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         && lint_ty_kind_usage(cx, &segment.res)
 122         {
 123             let span = path.span.with_hi(
 124                 segment.args.map_or(segment.ident.span, |a| a.span_ext).hi()
 125             );
 126             cx.struct_span_lint(USAGE_OF_TY_TYKIND, path.span, |lint| {
 127                 lint.build(fluent::lint::tykind_kind)
 128                     .span_suggestion(
 129                         span,
 130                         fluent::lint::suggestion,
 131                         "ty",
 132                         Applicability::MaybeIncorrect, // ty maybe needs an import
 133                     )
 134                     .emit();
 135             });
 136         }
 137     }
 138
 139     fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx Ty<'tcx>) {
 140         match &ty.kind {
 141             TyKind::Path(QPath::Resolved(_, path)) => {
 142                 if lint_ty_kind_usage(cx, &path.res) {
 143                     cx.struct_span_lint(USAGE_OF_TY_TYKIND, path.span, |lint| {
 144                         let hir = cx.tcx.hir();
 145                         match hir.find(hir.get_parent_node(ty.hir_id)) {
 146                             Some(Node::Pat(Pat {
 147                                 kind:
 148                                     PatKind::Path(qpath)
 149                                     | PatKind::TupleStruct(qpath, ..)
 150                                     | PatKind::Struct(qpath, ..),
 151                                 ..
 152                             })) => {
 153                                 if let QPath::TypeRelative(qpath_ty, ..) = qpath
 154                                     && qpath_ty.hir_id == ty.hir_id
 155                                 {
 156                                     lint.build(fluent::lint::tykind_kind)
 157                                         .span_suggestion(
 158                                             path.span,
 159                                             fluent::lint::suggestion,
 160                                             "ty",
 161                                             Applicability::MaybeIncorrect, // ty maybe needs an import
 162                                         )
 163                                         .emit();
 164                                     return;
 165                                 }
 166                             }
 167                             Some(Node::Expr(Expr {
 168                                 kind: ExprKind::Path(qpath),
 169                                 ..
 170                             })) => {
 171                                 if let QPath::TypeRelative(qpath_ty, ..) = qpath
 172                                     && qpath_ty.hir_id == ty.hir_id
 173                                 {
 174                                     lint.build(fluent::lint::tykind_kind)
 175                                         .span_suggestion(
 176                                             path.span,
 177                                             fluent::lint::suggestion,
 178                                             "ty",
 179                                             Applicability::MaybeIncorrect, // ty maybe needs an import
 180                                         )
 181                                         .emit();
 182                                     return;
 183                                 }
 184                             }
 185                             // Can't unify these two branches because qpath below is `&&` and above is `&`
 186                             // and `A | B` paths don't play well together with adjustments, apparently.
 187                             Some(Node::Expr(Expr {
 188                                 kind: ExprKind::Struct(qpath, ..),
 189                                 ..
 190                             })) => {
 191                                 if let QPath::TypeRelative(qpath_ty, ..) = qpath
 192                                     && qpath_ty.hir_id == ty.hir_id
 193                                 {
 194                                     lint.build(fluent::lint::tykind_kind)
 195                                         .span_suggestion(
 196                                             path.span,
 197                                             fluent::lint::suggestion,
 198                                             "ty",
 199                                             Applicability::MaybeIncorrect, // ty maybe needs an import
 200                                         )
 201                                         .emit();
 202                                     return;
 203                                 }
 204                             }
 205                             _ => {}
 206                         }
 207                         lint.build(fluent::lint::tykind).help(fluent::lint::help).emit();
 208                     })
 209                 } else if !ty.span.from_expansion() && let Some(t) = is_ty_or_ty_ctxt(cx, &path) {
 210                     if path.segments.len() > 1 {
 211                         cx.struct_span_lint(USAGE_OF_QUALIFIED_TY, path.span, |lint| {
 212                             lint.build(fluent::lint::ty_qualified)
 213                                 .set_arg("ty", t.clone())
 214                                 .span_suggestion(
 215                                     path.span,
 216                                     fluent::lint::suggestion,
 217                                     t,
 218                                     // The import probably needs to be changed
 219                                     Applicability::MaybeIncorrect,
 220                                 )
 221                                 .emit();
 222                         })
 223                     }
 224                 }
 225             }
 226             _ => {}
 227         }
 228     }
 229 }
 230
 231 fn lint_ty_kind_usage(cx: &LateContext<'_>, res: &Res) -> bool {
 232     if let Some(did) = res.opt_def_id() {
 233         cx.tcx.is_diagnostic_item(sym::TyKind, did) || cx.tcx.is_diagnostic_item(sym::IrTyKind, did)
 234     } else {
 235         false
 236     }
 237 }
 238
 239 fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, path: &Path<'_>) -> Option<String> {
 240     match &path.res {
 241         Res::Def(_, def_id) => {
 242             if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(*def_id) {
 243                 return Some(format!("{}{}", name, gen_args(path.segments.last().unwrap())));
 244             }
 245         }
 246         // Only lint on `&Ty` and `&TyCtxt` if it is used outside of a trait.
 247         Res::SelfTy { trait_: None, alias_to: Some((did, _)) } => {
 248             if let ty::Adt(adt, substs) = cx.tcx.type_of(did).kind() {
 249                 if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(adt.did())
 250                 {
 251                     // NOTE: This path is currently unreachable as `Ty<'tcx>` is
 252                     // defined as a type alias meaning that `impl<'tcx> Ty<'tcx>`
 253                     // is not actually allowed.
 254                     //
 255                     // I(@lcnr) still kept this branch in so we don't miss this
 256                     // if we ever change it in the future.
 257                     return Some(format!("{}<{}>", name, substs[0]));
 258                 }
 259             }
 260         }
 261         _ => (),
 262     }
 263
 264     None
 265 }
 266
 267 fn gen_args(segment: &PathSegment<'_>) -> String {
 268     if let Some(args) = &segment.args {
 269         let lifetimes = args
 270             .args
 271             .iter()
 272             .filter_map(|arg| {
 273                 if let GenericArg::Lifetime(lt) = arg {
 274                     Some(lt.name.ident().to_string())
 275                 } else {
 276                     None
 277                 }
 278             })
 279             .collect::<Vec<_>>();
 280
 281         if !lifetimes.is_empty() {
 282             return format!("<{}>", lifetimes.join(", "));
 283         }
 284     }
 285
 286     String::new()
 287 }
 288
 289 declare_tool_lint! {
 290     pub rustc::LINT_PASS_IMPL_WITHOUT_MACRO,
 291     Allow,
 292     "`impl LintPass` without the `declare_lint_pass!` or `impl_lint_pass!` macros"
 293 }
 294
 295 declare_lint_pass!(LintPassImpl => [LINT_PASS_IMPL_WITHOUT_MACRO]);
 296
 297 impl EarlyLintPass for LintPassImpl {
 298     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
 299         if let ast::ItemKind::Impl(box ast::Impl { of_trait: Some(lint_pass), .. }) = &item.kind {
 300             if let Some(last) = lint_pass.path.segments.last() {
 301                 if last.ident.name == sym::LintPass {
 302                     let expn_data = lint_pass.path.span.ctxt().outer_expn_data();
 303                     let call_site = expn_data.call_site;
 304                     if expn_data.kind != ExpnKind::Macro(MacroKind::Bang, sym::impl_lint_pass)
 305                         && call_site.ctxt().outer_expn_data().kind
 306                             != ExpnKind::Macro(MacroKind::Bang, sym::declare_lint_pass)
 307                     {
 308                         cx.struct_span_lint(
 309                             LINT_PASS_IMPL_WITHOUT_MACRO,
 310                             lint_pass.path.span,
 311                             |lint| {
 312                                 lint.build(fluent::lint::lintpass_by_hand)
 313                                     .help(fluent::lint::help)
 314                                     .emit();
 315                             },
 316                         )
 317                     }
 318                 }
 319             }
 320         }
 321     }
 322 }
 323
 324 declare_tool_lint! {
 325     pub rustc::EXISTING_DOC_KEYWORD,
 326     Allow,
 327     "Check that documented keywords in std and core actually exist",
 328     report_in_external_macro: true
 329 }
 330
 331 declare_lint_pass!(ExistingDocKeyword => [EXISTING_DOC_KEYWORD]);
 332
 333 fn is_doc_keyword(s: Symbol) -> bool {
 334     s <= kw::Union
 335 }
 336
 337 impl<'tcx> LateLintPass<'tcx> for ExistingDocKeyword {
 338     fn check_item(&mut self, cx: &LateContext<'_>, item: &rustc_hir::Item<'_>) {
 339         for attr in cx.tcx.hir().attrs(item.hir_id()) {
 340             if !attr.has_name(sym::doc) {
 341                 continue;
 342             }
 343             if let Some(list) = attr.meta_item_list() {
 344                 for nested in list {
 345                     if nested.has_name(sym::keyword) {
 346                         let v = nested
 347                             .value_str()
 348                             .expect("#[doc(keyword = \"...\")] expected a value!");
 349                         if is_doc_keyword(v) {
 350                             return;
 351                         }
 352                         cx.struct_span_lint(EXISTING_DOC_KEYWORD, attr.span, |lint| {
 353                             lint.build(fluent::lint::non_existant_doc_keyword)
 354                                 .set_arg("keyword", v)
 355                                 .help(fluent::lint::help)
 356                                 .emit();
 357                         });
 358                     }
 359                 }
 360             }
 361         }
 362     }
 363 }
 364
 365 declare_tool_lint! {
 366     pub rustc::UNTRANSLATABLE_DIAGNOSTIC,
 367     Allow,
 368     "prevent creation of diagnostics which cannot be translated",
 369     report_in_external_macro: true
 370 }
 371
 372 declare_tool_lint! {
 373     pub rustc::DIAGNOSTIC_OUTSIDE_OF_IMPL,
 374     Allow,
 375     "prevent creation of diagnostics outside of `IntoDiagnostic`/`AddToDiagnostic` impls",
 376     report_in_external_macro: true
 377 }
 378
 379 declare_lint_pass!(Diagnostics => [ UNTRANSLATABLE_DIAGNOSTIC, DIAGNOSTIC_OUTSIDE_OF_IMPL ]);
 380
 381 impl LateLintPass<'_> for Diagnostics {
 382     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
 383         let Some((span, def_id, substs)) = typeck_results_of_method_fn(cx, expr) else { return };
 384         debug!(?span, ?def_id, ?substs);
 385         let has_attr = ty::Instance::resolve(cx.tcx, cx.param_env, def_id, substs)
 386             .ok()
 387             .and_then(|inst| inst)
 388             .map(|inst| cx.tcx.has_attr(inst.def_id(), sym::rustc_lint_diagnostics))
 389             .unwrap_or(false);
 390         if !has_attr {
 391             return;
 392         }
 393
 394         let mut found_parent_with_attr = false;
 395         let mut found_impl = false;
 396         for (hir_id, parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
 397             if let Some(owner_did) = hir_id.as_owner() {
 398                 found_parent_with_attr = found_parent_with_attr
 399                     || cx.tcx.has_attr(owner_did.to_def_id(), sym::rustc_lint_diagnostics);
 400             }
 401
 402             debug!(?parent);
 403             if let Node::Item(Item { kind: ItemKind::Impl(impl_), .. }) = parent &&
 404                 let Impl { of_trait: Some(of_trait), .. } = impl_ &&
 405                 let Some(def_id) = of_trait.trait_def_id() &&
 406                 let Some(name) = cx.tcx.get_diagnostic_name(def_id) &&
 407                 matches!(name, sym::IntoDiagnostic | sym::AddToDiagnostic | sym::DecorateLint)
 408             {
 409                 found_impl = true;
 410                 break;
 411             }
 412         }
 413         debug!(?found_impl);
 414         if !found_parent_with_attr && !found_impl {
 415             cx.struct_span_lint(DIAGNOSTIC_OUTSIDE_OF_IMPL, span, |lint| {
 416                 lint.build(fluent::lint::diag_out_of_impl).emit();
 417             })
 418         }
 419
 420         let mut found_diagnostic_message = false;
 421         for ty in substs.types() {
 422             debug!(?ty);
 423             if let Some(adt_def) = ty.ty_adt_def() &&
 424                 let Some(name) =  cx.tcx.get_diagnostic_name(adt_def.did()) &&
 425                 matches!(name, sym::DiagnosticMessage | sym::SubdiagnosticMessage)
 426             {
 427                 found_diagnostic_message = true;
 428                 break;
 429             }
 430         }
 431         debug!(?found_diagnostic_message);
 432         if !found_parent_with_attr && !found_diagnostic_message {
 433             cx.struct_span_lint(UNTRANSLATABLE_DIAGNOSTIC, span, |lint| {
 434                 lint.build(fluent::lint::untranslatable_diag).emit();
 435             })
 436         }
 437     }
 438 }
 439
 440 declare_tool_lint! {
 441     pub rustc::BAD_OPT_ACCESS,
 442     Deny,
 443     "prevent using options by field access when there is a wrapper function",
 444     report_in_external_macro: true
 445 }
 446
 447 declare_lint_pass!(BadOptAccess => [ BAD_OPT_ACCESS ]);
 448
 449 impl LateLintPass<'_> for BadOptAccess {
 450     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
 451         let ExprKind::Field(base, target) = expr.kind else { return };
 452         let Some(adt_def) = cx.typeck_results().expr_ty(base).ty_adt_def() else { return };
 453         // Skip types without `#[rustc_lint_opt_ty]` - only so that the rest of the lint can be
 454         // avoided.
 455         if !cx.tcx.has_attr(adt_def.did(), sym::rustc_lint_opt_ty) {
 456             return;
 457         }
 458
 459         for field in adt_def.all_fields() {
 460             if field.name == target.name &&
 461                 let Some(attr) = cx.tcx.get_attr(field.did, sym::rustc_lint_opt_deny_field_access) &&
 462                 let Some(items) = attr.meta_item_list()  &&
 463                 let Some(item) = items.first()  &&
 464                 let Some(literal) = item.literal()  &&
 465                 let ast::LitKind::Str(val, _) = literal.kind
 466             {
 467                 cx.struct_span_lint(BAD_OPT_ACCESS, expr.span, |lint| {
 468                     lint.build(val.as_str()).emit(); }
 469                 );
 470             }
 471         }
 472     }
 473 }