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 /// // ./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 Expr_::ExprIf(ref cond, ref then, None) = item.node,
  35 ///     if let Expr_::ExprBinary(BinOp::Eq, ref left, ref right) = cond.node,
  36 ///     if let Expr_::ExprPath(ref path) = left.node,
  37 ///     if let Expr_::ExprLit(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
  58 fn prelude() {
  59     println!("if_chain! {{");
  60 }
  61
  62 fn done() {
  63     println!("    then {{");
  64     println!("        // report your lint here");
  65     println!("    }}");
  66     println!("}}");
  67 }
  68
  69 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
  70     fn check_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
  71         if !has_attr(&item.attrs) {
  72             return;
  73         }
  74         prelude();
  75         PrintVisitor::new("item").visit_item(item);
  76         done();
  77     }
  78
  79     fn check_impl_item(&mut self, _cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) {
  80         if !has_attr(&item.attrs) {
  81             return;
  82         }
  83         prelude();
  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     fn print_qpath(&mut self, path: &QPath) {
 178         print!("    if match_qpath({}, &[", self.current);
 179         print_path(path, &mut true);
 180         println!("]);");
 181     }
 182 }
 183
 184 struct PrintVisitor {
 185     /// Fields are the current index that needs to be appended to pattern
 186     /// binding names
 187     ids: HashMap<&'static str, usize>,
 188     /// the name that needs to be destructured
 189     current: String,
 190 }
 191
 192 impl<'tcx> Visitor<'tcx> for PrintVisitor {
 193     fn visit_expr(&mut self, expr: &Expr) {
 194         print!("    if let Expr_::Expr");
 195         let current = format!("{}.node", self.current);
 196         match expr.node {
 197             Expr_::ExprBox(ref inner) => {
 198                 let inner_pat = self.next("inner");
 199                 println!("Box(ref {}) = {};", inner_pat, current);
 200                 self.current = inner_pat;
 201                 self.visit_expr(inner);
 202             },
 203             Expr_::ExprArray(ref elements) => {
 204                 let elements_pat = self.next("elements");
 205                 println!("Array(ref {}) = {};", elements_pat, current);
 206                 println!("    if {}.len() == {};", elements_pat, elements.len());
 207                 for (i, element) in elements.iter().enumerate() {
 208                     self.current = format!("{}[{}]", elements_pat, i);
 209                     self.visit_expr(element);
 210                 }
 211             },
 212             Expr_::ExprCall(ref _func, ref _args) => {
 213                 println!("Call(ref func, ref args) = {};", current);
 214                 println!("    // unimplemented: `ExprCall` is not further destructured at the moment");
 215             },
 216             Expr_::ExprMethodCall(ref _method_name, ref _generics, ref _args) => {
 217                 println!("MethodCall(ref method_name, ref generics, ref args) = {};", current);
 218                 println!("    // unimplemented: `ExprMethodCall` is not further destructured at the moment");
 219             },
 220             Expr_::ExprTup(ref elements) => {
 221                 let elements_pat = self.next("elements");
 222                 println!("Tup(ref {}) = {};", elements_pat, current);
 223                 println!("    if {}.len() == {};", elements_pat, elements.len());
 224                 for (i, element) in elements.iter().enumerate() {
 225                     self.current = format!("{}[{}]", elements_pat, i);
 226                     self.visit_expr(element);
 227                 }
 228             },
 229             Expr_::ExprBinary(ref op, ref left, ref right) => {
 230                 let op_pat = self.next("op");
 231                 let left_pat = self.next("left");
 232                 let right_pat = self.next("right");
 233                 println!("Binary(ref {}, ref {}, ref {}) = {};", op_pat, left_pat, right_pat, current);
 234                 println!("    if BinOp_::{:?} == {}.node;", op.node, op_pat);
 235                 self.current = left_pat;
 236                 self.visit_expr(left);
 237                 self.current = right_pat;
 238                 self.visit_expr(right);
 239             },
 240             Expr_::ExprUnary(ref op, ref inner) => {
 241                 let inner_pat = self.next("inner");
 242                 println!("Unary(UnOp::{:?}, ref {}) = {};", op, inner_pat, current);
 243                 self.current = inner_pat;
 244                 self.visit_expr(inner);
 245             },
 246             Expr_::ExprLit(ref lit) => {
 247                 let lit_pat = self.next("lit");
 248                 println!("Lit(ref {}) = {};", lit_pat, current);
 249                 match lit.node {
 250                     LitKind::Bool(val) => println!("    if let LitKind::Bool({:?}) = {}.node;", val, lit_pat),
 251                     LitKind::Char(c) => println!("    if let LitKind::Char({:?}) = {}.node;", c, lit_pat),
 252                     LitKind::Byte(b) => println!("    if let LitKind::Byte({}) = {}.node;", b, lit_pat),
 253                     // FIXME: also check int type
 254                     LitKind::Int(i, _) => println!("    if let LitKind::Int({}, _) = {}.node;", i, lit_pat),
 255                     LitKind::Float(..) => println!("    if let LitKind::Float(..) = {}.node;", lit_pat),
 256                     LitKind::FloatUnsuffixed(_) => {
 257                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 258                     },
 259                     LitKind::ByteStr(ref vec) => {
 260                         let vec_pat = self.next("vec");
 261                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 262                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 263                     },
 264                     LitKind::Str(ref text, _) => {
 265                         let str_pat = self.next("s");
 266                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 267                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 268                     },
 269                 }
 270             },
 271             Expr_::ExprCast(ref expr, ref ty) => {
 272                 let cast_pat = self.next("expr");
 273                 let cast_ty = self.next("cast_ty");
 274                 let qp_label = self.next("qp");
 275
 276                 println!("Cast(ref {}, ref {}) = {};", cast_pat, cast_ty, current);
 277                 if let Ty_::TyPath(ref qp) = ty.node {
 278                     println!("    if let Ty_::TyPath(ref {}) = {}.node;", qp_label, cast_ty);
 279                     self.current = qp_label;
 280                     self.print_qpath(qp);
 281                 }
 282                 self.current = cast_pat;
 283                 self.visit_expr(expr);
 284             },
 285             Expr_::ExprType(ref expr, ref _ty) => {
 286                 let cast_pat = self.next("expr");
 287                 println!("Type(ref {}, _) = {};", cast_pat, current);
 288                 self.current = cast_pat;
 289                 self.visit_expr(expr);
 290             },
 291             Expr_::ExprIf(ref cond, ref then, ref opt_else) => {
 292                 let cond_pat = self.next("cond");
 293                 let then_pat = self.next("then");
 294                 if let Some(ref else_) = *opt_else {
 295                     let else_pat = self.next("else_");
 296                     println!("If(ref {}, ref {}, Some(ref {})) = {};", cond_pat, then_pat, else_pat, current);
 297                     self.current = else_pat;
 298                     self.visit_expr(else_);
 299                 } else {
 300                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 301                 }
 302                 self.current = cond_pat;
 303                 self.visit_expr(cond);
 304                 self.current = then_pat;
 305                 self.visit_expr(then);
 306             },
 307             Expr_::ExprWhile(ref cond, ref body, _) => {
 308                 let cond_pat = self.next("cond");
 309                 let body_pat = self.next("body");
 310                 let label_pat = self.next("label");
 311                 println!("While(ref {}, ref {}, ref {}) = {};", cond_pat, body_pat, label_pat, current);
 312                 self.current = cond_pat;
 313                 self.visit_expr(cond);
 314                 self.current = body_pat;
 315                 self.visit_block(body);
 316             },
 317             Expr_::ExprLoop(ref body, _, desugaring) => {
 318                 let body_pat = self.next("body");
 319                 let des = loop_desugaring_name(desugaring);
 320                 let label_pat = self.next("label");
 321                 println!("Loop(ref {}, ref {}, {}) = {};", body_pat, label_pat, des, current);
 322                 self.current = body_pat;
 323                 self.visit_block(body);
 324             },
 325             Expr_::ExprMatch(ref _expr, ref _arms, desugaring) => {
 326                 let des = desugaring_name(desugaring);
 327                 println!("Match(ref expr, ref arms, {}) = {};", des, current);
 328                 println!("    // unimplemented: `ExprMatch` is not further destructured at the moment");
 329             },
 330             Expr_::ExprClosure(ref _capture_clause, ref _func, _, _, _) => {
 331                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 332                 println!("    // unimplemented: `ExprClosure` is not further destructured at the moment");
 333             },
 334             Expr_::ExprYield(ref sub) => {
 335                 let sub_pat = self.next("sub");
 336                 println!("Yield(ref sub) = {};", current);
 337                 self.current = sub_pat;
 338                 self.visit_expr(sub);
 339             },
 340             Expr_::ExprBlock(ref block) => {
 341                 let block_pat = self.next("block");
 342                 println!("Block(ref {}) = {};", block_pat, current);
 343                 self.current = block_pat;
 344                 self.visit_block(block);
 345             },
 346             Expr_::ExprAssign(ref target, ref value) => {
 347                 let target_pat = self.next("target");
 348                 let value_pat = self.next("value");
 349                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 350                 self.current = target_pat;
 351                 self.visit_expr(target);
 352                 self.current = value_pat;
 353                 self.visit_expr(value);
 354             },
 355             Expr_::ExprAssignOp(ref op, ref target, ref value) => {
 356                 let op_pat = self.next("op");
 357                 let target_pat = self.next("target");
 358                 let value_pat = self.next("value");
 359                 println!("AssignOp(ref {}, ref {}, ref {}) = {};", op_pat, target_pat, value_pat, current);
 360                 println!("    if BinOp_::{:?} == {}.node;", op.node, op_pat);
 361                 self.current = target_pat;
 362                 self.visit_expr(target);
 363                 self.current = value_pat;
 364                 self.visit_expr(value);
 365             },
 366             Expr_::ExprField(ref object, ref field_name) => {
 367                 let obj_pat = self.next("object");
 368                 let field_name_pat = self.next("field_name");
 369                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 370                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_name.node.as_str());
 371                 self.current = obj_pat;
 372                 self.visit_expr(object);
 373             },
 374             Expr_::ExprTupField(ref object, ref field_id) => {
 375                 let obj_pat = self.next("object");
 376                 let field_id_pat = self.next("field_id");
 377                 println!("TupField(ref {}, ref {}) = {};", obj_pat, field_id_pat, current);
 378                 println!("    if {}.node == {}", field_id_pat, field_id.node);
 379                 self.current = obj_pat;
 380                 self.visit_expr(object);
 381             },
 382             Expr_::ExprIndex(ref object, ref index) => {
 383                 let object_pat = self.next("object");
 384                 let index_pat = self.next("index");
 385                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 386                 self.current = object_pat;
 387                 self.visit_expr(object);
 388                 self.current = index_pat;
 389                 self.visit_expr(index);
 390             },
 391             Expr_::ExprPath(ref path) => {
 392                 let path_pat = self.next("path");
 393                 println!("Path(ref {}) = {};", path_pat, current);
 394                 self.current = path_pat;
 395                 self.print_qpath(path);
 396             },
 397             Expr_::ExprAddrOf(mutability, ref inner) => {
 398                 let inner_pat = self.next("inner");
 399                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 400                 self.current = inner_pat;
 401                 self.visit_expr(inner);
 402             },
 403             Expr_::ExprBreak(ref _destination, ref opt_value) => {
 404                 let destination_pat = self.next("destination");
 405                 if let Some(ref value) = *opt_value {
 406                     let value_pat = self.next("value");
 407                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 408                     self.current = value_pat;
 409                     self.visit_expr(value);
 410                 } else {
 411                     println!("Break(ref {}, None) = {};", destination_pat, current);
 412                 }
 413                 // FIXME: implement label printing
 414             },
 415             Expr_::ExprAgain(ref _destination) => {
 416                 let destination_pat = self.next("destination");
 417                 println!("Again(ref {}) = {};", destination_pat, current);
 418                 // FIXME: implement label printing
 419             },
 420             Expr_::ExprRet(ref opt_value) => if let Some(ref value) = *opt_value {
 421                 let value_pat = self.next("value");
 422                 println!("Ret(Some(ref {})) = {};", value_pat, current);
 423                 self.current = value_pat;
 424                 self.visit_expr(value);
 425             } else {
 426                 println!("Ret(None) = {};", current);
 427             },
 428             Expr_::ExprInlineAsm(_, ref _input, ref _output) => {
 429                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 430                 println!("    // unimplemented: `ExprInlineAsm` is not further destructured at the moment");
 431             },
 432             Expr_::ExprStruct(ref path, ref fields, ref opt_base) => {
 433                 let path_pat = self.next("path");
 434                 let fields_pat = self.next("fields");
 435                 if let Some(ref base) = *opt_base {
 436                     let base_pat = self.next("base");
 437                     println!(
 438                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 439                         path_pat,
 440                         fields_pat,
 441                         base_pat,
 442                         current
 443                     );
 444                     self.current = base_pat;
 445                     self.visit_expr(base);
 446                 } else {
 447                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 448                 }
 449                 self.current = path_pat;
 450                 self.print_qpath(path);
 451                 println!("    if {}.len() == {};", fields_pat, fields.len());
 452                 println!("    // unimplemented: field checks");
 453             },
 454             // FIXME: compute length (needs type info)
 455             Expr_::ExprRepeat(ref value, _) => {
 456                 let value_pat = self.next("value");
 457                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 458                 println!("// unimplemented: repeat count check");
 459                 self.current = value_pat;
 460                 self.visit_expr(value);
 461             },
 462         }
 463     }
 464
 465     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 466         NestedVisitorMap::None
 467     }
 468 }
 469
 470 fn has_attr(attrs: &[Attribute]) -> bool {
 471     attrs.iter().any(|attr| {
 472         attr.check_name("clippy") && attr.meta_item_list().map_or(false, |list| {
 473             list.len() == 1 && match list[0].node {
 474                 ast::NestedMetaItemKind::MetaItem(ref it) => it.name == "author",
 475                 ast::NestedMetaItemKind::Literal(_) => false,
 476             }
 477         })
 478     })
 479 }
 480
 481 fn desugaring_name(des: hir::MatchSource) -> String {
 482     match des {
 483         hir::MatchSource::ForLoopDesugar => "MatchSource::ForLoopDesugar".to_string(),
 484         hir::MatchSource::TryDesugar => "MatchSource::TryDesugar".to_string(),
 485         hir::MatchSource::WhileLetDesugar => "MatchSource::WhileLetDesugar".to_string(),
 486         hir::MatchSource::Normal => "MatchSource::Normal".to_string(),
 487         hir::MatchSource::IfLetDesugar { contains_else_clause } => format!("MatchSource::IfLetDesugar {{ contains_else_clause: {} }}", contains_else_clause),
 488     }
 489 }
 490
 491 fn loop_desugaring_name(des: hir::LoopSource) -> &'static str {
 492     match des {
 493         hir::LoopSource::ForLoop => "LoopSource::ForLoop",
 494         hir::LoopSource::Loop => "LoopSource::Loop",
 495         hir::LoopSource::WhileLet => "LoopSource::WhileLet",
 496     }
 497 }
 498
 499 fn print_path(path: &QPath, first: &mut bool) {
 500     match *path {
 501         QPath::Resolved(_, ref path) => for segment in &path.segments {
 502             if *first {
 503                 *first = false;
 504             } else {
 505                 print!(", ");
 506             }
 507             print!("{:?}", segment.name.as_str());
 508         },
 509         QPath::TypeRelative(ref ty, ref segment) => match ty.node {
 510             hir::Ty_::TyPath(ref inner_path) => {
 511                 print_path(inner_path, first);
 512                 if *first {
 513                     *first = false;
 514                 } else {
 515                     print!(", ");
 516                 }
 517                 print!("{:?}", segment.name.as_str());
 518             },
 519             ref other => print!("/* unimplemented: {:?}*/", other),
 520         },
 521     }
 522 }