compiler/rustc_lint/src/internal.rs

   1 //! Some lints that are only useful in the compiler or crates that use compiler internals, such as
   2 //! Clippy.
   3
   4 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
   5 use rustc_ast as ast;
   6 use rustc_errors::{fluent, Applicability};
   7 use rustc_hir::def::Res;
   8 use rustc_hir::{def_id::DefId, Expr, ExprKind, GenericArg, PatKind, Path, PathSegment, QPath};
   9 use rustc_hir::{HirId, Impl, Item, ItemKind, Node, Pat, Ty, TyKind};
  10 use rustc_middle::ty;
  11 use rustc_session::{declare_lint_pass, declare_tool_lint};
  12 use rustc_span::hygiene::{ExpnKind, MacroKind};
  13 use rustc_span::symbol::{kw, sym, Symbol};
  14 use rustc_span::Span;
  15
  16 declare_tool_lint! {
  17     pub rustc::DEFAULT_HASH_TYPES,
  18     Allow,
  19     "forbid HashMap and HashSet and suggest the FxHash* variants",
  20     report_in_external_macro: true
  21 }
  22
  23 declare_lint_pass!(DefaultHashTypes => [DEFAULT_HASH_TYPES]);
  24
  25 impl LateLintPass<'_> for DefaultHashTypes {
  26     fn check_path(&mut self, cx: &LateContext<'_>, path: &Path<'_>, hir_id: HirId) {
  27         let Res::Def(rustc_hir::def::DefKind::Struct, def_id) = path.res else { return };
  28         if matches!(cx.tcx.hir().get(hir_id), Node::Item(Item { kind: ItemKind::Use(..), .. })) {
  29             // don't lint imports, only actual usages
  30             return;
  31         }
  32         let replace = match cx.tcx.get_diagnostic_name(def_id) {
  33             Some(sym::HashMap) => "FxHashMap",
  34             Some(sym::HashSet) => "FxHashSet",
  35             _ => return,
  36         };
  37         cx.struct_span_lint(DEFAULT_HASH_TYPES, path.span, |lint| {
  38             lint.build(fluent::lint::default_hash_types)
  39                 .set_arg("preferred", replace)
  40                 .set_arg("used", cx.tcx.item_name(def_id))
  41                 .note(fluent::lint::note)
  42                 .emit();
  43         });
  44     }
  45 }
  46
  47 /// Helper function for lints that check for expressions with calls and use typeck results to
  48 /// get the `DefId` and `SubstsRef` of the function.
  49 fn typeck_results_of_method_fn<'tcx>(
  50     cx: &LateContext<'tcx>,
  51     expr: &Expr<'_>,
  52 ) -> Option<(Span, DefId, ty::subst::SubstsRef<'tcx>)> {
  53     match expr.kind {
  54         ExprKind::MethodCall(segment, _, _)
  55             if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) =>
  56         {
  57             Some((segment.ident.span, def_id, cx.typeck_results().node_substs(expr.hir_id)))
  58         },
  59         _ => {
  60             match cx.typeck_results().node_type(expr.hir_id).kind() {
  61                 &ty::FnDef(def_id, substs) => Some((expr.span, def_id, substs)),
  62                 _ => None,
  63             }
  64         }
  65     }
  66 }
  67
  68 declare_tool_lint! {
  69     pub rustc::POTENTIAL_QUERY_INSTABILITY,
  70     Allow,
  71     "require explicit opt-in when using potentially unstable methods or functions",
  72     report_in_external_macro: true
  73 }
  74
  75 declare_lint_pass!(QueryStability => [POTENTIAL_QUERY_INSTABILITY]);
  76
  77 impl LateLintPass<'_> for QueryStability {
  78     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
  79         let Some((span, def_id, substs)) = typeck_results_of_method_fn(cx, expr) else { return };
  80         if let Ok(Some(instance)) = ty::Instance::resolve(cx.tcx, cx.param_env, def_id, substs) {
  81             let def_id = instance.def_id();
  82             if cx.tcx.has_attr(def_id, sym::rustc_lint_query_instability) {
  83                 cx.struct_span_lint(POTENTIAL_QUERY_INSTABILITY, span, |lint| {
  84                     lint.build(fluent::lint::query_instability)
  85                         .set_arg("query", cx.tcx.item_name(def_id))
  86                         .note(fluent::lint::note)
  87                         .emit();
  88                 })
  89             }
  90         }
  91     }
  92 }
  93
  94 declare_tool_lint! {
  95     pub rustc::USAGE_OF_TY_TYKIND,
  96     Allow,
  97     "usage of `ty::TyKind` outside of the `ty::sty` module",
  98     report_in_external_macro: true
  99 }
 100
 101 declare_tool_lint! {
 102     pub rustc::USAGE_OF_QUALIFIED_TY,
 103     Allow,
 104     "using `ty::{Ty,TyCtxt}` instead of importing it",
 105     report_in_external_macro: true
 106 }
 107
 108 declare_lint_pass!(TyTyKind => [
 109     USAGE_OF_TY_TYKIND,
 110     USAGE_OF_QUALIFIED_TY,
 111 ]);
 112
 113 impl<'tcx> LateLintPass<'tcx> for TyTyKind {
 114     fn check_path(
 115         &mut self,
 116         cx: &LateContext<'tcx>,
 117         path: &'tcx rustc_hir::Path<'tcx>,
 118         _: rustc_hir::HirId,
 119     ) {
 120         if let Some(segment) = path.segments.iter().nth_back(1)
 121         && let Some(res) = &segment.res
 122         && lint_ty_kind_usage(cx, res)
 123         {
 124             let span = path.span.with_hi(
 125                 segment.args.map_or(segment.ident.span, |a| a.span_ext).hi()
 126             );
 127             cx.struct_span_lint(USAGE_OF_TY_TYKIND, path.span, |lint| {
 128                 lint.build(fluent::lint::tykind_kind)
 129                     .span_suggestion(
 130                         span,
 131                         fluent::lint::suggestion,
 132                         "ty",
 133                         Applicability::MaybeIncorrect, // ty maybe needs an import
 134                     )
 135                     .emit();
 136             });
 137         }
 138     }
 139
 140     fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx Ty<'tcx>) {
 141         match &ty.kind {
 142             TyKind::Path(QPath::Resolved(_, path)) => {
 143                 if lint_ty_kind_usage(cx, &path.res) {
 144                     cx.struct_span_lint(USAGE_OF_TY_TYKIND, path.span, |lint| {
 145                         let hir = cx.tcx.hir();
 146                         match hir.find(hir.get_parent_node(ty.hir_id)) {
 147                             Some(Node::Pat(Pat {
 148                                 kind:
 149                                     PatKind::Path(qpath)
 150                                     | PatKind::TupleStruct(qpath, ..)
 151                                     | PatKind::Struct(qpath, ..),
 152                                 ..
 153                             })) => {
 154                                 if let QPath::TypeRelative(qpath_ty, ..) = qpath
 155                                     && qpath_ty.hir_id == ty.hir_id
 156                                 {
 157                                     lint.build(fluent::lint::tykind_kind)
 158                                         .span_suggestion(
 159                                             path.span,
 160                                             fluent::lint::suggestion,
 161                                             "ty",
 162                                             Applicability::MaybeIncorrect, // ty maybe needs an import
 163                                         )
 164                                         .emit();
 165                                     return;
 166                                 }
 167                             }
 168                             Some(Node::Expr(Expr {
 169                                 kind: ExprKind::Path(qpath),
 170                                 ..
 171                             })) => {
 172                                 if let QPath::TypeRelative(qpath_ty, ..) = qpath
 173                                     && qpath_ty.hir_id == ty.hir_id
 174                                 {
 175                                     lint.build(fluent::lint::tykind_kind)
 176                                         .span_suggestion(
 177                                             path.span,
 178                                             fluent::lint::suggestion,
 179                                             "ty",
 180                                             Applicability::MaybeIncorrect, // ty maybe needs an import
 181                                         )
 182                                         .emit();
 183                                     return;
 184                                 }
 185                             }
 186                             // Can't unify these two branches because qpath below is `&&` and above is `&`
 187                             // and `A | B` paths don't play well together with adjustments, apparently.
 188                             Some(Node::Expr(Expr {
 189                                 kind: ExprKind::Struct(qpath, ..),
 190                                 ..
 191                             })) => {
 192                                 if let QPath::TypeRelative(qpath_ty, ..) = qpath
 193                                     && qpath_ty.hir_id == ty.hir_id
 194                                 {
 195                                     lint.build(fluent::lint::tykind_kind)
 196                                         .span_suggestion(
 197                                             path.span,
 198                                             fluent::lint::suggestion,
 199                                             "ty",
 200                                             Applicability::MaybeIncorrect, // ty maybe needs an import
 201                                         )
 202                                         .emit();
 203                                     return;
 204                                 }
 205                             }
 206                             _ => {}
 207                         }
 208                         lint.build(fluent::lint::tykind).help(fluent::lint::help).emit();
 209                     })
 210                 } else if !ty.span.from_expansion() && let Some(t) = is_ty_or_ty_ctxt(cx, &path) {
 211                     if path.segments.len() > 1 {
 212                         cx.struct_span_lint(USAGE_OF_QUALIFIED_TY, path.span, |lint| {
 213                             lint.build(fluent::lint::ty_qualified)
 214                                 .set_arg("ty", t.clone())
 215                                 .span_suggestion(
 216                                     path.span,
 217                                     fluent::lint::suggestion,
 218                                     t,
 219                                     // The import probably needs to be changed
 220                                     Applicability::MaybeIncorrect,
 221                                 )
 222                                 .emit();
 223                         })
 224                     }
 225                 }
 226             }
 227             _ => {}
 228         }
 229     }
 230 }
 231
 232 fn lint_ty_kind_usage(cx: &LateContext<'_>, res: &Res) -> bool {
 233     if let Some(did) = res.opt_def_id() {
 234         cx.tcx.is_diagnostic_item(sym::TyKind, did) || cx.tcx.is_diagnostic_item(sym::IrTyKind, did)
 235     } else {
 236         false
 237     }
 238 }
 239
 240 fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, path: &Path<'_>) -> Option<String> {
 241     match &path.res {
 242         Res::Def(_, def_id) => {
 243             if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(*def_id) {
 244                 return Some(format!("{}{}", name, gen_args(path.segments.last().unwrap())));
 245             }
 246         }
 247         // Only lint on `&Ty` and `&TyCtxt` if it is used outside of a trait.
 248         Res::SelfTy { trait_: None, alias_to: Some((did, _)) } => {
 249             if let ty::Adt(adt, substs) = cx.tcx.type_of(did).kind() {
 250                 if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(adt.did())
 251                 {
 252                     // NOTE: This path is currently unreachable as `Ty<'tcx>` is
 253                     // defined as a type alias meaning that `impl<'tcx> Ty<'tcx>`
 254                     // is not actually allowed.
 255                     //
 256                     // I(@lcnr) still kept this branch in so we don't miss this
 257                     // if we ever change it in the future.
 258                     return Some(format!("{}<{}>", name, substs[0]));
 259                 }
 260             }
 261         }
 262         _ => (),
 263     }
 264
 265     None
 266 }
 267
 268 fn gen_args(segment: &PathSegment<'_>) -> String {
 269     if let Some(args) = &segment.args {
 270         let lifetimes = args
 271             .args
 272             .iter()
 273             .filter_map(|arg| {
 274                 if let GenericArg::Lifetime(lt) = arg {
 275                     Some(lt.name.ident().to_string())
 276                 } else {
 277                     None
 278                 }
 279             })
 280             .collect::<Vec<_>>();
 281
 282         if !lifetimes.is_empty() {
 283             return format!("<{}>", lifetimes.join(", "));
 284         }
 285     }
 286
 287     String::new()
 288 }
 289
 290 declare_tool_lint! {
 291     pub rustc::LINT_PASS_IMPL_WITHOUT_MACRO,
 292     Allow,
 293     "`impl LintPass` without the `declare_lint_pass!` or `impl_lint_pass!` macros"
 294 }
 295
 296 declare_lint_pass!(LintPassImpl => [LINT_PASS_IMPL_WITHOUT_MACRO]);
 297
 298 impl EarlyLintPass for LintPassImpl {
 299     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
 300         if let ast::ItemKind::Impl(box ast::Impl { of_trait: Some(lint_pass), .. }) = &item.kind {
 301             if let Some(last) = lint_pass.path.segments.last() {
 302                 if last.ident.name == sym::LintPass {
 303                     let expn_data = lint_pass.path.span.ctxt().outer_expn_data();
 304                     let call_site = expn_data.call_site;
 305                     if expn_data.kind != ExpnKind::Macro(MacroKind::Bang, sym::impl_lint_pass)
 306                         && call_site.ctxt().outer_expn_data().kind
 307                             != ExpnKind::Macro(MacroKind::Bang, sym::declare_lint_pass)
 308                     {
 309                         cx.struct_span_lint(
 310                             LINT_PASS_IMPL_WITHOUT_MACRO,
 311                             lint_pass.path.span,
 312                             |lint| {
 313                                 lint.build(fluent::lint::lintpass_by_hand)
 314                                     .help(fluent::lint::help)
 315                                     .emit();
 316                             },
 317                         )
 318                     }
 319                 }
 320             }
 321         }
 322     }
 323 }
 324
 325 declare_tool_lint! {
 326     pub rustc::EXISTING_DOC_KEYWORD,
 327     Allow,
 328     "Check that documented keywords in std and core actually exist",
 329     report_in_external_macro: true
 330 }
 331
 332 declare_lint_pass!(ExistingDocKeyword => [EXISTING_DOC_KEYWORD]);
 333
 334 fn is_doc_keyword(s: Symbol) -> bool {
 335     s <= kw::Union
 336 }
 337
 338 impl<'tcx> LateLintPass<'tcx> for ExistingDocKeyword {
 339     fn check_item(&mut self, cx: &LateContext<'_>, item: &rustc_hir::Item<'_>) {
 340         for attr in cx.tcx.hir().attrs(item.hir_id()) {
 341             if !attr.has_name(sym::doc) {
 342                 continue;
 343             }
 344             if let Some(list) = attr.meta_item_list() {
 345                 for nested in list {
 346                     if nested.has_name(sym::keyword) {
 347                         let v = nested
 348                             .value_str()
 349                             .expect("#[doc(keyword = \"...\")] expected a value!");
 350                         if is_doc_keyword(v) {
 351                             return;
 352                         }
 353                         cx.struct_span_lint(EXISTING_DOC_KEYWORD, attr.span, |lint| {
 354                             lint.build(fluent::lint::non_existant_doc_keyword)
 355                                 .set_arg("keyword", v)
 356                                 .help(fluent::lint::help)
 357                                 .emit();
 358                         });
 359                     }
 360                 }
 361             }
 362         }
 363     }
 364 }
 365
 366 declare_tool_lint! {
 367     pub rustc::UNTRANSLATABLE_DIAGNOSTIC,
 368     Allow,
 369     "prevent creation of diagnostics which cannot be translated",
 370     report_in_external_macro: true
 371 }
 372
 373 declare_tool_lint! {
 374     pub rustc::DIAGNOSTIC_OUTSIDE_OF_IMPL,
 375     Allow,
 376     "prevent creation of diagnostics outside of `SessionDiagnostic`/`AddSubdiagnostic` impls",
 377     report_in_external_macro: true
 378 }
 379
 380 declare_lint_pass!(Diagnostics => [ UNTRANSLATABLE_DIAGNOSTIC, DIAGNOSTIC_OUTSIDE_OF_IMPL ]);
 381
 382 impl LateLintPass<'_> for Diagnostics {
 383     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
 384         let Some((span, def_id, substs)) = typeck_results_of_method_fn(cx, expr) else { return };
 385         debug!(?span, ?def_id, ?substs);
 386         let has_attr = ty::Instance::resolve(cx.tcx, cx.param_env, def_id, substs)
 387             .ok()
 388             .and_then(|inst| inst)
 389             .map(|inst| cx.tcx.has_attr(inst.def_id(), sym::rustc_lint_diagnostics))
 390             .unwrap_or(false);
 391         if !has_attr {
 392             return;
 393         }
 394
 395         let mut found_parent_with_attr = false;
 396         let mut found_impl = false;
 397         for (hir_id, parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
 398             if let Some(owner_did) = hir_id.as_owner() {
 399                 found_parent_with_attr = found_parent_with_attr
 400                     || cx.tcx.has_attr(owner_did.to_def_id(), sym::rustc_lint_diagnostics);
 401             }
 402
 403             debug!(?parent);
 404             if let Node::Item(Item { kind: ItemKind::Impl(impl_), .. }) = parent &&
 405                 let Impl { of_trait: Some(of_trait), .. } = impl_ &&
 406                 let Some(def_id) = of_trait.trait_def_id() &&
 407                 let Some(name) = cx.tcx.get_diagnostic_name(def_id) &&
 408                 matches!(name, sym::SessionDiagnostic | sym::AddSubdiagnostic | sym::DecorateLint)
 409             {
 410                 found_impl = true;
 411                 break;
 412             }
 413         }
 414         debug!(?found_impl);
 415         if !found_parent_with_attr && !found_impl {
 416             cx.struct_span_lint(DIAGNOSTIC_OUTSIDE_OF_IMPL, span, |lint| {
 417                 lint.build(fluent::lint::diag_out_of_impl).emit();
 418             })
 419         }
 420
 421         let mut found_diagnostic_message = false;
 422         for ty in substs.types() {
 423             debug!(?ty);
 424             if let Some(adt_def) = ty.ty_adt_def() &&
 425                 let Some(name) =  cx.tcx.get_diagnostic_name(adt_def.did()) &&
 426                 matches!(name, sym::DiagnosticMessage | sym::SubdiagnosticMessage)
 427             {
 428                 found_diagnostic_message = true;
 429                 break;
 430             }
 431         }
 432         debug!(?found_diagnostic_message);
 433         if !found_parent_with_attr && !found_diagnostic_message {
 434             cx.struct_span_lint(UNTRANSLATABLE_DIAGNOSTIC, span, |lint| {
 435                 lint.build(fluent::lint::untranslatable_diag).emit();
 436             })
 437         }
 438     }
 439 }
 440
 441 declare_tool_lint! {
 442     pub rustc::BAD_OPT_ACCESS,
 443     Deny,
 444     "prevent using options by field access when there is a wrapper function",
 445     report_in_external_macro: true
 446 }
 447
 448 declare_lint_pass!(BadOptAccess => [ BAD_OPT_ACCESS ]);
 449
 450 impl LateLintPass<'_> for BadOptAccess {
 451     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
 452         let ExprKind::Field(base, target) = expr.kind else { return };
 453         let Some(adt_def) = cx.typeck_results().expr_ty(base).ty_adt_def() else { return };
 454         // Skip types without `#[rustc_lint_opt_ty]` - only so that the rest of the lint can be
 455         // avoided.
 456         if !cx.tcx.has_attr(adt_def.did(), sym::rustc_lint_opt_ty) {
 457             return;
 458         }
 459
 460         for field in adt_def.all_fields() {
 461             if field.name == target.name &&
 462                 let Some(attr) = cx.tcx.get_attr(field.did, sym::rustc_lint_opt_deny_field_access) &&
 463                 let Some(items) = attr.meta_item_list()  &&
 464                 let Some(item) = items.first()  &&
 465                 let Some(literal) = item.literal()  &&
 466                 let ast::LitKind::Str(val, _) = literal.kind
 467             {
 468                 cx.struct_span_lint(BAD_OPT_ACCESS, expr.span, |lint| {
 469                     lint.build(val.as_str()).emit(); }
 470                 );
 471             }
 472         }
 473     }
 474 }