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(_) => {
 249                         println!("    if let LitKind::FloatUnsuffixed(_) = {}.node;", lit_pat)
 250                     },
 251                     LitKind::ByteStr(ref vec) => {
 252                         let vec_pat = self.next("vec");
 253                         println!("    if let LitKind::ByteStr(ref {}) = {}.node;", vec_pat, lit_pat);
 254                         println!("    if let [{:?}] = **{};", vec, vec_pat);
 255                     },
 256                     LitKind::Str(ref text, _) => {
 257                         let str_pat = self.next("s");
 258                         println!("    if let LitKind::Str(ref {}) = {}.node;", str_pat, lit_pat);
 259                         println!("    if {}.as_str() == {:?}", str_pat, &*text.as_str())
 260                     },
 261                 }
 262             },
 263             Expr_::ExprCast(ref expr, ref _ty) => {
 264                 let cast_pat = self.next("expr");
 265                 println!("Cast(ref {}, _) = {};", cast_pat, current);
 266                 self.current = cast_pat;
 267                 self.visit_expr(expr);
 268             },
 269             Expr_::ExprType(ref expr, ref _ty) => {
 270                 let cast_pat = self.next("expr");
 271                 println!("Type(ref {}, _) = {};", cast_pat, current);
 272                 self.current = cast_pat;
 273                 self.visit_expr(expr);
 274             },
 275             Expr_::ExprIf(ref cond, ref then, ref opt_else) => {
 276                 let cond_pat = self.next("cond");
 277                 let then_pat = self.next("then");
 278                 if let Some(ref else_) = *opt_else {
 279                     let else_pat = self.next("else_");
 280                     println!("If(ref {}, ref {}, Some(ref {})) = {};", cond_pat, then_pat, else_pat, current);
 281                     self.current = else_pat;
 282                     self.visit_expr(else_);
 283                 } else {
 284                     println!("If(ref {}, ref {}, None) = {};", cond_pat, then_pat, current);
 285                 }
 286                 self.current = cond_pat;
 287                 self.visit_expr(cond);
 288                 self.current = then_pat;
 289                 self.visit_expr(then);
 290             },
 291             Expr_::ExprWhile(ref _cond, ref _body, ref _opt_label) => {
 292                 println!("While(ref cond, ref body, ref opt_label) = {};", current);
 293                 println!("    // unimplemented: `ExprWhile` is not further destructured at the moment");
 294             },
 295             Expr_::ExprLoop(ref _body, ref _opt_label, ref _desuraging) => {
 296                 println!("Loop(ref body, ref opt_label, ref desugaring) = {};", current);
 297                 println!("    // unimplemented: `ExprLoop` is not further destructured at the moment");
 298             },
 299             Expr_::ExprMatch(ref _expr, ref _arms, ref _desugaring) => {
 300                 println!("Match(ref expr, ref arms, ref desugaring) = {};", current);
 301                 println!("    // unimplemented: `ExprMatch` is not further destructured at the moment");
 302             },
 303             Expr_::ExprClosure(ref _capture_clause, ref _func, _, _, _) => {
 304                 println!("Closure(ref capture_clause, ref func, _, _, _) = {};", current);
 305                 println!("    // unimplemented: `ExprClosure` is not further destructured at the moment");
 306             },
 307             Expr_::ExprYield(ref sub) => {
 308                 let sub_pat = self.next("sub");
 309                 println!("Yield(ref sub) = {};", current);
 310                 self.current = sub_pat;
 311                 self.visit_expr(sub);
 312             },
 313             Expr_::ExprBlock(ref block) => {
 314                 let block_pat = self.next("block");
 315                 println!("Block(ref {}) = {};", block_pat, current);
 316                 self.current = block_pat;
 317                 self.visit_block(block);
 318             },
 319             Expr_::ExprAssign(ref target, ref value) => {
 320                 let target_pat = self.next("target");
 321                 let value_pat = self.next("value");
 322                 println!("Assign(ref {}, ref {}) = {};", target_pat, value_pat, current);
 323                 self.current = target_pat;
 324                 self.visit_expr(target);
 325                 self.current = value_pat;
 326                 self.visit_expr(value);
 327             },
 328             Expr_::ExprAssignOp(ref op, ref target, ref value) => {
 329                 let op_pat = self.next("op");
 330                 let target_pat = self.next("target");
 331                 let value_pat = self.next("value");
 332                 println!("AssignOp(ref {}, ref {}, ref {}) = {};", op_pat, target_pat, value_pat, current);
 333                 println!("    if BinOp_::{:?} == {}.node;", op.node, op_pat);
 334                 self.current = target_pat;
 335                 self.visit_expr(target);
 336                 self.current = value_pat;
 337                 self.visit_expr(value);
 338             },
 339             Expr_::ExprField(ref object, ref field_name) => {
 340                 let obj_pat = self.next("object");
 341                 let field_name_pat = self.next("field_name");
 342                 println!("Field(ref {}, ref {}) = {};", obj_pat, field_name_pat, current);
 343                 println!("    if {}.node.as_str() == {:?}", field_name_pat, field_name.node.as_str());
 344                 self.current = obj_pat;
 345                 self.visit_expr(object);
 346             },
 347             Expr_::ExprTupField(ref object, ref field_id) => {
 348                 let obj_pat = self.next("object");
 349                 let field_id_pat = self.next("field_id");
 350                 println!("TupField(ref {}, ref {}) = {};", obj_pat, field_id_pat, current);
 351                 println!("    if {}.node == {}", field_id_pat, field_id.node);
 352                 self.current = obj_pat;
 353                 self.visit_expr(object);
 354             },
 355             Expr_::ExprIndex(ref object, ref index) => {
 356                 let object_pat = self.next("object");
 357                 let index_pat = self.next("index");
 358                 println!("Index(ref {}, ref {}) = {};", object_pat, index_pat, current);
 359                 self.current = object_pat;
 360                 self.visit_expr(object);
 361                 self.current = index_pat;
 362                 self.visit_expr(index);
 363             },
 364             Expr_::ExprPath(ref path) => {
 365                 let path_pat = self.next("path");
 366                 println!("Path(ref {}) = {};", path_pat, current);
 367                 self.current = path_pat;
 368                 self.visit_qpath(path, expr.id, expr.span);
 369             },
 370             Expr_::ExprAddrOf(mutability, ref inner) => {
 371                 let inner_pat = self.next("inner");
 372                 println!("AddrOf({:?}, ref {}) = {};", mutability, inner_pat, current);
 373                 self.current = inner_pat;
 374                 self.visit_expr(inner);
 375             },
 376             Expr_::ExprBreak(ref _destination, ref opt_value) => {
 377                 let destination_pat = self.next("destination");
 378                 if let Some(ref value) = *opt_value {
 379                     let value_pat = self.next("value");
 380                     println!("Break(ref {}, Some(ref {})) = {};", destination_pat, value_pat, current);
 381                     self.current = value_pat;
 382                     self.visit_expr(value);
 383                 } else {
 384                     println!("Break(ref {}, None) = {};", destination_pat, current);
 385                 }
 386                 // FIXME: implement label printing
 387             },
 388             Expr_::ExprAgain(ref _destination) => {
 389                 let destination_pat = self.next("destination");
 390                 println!("Again(ref {}) = {};", destination_pat, current);
 391                 // FIXME: implement label printing
 392             },
 393             Expr_::ExprRet(ref opt_value) => if let Some(ref value) = *opt_value {
 394                 let value_pat = self.next("value");
 395                 println!("Ret(Some(ref {})) = {};", value_pat, current);
 396                 self.current = value_pat;
 397                 self.visit_expr(value);
 398             } else {
 399                 println!("Ret(None) = {};", current);
 400             },
 401             Expr_::ExprInlineAsm(_, ref _input, ref _output) => {
 402                 println!("InlineAsm(_, ref input, ref output) = {};", current);
 403                 println!("    // unimplemented: `ExprInlineAsm` is not further destructured at the moment");
 404             },
 405             Expr_::ExprStruct(ref path, ref fields, ref opt_base) => {
 406                 let path_pat = self.next("path");
 407                 let fields_pat = self.next("fields");
 408                 if let Some(ref base) = *opt_base {
 409                     let base_pat = self.next("base");
 410                     println!(
 411                         "Struct(ref {}, ref {}, Some(ref {})) = {};",
 412                         path_pat,
 413                         fields_pat,
 414                         base_pat,
 415                         current
 416                     );
 417                     self.current = base_pat;
 418                     self.visit_expr(base);
 419                 } else {
 420                     println!("Struct(ref {}, ref {}, None) = {};", path_pat, fields_pat, current);
 421                 }
 422                 self.current = path_pat;
 423                 self.visit_qpath(path, expr.id, expr.span);
 424                 println!("    if {}.len() == {};", fields_pat, fields.len());
 425                 println!("    // unimplemented: field checks");
 426             },
 427             // FIXME: compute length (needs type info)
 428             Expr_::ExprRepeat(ref value, _) => {
 429                 let value_pat = self.next("value");
 430                 println!("Repeat(ref {}, _) = {};", value_pat, current);
 431                 println!("// unimplemented: repeat count check");
 432                 self.current = value_pat;
 433                 self.visit_expr(value);
 434             },
 435         }
 436     }
 437
 438     fn visit_qpath(&mut self, path: &QPath, _: NodeId, _: Span) {
 439         print!("    if match_qpath({}, &[", self.current);
 440         print_path(path, &mut true);
 441         println!("]);");
 442     }
 443     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
 444         NestedVisitorMap::None
 445     }
 446 }
 447
 448 fn has_attr(attrs: &[Attribute]) -> bool {
 449     attrs.iter().any(|attr| {
 450         attr.check_name("clippy") && attr.meta_item_list().map_or(false, |list| {
 451             list.len() == 1 && match list[0].node {
 452                 ast::NestedMetaItemKind::MetaItem(ref it) => it.name == "author",
 453                 ast::NestedMetaItemKind::Literal(_) => false,
 454             }
 455         })
 456     })
 457 }
 458
 459 fn print_path(path: &QPath, first: &mut bool) {
 460     match *path {
 461         QPath::Resolved(_, ref path) => for segment in &path.segments {
 462             if *first {
 463                 *first = false;
 464             } else {
 465                 print!(", ");
 466             }
 467             print!("{:?}", segment.name.as_str());
 468         },
 469         QPath::TypeRelative(ref ty, ref segment) => match ty.node {
 470             hir::Ty_::TyPath(ref inner_path) => {
 471                 print_path(inner_path, first);
 472                 if *first {
 473                     *first = false;
 474                 } else {
 475                     print!(", ");
 476                 }
 477                 print!("{:?}", segment.name.as_str());
 478             },
 479             ref other => print!("/* unimplemented: {:?}*/", other),
 480         },
 481     }
 482 }