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