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 #![allow(print_stdout, use_debug)]
   5
   6 use rustc::lint::*;
   7 use rustc::hir;
   8 use rustc::hir::{Expr, Expr_, QPath, Ty_};
   9 use rustc::hir::intravisit::{NestedVisitorMap, Visitor, walk_decl};
  10 use rustc::hir::Decl;
  11 use syntax::ast::{self, Attribute, LitKind, NodeId, DUMMY_NODE_ID};
  12 use syntax::codemap::Span;
  13 use std::collections::HashMap;
  14
  15 /// **What it does:** Generates clippy code that detects the offending pattern
  16 ///
  17 /// **Example:**
  18 /// ```rust
  19 /// fn foo() {
  20 ///     // detect the following pattern
  21 ///     #[clippy(author)]
  22 ///     if x == 42 {
  23 ///         // but ignore everything from here on
  24 ///         #![clippy(author = "ignore")]
  25 ///     }
  26 /// }
  27 /// ```
  28 ///
  29 /// prints
  30 ///
  31 /// ```
  32 /// if_chain!{
  33 ///     if let Expr_::ExprIf(ref cond, ref then, None) = item.node,
  34 ///     if let Expr_::ExprBinary(BinOp::Eq, ref left, ref right) = cond.node,
  35 ///     if let Expr_::ExprPath(ref path) = left.node,
  36 ///     if let Expr_::ExprLit(ref lit) = right.node,
  37 ///     if let LitKind::Int(42, _) = lit.node,
  38 ///     then {
  39 ///         // report your lint here
  40 ///     }
  41 /// }
  42 /// ```
  43 declare_lint! {
  44     pub LINT_AUTHOR,
  45     Warn,
  46     "helper for writing lints"
  47 }
  48
  49 pub struct Pass;
  50
  51 impl LintPass for Pass {
  52     fn get_lints(&self) -> LintArray {
  53         lint_array!(LINT_AUTHOR)
  54     }
  55 }
  56
  57 fn prelude() {
  58     println!("if_chain! {{");
  59 }
  60
  61 fn done() {
  62     println!("    then {{");
  63     println!("        // report your lint here");
  64     println!("    }}");
  65     println!("}}");
  66 }
  67
  68 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
  69     fn check_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
  70         if !has_attr(&item.attrs) {
  71             return;
  72         }
  73         prelude();
  74         PrintVisitor::new("item").visit_item(item);
  75         done();
  76     }
  77
  78     fn check_impl_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
  79         if !has_attr(&item.attrs) {
  80             return;
  81         }
  82         prelude();
  83
  84         PrintVisitor::new("item").visit_impl_item(item);
  85         done();
  86     }
  87
  88     fn check_trait_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
  89         if !has_attr(&item.attrs) {
  90             return;
  91         }
  92         prelude();
  93         PrintVisitor::new("item").visit_trait_item(item);
  94         done();
  95     }
  96
  97     fn check_variant(&mut self, _cx: &LateContext<'a, 'tcx>, var: &'tcx hir::Variant, generics: &hir::Generics) {
  98         if !has_attr(&var.node.attrs) {
  99             return;
 100         }
 101         prelude();
 102         PrintVisitor::new("var").visit_variant(var, generics, DUMMY_NODE_ID);
 103         done();
 104     }
 105
 106     fn check_struct_field(&mut self, _cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
 107         if !has_attr(&field.attrs) {
 108             return;
 109         }
 110         prelude();
 111         PrintVisitor::new("field").visit_struct_field(field);
 112         done();
 113     }
 114
 115     fn check_expr(&mut self, _cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
 116         if !has_attr(&expr.attrs) {
 117             return;
 118         }
 119         prelude();
 120         PrintVisitor::new("expr").visit_expr(expr);
 121         done();
 122     }
 123
 124     fn check_arm(&mut self, _cx: &LateContext<'a, 'tcx>, arm: &'tcx hir::Arm) {
 125         if !has_attr(&arm.attrs) {
 126             return;
 127         }
 128         prelude();
 129         PrintVisitor::new("arm").visit_arm(arm);
 130         done();
 131     }
 132
 133     fn check_stmt(&mut self, _cx: &LateContext<'a, 'tcx>, stmt: &'tcx hir::Stmt) {
 134         if !has_attr(stmt.node.attrs()) {
 135             return;
 136         }
 137         prelude();
 138         PrintVisitor::new("stmt").visit_stmt(stmt);
 139         done();
 140     }
 141
 142     fn check_foreign_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ForeignItem) {
 143         if !has_attr(&item.attrs) {
 144             return;
 145         }
 146         prelude();
 147         PrintVisitor::new("item").visit_foreign_item(item);
 148         done();
 149     }
 150 }
 151
 152 impl PrintVisitor {
 153     fn new(s: &'static str) -> Self {
 154         Self {
 155             ids: HashMap::new(),
 156             current: s.to_owned(),
 157         }
 158     }
 159
 160     fn next(&mut self, s: &'static str) -> String {
 161         use std::collections::hash_map::Entry::*;
 162         match self.ids.entry(s) {
 163             // already there: start numbering from `1`
 164             Occupied(mut occ) => {
 165                 let val = occ.get_mut();
 166                 *val += 1;
 167                 format!("{}{}", s, *val)
 168             },
 169             // not there: insert and return name as given
 170             Vacant(vac) => {
 171                 vac.insert(0);
 172                 s.to_owned()
 173             },
 174         }
 175     }
 176 }
 177
 178 struct PrintVisitor {
 179     /// Fields are the current index that needs to be appended to pattern
 180     /// binding names
 181     ids: HashMap<&'static str, usize>,
 182     /// the name that needs to be destructured
 183     current: String,
 184 }
 185
 186 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 187     fn visit_decl(&mut self, d: &'tcx Decl) {
 188         match d.node {
 189             hir::DeclLocal(ref local) => {
 190                 self.visit_pat(&local.pat);
 191                 if let Some(ref e) = local.init {
 192                     self.visit_expr(e);
 193                 }
 194             },
 195             _ => walk_decl(self, d)
 196         }
 197     }
 198
 199     fn visit_expr(&mut self, expr: &Expr) {
 200         print!("    if let Expr_::Expr");
 201         let current = format!("{}.node", self.current);
 202         match expr.node {
 203             Expr_::ExprBox(ref inner) => {
 204                 let inner_pat = self.next("inner");
 205                 println!("Box(ref {}) = {};", inner_pat, current);
 206                 self.current = inner_pat;
 207                 self.visit_expr(inner);
 208             },
 209             Expr_::ExprArray(ref elements) => {
 210                 let elements_pat = self.next("elements");
 211                 println!("Array(ref {}) = {};", elements_pat, current);
 212                 println!("    if {}.len() == {};", elements_pat, elements.len());
 213                 for (i, element) in elements.iter().enumerate() {
 214                     self.current = format!("{}[{}]", elements_pat, i);
 215                     self.visit_expr(element);
 216                 }
 217             },
 218             Expr_::ExprCall(ref _func, ref _args) => {
 219                 println!("Call(ref func, ref args) = {};", current);
 220                 println!("    // unimplemented: `ExprCall` is not further destructured at the moment");
 221             },
 222             Expr_::ExprMethodCall(ref _method_name, ref _generics, ref _args) => {
 223                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 224                 println!("    // unimplemented: `ExprMethodCall` is not further destructured at the moment");
 225             },
 226             Expr_::ExprTup(ref elements) => {
 227                 let elements_pat = self.next("elements");
 228                 println!("Tup(ref {}) = {};", elements_pat, current);
 229                 println!("    if {}.len() == {};", elements_pat, elements.len());
 230                 for (i, element) in elements.iter().enumerate() {
 231                     self.current = format!("{}[{}]", elements_pat, i);
 232                     self.visit_expr(element);
 233                 }
 234             },
 235             Expr_::ExprBinary(ref op, ref left, ref right) => {
 236                 let op_pat = self.next("op");
 237                 let left_pat = self.next("left");
 238                 let right_pat = self.next("right");
 239                 println!("Binary(ref {}, ref {}, ref {}) = {};", op_pat, left_pat, right_pat, current);
 240                 println!("    if BinOp_::{:?} == {}.node;", op.node, op_pat);
 241                 self.current = left_pat;
 242                 self.visit_expr(left);
 243                 self.current = right_pat;
 244                 self.visit_expr(right);
 245             },
 246             Expr_::ExprUnary(ref op, ref inner) => {
 247                 let inner_pat = self.next("inner");
 248                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 249                 self.current = inner_pat;
 250                 self.visit_expr(inner);
 251             },
 252             Expr_::ExprLit(ref lit) => {
 253                 let lit_pat = self.next("lit");
 254                 println!("Lit(ref {}) = {};", lit_pat, current);
 255                 match lit.node {
 256                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 257                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 258                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 259                     // FIXME: also check int type
 260                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 261                     LitKind::Float(..) => println!("    if let LitKind::Float(..) = {}.node;", lit_pat),
 262                     LitKind::FloatUnsuffixed(_) => {
 263                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 264                     },
 265                     LitKind::ByteStr(ref vec) => {
 266                         let vec_pat = self.next("vec");
 267                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 268                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 269                     },
 270                     LitKind::Str(ref text, _) => {
 271                         let str_pat = self.next("s");
 272                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 273                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 274                     },
 275                 }
 276             },
 277             Expr_::ExprCast(ref expr, ref ty) => {
 278                 let cast_pat = self.next("expr");
 279                 let cast_ty = self.next("cast_ty");
 280                 let qp_label = self.next("qp");
 281
 282                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 283                 if let Ty_::TyPath(ref qp) = ty.node {
 284                     println!("    if let Ty_::TyPath(ref {}) = {}.node;", qp_label, cast_ty);
 285                     self.current = qp_label;
 286                     self.visit_qpath(&qp, ty.id, ty.span);
 287                 }
 288                 self.current = cast_pat;
 289                 self.visit_expr(expr);
 290             },
 291             Expr_::ExprType(ref expr, ref _ty) => {
 292                 let cast_pat = self.next("expr");
 293                 println!("Type(ref {}, _) = {};", cast_pat, current);
 294                 self.current = cast_pat;
 295                 self.visit_expr(expr);
 296             },
 297             Expr_::ExprIf(ref cond, ref then, ref opt_else) => {
 298                 let cond_pat = self.next("cond");
 299                 let then_pat = self.next("then");
 300                 if let Some(ref else_) = *opt_else {
 301                     let else_pat = self.next("else_");
 302                     println!("If(ref {}, ref {}, Some(ref {})) = {};", cond_pat, then_pat, else_pat, current);
 303                     self.current = else_pat;
 304                     self.visit_expr(else_);
 305                 } else {
 306                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 307                 }
 308                 self.current = cond_pat;
 309                 self.visit_expr(cond);
 310                 self.current = then_pat;
 311                 self.visit_expr(then);
 312             },
 313             Expr_::ExprWhile(ref cond, ref body, _) => {
 314                 let cond_pat = self.next("cond");
 315                 let body_pat = self.next("body");
 316                 let label_pat = self.next("label");
 317                 println!("While(ref {}, ref {}, ref {}) = {};", cond_pat, body_pat, label_pat, current);
 318                 self.current = cond_pat;
 319                 self.visit_expr(cond);
 320                 self.current = body_pat;
 321                 self.visit_block(body);
 322             },
 323             Expr_::ExprLoop(ref body, _, desugaring) => {
 324                 let body_pat = self.next("body");
 325                 let des = loop_desugaring_name(desugaring);
 326                 let label_pat = self.next("label");
 327                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 328                 self.current = body_pat;
 329                 self.visit_block(body);
 330             },
 331             Expr_::ExprMatch(ref _expr, ref _arms, desugaring) => {
 332                 let des = desugaring_name(desugaring);
 333                 println!("Match(ref expr, ref arms, {}) = {};", des, current);
 334                 println!("    // unimplemented: `ExprMatch` is not further destructured at the moment");
 335             },
 336             Expr_::ExprClosure(ref _capture_clause, ref _func, _, _, _) => {
 337                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 338                 println!("    // unimplemented: `ExprClosure` is not further destructured at the moment");
 339             },
 340             Expr_::ExprYield(ref sub) => {
 341                 let sub_pat = self.next("sub");
 342                 println!("Yield(ref sub) = {};", current);
 343                 self.current = sub_pat;
 344                 self.visit_expr(sub);
 345             },
 346             Expr_::ExprBlock(ref block) => {
 347                 let block_pat = self.next("block");
 348                 println!("Block(ref {}) = {};", block_pat, current);
 349                 self.current = block_pat;
 350                 self.visit_block(block);
 351             },
 352             Expr_::ExprAssign(ref target, ref value) => {
 353                 let target_pat = self.next("target");
 354                 let value_pat = self.next("value");
 355                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 356                 self.current = target_pat;
 357                 self.visit_expr(target);
 358                 self.current = value_pat;
 359                 self.visit_expr(value);
 360             },
 361             Expr_::ExprAssignOp(ref op, ref target, ref value) => {
 362                 let op_pat = self.next("op");
 363                 let target_pat = self.next("target");
 364                 let value_pat = self.next("value");
 365                 println!("AssignOp(ref {}, ref {}, ref {}) = {};", op_pat, target_pat, value_pat, current);
 366                 println!("    if BinOp_::{:?} == {}.node;", op.node, op_pat);
 367                 self.current = target_pat;
 368                 self.visit_expr(target);
 369                 self.current = value_pat;
 370                 self.visit_expr(value);
 371             },
 372             Expr_::ExprField(ref object, ref field_name) => {
 373                 let obj_pat = self.next("object");
 374                 let field_name_pat = self.next("field_name");
 375                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 376                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_name.node.as_str());
 377                 self.current = obj_pat;
 378                 self.visit_expr(object);
 379             },
 380             Expr_::ExprTupField(ref object, ref field_id) => {
 381                 let obj_pat = self.next("object");
 382                 let field_id_pat = self.next("field_id");
 383                 println!("TupField(ref {}, ref {}) = {};", obj_pat, field_id_pat, current);
 384                 println!("    if {}.node == {}", field_id_pat, field_id.node);
 385                 self.current = obj_pat;
 386                 self.visit_expr(object);
 387             },
 388             Expr_::ExprIndex(ref object, ref index) => {
 389                 let object_pat = self.next("object");
 390                 let index_pat = self.next("index");
 391                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 392                 self.current = object_pat;
 393                 self.visit_expr(object);
 394                 self.current = index_pat;
 395                 self.visit_expr(index);
 396             },
 397             Expr_::ExprPath(ref path) => {
 398                 let path_pat = self.next("path");
 399                 println!("Path(ref {}) = {};", path_pat, current);
 400                 self.current = path_pat;
 401                 self.visit_qpath(path, expr.id, expr.span);
 402             },
 403             Expr_::ExprAddrOf(mutability, ref inner) => {
 404                 let inner_pat = self.next("inner");
 405                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 406                 self.current = inner_pat;
 407                 self.visit_expr(inner);
 408             },
 409             Expr_::ExprBreak(ref _destination, ref opt_value) => {
 410                 let destination_pat = self.next("destination");
 411                 if let Some(ref value) = *opt_value {
 412                     let value_pat = self.next("value");
 413                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 414                     self.current = value_pat;
 415                     self.visit_expr(value);
 416                 } else {
 417                     println!("Break(ref {}, None) = {};", destination_pat, current);
 418                 }
 419                 // FIXME: implement label printing
 420             },
 421             Expr_::ExprAgain(ref _destination) => {
 422                 let destination_pat = self.next("destination");
 423                 println!("Again(ref {}) = {};", destination_pat, current);
 424                 // FIXME: implement label printing
 425             },
 426             Expr_::ExprRet(ref opt_value) => if let Some(ref value) = *opt_value {
 427                 let value_pat = self.next("value");
 428                 println!("Ret(Some(ref {})) = {};", value_pat, current);
 429                 self.current = value_pat;
 430                 self.visit_expr(value);
 431             } else {
 432                 println!("Ret(None) = {};", current);
 433             },
 434             Expr_::ExprInlineAsm(_, ref _input, ref _output) => {
 435                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 436                 println!("    // unimplemented: `ExprInlineAsm` is not further destructured at the moment");
 437             },
 438             Expr_::ExprStruct(ref path, ref fields, ref opt_base) => {
 439                 let path_pat = self.next("path");
 440                 let fields_pat = self.next("fields");
 441                 if let Some(ref base) = *opt_base {
 442                     let base_pat = self.next("base");
 443                     println!(
 444                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 445                         path_pat,
 446                         fields_pat,
 447                         base_pat,
 448                         current
 449                     );
 450                     self.current = base_pat;
 451                     self.visit_expr(base);
 452                 } else {
 453                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 454                 }
 455                 self.current = path_pat;
 456                 self.visit_qpath(path, expr.id, expr.span);
 457                 println!("    if {}.len() == {};", fields_pat, fields.len());
 458                 println!("    // unimplemented: field checks");
 459             },
 460             // FIXME: compute length (needs type info)
 461             Expr_::ExprRepeat(ref value, _) => {
 462                 let value_pat = self.next("value");
 463                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 464                 println!("// unimplemented: repeat count check");
 465                 self.current = value_pat;
 466                 self.visit_expr(value);
 467             },
 468         }
 469     }
 470
 471     fn visit_qpath(&mut self, path: &QPath, _: NodeId, _: Span) {
 472         print!("    if match_qpath({}, &[", self.current);
 473         print_path(path, &mut true);
 474         println!("]);");
 475     }
 476     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 477         NestedVisitorMap::None
 478     }
 479 }
 480
 481 fn has_attr(attrs: &[Attribute]) -> bool {
 482     attrs.iter().any(|attr| {
 483         attr.check_name("clippy") && attr.meta_item_list().map_or(false, |list| {
 484             list.len() == 1 && match list[0].node {
 485                 ast::NestedMetaItemKind::MetaItem(ref it) => it.name == "author",
 486                 ast::NestedMetaItemKind::Literal(_) => false,
 487             }
 488         })
 489     })
 490 }
 491
 492 fn desugaring_name(des: hir::MatchSource) -> String {
 493     match des {
 494         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 495         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 496         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 497         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 498         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!("MatchSource::IfLetDesugar {{ contains_else_clause: {} }}", contains_else_clause),
 499     }
 500 }
 501
 502 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 503     match des {
 504         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 505         hir::LoopSource::Loop => "LoopSource::Loop",
 506         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 507     }
 508 }
 509
 510 fn print_path(path: &QPath, first: &mut bool) {
 511     match *path {
 512         QPath::Resolved(_, ref path) => for segment in &path.segments {
 513             if *first {
 514                 *first = false;
 515             } else {
 516                 print!(", ");
 517             }
 518             print!("{:?}", segment.name.as_str());
 519         },
 520         QPath::TypeRelative(ref ty, ref segment) => match ty.node {
 521             hir::Ty_::TyPath(ref inner_path) => {
 522                 print_path(inner_path, first);
 523                 if *first {
 524                     *first = false;
 525                 } else {
 526                     print!(", ");
 527                 }
 528                 print!("{:?}", segment.name.as_str());
 529             },
 530             ref other => print!("/* unimplemented: {:?}*/", other),
 531         },
 532     }
 533 }