 490             ExprKind::Repeat(ref value, _) => {
 491                 let value_pat = self.next("value");
 492                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 493                 println!("// unimplemented: repeat count check");
 494                 self.current = value_pat;
 495                 self.visit_expr(value);
 496             },
 497         }
 498     }
 499
 500     fn visit_pat(&mut self, pat: &Pat) {
 501         print!("    if let PatKind::");
 502         let current = format!("{}.node", self.current);
 503         match pat.node {
 504             PatKind::Wild => println!("Wild = {};", current),
 505             PatKind::Binding(anno, _, ident, ref sub) => {
 506                 let anno_pat = match anno {
 507                     BindingAnnotation::Unannotated => "BindingAnnotation::Unannotated",
 508                     BindingAnnotation::Mutable => "BindingAnnotation::Mutable",
 509                     BindingAnnotation::Ref => "BindingAnnotation::Ref",
 510                     BindingAnnotation::RefMut => "BindingAnnotation::RefMut",
 511                 };
 512                 let name_pat = self.next("name");
 513                 if let Some(ref sub) = *sub {
 514                     let sub_pat = self.next("sub");
 515                     println!("Binding({}, _, {}, Some(ref {})) = {};", anno_pat, name_pat, sub_pat, current);
 516                     self.current = sub_pat;
 517                     self.visit_pat(sub);
 518                 } else {
 519                     println!("Binding({}, _, {}, None) = {};", anno_pat, name_pat, current);
 520                 }
 521                 println!("    if {}.node.as_str() == \"{}\";", name_pat, ident.as_str());
 522             }
 523             PatKind::Struct(ref path, ref fields, ignore) => {
 524                 let path_pat = self.next("path");
 525                 let fields_pat = self.next("fields");
 526                 println!("Struct(ref {}, ref {}, {}) = {};", path_pat, fields_pat, ignore, current);
 527                 self.current = path_pat;
 528                 self.print_qpath(path);
 529                 println!("    if {}.len() == {};", fields_pat, fields.len());
 530                 println!("    // unimplemented: field checks");
 531             }
 532             PatKind::TupleStruct(ref path, ref fields, skip_pos) => {
 533                 let path_pat = self.next("path");
 534                 let fields_pat = self.next("fields");
 535                 println!("TupleStruct(ref {}, ref {}, {:?}) = {};", path_pat, fields_pat, skip_pos, current);
 536                 self.current = path_pat;
 537                 self.print_qpath(path);
 538                 println!("    if {}.len() == {};", fields_pat, fields.len());
 539                 println!("    // unimplemented: field checks");
 540             },
 541             PatKind::Path(ref path) => {
 542                 let path_pat = self.next("path");
 543                 println!("Path(ref {}) = {};", path_pat, current);
 544                 self.current = path_pat;
 545                 self.print_qpath(path);
 546             }
 547             PatKind::Tuple(ref fields, skip_pos) => {
 548                 let fields_pat = self.next("fields");
 549                 println!("Tuple(ref {}, {:?}) = {};", fields_pat, skip_pos, current);
 550                 println!("    if {}.len() == {};", fields_pat, fields.len());
 551                 println!("    // unimplemented: field checks");
 552             }
 553             PatKind::Box(ref pat) => {
 554                 let pat_pat = self.next("pat");
 555                 println!("Box(ref {}) = {};", pat_pat, current);
 556                 self.current = pat_pat;
 557                 self.visit_pat(pat);
 558             },
 559             PatKind::Ref(ref pat, muta) => {
 560                 let pat_pat = self.next("pat");
 561                 println!("Ref(ref {}, Mutability::{:?}) = {};", pat_pat, muta, current);
 562                 self.current = pat_pat;
 563                 self.visit_pat(pat);
 564             },
 565             PatKind::Lit(ref lit_expr) => {
 566                 let lit_expr_pat = self.next("lit_expr");
 567                 println!("Lit(ref {}) = {}", lit_expr_pat, current);
 568                 self.current = lit_expr_pat;
 569                 self.visit_expr(lit_expr);
 570             }
 571             PatKind::Range(ref start, ref end, end_kind) => {
 572                 let start_pat = self.next("start");
 573                 let end_pat = self.next("end");
 574                 println!("Range(ref {}, ref {}, RangeEnd::{:?}) = {};", start_pat, end_pat, end_kind, current);
 575                 self.current = start_pat;
 576                 self.visit_expr(start);
 577                 self.current = end_pat;
 578                 self.visit_expr(end);
 579             }
 580             PatKind::Slice(ref start, ref middle, ref end) => {
 581                 let start_pat = self.next("start");
 582                 let end_pat = self.next("end");
 583                 if let Some(ref middle) = middle {
 584                     let middle_pat = self.next("middle");
 585                     println!("Slice(ref {}, Some(ref {}), ref {}) = {};", start_pat, middle_pat, end_pat, current);
 586                     self.current = middle_pat;
 587                     self.visit_pat(middle);
 588                 } else {
 589                     println!("Slice(ref {}, None, ref {}) = {};", start_pat, end_pat, current);
 590                 }
 591                 println!("    if {}.len() == {};", start_pat, start.len());
 592                 for (i, pat) in start.iter().enumerate() {
 593                     self.current = format!("{}[{}]", start_pat, i);
 594                     self.visit_pat(pat);
 595                 }
 596                 println!("    if {}.len() == {};", end_pat, end.len());
 597                 for (i, pat) in end.iter().enumerate() {
 598                     self.current = format!("{}[{}]", end_pat, i);
 599                     self.visit_pat(pat);
 600                 }
 601             }
 602         }
 603     }
 604
 605     fn visit_stmt(&mut self, s: &Stmt) {
 606         print!("    if let StmtKind::");
 607         let current = format!("{}.node", self.current);
 608         match s.node {
 609             // Could be an item or a local (let) binding:
 610             StmtKind::Decl(ref decl, _) => {
 611                 let decl_pat = self.next("decl");
 612                 println!("Decl(ref {}, _) = {}", decl_pat, current);
 613                 print!("    if let DeclKind::");
 614                 let current = format!("{}.node", decl_pat);
 615                 match decl.node {
 616                     // A local (let) binding:
 617                     DeclKind::Local(ref local) => {
 618                         let local_pat = self.next("local");
 619                         println!("Local(ref {}) = {};", local_pat, current);
 620                         if let Some(ref init) = local.init {
 621                             let init_pat = self.next("init");
 622                             println!("    if let Some(ref {}) = {}.init", init_pat, local_pat);
 623                             self.current = init_pat;
 624                             self.visit_expr(init);
 625                         }
 626                         self.current = format!("{}.pat", local_pat);
 627                         self.visit_pat(&local.pat);
 628                     },
 629                     // An item binding:
 630                     DeclKind::Item(_) => {
 631                         println!("Item(item_id) = {};", current);
 632                     },
 633                 }
 634             }
 635
 636             // Expr without trailing semi-colon (must have unit type):
 637             StmtKind::Expr(ref e, _) => {
 638                 let e_pat = self.next("e");
 639                 println!("Expr(ref {}, _) = {}", e_pat, current);
 640                 self.current = e_pat;
 641                 self.visit_expr(e);
 642             },
 643
 644             // Expr with trailing semi-colon (may have any type):
 645             StmtKind::Semi(ref e, _) => {
 646                 let e_pat = self.next("e");
 647                 println!("Semi(ref {}, _) = {}", e_pat, current);
 648                 self.current = e_pat;
 649                 self.visit_expr(e);
 650             },
 651         }
 652     }
 653
 654     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 655         NestedVisitorMap::None
 656     }
 657 }
 658
 659 fn has_attr(attrs: &[Attribute]) -> bool {
 660     get_attr(attrs, "author").count() > 0
 661 }
 662
 663 fn desugaring_name(des: hir::MatchSource) -> String {
 664     match des {
 665         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 666         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 667         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 668         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 669         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!("MatchSource::IfLetDesugar {{ contains_else_clause: {} }}", contains_else_clause),
 670     }
 671 }
 672
 673 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 674     match des {
 675         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 676         hir::LoopSource::Loop => "LoopSource::Loop",
 677         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 678     }
 679 }
 680
 681 fn print_path(path: &QPath, first: &mut bool) {
 682     match *path {
 683         QPath::Resolved(_, ref path) => for segment in &path.segments {
 684             if *first {
 685                 *first = false;
 686             } else {
 687                 print!(", ");
 688             }
 689             print!("{:?}", segment.ident.as_str());
 690         },
 691         QPath::TypeRelative(ref ty, ref segment) => match ty.node {
 692             hir::TyKind::Path(ref inner_path) => {
 693                 print_path(inner_path, first);
 694                 if *first {
 695                     *first = false;
 696                 } else {
 697                     print!(", ");
 698                 }
 699                 print!("{:?}", segment.ident.as_str());
 700             },
 701             ref other => print!("/* unimplemented: {:?}*/", other),
 702         },
 703     }
 704 }