src/librustc_lint/builtin.rs

   1 //! Lints in the Rust compiler.
   2 //!
   3 //! This contains lints which can feasibly be implemented as their own
   4 //! AST visitor. Also see `rustc::lint::builtin`, which contains the
   5 //! definitions of lints that are emitted directly inside the main
   6 //! compiler.
   7 //!
   8 //! To add a new lint to rustc, declare it here using `declare_lint!()`.
   9 //! Then add code to emit the new lint in the appropriate circumstances.
  10 //! You can do that in an existing `LintPass` if it makes sense, or in a
  11 //! new `LintPass`, or using `Session::add_lint` elsewhere in the
  12 //! compiler. Only do the latter if the check can't be written cleanly as a
  13 //! `LintPass` (also, note that such lints will need to be defined in
  14 //! `rustc::lint::builtin`, not here).
  15 //!
  16 //! If you define a new `EarlyLintPass`, you will also need to add it to the
  17 //! `add_early_builtin!` or `add_early_builtin_with_new!` invocation in
  18 //! `lib.rs`. Use the former for unit-like structs and the latter for structs
  19 //! with a `pub fn new()`.
  20 //!
  21 //! If you define a new `LateLintPass`, you will also need to add it to the
  22 //! `late_lint_methods!` invocation in `lib.rs`.
  23
  24 use rustc::hir::def::Def;
  25 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
  26 use rustc::ty::{self, Ty};
  27 use rustc::{lint, util};
  28 use hir::Node;
  29 use util::nodemap::NodeSet;
  30 use lint::{LateContext, LintContext, LintArray};
  31 use lint::{LintPass, LateLintPass, EarlyLintPass, EarlyContext};
  32
  33 use rustc::util::nodemap::FxHashSet;
  34
  35 use syntax::tokenstream::{TokenTree, TokenStream};
  36 use syntax::ast;
  37 use syntax::ptr::P;
  38 use syntax::ast::Expr;
  39 use syntax::attr;
  40 use syntax::source_map::Spanned;
  41 use syntax::edition::Edition;
  42 use syntax::feature_gate::{AttributeGate, AttributeTemplate, AttributeType};
  43 use syntax::feature_gate::{Stability, deprecated_attributes};
  44 use syntax_pos::{BytePos, Span, SyntaxContext};
  45 use syntax::symbol::keywords;
  46 use syntax::errors::{Applicability, DiagnosticBuilder};
  47 use syntax::print::pprust::expr_to_string;
  48 use syntax::visit::FnKind;
  49 use syntax::struct_span_err;
  50
  51 use rustc::hir::{self, GenericParamKind, PatKind};
  52
  53 use crate::nonstandard_style::{MethodLateContext, method_context};
  54
  55 use log::debug;
  56
  57 // hardwired lints from librustc
  58 pub use lint::builtin::*;
  59
  60 declare_lint! {
  61     WHILE_TRUE,
  62     Warn,
  63     "suggest using `loop { }` instead of `while true { }`"
  64 }
  65
  66 #[derive(Copy, Clone)]
  67 pub struct WhileTrue;
  68
  69 impl LintPass for WhileTrue {
  70     fn name(&self) -> &'static str {
  71         "WhileTrue"
  72     }
  73
  74     fn get_lints(&self) -> LintArray {
  75         lint_array!(WHILE_TRUE)
  76     }
  77 }
  78
  79 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for WhileTrue {
  80     fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
  81         if let hir::ExprKind::While(ref cond, ..) = e.node {
  82             if let hir::ExprKind::Lit(ref lit) = cond.node {
  83                 if let ast::LitKind::Bool(true) = lit.node {
  84                     if lit.span.ctxt() == SyntaxContext::empty() {
  85                         let msg = "denote infinite loops with `loop { ... }`";
  86                         let condition_span = cx.tcx.sess.source_map().def_span(e.span);
  87                         let mut err = cx.struct_span_lint(WHILE_TRUE, condition_span, msg);
  88                         err.span_suggestion_short(
  89                             condition_span,
  90                             "use `loop`",
  91                             "loop".to_owned(),
  92                             Applicability::MachineApplicable
  93                         );
  94                         err.emit();
  95                     }
  96                 }
  97             }
  98         }
  99     }
 100 }
 101
 102 declare_lint! {
 103     BOX_POINTERS,
 104     Allow,
 105     "use of owned (Box type) heap memory"
 106 }
 107
 108 #[derive(Copy, Clone)]
 109 pub struct BoxPointers;
 110
 111 impl BoxPointers {
 112     fn check_heap_type<'a, 'tcx>(&self, cx: &LateContext<'_, '_>, span: Span, ty: Ty<'_>) {
 113         for leaf_ty in ty.walk() {
 114             if leaf_ty.is_box() {
 115                 let m = format!("type uses owned (Box type) pointers: {}", ty);
 116                 cx.span_lint(BOX_POINTERS, span, &m);
 117             }
 118         }
 119     }
 120 }
 121
 122 impl LintPass for BoxPointers {
 123     fn name(&self) -> &'static str {
 124         "BoxPointers"
 125     }
 126
 127     fn get_lints(&self) -> LintArray {
 128         lint_array!(BOX_POINTERS)
 129     }
 130 }
 131
 132 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
 133     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
 134         match it.node {
 135             hir::ItemKind::Fn(..) |
 136             hir::ItemKind::Ty(..) |
 137             hir::ItemKind::Enum(..) |
 138             hir::ItemKind::Struct(..) |
 139             hir::ItemKind::Union(..) => {
 140                 let def_id = cx.tcx.hir().local_def_id(it.id);
 141                 self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
 142             }
 143             _ => ()
 144         }
 145
 146         // If it's a struct, we also have to check the fields' types
 147         match it.node {
 148             hir::ItemKind::Struct(ref struct_def, _) |
 149             hir::ItemKind::Union(ref struct_def, _) => {
 150                 for struct_field in struct_def.fields() {
 151                     let def_id = cx.tcx.hir().local_def_id(struct_field.id);
 152                     self.check_heap_type(cx, struct_field.span,
 153                                          cx.tcx.type_of(def_id));
 154                 }
 155             }
 156             _ => (),
 157         }
 158     }
 159
 160     fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
 161         let ty = cx.tables.node_type(e.hir_id);
 162         self.check_heap_type(cx, e.span, ty);
 163     }
 164 }
 165
 166 declare_lint! {
 167     NON_SHORTHAND_FIELD_PATTERNS,
 168     Warn,
 169     "using `Struct { x: x }` instead of `Struct { x }` in a pattern"
 170 }
 171
 172 #[derive(Copy, Clone)]
 173 pub struct NonShorthandFieldPatterns;
 174
 175 impl LintPass for NonShorthandFieldPatterns {
 176     fn name(&self) -> &'static str {
 177         "NonShorthandFieldPatterns"
 178     }
 179
 180     fn get_lints(&self) -> LintArray {
 181         lint_array!(NON_SHORTHAND_FIELD_PATTERNS)
 182     }
 183 }
 184
 185 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
 186     fn check_pat(&mut self, cx: &LateContext<'_, '_>, pat: &hir::Pat) {
 187         if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.node {
 188             let variant = cx.tables.pat_ty(pat).ty_adt_def()
 189                                    .expect("struct pattern type is not an ADT")
 190                                    .variant_of_def(cx.tables.qpath_def(qpath, pat.hir_id));
 191             for fieldpat in field_pats {
 192                 if fieldpat.node.is_shorthand {
 193                     continue;
 194                 }
 195                 if fieldpat.span.ctxt().outer().expn_info().is_some() {
 196                     // Don't lint if this is a macro expansion: macro authors
 197                     // shouldn't have to worry about this kind of style issue
 198                     // (Issue #49588)
 199                     continue;
 200                 }
 201                 if let PatKind::Binding(_, _, _, ident, None) = fieldpat.node.pat.node {
 202                     if cx.tcx.find_field_index(ident, &variant) ==
 203                        Some(cx.tcx.field_index(fieldpat.node.id, cx.tables)) {
 204                         let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
 205                                      fieldpat.span,
 206                                      &format!("the `{}:` in this pattern is redundant", ident));
 207                         let subspan = cx.tcx.sess.source_map().span_through_char(fieldpat.span,
 208                                                                                  ':');
 209                         err.span_suggestion_short(
 210                             subspan,
 211                             "remove this",
 212                             ident.to_string(),
 213                             Applicability::MachineApplicable
 214                         );
 215                         err.emit();
 216                     }
 217                 }
 218             }
 219         }
 220     }
 221 }
 222
 223 declare_lint! {
 224     UNSAFE_CODE,
 225     Allow,
 226     "usage of `unsafe` code"
 227 }
 228
 229 #[derive(Copy, Clone)]
 230 pub struct UnsafeCode;
 231
 232 impl LintPass for UnsafeCode {
 233     fn name(&self) -> &'static str {
 234         "UnsafeCode"
 235     }
 236
 237     fn get_lints(&self) -> LintArray {
 238         lint_array!(UNSAFE_CODE)
 239     }
 240 }
 241
 242 impl UnsafeCode {
 243     fn report_unsafe(&self, cx: &EarlyContext<'_>, span: Span, desc: &'static str) {
 244         // This comes from a macro that has #[allow_internal_unsafe].
 245         if span.allows_unsafe() {
 246             return;
 247         }
 248
 249         cx.span_lint(UNSAFE_CODE, span, desc);
 250     }
 251 }
 252
 253 impl EarlyLintPass for UnsafeCode {
 254     fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
 255         if attr.check_name("allow_internal_unsafe") {
 256             self.report_unsafe(cx, attr.span, "`allow_internal_unsafe` allows defining \
 257                                                macros using unsafe without triggering \
 258                                                the `unsafe_code` lint at their call site");
 259         }
 260     }
 261
 262     fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
 263         if let ast::ExprKind::Block(ref blk, _) = e.node {
 264             // Don't warn about generated blocks, that'll just pollute the output.
 265             if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
 266                 self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
 267             }
 268         }
 269     }
 270
 271     fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
 272         match it.node {
 273             ast::ItemKind::Trait(_, ast::Unsafety::Unsafe, ..) => {
 274                 self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
 275             }
 276
 277             ast::ItemKind::Impl(ast::Unsafety::Unsafe, ..) => {
 278                 self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
 279             }
 280
 281             _ => return,
 282         }
 283     }
 284
 285     fn check_fn(&mut self,
 286                 cx: &EarlyContext<'_>,
 287                 fk: FnKind<'_>,
 288                 _: &ast::FnDecl,
 289                 span: Span,
 290                 _: ast::NodeId) {
 291         match fk {
 292             FnKind::ItemFn(_, ast::FnHeader { unsafety: ast::Unsafety::Unsafe, .. }, ..) => {
 293                 self.report_unsafe(cx, span, "declaration of an `unsafe` function")
 294             }
 295
 296             FnKind::Method(_, sig, ..) => {
 297                 if sig.header.unsafety == ast::Unsafety::Unsafe {
 298                     self.report_unsafe(cx, span, "implementation of an `unsafe` method")
 299                 }
 300             }
 301
 302             _ => (),
 303         }
 304     }
 305
 306     fn check_trait_item(&mut self, cx: &EarlyContext<'_>, item: &ast::TraitItem) {
 307         if let ast::TraitItemKind::Method(ref sig, None) = item.node {
 308             if sig.header.unsafety == ast::Unsafety::Unsafe {
 309                 self.report_unsafe(cx, item.span, "declaration of an `unsafe` method")
 310             }
 311         }
 312     }
 313 }
 314
 315 declare_lint! {
 316     pub MISSING_DOCS,
 317     Allow,
 318     "detects missing documentation for public members",
 319     report_in_external_macro: true
 320 }
 321
 322 pub struct MissingDoc {
 323     /// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
 324     doc_hidden_stack: Vec<bool>,
 325
 326     /// Private traits or trait items that leaked through. Don't check their methods.
 327     private_traits: FxHashSet<ast::NodeId>,
 328 }
 329
 330 fn has_doc(attr: &ast::Attribute) -> bool {
 331     if !attr.check_name("doc") {
 332         return false;
 333     }
 334
 335     if attr.is_value_str() {
 336         return true;
 337     }
 338
 339     if let Some(list) = attr.meta_item_list() {
 340         for meta in list {
 341             if meta.check_name("include") || meta.check_name("hidden") {
 342                 return true;
 343             }
 344         }
 345     }
 346
 347     false
 348 }
 349
 350 impl MissingDoc {
 351     pub fn new() -> MissingDoc {
 352         MissingDoc {
 353             doc_hidden_stack: vec![false],
 354             private_traits: FxHashSet::default(),
 355         }
 356     }
 357
 358     fn doc_hidden(&self) -> bool {
 359         *self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
 360     }
 361
 362     fn check_missing_docs_attrs(&self,
 363                                 cx: &LateContext<'_, '_>,
 364                                 id: Option<ast::NodeId>,
 365                                 attrs: &[ast::Attribute],
 366                                 sp: Span,
 367                                 desc: &'static str) {
 368         // If we're building a test harness, then warning about
 369         // documentation is probably not really relevant right now.
 370         if cx.sess().opts.test {
 371             return;
 372         }
 373
 374         // `#[doc(hidden)]` disables missing_docs check.
 375         if self.doc_hidden() {
 376             return;
 377         }
 378
 379         // Only check publicly-visible items, using the result from the privacy pass.
 380         // It's an option so the crate root can also use this function (it doesn't
 381         // have a NodeId).
 382         if let Some(id) = id {
 383             if !cx.access_levels.is_exported(id) {
 384                 return;
 385             }
 386         }
 387
 388         let has_doc = attrs.iter().any(|a| has_doc(a));
 389         if !has_doc {
 390             cx.span_lint(MISSING_DOCS,
 391                          cx.tcx.sess.source_map().def_span(sp),
 392                          &format!("missing documentation for {}", desc));
 393         }
 394     }
 395 }
 396
 397 impl LintPass for MissingDoc {
 398     fn name(&self) -> &'static str {
 399         "MissingDoc"
 400     }
 401
 402     fn get_lints(&self) -> LintArray {
 403         lint_array!(MISSING_DOCS)
 404     }
 405 }
 406
 407 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
 408     fn enter_lint_attrs(&mut self, _: &LateContext<'_, '_>, attrs: &[ast::Attribute]) {
 409         let doc_hidden = self.doc_hidden() ||
 410                          attrs.iter().any(|attr| {
 411             attr.check_name("doc") &&
 412             match attr.meta_item_list() {
 413                 None => false,
 414                 Some(l) => attr::list_contains_name(&l, "hidden"),
 415             }
 416         });
 417         self.doc_hidden_stack.push(doc_hidden);
 418     }
 419
 420     fn exit_lint_attrs(&mut self, _: &LateContext<'_, '_>, _attrs: &[ast::Attribute]) {
 421         self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
 422     }
 423
 424     fn check_crate(&mut self, cx: &LateContext<'_, '_>, krate: &hir::Crate) {
 425         self.check_missing_docs_attrs(cx, None, &krate.attrs, krate.span, "crate");
 426
 427         for macro_def in &krate.exported_macros {
 428             let has_doc = macro_def.attrs.iter().any(|a| has_doc(a));
 429             if !has_doc {
 430                 cx.span_lint(MISSING_DOCS,
 431                              cx.tcx.sess.source_map().def_span(macro_def.span),
 432                              "missing documentation for macro");
 433             }
 434         }
 435     }
 436
 437     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
 438         let desc = match it.node {
 439             hir::ItemKind::Fn(..) => "a function",
 440             hir::ItemKind::Mod(..) => "a module",
 441             hir::ItemKind::Enum(..) => "an enum",
 442             hir::ItemKind::Struct(..) => "a struct",
 443             hir::ItemKind::Union(..) => "a union",
 444             hir::ItemKind::Trait(.., ref trait_item_refs) => {
 445                 // Issue #11592, traits are always considered exported, even when private.
 446                 if let hir::VisibilityKind::Inherited = it.vis.node {
 447                     self.private_traits.insert(it.id);
 448                     for trait_item_ref in trait_item_refs {
 449                         self.private_traits.insert(trait_item_ref.id.node_id);
 450                     }
 451                     return;
 452                 }
 453                 "a trait"
 454             }
 455             hir::ItemKind::Ty(..) => "a type alias",
 456             hir::ItemKind::Impl(.., Some(ref trait_ref), _, ref impl_item_refs) => {
 457                 // If the trait is private, add the impl items to private_traits so they don't get
 458                 // reported for missing docs.
 459                 let real_trait = trait_ref.path.def.def_id();
 460                 if let Some(node_id) = cx.tcx.hir().as_local_node_id(real_trait) {
 461                     match cx.tcx.hir().find(node_id) {
 462                         Some(Node::Item(item)) => {
 463                             if let hir::VisibilityKind::Inherited = item.vis.node {
 464                                 for impl_item_ref in impl_item_refs {
 465                                     self.private_traits.insert(impl_item_ref.id.node_id);
 466                                 }
 467                             }
 468                         }
 469                         _ => {}
 470                     }
 471                 }
 472                 return;
 473             }
 474             hir::ItemKind::Const(..) => "a constant",
 475             hir::ItemKind::Static(..) => "a static",
 476             _ => return,
 477         };
 478
 479         self.check_missing_docs_attrs(cx, Some(it.id), &it.attrs, it.span, desc);
 480     }
 481
 482     fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, trait_item: &hir::TraitItem) {
 483         if self.private_traits.contains(&trait_item.id) {
 484             return;
 485         }
 486
 487         let desc = match trait_item.node {
 488             hir::TraitItemKind::Const(..) => "an associated constant",
 489             hir::TraitItemKind::Method(..) => "a trait method",
 490             hir::TraitItemKind::Type(..) => "an associated type",
 491         };
 492
 493         self.check_missing_docs_attrs(cx,
 494                                       Some(trait_item.id),
 495                                       &trait_item.attrs,
 496                                       trait_item.span,
 497                                       desc);
 498     }
 499
 500     fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
 501         // If the method is an impl for a trait, don't doc.
 502         if method_context(cx, impl_item.id) == MethodLateContext::TraitImpl {
 503             return;
 504         }
 505
 506         let desc = match impl_item.node {
 507             hir::ImplItemKind::Const(..) => "an associated constant",
 508             hir::ImplItemKind::Method(..) => "a method",
 509             hir::ImplItemKind::Type(_) => "an associated type",
 510             hir::ImplItemKind::Existential(_) => "an associated existential type",
 511         };
 512         self.check_missing_docs_attrs(cx,
 513                                       Some(impl_item.id),
 514                                       &impl_item.attrs,
 515                                       impl_item.span,
 516                                       desc);
 517     }
 518
 519     fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, sf: &hir::StructField) {
 520         if !sf.is_positional() {
 521             self.check_missing_docs_attrs(cx,
 522                                           Some(sf.id),
 523                                           &sf.attrs,
 524                                           sf.span,
 525                                           "a struct field")
 526         }
 527     }
 528
 529     fn check_variant(&mut self, cx: &LateContext<'_, '_>, v: &hir::Variant, _: &hir::Generics) {
 530         self.check_missing_docs_attrs(cx,
 531                                       Some(v.node.data.id()),
 532                                       &v.node.attrs,
 533                                       v.span,
 534                                       "a variant");
 535     }
 536 }
 537
 538 declare_lint! {
 539     pub MISSING_COPY_IMPLEMENTATIONS,
 540     Allow,
 541     "detects potentially-forgotten implementations of `Copy`"
 542 }
 543
 544 #[derive(Copy, Clone)]
 545 pub struct MissingCopyImplementations;
 546
 547 impl LintPass for MissingCopyImplementations {
 548     fn name(&self) -> &'static str {
 549         "MissingCopyImplementations"
 550     }
 551
 552     fn get_lints(&self) -> LintArray {
 553         lint_array!(MISSING_COPY_IMPLEMENTATIONS)
 554     }
 555 }
 556
 557 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingCopyImplementations {
 558     fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
 559         if !cx.access_levels.is_reachable(item.id) {
 560             return;
 561         }
 562         let (def, ty) = match item.node {
 563             hir::ItemKind::Struct(_, ref ast_generics) => {
 564                 if !ast_generics.params.is_empty() {
 565                     return;
 566                 }
 567                 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.id));
 568                 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
 569             }
 570             hir::ItemKind::Union(_, ref ast_generics) => {
 571                 if !ast_generics.params.is_empty() {
 572                     return;
 573                 }
 574                 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.id));
 575                 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
 576             }
 577             hir::ItemKind::Enum(_, ref ast_generics) => {
 578                 if !ast_generics.params.is_empty() {
 579                     return;
 580                 }
 581                 let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.id));
 582                 (def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
 583             }
 584             _ => return,
 585         };
 586         if def.has_dtor(cx.tcx) {
 587             return;
 588         }
 589         let param_env = ty::ParamEnv::empty();
 590         if ty.is_copy_modulo_regions(cx.tcx, param_env, item.span) {
 591             return;
 592         }
 593         if param_env.can_type_implement_copy(cx.tcx, ty).is_ok() {
 594             cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
 595                          item.span,
 596                          "type could implement `Copy`; consider adding `impl \
 597                           Copy`")
 598         }
 599     }
 600 }
 601
 602 declare_lint! {
 603     MISSING_DEBUG_IMPLEMENTATIONS,
 604     Allow,
 605     "detects missing implementations of fmt::Debug"
 606 }
 607
 608 pub struct MissingDebugImplementations {
 609     impling_types: Option<NodeSet>,
 610 }
 611
 612 impl MissingDebugImplementations {
 613     pub fn new() -> MissingDebugImplementations {
 614         MissingDebugImplementations { impling_types: None }
 615     }
 616 }
 617
 618 impl LintPass for MissingDebugImplementations {
 619     fn name(&self) -> &'static str {
 620         "MissingDebugImplementations"
 621     }
 622
 623     fn get_lints(&self) -> LintArray {
 624         lint_array!(MISSING_DEBUG_IMPLEMENTATIONS)
 625     }
 626 }
 627
 628 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
 629     fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
 630         if !cx.access_levels.is_reachable(item.id) {
 631             return;
 632         }
 633
 634         match item.node {
 635             hir::ItemKind::Struct(..) |
 636             hir::ItemKind::Union(..) |
 637             hir::ItemKind::Enum(..) => {}
 638             _ => return,
 639         }
 640
 641         let debug = match cx.tcx.lang_items().debug_trait() {
 642             Some(debug) => debug,
 643             None => return,
 644         };
 645
 646         if self.impling_types.is_none() {
 647             let mut impls = NodeSet::default();
 648             cx.tcx.for_each_impl(debug, |d| {
 649                 if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
 650                     if let Some(node_id) = cx.tcx.hir().as_local_node_id(ty_def.did) {
 651                         impls.insert(node_id);
 652                     }
 653                 }
 654             });
 655
 656             self.impling_types = Some(impls);
 657             debug!("{:?}", self.impling_types);
 658         }
 659
 660         if !self.impling_types.as_ref().unwrap().contains(&item.id) {
 661             cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
 662                          item.span,
 663                          "type does not implement `fmt::Debug`; consider adding #[derive(Debug)] \
 664                           or a manual implementation")
 665         }
 666     }
 667 }
 668
 669 declare_lint! {
 670     pub ANONYMOUS_PARAMETERS,
 671     Allow,
 672     "detects anonymous parameters"
 673 }
 674
 675 /// Checks for use of anonymous parameters (RFC 1685).
 676 #[derive(Copy, Clone)]
 677 pub struct AnonymousParameters;
 678
 679 impl LintPass for AnonymousParameters {
 680     fn name(&self) -> &'static str {
 681         "AnonymousParameters"
 682     }
 683
 684     fn get_lints(&self) -> LintArray {
 685         lint_array!(ANONYMOUS_PARAMETERS)
 686     }
 687 }
 688
 689 impl EarlyLintPass for AnonymousParameters {
 690     fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::TraitItem) {
 691         match it.node {
 692             ast::TraitItemKind::Method(ref sig, _) => {
 693                 for arg in sig.decl.inputs.iter() {
 694                     match arg.pat.node {
 695                         ast::PatKind::Ident(_, ident, None) => {
 696                             if ident.name == keywords::Invalid.name() {
 697                                 let ty_snip = cx
 698                                     .sess
 699                                     .source_map()
 700                                     .span_to_snippet(arg.ty.span);
 701
 702                                 let (ty_snip, appl) = if let Ok(snip) = ty_snip {
 703                                     (snip, Applicability::MachineApplicable)
 704                                 } else {
 705                                     ("<type>".to_owned(), Applicability::HasPlaceholders)
 706                                 };
 707
 708                                 cx.struct_span_lint(
 709                                     ANONYMOUS_PARAMETERS,
 710                                     arg.pat.span,
 711                                     "anonymous parameters are deprecated and will be \
 712                                      removed in the next edition."
 713                                 ).span_suggestion(
 714                                     arg.pat.span,
 715                                     "Try naming the parameter or explicitly \
 716                                     ignoring it",
 717                                     format!("_: {}", ty_snip),
 718                                     appl
 719                                 ).emit();
 720                             }
 721                         }
 722                         _ => (),
 723                     }
 724                 }
 725             },
 726             _ => (),
 727         }
 728     }
 729 }
 730
 731 /// Check for use of attributes which have been deprecated.
 732 #[derive(Clone)]
 733 pub struct DeprecatedAttr {
 734     // This is not free to compute, so we want to keep it around, rather than
 735     // compute it for every attribute.
 736     depr_attrs: Vec<&'static (&'static str, AttributeType, AttributeTemplate, AttributeGate)>,
 737 }
 738
 739 impl DeprecatedAttr {
 740     pub fn new() -> DeprecatedAttr {
 741         DeprecatedAttr {
 742             depr_attrs: deprecated_attributes(),
 743         }
 744     }
 745 }
 746
 747 impl LintPass for DeprecatedAttr {
 748     fn name(&self) -> &'static str {
 749         "DeprecatedAttr"
 750     }
 751
 752     fn get_lints(&self) -> LintArray {
 753         lint_array!()
 754     }
 755 }
 756
 757 impl EarlyLintPass for DeprecatedAttr {
 758     fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
 759         for &&(n, _, _, ref g) in &self.depr_attrs {
 760             if attr.name() == n {
 761                 if let &AttributeGate::Gated(Stability::Deprecated(link, suggestion),
 762                                              ref name,
 763                                              ref reason,
 764                                              _) = g {
 765                     let msg = format!("use of deprecated attribute `{}`: {}. See {}",
 766                                       name, reason, link);
 767                     let mut err = cx.struct_span_lint(DEPRECATED, attr.span, &msg);
 768                     err.span_suggestion_short(
 769                         attr.span,
 770                         suggestion.unwrap_or("remove this attribute"),
 771                         String::new(),
 772                         Applicability::MachineApplicable
 773                     );
 774                     err.emit();
 775                 }
 776                 return;
 777             }
 778         }
 779     }
 780 }
 781
 782 declare_lint! {
 783     pub UNUSED_DOC_COMMENTS,
 784     Warn,
 785     "detects doc comments that aren't used by rustdoc"
 786 }
 787
 788 #[derive(Copy, Clone)]
 789 pub struct UnusedDocComment;
 790
 791 impl LintPass for UnusedDocComment {
 792     fn name(&self) -> &'static str {
 793         "UnusedDocComment"
 794     }
 795
 796     fn get_lints(&self) -> LintArray {
 797         lint_array![UNUSED_DOC_COMMENTS]
 798     }
 799 }
 800
 801 impl UnusedDocComment {
 802     fn warn_if_doc<'a, 'tcx,
 803                    I: Iterator<Item=&'a ast::Attribute>,
 804                    C: LintContext<'tcx>>(&self, mut attrs: I, cx: &C) {
 805         if let Some(attr) = attrs.find(|a| a.is_value_str() && a.check_name("doc")) {
 806             cx.struct_span_lint(UNUSED_DOC_COMMENTS, attr.span, "doc comment not used by rustdoc")
 807               .emit();
 808         }
 809     }
 810 }
 811
 812 impl EarlyLintPass for UnusedDocComment {
 813     fn check_local(&mut self, cx: &EarlyContext<'_>, decl: &ast::Local) {
 814         self.warn_if_doc(decl.attrs.iter(), cx);
 815     }
 816
 817     fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
 818         self.warn_if_doc(arm.attrs.iter(), cx);
 819     }
 820
 821     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
 822         self.warn_if_doc(expr.attrs.iter(), cx);
 823     }
 824 }
 825
 826 declare_lint! {
 827     PLUGIN_AS_LIBRARY,
 828     Warn,
 829     "compiler plugin used as ordinary library in non-plugin crate"
 830 }
 831
 832 #[derive(Copy, Clone)]
 833 pub struct PluginAsLibrary;
 834
 835 impl LintPass for PluginAsLibrary {
 836     fn name(&self) -> &'static str {
 837         "PluginAsLibrary"
 838     }
 839
 840     fn get_lints(&self) -> LintArray {
 841         lint_array![PLUGIN_AS_LIBRARY]
 842     }
 843 }
 844
 845 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
 846     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
 847         if cx.tcx.plugin_registrar_fn(LOCAL_CRATE).is_some() {
 848             // We're compiling a plugin; it's fine to link other plugins.
 849             return;
 850         }
 851
 852         match it.node {
 853             hir::ItemKind::ExternCrate(..) => (),
 854             _ => return,
 855         };
 856
 857         let def_id = cx.tcx.hir().local_def_id(it.id);
 858         let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
 859             Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
 860             None => {
 861                 // Probably means we aren't linking the crate for some reason.
 862                 //
 863                 // Not sure if / when this could happen.
 864                 return;
 865             }
 866         };
 867
 868         if prfn.is_some() {
 869             cx.span_lint(PLUGIN_AS_LIBRARY,
 870                          it.span,
 871                          "compiler plugin used as an ordinary library");
 872         }
 873     }
 874 }
 875
 876 declare_lint! {
 877     NO_MANGLE_CONST_ITEMS,
 878     Deny,
 879     "const items will not have their symbols exported"
 880 }
 881
 882 declare_lint! {
 883     NO_MANGLE_GENERIC_ITEMS,
 884     Warn,
 885     "generic items must be mangled"
 886 }
 887
 888 #[derive(Copy, Clone)]
 889 pub struct InvalidNoMangleItems;
 890
 891 impl LintPass for InvalidNoMangleItems {
 892     fn name(&self) -> &'static str {
 893         "InvalidNoMangleItems"
 894     }
 895
 896     fn get_lints(&self) -> LintArray {
 897         lint_array!(NO_MANGLE_CONST_ITEMS,
 898                     NO_MANGLE_GENERIC_ITEMS)
 899     }
 900 }
 901
 902 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
 903     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
 904         match it.node {
 905             hir::ItemKind::Fn(.., ref generics, _) => {
 906                 if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, "no_mangle") {
 907                     for param in &generics.params {
 908                         match param.kind {
 909                             GenericParamKind::Lifetime { .. } => {}
 910                             GenericParamKind::Type { .. } => {
 911                                 let mut err = cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS,
 912                                                                   it.span,
 913                                                                   "functions generic over \
 914                                                                    types must be mangled");
 915                                 err.span_suggestion_short(
 916                                     no_mangle_attr.span,
 917                                     "remove this attribute",
 918                                     String::new(),
 919                                     // Use of `#[no_mangle]` suggests FFI intent; correct
 920                                     // fix may be to monomorphize source by hand
 921                                     Applicability::MaybeIncorrect
 922                                 );
 923                                 err.emit();
 924                                 break;
 925                             }
 926                         }
 927                     }
 928                 }
 929             }
 930             hir::ItemKind::Const(..) => {
 931                 if attr::contains_name(&it.attrs, "no_mangle") {
 932                     // Const items do not refer to a particular location in memory, and therefore
 933                     // don't have anything to attach a symbol to
 934                     let msg = "const items should never be #[no_mangle]";
 935                     let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
 936
 937                     // account for "pub const" (#45562)
 938                     let start = cx.tcx.sess.source_map().span_to_snippet(it.span)
 939                         .map(|snippet| snippet.find("const").unwrap_or(0))
 940                         .unwrap_or(0) as u32;
 941                     // `const` is 5 chars
 942                     let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
 943                     err.span_suggestion(
 944                         const_span,
 945                         "try a static value",
 946                         "pub static".to_owned(),
 947                         Applicability::MachineApplicable
 948                     );
 949                     err.emit();
 950                 }
 951             }
 952             _ => {}
 953         }
 954     }
 955 }
 956
 957 #[derive(Clone, Copy)]
 958 pub struct MutableTransmutes;
 959
 960 declare_lint! {
 961     MUTABLE_TRANSMUTES,
 962     Deny,
 963     "mutating transmuted &mut T from &T may cause undefined behavior"
 964 }
 965
 966 impl LintPass for MutableTransmutes {
 967     fn name(&self) -> &'static str {
 968         "MutableTransmutes"
 969     }
 970
 971     fn get_lints(&self) -> LintArray {
 972         lint_array!(MUTABLE_TRANSMUTES)
 973     }
 974 }
 975
 976 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
 977     fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &hir::Expr) {
 978         use rustc_target::spec::abi::Abi::RustIntrinsic;
 979
 980         let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
 981                    consider instead using an UnsafeCell";
 982         match get_transmute_from_to(cx, expr) {
 983             Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) => {
 984                 if to_mt == hir::Mutability::MutMutable &&
 985                    from_mt == hir::Mutability::MutImmutable {
 986                     cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
 987                 }
 988             }
 989             _ => (),
 990         }
 991
 992         fn get_transmute_from_to<'a, 'tcx>
 993             (cx: &LateContext<'a, 'tcx>,
 994              expr: &hir::Expr)
 995              -> Option<(&'tcx ty::TyKind<'tcx>, &'tcx ty::TyKind<'tcx>)> {
 996             let def = if let hir::ExprKind::Path(ref qpath) = expr.node {
 997                 cx.tables.qpath_def(qpath, expr.hir_id)
 998             } else {
 999                 return None;
1000             };
1001             if let Def::Fn(did) = def {
1002                 if !def_id_is_transmute(cx, did) {
1003                     return None;
1004                 }
1005                 let sig = cx.tables.node_type(expr.hir_id).fn_sig(cx.tcx);
1006                 let from = sig.inputs().skip_binder()[0];
1007                 let to = *sig.output().skip_binder();
1008                 return Some((&from.sty, &to.sty));
1009             }
1010             None
1011         }
1012
1013         fn def_id_is_transmute(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
1014             cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
1015             cx.tcx.item_name(def_id) == "transmute"
1016         }
1017     }
1018 }
1019
1020 /// Forbids using the `#[feature(...)]` attribute
1021 #[derive(Copy, Clone)]
1022 pub struct UnstableFeatures;
1023
1024 declare_lint! {
1025     UNSTABLE_FEATURES,
1026     Allow,
1027     "enabling unstable features (deprecated. do not use)"
1028 }
1029
1030 impl LintPass for UnstableFeatures {
1031     fn name(&self) -> &'static str {
1032         "UnstableFeatures"
1033     }
1034
1035     fn get_lints(&self) -> LintArray {
1036         lint_array!(UNSTABLE_FEATURES)
1037     }
1038 }
1039
1040 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
1041     fn check_attribute(&mut self, ctx: &LateContext<'_, '_>, attr: &ast::Attribute) {
1042         if attr.check_name("feature") {
1043             if let Some(items) = attr.meta_item_list() {
1044                 for item in items {
1045                     ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
1046                 }
1047             }
1048         }
1049     }
1050 }
1051
1052 /// Lint for unions that contain fields with possibly non-trivial destructors.
1053 pub struct UnionsWithDropFields;
1054
1055 declare_lint! {
1056     UNIONS_WITH_DROP_FIELDS,
1057     Warn,
1058     "use of unions that contain fields with possibly non-trivial drop code"
1059 }
1060
1061 impl LintPass for UnionsWithDropFields {
1062     fn name(&self) -> &'static str {
1063         "UnionsWithDropFields"
1064     }
1065
1066     fn get_lints(&self) -> LintArray {
1067         lint_array!(UNIONS_WITH_DROP_FIELDS)
1068     }
1069 }
1070
1071 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
1072     fn check_item(&mut self, ctx: &LateContext<'_, '_>, item: &hir::Item) {
1073         if let hir::ItemKind::Union(ref vdata, _) = item.node {
1074             for field in vdata.fields() {
1075                 let field_ty = ctx.tcx.type_of(ctx.tcx.hir().local_def_id(field.id));
1076                 if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
1077                     ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
1078                                   field.span,
1079                                   "union contains a field with possibly non-trivial drop code, \
1080                                    drop code of union fields is ignored when dropping the union");
1081                     return;
1082                 }
1083             }
1084         }
1085     }
1086 }
1087
1088 /// Lint for items marked `pub` that aren't reachable from other crates.
1089 #[derive(Copy, Clone)]
1090 pub struct UnreachablePub;
1091
1092 declare_lint! {
1093     pub UNREACHABLE_PUB,
1094     Allow,
1095     "`pub` items not reachable from crate root"
1096 }
1097
1098 impl LintPass for UnreachablePub {
1099     fn name(&self) -> &'static str {
1100         "UnreachablePub"
1101     }
1102
1103     fn get_lints(&self) -> LintArray {
1104         lint_array!(UNREACHABLE_PUB)
1105     }
1106 }
1107
1108 impl UnreachablePub {
1109     fn perform_lint(&self, cx: &LateContext<'_, '_>, what: &str, id: ast::NodeId,
1110                     vis: &hir::Visibility, span: Span, exportable: bool) {
1111         let mut applicability = Applicability::MachineApplicable;
1112         match vis.node {
1113             hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
1114                 if span.ctxt().outer().expn_info().is_some() {
1115                     applicability = Applicability::MaybeIncorrect;
1116                 }
1117                 let def_span = cx.tcx.sess.source_map().def_span(span);
1118                 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1119                                                   &format!("unreachable `pub` {}", what));
1120                 let replacement = if cx.tcx.features().crate_visibility_modifier {
1121                     "crate"
1122                 } else {
1123                     "pub(crate)"
1124                 }.to_owned();
1125
1126                 err.span_suggestion(
1127                     vis.span,
1128                     "consider restricting its visibility",
1129                     replacement,
1130                     applicability,
1131                 );
1132                 if exportable {
1133                     err.help("or consider exporting it for use by other crates");
1134                 }
1135                 err.emit();
1136             },
1137             _ => {}
1138         }
1139     }
1140 }
1141
1142
1143 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1144     fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
1145         self.perform_lint(cx, "item", item.id, &item.vis, item.span, true);
1146     }
1147
1148     fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, foreign_item: &hir::ForeignItem) {
1149         self.perform_lint(cx, "item", foreign_item.id, &foreign_item.vis,
1150                           foreign_item.span, true);
1151     }
1152
1153     fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField) {
1154         self.perform_lint(cx, "field", field.id, &field.vis, field.span, false);
1155     }
1156
1157     fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
1158         self.perform_lint(cx, "item", impl_item.id, &impl_item.vis, impl_item.span, false);
1159     }
1160 }
1161
1162 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1163 /// They are relevant when using associated types, but otherwise neither checked
1164 /// at definition site nor enforced at use site.
1165
1166 pub struct TypeAliasBounds;
1167
1168 declare_lint! {
1169     TYPE_ALIAS_BOUNDS,
1170     Warn,
1171     "bounds in type aliases are not enforced"
1172 }
1173
1174 impl LintPass for TypeAliasBounds {
1175     fn name(&self) -> &'static str {
1176         "TypeAliasBounds"
1177     }
1178
1179     fn get_lints(&self) -> LintArray {
1180         lint_array!(TYPE_ALIAS_BOUNDS)
1181     }
1182 }
1183
1184 impl TypeAliasBounds {
1185     fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1186         match *qpath {
1187             hir::QPath::TypeRelative(ref ty, _) => {
1188                 // If this is a type variable, we found a `T::Assoc`.
1189                 match ty.node {
1190                     hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1191                         match path.def {
1192                             Def::TyParam(_) => true,
1193                             _ => false
1194                         }
1195                     }
1196                     _ => false
1197                 }
1198             }
1199             hir::QPath::Resolved(..) => false,
1200         }
1201     }
1202
1203     fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder<'_>) {
1204         // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1205         // bound.  Let's see if this type does that.
1206
1207         // We use a HIR visitor to walk the type.
1208         use rustc::hir::intravisit::{self, Visitor};
1209         struct WalkAssocTypes<'a, 'db> where 'db: 'a {
1210             err: &'a mut DiagnosticBuilder<'db>
1211         }
1212         impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1213             fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1214             {
1215                 intravisit::NestedVisitorMap::None
1216             }
1217
1218             fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: hir::HirId, span: Span) {
1219                 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1220                     self.err.span_help(span,
1221                         "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1222                          associated types in type aliases");
1223                 }
1224                 intravisit::walk_qpath(self, qpath, id, span)
1225             }
1226         }
1227
1228         // Let's go for a walk!
1229         let mut visitor = WalkAssocTypes { err };
1230         visitor.visit_ty(ty);
1231     }
1232 }
1233
1234 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1235     fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
1236         let (ty, type_alias_generics) = match item.node {
1237             hir::ItemKind::Ty(ref ty, ref generics) => (&*ty, generics),
1238             _ => return,
1239         };
1240         let mut suggested_changing_assoc_types = false;
1241         // There must not be a where clause
1242         if !type_alias_generics.where_clause.predicates.is_empty() {
1243             let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1244                 .map(|pred| pred.span()).collect();
1245             let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1246                 "where clauses are not enforced in type aliases");
1247             err.help("the clause will not be checked when the type alias is used, \
1248                       and should be removed");
1249             if !suggested_changing_assoc_types {
1250                 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1251                 suggested_changing_assoc_types = true;
1252             }
1253             err.emit();
1254         }
1255         // The parameters must not have bounds
1256         for param in type_alias_generics.params.iter() {
1257             let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
1258             if !spans.is_empty() {
1259                 let mut err = cx.struct_span_lint(
1260                     TYPE_ALIAS_BOUNDS,
1261                     spans,
1262                     "bounds on generic parameters are not enforced in type aliases",
1263                 );
1264                 err.help("the bound will not be checked when the type alias is used, \
1265                           and should be removed");
1266                 if !suggested_changing_assoc_types {
1267                     TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1268                     suggested_changing_assoc_types = true;
1269                 }
1270                 err.emit();
1271             }
1272         }
1273     }
1274 }
1275
1276 /// Lint constants that are erroneous.
1277 /// Without this lint, we might not get any diagnostic if the constant is
1278 /// unused within this crate, even though downstream crates can't use it
1279 /// without producing an error.
1280 pub struct UnusedBrokenConst;
1281
1282 impl LintPass for UnusedBrokenConst {
1283     fn name(&self) -> &'static str {
1284         "UnusedBrokenConst"
1285     }
1286
1287     fn get_lints(&self) -> LintArray {
1288         lint_array!()
1289     }
1290 }
1291 fn check_const(cx: &LateContext<'_, '_>, body_id: hir::BodyId) {
1292     let def_id = cx.tcx.hir().body_owner_def_id(body_id);
1293     let is_static = cx.tcx.is_static(def_id).is_some();
1294     let param_env = if is_static {
1295         // Use the same param_env as `codegen_static_initializer`, to reuse the cache.
1296         ty::ParamEnv::reveal_all()
1297     } else {
1298         cx.tcx.param_env(def_id)
1299     };
1300     let cid = ::rustc::mir::interpret::GlobalId {
1301         instance: ty::Instance::mono(cx.tcx, def_id),
1302         promoted: None
1303     };
1304     // trigger the query once for all constants since that will already report the errors
1305     let _ = cx.tcx.const_eval(param_env.and(cid));
1306 }
1307
1308 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1309     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1310         match it.node {
1311             hir::ItemKind::Const(_, body_id) => {
1312                 check_const(cx, body_id);
1313             },
1314             hir::ItemKind::Static(_, _, body_id) => {
1315                 check_const(cx, body_id);
1316             },
1317             _ => {},
1318         }
1319     }
1320 }
1321
1322 /// Lint for trait and lifetime bounds that don't depend on type parameters
1323 /// which either do nothing, or stop the item from being used.
1324 pub struct TrivialConstraints;
1325
1326 declare_lint! {
1327     TRIVIAL_BOUNDS,
1328     Warn,
1329     "these bounds don't depend on an type parameters"
1330 }
1331
1332 impl LintPass for TrivialConstraints {
1333     fn name(&self) -> &'static str {
1334         "TrivialConstraints"
1335     }
1336
1337     fn get_lints(&self) -> LintArray {
1338         lint_array!(TRIVIAL_BOUNDS)
1339     }
1340 }
1341
1342 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1343     fn check_item(
1344         &mut self,
1345         cx: &LateContext<'a, 'tcx>,
1346         item: &'tcx hir::Item,
1347     ) {
1348         use rustc::ty::fold::TypeFoldable;
1349         use rustc::ty::Predicate::*;
1350
1351
1352         if cx.tcx.features().trivial_bounds {
1353             let def_id = cx.tcx.hir().local_def_id(item.id);
1354             let predicates = cx.tcx.predicates_of(def_id);
1355             for &(predicate, span) in &predicates.predicates {
1356                 let predicate_kind_name = match predicate {
1357                     Trait(..) => "Trait",
1358                     TypeOutlives(..) |
1359                     RegionOutlives(..) => "Lifetime",
1360
1361                     // Ignore projections, as they can only be global
1362                     // if the trait bound is global
1363                     Projection(..) |
1364                     // Ignore bounds that a user can't type
1365                     WellFormed(..) |
1366                     ObjectSafe(..) |
1367                     ClosureKind(..) |
1368                     Subtype(..) |
1369                     ConstEvaluatable(..) => continue,
1370                 };
1371                 if predicate.is_global() {
1372                     cx.span_lint(
1373                         TRIVIAL_BOUNDS,
1374                         span,
1375                         &format!("{} bound {} does not depend on any type \
1376                                 or lifetime parameters", predicate_kind_name, predicate),
1377                     );
1378                 }
1379             }
1380         }
1381     }
1382 }
1383
1384
1385 /// Does nothing as a lint pass, but registers some `Lint`s
1386 /// which are used by other parts of the compiler.
1387 #[derive(Copy, Clone)]
1388 pub struct SoftLints;
1389
1390 impl LintPass for SoftLints {
1391     fn name(&self) -> &'static str {
1392         "SoftLints"
1393     }
1394
1395     fn get_lints(&self) -> LintArray {
1396         lint_array!(
1397             WHILE_TRUE,
1398             BOX_POINTERS,
1399             NON_SHORTHAND_FIELD_PATTERNS,
1400             UNSAFE_CODE,
1401             MISSING_DOCS,
1402             MISSING_COPY_IMPLEMENTATIONS,
1403             MISSING_DEBUG_IMPLEMENTATIONS,
1404             ANONYMOUS_PARAMETERS,
1405             UNUSED_DOC_COMMENTS,
1406             PLUGIN_AS_LIBRARY,
1407             NO_MANGLE_CONST_ITEMS,
1408             NO_MANGLE_GENERIC_ITEMS,
1409             MUTABLE_TRANSMUTES,
1410             UNSTABLE_FEATURES,
1411             UNIONS_WITH_DROP_FIELDS,
1412             UNREACHABLE_PUB,
1413             TYPE_ALIAS_BOUNDS,
1414             TRIVIAL_BOUNDS
1415         )
1416     }
1417 }
1418
1419 declare_lint! {
1420     pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1421     Allow,
1422     "`...` range patterns are deprecated"
1423 }
1424
1425
1426 pub struct EllipsisInclusiveRangePatterns;
1427
1428 impl LintPass for EllipsisInclusiveRangePatterns {
1429     fn name(&self) -> &'static str {
1430         "EllipsisInclusiveRangePatterns"
1431     }
1432
1433     fn get_lints(&self) -> LintArray {
1434         lint_array!(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS)
1435     }
1436 }
1437
1438 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1439     fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat, visit_subpats: &mut bool) {
1440         use self::ast::{PatKind, RangeEnd, RangeSyntax::DotDotDot};
1441
1442         /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1443         /// corresponding to the ellipsis.
1444         fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(&P<Expr>, &P<Expr>, Span)> {
1445             match &pat.node {
1446                 PatKind::Range(a, b, Spanned { span, node: RangeEnd::Included(DotDotDot), .. }) => {
1447                     Some((a, b, *span))
1448                 }
1449                 _ => None,
1450             }
1451         }
1452
1453         let (parenthesise, endpoints) = match &pat.node {
1454             PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1455             _ => (false, matches_ellipsis_pat(pat)),
1456         };
1457
1458         if let Some((start, end, join)) = endpoints {
1459             let msg = "`...` range patterns are deprecated";
1460             let suggestion = "use `..=` for an inclusive range";
1461             if parenthesise {
1462                 *visit_subpats = false;
1463                 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg);
1464                 err.span_suggestion(
1465                     pat.span,
1466                     suggestion,
1467                     format!("&({}..={})", expr_to_string(&start), expr_to_string(&end)),
1468                     Applicability::MachineApplicable,
1469                 );
1470                 err.emit();
1471             } else {
1472                 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg);
1473                 err.span_suggestion_short(
1474                     join,
1475                     suggestion,
1476                     "..=".to_owned(),
1477                     Applicability::MachineApplicable,
1478                 );
1479                 err.emit();
1480             };
1481         }
1482     }
1483 }
1484
1485 declare_lint! {
1486     UNNAMEABLE_TEST_ITEMS,
1487     Warn,
1488     "detects an item that cannot be named being marked as #[test_case]",
1489     report_in_external_macro: true
1490 }
1491
1492 pub struct UnnameableTestItems {
1493     boundary: ast::NodeId, // NodeId of the item under which things are not nameable
1494     items_nameable: bool,
1495 }
1496
1497 impl UnnameableTestItems {
1498     pub fn new() -> Self {
1499         Self {
1500             boundary: ast::DUMMY_NODE_ID,
1501             items_nameable: true
1502         }
1503     }
1504 }
1505
1506 impl LintPass for UnnameableTestItems {
1507     fn name(&self) -> &'static str {
1508         "UnnameableTestItems"
1509     }
1510
1511     fn get_lints(&self) -> LintArray {
1512         lint_array!(UNNAMEABLE_TEST_ITEMS)
1513     }
1514 }
1515
1516 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
1517     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1518         if self.items_nameable {
1519             if let hir::ItemKind::Mod(..) = it.node {}
1520             else {
1521                 self.items_nameable = false;
1522                 self.boundary = it.id;
1523             }
1524             return;
1525         }
1526
1527         if let Some(attr) = attr::find_by_name(&it.attrs, "rustc_test_marker") {
1528             cx.struct_span_lint(
1529                 UNNAMEABLE_TEST_ITEMS,
1530                 attr.span,
1531                 "cannot test inner items",
1532             ).emit();
1533         }
1534     }
1535
1536     fn check_item_post(&mut self, _cx: &LateContext<'_, '_>, it: &hir::Item) {
1537         if !self.items_nameable && self.boundary == it.id {
1538             self.items_nameable = true;
1539         }
1540     }
1541 }
1542
1543 declare_lint! {
1544     pub KEYWORD_IDENTS,
1545     Allow,
1546     "detects edition keywords being used as an identifier"
1547 }
1548
1549 /// Check for uses of edition keywords used as an identifier.
1550 #[derive(Copy, Clone)]
1551 pub struct KeywordIdents;
1552
1553 impl LintPass for KeywordIdents {
1554     fn name(&self) -> &'static str {
1555         "KeywordIdents"
1556     }
1557
1558     fn get_lints(&self) -> LintArray {
1559         lint_array!(KEYWORD_IDENTS)
1560     }
1561 }
1562
1563 impl KeywordIdents {
1564     fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1565         for tt in tokens.into_trees() {
1566             match tt {
1567                 TokenTree::Token(span, tok) => match tok.ident() {
1568                     // only report non-raw idents
1569                     Some((ident, false)) => {
1570                         self.check_ident(cx, ast::Ident {
1571                             span: span.substitute_dummy(ident.span),
1572                             ..ident
1573                         });
1574                     }
1575                     _ => {},
1576                 }
1577                 TokenTree::Delimited(_, _, tts) => {
1578                     self.check_tokens(cx, tts)
1579                 },
1580             }
1581         }
1582     }
1583 }
1584
1585 impl EarlyLintPass for KeywordIdents {
1586     fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef, _id: ast::NodeId) {
1587         self.check_tokens(cx, mac_def.stream());
1588     }
1589     fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::Mac) {
1590         self.check_tokens(cx, mac.node.tts.clone().into());
1591     }
1592     fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: ast::Ident) {
1593         let ident_str = &ident.as_str()[..];
1594         let cur_edition = cx.sess.edition();
1595         let is_raw_ident = |ident: ast::Ident| {
1596             cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&ident.span)
1597         };
1598         let next_edition = match cur_edition {
1599             Edition::Edition2015 => {
1600                 match ident_str {
1601                     "async" | "try" | "dyn" => Edition::Edition2018,
1602                     // Only issue warnings for `await` if the `async_await`
1603                     // feature isn't being used. Otherwise, users need
1604                     // to keep using `await` for the macro exposed by std.
1605                     "await" if !cx.sess.features_untracked().async_await => Edition::Edition2018,
1606                     _ => return,
1607                 }
1608             }
1609
1610             // There are no new keywords yet for the 2018 edition and beyond.
1611             // However, `await` is a "false" keyword in the 2018 edition,
1612             // and can only be used if the `async_await` feature is enabled.
1613             // Otherwise, we emit an error.
1614             _ => {
1615                 if "await" == ident_str
1616                     && !cx.sess.features_untracked().async_await
1617                     && !is_raw_ident(ident)
1618                 {
1619                     let mut err = struct_span_err!(
1620                         cx.sess,
1621                         ident.span,
1622                         E0721,
1623                         "`await` is a keyword in the {} edition", cur_edition,
1624                     );
1625                     err.span_suggestion(
1626                         ident.span,
1627                         "you can use a raw identifier to stay compatible",
1628                         "r#await".to_string(),
1629                         Applicability::MachineApplicable,
1630                     );
1631                     err.emit();
1632                 }
1633                 return
1634             },
1635         };
1636
1637         // don't lint `r#foo`
1638         if is_raw_ident(ident) {
1639             return;
1640         }
1641
1642         let mut lint = cx.struct_span_lint(
1643             KEYWORD_IDENTS,
1644             ident.span,
1645             &format!("`{}` is a keyword in the {} edition",
1646                      ident.as_str(),
1647                      next_edition),
1648         );
1649         lint.span_suggestion(
1650             ident.span,
1651             "you can use a raw identifier to stay compatible",
1652             format!("r#{}", ident.as_str()),
1653             Applicability::MachineApplicable,
1654         );
1655         lint.emit()
1656     }
1657 }
1658
1659
1660 pub struct ExplicitOutlivesRequirements;
1661
1662 impl LintPass for ExplicitOutlivesRequirements {
1663     fn name(&self) -> &'static str {
1664         "ExplicitOutlivesRequirements"
1665     }
1666
1667     fn get_lints(&self) -> LintArray {
1668         lint_array![EXPLICIT_OUTLIVES_REQUIREMENTS]
1669     }
1670 }
1671
1672 impl ExplicitOutlivesRequirements {
1673     fn collect_outlives_bound_spans(
1674         &self,
1675         cx: &LateContext<'_, '_>,
1676         item_def_id: DefId,
1677         param_name: &str,
1678         bounds: &hir::GenericBounds,
1679         infer_static: bool
1680     ) -> Vec<(usize, Span)> {
1681         // For lack of a more elegant strategy for comparing the `ty::Predicate`s
1682         // returned by this query with the params/bounds grabbed from the HIR—and
1683         // with some regrets—we're going to covert the param/lifetime names to
1684         // strings
1685         let inferred_outlives = cx.tcx.inferred_outlives_of(item_def_id);
1686
1687         let ty_lt_names = inferred_outlives.iter().filter_map(|pred| {
1688             let binder = match pred {
1689                 ty::Predicate::TypeOutlives(binder) => binder,
1690                 _ => { return None; }
1691             };
1692             let ty_outlives_pred = binder.skip_binder();
1693             let ty_name = match ty_outlives_pred.0.sty {
1694                 ty::Param(param) => param.name.to_string(),
1695                 _ => { return None; }
1696             };
1697             let lt_name = match ty_outlives_pred.1 {
1698                 ty::RegionKind::ReEarlyBound(region) => {
1699                     region.name.to_string()
1700                 },
1701                 _ => { return None; }
1702             };
1703             Some((ty_name, lt_name))
1704         }).collect::<Vec<_>>();
1705
1706         let mut bound_spans = Vec::new();
1707         for (i, bound) in bounds.iter().enumerate() {
1708             if let hir::GenericBound::Outlives(lifetime) = bound {
1709                 let is_static = match lifetime.name {
1710                     hir::LifetimeName::Static => true,
1711                     _ => false
1712                 };
1713                 if is_static && !infer_static {
1714                     // infer-outlives for 'static is still feature-gated (tracking issue #44493)
1715                     continue;
1716                 }
1717
1718                 let lt_name = &lifetime.name.ident().to_string();
1719                 if ty_lt_names.contains(&(param_name.to_owned(), lt_name.to_owned())) {
1720                     bound_spans.push((i, bound.span()));
1721                 }
1722             }
1723         }
1724         bound_spans
1725     }
1726
1727     fn consolidate_outlives_bound_spans(
1728         &self,
1729         lo: Span,
1730         bounds: &hir::GenericBounds,
1731         bound_spans: Vec<(usize, Span)>
1732     ) -> Vec<Span> {
1733         if bounds.is_empty() {
1734             return Vec::new();
1735         }
1736         if bound_spans.len() == bounds.len() {
1737             let (_, last_bound_span) = bound_spans[bound_spans.len()-1];
1738             // If all bounds are inferable, we want to delete the colon, so
1739             // start from just after the parameter (span passed as argument)
1740             vec![lo.to(last_bound_span)]
1741         } else {
1742             let mut merged = Vec::new();
1743             let mut last_merged_i = None;
1744
1745             let mut from_start = true;
1746             for (i, bound_span) in bound_spans {
1747                 match last_merged_i {
1748                     // If the first bound is inferable, our span should also eat the trailing `+`
1749                     None if i == 0 => {
1750                         merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
1751                         last_merged_i = Some(0);
1752                     },
1753                     // If consecutive bounds are inferable, merge their spans
1754                     Some(h) if i == h+1 => {
1755                         if let Some(tail) = merged.last_mut() {
1756                             // Also eat the trailing `+` if the first
1757                             // more-than-one bound is inferable
1758                             let to_span = if from_start && i < bounds.len() {
1759                                 bounds[i+1].span().shrink_to_lo()
1760                             } else {
1761                                 bound_span
1762                             };
1763                             *tail = tail.to(to_span);
1764                             last_merged_i = Some(i);
1765                         } else {
1766                             bug!("another bound-span visited earlier");
1767                         }
1768                     },
1769                     _ => {
1770                         // When we find a non-inferable bound, subsequent inferable bounds
1771                         // won't be consecutive from the start (and we'll eat the leading
1772                         // `+` rather than the trailing one)
1773                         from_start = false;
1774                         merged.push(bounds[i-1].span().shrink_to_hi().to(bound_span));
1775                         last_merged_i = Some(i);
1776                     }
1777                 }
1778             }
1779             merged
1780         }
1781     }
1782 }
1783
1784 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitOutlivesRequirements {
1785     fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
1786         let infer_static = cx.tcx.features().infer_static_outlives_requirements;
1787         let def_id = cx.tcx.hir().local_def_id(item.id);
1788         if let hir::ItemKind::Struct(_, ref generics) = item.node {
1789             let mut bound_count = 0;
1790             let mut lint_spans = Vec::new();
1791
1792             for param in &generics.params {
1793                 let param_name = match param.kind {
1794                     hir::GenericParamKind::Lifetime { .. } => { continue; },
1795                     hir::GenericParamKind::Type { .. } => {
1796                         match param.name {
1797                             hir::ParamName::Fresh(_) => { continue; },
1798                             hir::ParamName::Error => { continue; },
1799                             hir::ParamName::Plain(name) => name.to_string()
1800                         }
1801                     }
1802                 };
1803                 let bound_spans = self.collect_outlives_bound_spans(
1804                     cx, def_id, &param_name, &param.bounds, infer_static
1805                 );
1806                 bound_count += bound_spans.len();
1807                 lint_spans.extend(
1808                     self.consolidate_outlives_bound_spans(
1809                         param.span.shrink_to_hi(), &param.bounds, bound_spans
1810                     )
1811                 );
1812             }
1813
1814             let mut where_lint_spans = Vec::new();
1815             let mut dropped_predicate_count = 0;
1816             let num_predicates = generics.where_clause.predicates.len();
1817             for (i, where_predicate) in generics.where_clause.predicates.iter().enumerate() {
1818                 if let hir::WherePredicate::BoundPredicate(predicate) = where_predicate {
1819                     let param_name = match predicate.bounded_ty.node {
1820                         hir::TyKind::Path(ref qpath) => {
1821                             if let hir::QPath::Resolved(None, ty_param_path) = qpath {
1822                                 ty_param_path.segments[0].ident.to_string()
1823                             } else {
1824                                 continue;
1825                             }
1826                         },
1827                         _ => { continue; }
1828                     };
1829                     let bound_spans = self.collect_outlives_bound_spans(
1830                         cx, def_id, &param_name, &predicate.bounds, infer_static
1831                     );
1832                     bound_count += bound_spans.len();
1833
1834                     let drop_predicate = bound_spans.len() == predicate.bounds.len();
1835                     if drop_predicate {
1836                         dropped_predicate_count += 1;
1837                     }
1838
1839                     // If all the bounds on a predicate were inferable and there are
1840                     // further predicates, we want to eat the trailing comma
1841                     if drop_predicate && i + 1 < num_predicates {
1842                         let next_predicate_span = generics.where_clause.predicates[i+1].span();
1843                         where_lint_spans.push(
1844                             predicate.span.to(next_predicate_span.shrink_to_lo())
1845                         );
1846                     } else {
1847                         where_lint_spans.extend(
1848                             self.consolidate_outlives_bound_spans(
1849                                 predicate.span.shrink_to_lo(),
1850                                 &predicate.bounds,
1851                                 bound_spans
1852                             )
1853                         );
1854                     }
1855                 }
1856             }
1857
1858             // If all predicates are inferable, drop the entire clause
1859             // (including the `where`)
1860             if num_predicates > 0 && dropped_predicate_count == num_predicates {
1861                 let full_where_span = generics.span.shrink_to_hi()
1862                     .to(generics.where_clause.span()
1863                     .expect("span of (nonempty) where clause should exist"));
1864                 lint_spans.push(
1865                     full_where_span
1866                 );
1867             } else {
1868                 lint_spans.extend(where_lint_spans);
1869             }
1870
1871             if !lint_spans.is_empty() {
1872                 let mut err = cx.struct_span_lint(
1873                     EXPLICIT_OUTLIVES_REQUIREMENTS,
1874                     lint_spans.clone(),
1875                     "outlives requirements can be inferred"
1876                 );
1877                 err.multipart_suggestion(
1878                     if bound_count == 1 {
1879                         "remove this bound"
1880                     } else {
1881                         "remove these bounds"
1882                     },
1883                     lint_spans.into_iter().map(|span| (span, "".to_owned())).collect::<Vec<_>>(),
1884                     Applicability::MachineApplicable
1885                 );
1886                 err.emit();
1887             }
1888
1889         }
1890     }
1891
1892 }