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