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