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