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