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