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                             GenericParamKind::Const { .. } => {
 912                                 let mut err = cx.struct_span_lint(
 913                                     NO_MANGLE_GENERIC_ITEMS,
 914                                     it.span,
 915                                     "functions generic over types or consts must be mangled",
 916                                 );
 917                                 err.span_suggestion_short(
 918                                     no_mangle_attr.span,
 919                                     "remove this attribute",
 920                                     String::new(),
 921                                     // Use of `#[no_mangle]` suggests FFI intent; correct
 922                                     // fix may be to monomorphize source by hand
 923                                     Applicability::MaybeIncorrect
 924                                 );
 925                                 err.emit();
 926                                 break;
 927                             }
 928                         }
 929                     }
 930                 }
 931             }
 932             hir::ItemKind::Const(..) => {
 933                 if attr::contains_name(&it.attrs, "no_mangle") {
 934                     // Const items do not refer to a particular location in memory, and therefore
 935                     // don't have anything to attach a symbol to
 936                     let msg = "const items should never be #[no_mangle]";
 937                     let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
 938
 939                     // account for "pub const" (#45562)
 940                     let start = cx.tcx.sess.source_map().span_to_snippet(it.span)
 941                         .map(|snippet| snippet.find("const").unwrap_or(0))
 942                         .unwrap_or(0) as u32;
 943                     // `const` is 5 chars
 944                     let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
 945                     err.span_suggestion(
 946                         const_span,
 947                         "try a static value",
 948                         "pub static".to_owned(),
 949                         Applicability::MachineApplicable
 950                     );
 951                     err.emit();
 952                 }
 953             }
 954             _ => {}
 955         }
 956     }
 957 }
 958
 959 #[derive(Clone, Copy)]
 960 pub struct MutableTransmutes;
 961
 962 declare_lint! {
 963     MUTABLE_TRANSMUTES,
 964     Deny,
 965     "mutating transmuted &mut T from &T may cause undefined behavior"
 966 }
 967
 968 impl LintPass for MutableTransmutes {
 969     fn name(&self) -> &'static str {
 970         "MutableTransmutes"
 971     }
 972
 973     fn get_lints(&self) -> LintArray {
 974         lint_array!(MUTABLE_TRANSMUTES)
 975     }
 976 }
 977
 978 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
 979     fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &hir::Expr) {
 980         use rustc_target::spec::abi::Abi::RustIntrinsic;
 981
 982         let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
 983                    consider instead using an UnsafeCell";
 984         match get_transmute_from_to(cx, expr) {
 985             Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) => {
 986                 if to_mt == hir::Mutability::MutMutable &&
 987                    from_mt == hir::Mutability::MutImmutable {
 988                     cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
 989                 }
 990             }
 991             _ => (),
 992         }
 993
 994         fn get_transmute_from_to<'a, 'tcx>
 995             (cx: &LateContext<'a, 'tcx>,
 996              expr: &hir::Expr)
 997              -> Option<(&'tcx ty::TyKind<'tcx>, &'tcx ty::TyKind<'tcx>)> {
 998             let def = if let hir::ExprKind::Path(ref qpath) = expr.node {
 999                 cx.tables.qpath_def(qpath, expr.hir_id)
1000             } else {
1001                 return None;
1002             };
1003             if let Def::Fn(did) = def {
1004                 if !def_id_is_transmute(cx, did) {
1005                     return None;
1006                 }
1007                 let sig = cx.tables.node_type(expr.hir_id).fn_sig(cx.tcx);
1008                 let from = sig.inputs().skip_binder()[0];
1009                 let to = *sig.output().skip_binder();
1010                 return Some((&from.sty, &to.sty));
1011             }
1012             None
1013         }
1014
1015         fn def_id_is_transmute(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
1016             cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
1017             cx.tcx.item_name(def_id) == "transmute"
1018         }
1019     }
1020 }
1021
1022 /// Forbids using the `#[feature(...)]` attribute
1023 #[derive(Copy, Clone)]
1024 pub struct UnstableFeatures;
1025
1026 declare_lint! {
1027     UNSTABLE_FEATURES,
1028     Allow,
1029     "enabling unstable features (deprecated. do not use)"
1030 }
1031
1032 impl LintPass for UnstableFeatures {
1033     fn name(&self) -> &'static str {
1034         "UnstableFeatures"
1035     }
1036
1037     fn get_lints(&self) -> LintArray {
1038         lint_array!(UNSTABLE_FEATURES)
1039     }
1040 }
1041
1042 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
1043     fn check_attribute(&mut self, ctx: &LateContext<'_, '_>, attr: &ast::Attribute) {
1044         if attr.check_name("feature") {
1045             if let Some(items) = attr.meta_item_list() {
1046                 for item in items {
1047                     ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
1048                 }
1049             }
1050         }
1051     }
1052 }
1053
1054 /// Lint for unions that contain fields with possibly non-trivial destructors.
1055 pub struct UnionsWithDropFields;
1056
1057 declare_lint! {
1058     UNIONS_WITH_DROP_FIELDS,
1059     Warn,
1060     "use of unions that contain fields with possibly non-trivial drop code"
1061 }
1062
1063 impl LintPass for UnionsWithDropFields {
1064     fn name(&self) -> &'static str {
1065         "UnionsWithDropFields"
1066     }
1067
1068     fn get_lints(&self) -> LintArray {
1069         lint_array!(UNIONS_WITH_DROP_FIELDS)
1070     }
1071 }
1072
1073 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
1074     fn check_item(&mut self, ctx: &LateContext<'_, '_>, item: &hir::Item) {
1075         if let hir::ItemKind::Union(ref vdata, _) = item.node {
1076             for field in vdata.fields() {
1077                 let field_ty = ctx.tcx.type_of(ctx.tcx.hir().local_def_id(field.id));
1078                 if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
1079                     ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
1080                                   field.span,
1081                                   "union contains a field with possibly non-trivial drop code, \
1082                                    drop code of union fields is ignored when dropping the union");
1083                     return;
1084                 }
1085             }
1086         }
1087     }
1088 }
1089
1090 /// Lint for items marked `pub` that aren't reachable from other crates.
1091 #[derive(Copy, Clone)]
1092 pub struct UnreachablePub;
1093
1094 declare_lint! {
1095     pub UNREACHABLE_PUB,
1096     Allow,
1097     "`pub` items not reachable from crate root"
1098 }
1099
1100 impl LintPass for UnreachablePub {
1101     fn name(&self) -> &'static str {
1102         "UnreachablePub"
1103     }
1104
1105     fn get_lints(&self) -> LintArray {
1106         lint_array!(UNREACHABLE_PUB)
1107     }
1108 }
1109
1110 impl UnreachablePub {
1111     fn perform_lint(&self, cx: &LateContext<'_, '_>, what: &str, id: ast::NodeId,
1112                     vis: &hir::Visibility, span: Span, exportable: bool) {
1113         let mut applicability = Applicability::MachineApplicable;
1114         match vis.node {
1115             hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
1116                 if span.ctxt().outer().expn_info().is_some() {
1117                     applicability = Applicability::MaybeIncorrect;
1118                 }
1119                 let def_span = cx.tcx.sess.source_map().def_span(span);
1120                 let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
1121                                                   &format!("unreachable `pub` {}", what));
1122                 let replacement = if cx.tcx.features().crate_visibility_modifier {
1123                     "crate"
1124                 } else {
1125                     "pub(crate)"
1126                 }.to_owned();
1127
1128                 err.span_suggestion(
1129                     vis.span,
1130                     "consider restricting its visibility",
1131                     replacement,
1132                     applicability,
1133                 );
1134                 if exportable {
1135                     err.help("or consider exporting it for use by other crates");
1136                 }
1137                 err.emit();
1138             },
1139             _ => {}
1140         }
1141     }
1142 }
1143
1144
1145 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
1146     fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
1147         self.perform_lint(cx, "item", item.id, &item.vis, item.span, true);
1148     }
1149
1150     fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, foreign_item: &hir::ForeignItem) {
1151         self.perform_lint(cx, "item", foreign_item.id, &foreign_item.vis,
1152                           foreign_item.span, true);
1153     }
1154
1155     fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField) {
1156         self.perform_lint(cx, "field", field.id, &field.vis, field.span, false);
1157     }
1158
1159     fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
1160         self.perform_lint(cx, "item", impl_item.id, &impl_item.vis, impl_item.span, false);
1161     }
1162 }
1163
1164 /// Lint for trait and lifetime bounds in type aliases being mostly ignored.
1165 /// They are relevant when using associated types, but otherwise neither checked
1166 /// at definition site nor enforced at use site.
1167
1168 pub struct TypeAliasBounds;
1169
1170 declare_lint! {
1171     TYPE_ALIAS_BOUNDS,
1172     Warn,
1173     "bounds in type aliases are not enforced"
1174 }
1175
1176 impl LintPass for TypeAliasBounds {
1177     fn name(&self) -> &'static str {
1178         "TypeAliasBounds"
1179     }
1180
1181     fn get_lints(&self) -> LintArray {
1182         lint_array!(TYPE_ALIAS_BOUNDS)
1183     }
1184 }
1185
1186 impl TypeAliasBounds {
1187     fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
1188         match *qpath {
1189             hir::QPath::TypeRelative(ref ty, _) => {
1190                 // If this is a type variable, we found a `T::Assoc`.
1191                 match ty.node {
1192                     hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1193                         match path.def {
1194                             Def::TyParam(_) => true,
1195                             _ => false
1196                         }
1197                     }
1198                     _ => false
1199                 }
1200             }
1201             hir::QPath::Resolved(..) => false,
1202         }
1203     }
1204
1205     fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder<'_>) {
1206         // Access to associates types should use `<T as Bound>::Assoc`, which does not need a
1207         // bound.  Let's see if this type does that.
1208
1209         // We use a HIR visitor to walk the type.
1210         use rustc::hir::intravisit::{self, Visitor};
1211         struct WalkAssocTypes<'a, 'db> where 'db: 'a {
1212             err: &'a mut DiagnosticBuilder<'db>
1213         }
1214         impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
1215             fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
1216             {
1217                 intravisit::NestedVisitorMap::None
1218             }
1219
1220             fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: hir::HirId, span: Span) {
1221                 if TypeAliasBounds::is_type_variable_assoc(qpath) {
1222                     self.err.span_help(span,
1223                         "use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
1224                          associated types in type aliases");
1225                 }
1226                 intravisit::walk_qpath(self, qpath, id, span)
1227             }
1228         }
1229
1230         // Let's go for a walk!
1231         let mut visitor = WalkAssocTypes { err };
1232         visitor.visit_ty(ty);
1233     }
1234 }
1235
1236 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
1237     fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
1238         let (ty, type_alias_generics) = match item.node {
1239             hir::ItemKind::Ty(ref ty, ref generics) => (&*ty, generics),
1240             _ => return,
1241         };
1242         let mut suggested_changing_assoc_types = false;
1243         // There must not be a where clause
1244         if !type_alias_generics.where_clause.predicates.is_empty() {
1245             let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
1246                 .map(|pred| pred.span()).collect();
1247             let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
1248                 "where clauses are not enforced in type aliases");
1249             err.help("the clause will not be checked when the type alias is used, \
1250                       and should be removed");
1251             if !suggested_changing_assoc_types {
1252                 TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1253                 suggested_changing_assoc_types = true;
1254             }
1255             err.emit();
1256         }
1257         // The parameters must not have bounds
1258         for param in type_alias_generics.params.iter() {
1259             let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
1260             if !spans.is_empty() {
1261                 let mut err = cx.struct_span_lint(
1262                     TYPE_ALIAS_BOUNDS,
1263                     spans,
1264                     "bounds on generic parameters are not enforced in type aliases",
1265                 );
1266                 err.help("the bound will not be checked when the type alias is used, \
1267                           and should be removed");
1268                 if !suggested_changing_assoc_types {
1269                     TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
1270                     suggested_changing_assoc_types = true;
1271                 }
1272                 err.emit();
1273             }
1274         }
1275     }
1276 }
1277
1278 /// Lint constants that are erroneous.
1279 /// Without this lint, we might not get any diagnostic if the constant is
1280 /// unused within this crate, even though downstream crates can't use it
1281 /// without producing an error.
1282 pub struct UnusedBrokenConst;
1283
1284 impl LintPass for UnusedBrokenConst {
1285     fn name(&self) -> &'static str {
1286         "UnusedBrokenConst"
1287     }
1288
1289     fn get_lints(&self) -> LintArray {
1290         lint_array!()
1291     }
1292 }
1293 fn check_const(cx: &LateContext<'_, '_>, body_id: hir::BodyId) {
1294     let def_id = cx.tcx.hir().body_owner_def_id(body_id);
1295     let is_static = cx.tcx.is_static(def_id).is_some();
1296     let param_env = if is_static {
1297         // Use the same param_env as `codegen_static_initializer`, to reuse the cache.
1298         ty::ParamEnv::reveal_all()
1299     } else {
1300         cx.tcx.param_env(def_id)
1301     };
1302     let cid = ::rustc::mir::interpret::GlobalId {
1303         instance: ty::Instance::mono(cx.tcx, def_id),
1304         promoted: None
1305     };
1306     // trigger the query once for all constants since that will already report the errors
1307     let _ = cx.tcx.const_eval(param_env.and(cid));
1308 }
1309
1310 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
1311     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1312         match it.node {
1313             hir::ItemKind::Const(_, body_id) => {
1314                 check_const(cx, body_id);
1315             },
1316             hir::ItemKind::Static(_, _, body_id) => {
1317                 check_const(cx, body_id);
1318             },
1319             _ => {},
1320         }
1321     }
1322 }
1323
1324 /// Lint for trait and lifetime bounds that don't depend on type parameters
1325 /// which either do nothing, or stop the item from being used.
1326 pub struct TrivialConstraints;
1327
1328 declare_lint! {
1329     TRIVIAL_BOUNDS,
1330     Warn,
1331     "these bounds don't depend on an type parameters"
1332 }
1333
1334 impl LintPass for TrivialConstraints {
1335     fn name(&self) -> &'static str {
1336         "TrivialConstraints"
1337     }
1338
1339     fn get_lints(&self) -> LintArray {
1340         lint_array!(TRIVIAL_BOUNDS)
1341     }
1342 }
1343
1344 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
1345     fn check_item(
1346         &mut self,
1347         cx: &LateContext<'a, 'tcx>,
1348         item: &'tcx hir::Item,
1349     ) {
1350         use rustc::ty::fold::TypeFoldable;
1351         use rustc::ty::Predicate::*;
1352
1353
1354         if cx.tcx.features().trivial_bounds {
1355             let def_id = cx.tcx.hir().local_def_id(item.id);
1356             let predicates = cx.tcx.predicates_of(def_id);
1357             for &(predicate, span) in &predicates.predicates {
1358                 let predicate_kind_name = match predicate {
1359                     Trait(..) => "Trait",
1360                     TypeOutlives(..) |
1361                     RegionOutlives(..) => "Lifetime",
1362
1363                     // Ignore projections, as they can only be global
1364                     // if the trait bound is global
1365                     Projection(..) |
1366                     // Ignore bounds that a user can't type
1367                     WellFormed(..) |
1368                     ObjectSafe(..) |
1369                     ClosureKind(..) |
1370                     Subtype(..) |
1371                     ConstEvaluatable(..) => continue,
1372                 };
1373                 if predicate.is_global() {
1374                     cx.span_lint(
1375                         TRIVIAL_BOUNDS,
1376                         span,
1377                         &format!("{} bound {} does not depend on any type \
1378                                 or lifetime parameters", predicate_kind_name, predicate),
1379                     );
1380                 }
1381             }
1382         }
1383     }
1384 }
1385
1386
1387 /// Does nothing as a lint pass, but registers some `Lint`s
1388 /// which are used by other parts of the compiler.
1389 #[derive(Copy, Clone)]
1390 pub struct SoftLints;
1391
1392 impl LintPass for SoftLints {
1393     fn name(&self) -> &'static str {
1394         "SoftLints"
1395     }
1396
1397     fn get_lints(&self) -> LintArray {
1398         lint_array!(
1399             WHILE_TRUE,
1400             BOX_POINTERS,
1401             NON_SHORTHAND_FIELD_PATTERNS,
1402             UNSAFE_CODE,
1403             MISSING_DOCS,
1404             MISSING_COPY_IMPLEMENTATIONS,
1405             MISSING_DEBUG_IMPLEMENTATIONS,
1406             ANONYMOUS_PARAMETERS,
1407             UNUSED_DOC_COMMENTS,
1408             PLUGIN_AS_LIBRARY,
1409             NO_MANGLE_CONST_ITEMS,
1410             NO_MANGLE_GENERIC_ITEMS,
1411             MUTABLE_TRANSMUTES,
1412             UNSTABLE_FEATURES,
1413             UNIONS_WITH_DROP_FIELDS,
1414             UNREACHABLE_PUB,
1415             TYPE_ALIAS_BOUNDS,
1416             TRIVIAL_BOUNDS
1417         )
1418     }
1419 }
1420
1421 declare_lint! {
1422     pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
1423     Allow,
1424     "`...` range patterns are deprecated"
1425 }
1426
1427
1428 pub struct EllipsisInclusiveRangePatterns;
1429
1430 impl LintPass for EllipsisInclusiveRangePatterns {
1431     fn name(&self) -> &'static str {
1432         "EllipsisInclusiveRangePatterns"
1433     }
1434
1435     fn get_lints(&self) -> LintArray {
1436         lint_array!(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS)
1437     }
1438 }
1439
1440 impl EarlyLintPass for EllipsisInclusiveRangePatterns {
1441     fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat, visit_subpats: &mut bool) {
1442         use self::ast::{PatKind, RangeEnd, RangeSyntax::DotDotDot};
1443
1444         /// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
1445         /// corresponding to the ellipsis.
1446         fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(&P<Expr>, &P<Expr>, Span)> {
1447             match &pat.node {
1448                 PatKind::Range(a, b, Spanned { span, node: RangeEnd::Included(DotDotDot), .. }) => {
1449                     Some((a, b, *span))
1450                 }
1451                 _ => None,
1452             }
1453         }
1454
1455         let (parenthesise, endpoints) = match &pat.node {
1456             PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
1457             _ => (false, matches_ellipsis_pat(pat)),
1458         };
1459
1460         if let Some((start, end, join)) = endpoints {
1461             let msg = "`...` range patterns are deprecated";
1462             let suggestion = "use `..=` for an inclusive range";
1463             if parenthesise {
1464                 *visit_subpats = false;
1465                 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg);
1466                 err.span_suggestion(
1467                     pat.span,
1468                     suggestion,
1469                     format!("&({}..={})", expr_to_string(&start), expr_to_string(&end)),
1470                     Applicability::MachineApplicable,
1471                 );
1472                 err.emit();
1473             } else {
1474                 let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg);
1475                 err.span_suggestion_short(
1476                     join,
1477                     suggestion,
1478                     "..=".to_owned(),
1479                     Applicability::MachineApplicable,
1480                 );
1481                 err.emit();
1482             };
1483         }
1484     }
1485 }
1486
1487 declare_lint! {
1488     UNNAMEABLE_TEST_ITEMS,
1489     Warn,
1490     "detects an item that cannot be named being marked as #[test_case]",
1491     report_in_external_macro: true
1492 }
1493
1494 pub struct UnnameableTestItems {
1495     boundary: ast::NodeId, // NodeId of the item under which things are not nameable
1496     items_nameable: bool,
1497 }
1498
1499 impl UnnameableTestItems {
1500     pub fn new() -> Self {
1501         Self {
1502             boundary: ast::DUMMY_NODE_ID,
1503             items_nameable: true
1504         }
1505     }
1506 }
1507
1508 impl LintPass for UnnameableTestItems {
1509     fn name(&self) -> &'static str {
1510         "UnnameableTestItems"
1511     }
1512
1513     fn get_lints(&self) -> LintArray {
1514         lint_array!(UNNAMEABLE_TEST_ITEMS)
1515     }
1516 }
1517
1518 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
1519     fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1520         if self.items_nameable {
1521             if let hir::ItemKind::Mod(..) = it.node {}
1522             else {
1523                 self.items_nameable = false;
1524                 self.boundary = it.id;
1525             }
1526             return;
1527         }
1528
1529         if let Some(attr) = attr::find_by_name(&it.attrs, "rustc_test_marker") {
1530             cx.struct_span_lint(
1531                 UNNAMEABLE_TEST_ITEMS,
1532                 attr.span,
1533                 "cannot test inner items",
1534             ).emit();
1535         }
1536     }
1537
1538     fn check_item_post(&mut self, _cx: &LateContext<'_, '_>, it: &hir::Item) {
1539         if !self.items_nameable && self.boundary == it.id {
1540             self.items_nameable = true;
1541         }
1542     }
1543 }
1544
1545 declare_lint! {
1546     pub KEYWORD_IDENTS,
1547     Allow,
1548     "detects edition keywords being used as an identifier"
1549 }
1550
1551 /// Check for uses of edition keywords used as an identifier.
1552 #[derive(Copy, Clone)]
1553 pub struct KeywordIdents;
1554
1555 impl LintPass for KeywordIdents {
1556     fn name(&self) -> &'static str {
1557         "KeywordIdents"
1558     }
1559
1560     fn get_lints(&self) -> LintArray {
1561         lint_array!(KEYWORD_IDENTS)
1562     }
1563 }
1564
1565 impl KeywordIdents {
1566     fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
1567         for tt in tokens.into_trees() {
1568             match tt {
1569                 TokenTree::Token(span, tok) => match tok.ident() {
1570                     // only report non-raw idents
1571                     Some((ident, false)) => {
1572                         self.check_ident(cx, ast::Ident {
1573                             span: span.substitute_dummy(ident.span),
1574                             ..ident
1575                         });
1576                     }
1577                     _ => {},
1578                 }
1579                 TokenTree::Delimited(_, _, tts) => {
1580                     self.check_tokens(cx, tts)
1581                 },
1582             }
1583         }
1584     }
1585 }
1586
1587 impl EarlyLintPass for KeywordIdents {
1588     fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef, _id: ast::NodeId) {
1589         self.check_tokens(cx, mac_def.stream());
1590     }
1591     fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::Mac) {
1592         self.check_tokens(cx, mac.node.tts.clone().into());
1593     }
1594     fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: ast::Ident) {
1595         let ident_str = &ident.as_str()[..];
1596         let cur_edition = cx.sess.edition();
1597         let is_raw_ident = |ident: ast::Ident| {
1598             cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&ident.span)
1599         };
1600         let next_edition = match cur_edition {
1601             Edition::Edition2015 => {
1602                 match ident_str {
1603                     "async" | "try" | "dyn" => Edition::Edition2018,
1604                     // Only issue warnings for `await` if the `async_await`
1605                     // feature isn't being used. Otherwise, users need
1606                     // to keep using `await` for the macro exposed by std.
1607                     "await" if !cx.sess.features_untracked().async_await => Edition::Edition2018,
1608                     _ => return,
1609                 }
1610             }
1611
1612             // There are no new keywords yet for the 2018 edition and beyond.
1613             // However, `await` is a "false" keyword in the 2018 edition,
1614             // and can only be used if the `async_await` feature is enabled.
1615             // Otherwise, we emit an error.
1616             _ => {
1617                 if "await" == ident_str
1618                     && !cx.sess.features_untracked().async_await
1619                     && !is_raw_ident(ident)
1620                 {
1621                     let mut err = struct_span_err!(
1622                         cx.sess,
1623                         ident.span,
1624                         E0721,
1625                         "`await` is a keyword in the {} edition", cur_edition,
1626                     );
1627                     err.span_suggestion(
1628                         ident.span,
1629                         "you can use a raw identifier to stay compatible",
1630                         "r#await".to_string(),
1631                         Applicability::MachineApplicable,
1632                     );
1633                     err.emit();
1634                 }
1635                 return
1636             },
1637         };
1638
1639         // don't lint `r#foo`
1640         if is_raw_ident(ident) {
1641             return;
1642         }
1643
1644         let mut lint = cx.struct_span_lint(
1645             KEYWORD_IDENTS,
1646             ident.span,
1647             &format!("`{}` is a keyword in the {} edition",
1648                      ident.as_str(),
1649                      next_edition),
1650         );
1651         lint.span_suggestion(
1652             ident.span,
1653             "you can use a raw identifier to stay compatible",
1654             format!("r#{}", ident.as_str()),
1655             Applicability::MachineApplicable,
1656         );
1657         lint.emit()
1658     }
1659 }
1660
1661
1662 pub struct ExplicitOutlivesRequirements;
1663
1664 impl LintPass for ExplicitOutlivesRequirements {
1665     fn name(&self) -> &'static str {
1666         "ExplicitOutlivesRequirements"
1667     }
1668
1669     fn get_lints(&self) -> LintArray {
1670         lint_array![EXPLICIT_OUTLIVES_REQUIREMENTS]
1671     }
1672 }
1673
1674 impl ExplicitOutlivesRequirements {
1675     fn collect_outlives_bound_spans(
1676         &self,
1677         cx: &LateContext<'_, '_>,
1678         item_def_id: DefId,
1679         param_name: &str,
1680         bounds: &hir::GenericBounds,
1681         infer_static: bool
1682     ) -> Vec<(usize, Span)> {
1683         // For lack of a more elegant strategy for comparing the `ty::Predicate`s
1684         // returned by this query with the params/bounds grabbed from the HIR—and
1685         // with some regrets—we're going to covert the param/lifetime names to
1686         // strings
1687         let inferred_outlives = cx.tcx.inferred_outlives_of(item_def_id);
1688
1689         let ty_lt_names = inferred_outlives.iter().filter_map(|pred| {
1690             let binder = match pred {
1691                 ty::Predicate::TypeOutlives(binder) => binder,
1692                 _ => { return None; }
1693             };
1694             let ty_outlives_pred = binder.skip_binder();
1695             let ty_name = match ty_outlives_pred.0.sty {
1696                 ty::Param(param) => param.name.to_string(),
1697                 _ => { return None; }
1698             };
1699             let lt_name = match ty_outlives_pred.1 {
1700                 ty::RegionKind::ReEarlyBound(region) => {
1701                     region.name.to_string()
1702                 },
1703                 _ => { return None; }
1704             };
1705             Some((ty_name, lt_name))
1706         }).collect::<Vec<_>>();
1707
1708         let mut bound_spans = Vec::new();
1709         for (i, bound) in bounds.iter().enumerate() {
1710             if let hir::GenericBound::Outlives(lifetime) = bound {
1711                 let is_static = match lifetime.name {
1712                     hir::LifetimeName::Static => true,
1713                     _ => false
1714                 };
1715                 if is_static && !infer_static {
1716                     // infer-outlives for 'static is still feature-gated (tracking issue #44493)
1717                     continue;
1718                 }
1719
1720                 let lt_name = &lifetime.name.ident().to_string();
1721                 if ty_lt_names.contains(&(param_name.to_owned(), lt_name.to_owned())) {
1722                     bound_spans.push((i, bound.span()));
1723                 }
1724             }
1725         }
1726         bound_spans
1727     }
1728
1729     fn consolidate_outlives_bound_spans(
1730         &self,
1731         lo: Span,
1732         bounds: &hir::GenericBounds,
1733         bound_spans: Vec<(usize, Span)>
1734     ) -> Vec<Span> {
1735         if bounds.is_empty() {
1736             return Vec::new();
1737         }
1738         if bound_spans.len() == bounds.len() {
1739             let (_, last_bound_span) = bound_spans[bound_spans.len()-1];
1740             // If all bounds are inferable, we want to delete the colon, so
1741             // start from just after the parameter (span passed as argument)
1742             vec![lo.to(last_bound_span)]
1743         } else {
1744             let mut merged = Vec::new();
1745             let mut last_merged_i = None;
1746
1747             let mut from_start = true;
1748             for (i, bound_span) in bound_spans {
1749                 match last_merged_i {
1750                     // If the first bound is inferable, our span should also eat the trailing `+`
1751                     None if i == 0 => {
1752                         merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
1753                         last_merged_i = Some(0);
1754                     },
1755                     // If consecutive bounds are inferable, merge their spans
1756                     Some(h) if i == h+1 => {
1757                         if let Some(tail) = merged.last_mut() {
1758                             // Also eat the trailing `+` if the first
1759                             // more-than-one bound is inferable
1760                             let to_span = if from_start && i < bounds.len() {
1761                                 bounds[i+1].span().shrink_to_lo()
1762                             } else {
1763                                 bound_span
1764                             };
1765                             *tail = tail.to(to_span);
1766                             last_merged_i = Some(i);
1767                         } else {
1768                             bug!("another bound-span visited earlier");
1769                         }
1770                     },
1771                     _ => {
1772                         // When we find a non-inferable bound, subsequent inferable bounds
1773                         // won't be consecutive from the start (and we'll eat the leading
1774                         // `+` rather than the trailing one)
1775                         from_start = false;
1776                         merged.push(bounds[i-1].span().shrink_to_hi().to(bound_span));
1777                         last_merged_i = Some(i);
1778                     }
1779                 }
1780             }
1781             merged
1782         }
1783     }
1784 }
1785
1786 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitOutlivesRequirements {
1787     fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
1788         let infer_static = cx.tcx.features().infer_static_outlives_requirements;
1789         let def_id = cx.tcx.hir().local_def_id(item.id);
1790         if let hir::ItemKind::Struct(_, ref generics) = item.node {
1791             let mut bound_count = 0;
1792             let mut lint_spans = Vec::new();
1793
1794             for param in &generics.params {
1795                 let param_name = match param.kind {
1796                     hir::GenericParamKind::Lifetime { .. } => continue,
1797                     hir::GenericParamKind::Type { .. } => {
1798                         match param.name {
1799                             hir::ParamName::Fresh(_) => continue,
1800                             hir::ParamName::Error => continue,
1801                             hir::ParamName::Plain(name) => name.to_string(),
1802                         }
1803                     }
1804                     hir::GenericParamKind::Const { .. } => continue,
1805                 };
1806                 let bound_spans = self.collect_outlives_bound_spans(
1807                     cx, def_id, &param_name, &param.bounds, infer_static
1808                 );
1809                 bound_count += bound_spans.len();
1810                 lint_spans.extend(
1811                     self.consolidate_outlives_bound_spans(
1812                         param.span.shrink_to_hi(), &param.bounds, bound_spans
1813                     )
1814                 );
1815             }
1816
1817             let mut where_lint_spans = Vec::new();
1818             let mut dropped_predicate_count = 0;
1819             let num_predicates = generics.where_clause.predicates.len();
1820             for (i, where_predicate) in generics.where_clause.predicates.iter().enumerate() {
1821                 if let hir::WherePredicate::BoundPredicate(predicate) = where_predicate {
1822                     let param_name = match predicate.bounded_ty.node {
1823                         hir::TyKind::Path(ref qpath) => {
1824                             if let hir::QPath::Resolved(None, ty_param_path) = qpath {
1825                                 ty_param_path.segments[0].ident.to_string()
1826                             } else {
1827                                 continue;
1828                             }
1829                         },
1830                         _ => { continue; }
1831                     };
1832                     let bound_spans = self.collect_outlives_bound_spans(
1833                         cx, def_id, &param_name, &predicate.bounds, infer_static
1834                     );
1835                     bound_count += bound_spans.len();
1836
1837                     let drop_predicate = bound_spans.len() == predicate.bounds.len();
1838                     if drop_predicate {
1839                         dropped_predicate_count += 1;
1840                     }
1841
1842                     // If all the bounds on a predicate were inferable and there are
1843                     // further predicates, we want to eat the trailing comma
1844                     if drop_predicate && i + 1 < num_predicates {
1845                         let next_predicate_span = generics.where_clause.predicates[i+1].span();
1846                         where_lint_spans.push(
1847                             predicate.span.to(next_predicate_span.shrink_to_lo())
1848                         );
1849                     } else {
1850                         where_lint_spans.extend(
1851                             self.consolidate_outlives_bound_spans(
1852                                 predicate.span.shrink_to_lo(),
1853                                 &predicate.bounds,
1854                                 bound_spans
1855                             )
1856                         );
1857                     }
1858                 }
1859             }
1860
1861             // If all predicates are inferable, drop the entire clause
1862             // (including the `where`)
1863             if num_predicates > 0 && dropped_predicate_count == num_predicates {
1864                 let full_where_span = generics.span.shrink_to_hi()
1865                     .to(generics.where_clause.span()
1866                     .expect("span of (nonempty) where clause should exist"));
1867                 lint_spans.push(
1868                     full_where_span
1869                 );
1870             } else {
1871                 lint_spans.extend(where_lint_spans);
1872             }
1873
1874             if !lint_spans.is_empty() {
1875                 let mut err = cx.struct_span_lint(
1876                     EXPLICIT_OUTLIVES_REQUIREMENTS,
1877                     lint_spans.clone(),
1878                     "outlives requirements can be inferred"
1879                 );
1880                 err.multipart_suggestion(
1881                     if bound_count == 1 {
1882                         "remove this bound"
1883                     } else {
1884                         "remove these bounds"
1885                     },
1886                     lint_spans.into_iter().map(|span| (span, "".to_owned())).collect::<Vec<_>>(),
1887                     Applicability::MachineApplicable
1888                 );
1889                 err.emit();
1890             }
1891
1892         }
1893     }
1894
1895 }