Rollup merge of rust-lang#138964 - compiler-errors:usage-of-interner, r=lcnr

Implement lint against using Interner and InferCtxtLike in random compiler crates

Often `Interner` defines similar methods to `TyCtxt` (but often simplified due to the simpler API surface of the type system layer for the new solver), which people will either unintentionally or intentionally import and use. Let's discourage that.

r? lcnr

Author: jhpratt

compiler/rustc_lint/messages.ftl

@@ -799,6 +799,9 @@ lint_tykind_kind = usage of `ty::TyKind::<kind>`
 lint_type_ir_inherent_usage = do not use `rustc_type_ir::inherent` unless you're inside of the trait solver
     .note = the method or struct you're looking for is likely defined somewhere else downstream in the compiler
 
+lint_type_ir_trait_usage = do not use `rustc_type_ir::Interner` or `rustc_type_ir::InferCtxtLike` unless you're inside of the trait solver
+    .note = the method or struct you're looking for is likely defined somewhere else downstream in the compiler
+
 lint_undropped_manually_drops = calls to `std::mem::drop` with `std::mem::ManuallyDrop` instead of the inner value does nothing
     .label = argument has type `{$arg_ty}`
     .suggestion = use `std::mem::ManuallyDrop::into_inner` to get the inner value

compiler/rustc_lint/src/internal.rs

@@ -1,24 +1,21 @@
 //! Some lints that are only useful in the compiler or crates that use compiler internals, such as
 //! Clippy.
 
-use rustc_ast as ast;
+use rustc_hir::HirId;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::DefId;
-use rustc_hir::{
-    AmbigArg, BinOp, BinOpKind, Expr, ExprKind, GenericArg, HirId, Impl, Item, ItemKind, Node, Pat,
-    PatExpr, PatExprKind, PatKind, Path, PathSegment, QPath, Ty, TyKind,
-};
 use rustc_middle::ty::{self, GenericArgsRef, Ty as MiddleTy};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::{Span, sym};
 use tracing::debug;
+use {rustc_ast as ast, rustc_hir as hir};
 
 use crate::lints::{
     BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand,
     NonGlobImportTypeIrInherent, QueryInstability, QueryUntracked, SpanUseEqCtxtDiag,
     SymbolInternStringLiteralDiag, TyQualified, TykindDiag, TykindKind, TypeIrInherentUsage,
-    UntranslatableDiag,
+    TypeIrTraitUsage, UntranslatableDiag,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 
@@ -37,9 +34,12 @@ declare_tool_lint! {
 declare_lint_pass!(DefaultHashTypes => [DEFAULT_HASH_TYPES]);
 
 impl LateLintPass<'_> for DefaultHashTypes {
-    fn check_path(&mut self, cx: &LateContext<'_>, path: &Path<'_>, hir_id: HirId) {
+    fn check_path(&mut self, cx: &LateContext<'_>, path: &hir::Path<'_>, hir_id: HirId) {
         let Res::Def(rustc_hir::def::DefKind::Struct, def_id) = path.res else { return };
-        if matches!(cx.tcx.hir_node(hir_id), Node::Item(Item { kind: ItemKind::Use(..), .. })) {
+        if matches!(
+            cx.tcx.hir_node(hir_id),
+            hir::Node::Item(hir::Item { kind: hir::ItemKind::Use(..), .. })
+        ) {
             // Don't lint imports, only actual usages.
             return;
         }
@@ -60,10 +60,10 @@ impl LateLintPass<'_> for DefaultHashTypes {
 /// get the `DefId` and `GenericArgsRef` of the function.
 fn typeck_results_of_method_fn<'tcx>(
     cx: &LateContext<'tcx>,
-    expr: &Expr<'_>,
+    expr: &hir::Expr<'_>,
 ) -> Option<(Span, DefId, ty::GenericArgsRef<'tcx>)> {
     match expr.kind {
-        ExprKind::MethodCall(segment, ..)
+        hir::ExprKind::MethodCall(segment, ..)
             if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) =>
         {
             Some((segment.ident.span, def_id, cx.typeck_results().node_args(expr.hir_id)))
@@ -102,7 +102,7 @@ declare_tool_lint! {
 declare_lint_pass!(QueryStability => [POTENTIAL_QUERY_INSTABILITY, UNTRACKED_QUERY_INFORMATION]);
 
 impl LateLintPass<'_> for QueryStability {
-    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
         let Some((span, def_id, args)) = typeck_results_of_method_fn(cx, expr) else { return };
         if let Ok(Some(instance)) = ty::Instance::try_resolve(cx.tcx, cx.typing_env(), def_id, args)
         {
@@ -164,21 +164,25 @@ impl<'tcx> LateLintPass<'tcx> for TyTyKind {
         }
     }
 
-    fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx Ty<'tcx, AmbigArg>) {
+    fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx hir::Ty<'tcx, hir::AmbigArg>) {
         match &ty.kind {
-            TyKind::Path(QPath::Resolved(_, path)) => {
+            hir::TyKind::Path(hir::QPath::Resolved(_, path)) => {
                 if lint_ty_kind_usage(cx, &path.res) {
                     let span = match cx.tcx.parent_hir_node(ty.hir_id) {
-                        Node::PatExpr(PatExpr { kind: PatExprKind::Path(qpath), .. })
-                        | Node::Pat(Pat {
-                            kind: PatKind::TupleStruct(qpath, ..) | PatKind::Struct(qpath, ..),
+                        hir::Node::PatExpr(hir::PatExpr {
+                            kind: hir::PatExprKind::Path(qpath),
+                            ..
+                        })
+                        | hir::Node::Pat(hir::Pat {
+                            kind:
+                                hir::PatKind::TupleStruct(qpath, ..) | hir::PatKind::Struct(qpath, ..),
                             ..
                         })
-                        | Node::Expr(
-                            Expr { kind: ExprKind::Path(qpath), .. }
-                            | &Expr { kind: ExprKind::Struct(qpath, ..), .. },
+                        | hir::Node::Expr(
+                            hir::Expr { kind: hir::ExprKind::Path(qpath), .. }
+                            | &hir::Expr { kind: hir::ExprKind::Struct(qpath, ..), .. },
                         ) => {
-                            if let QPath::TypeRelative(qpath_ty, ..) = qpath
+                            if let hir::QPath::TypeRelative(qpath_ty, ..) = qpath
                                 && qpath_ty.hir_id == ty.hir_id
                             {
                                 Some(path.span)
@@ -223,7 +227,7 @@ fn lint_ty_kind_usage(cx: &LateContext<'_>, res: &Res) -> bool {
     }
 }
 
-fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, path: &Path<'_>) -> Option<String> {
+fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, path: &hir::Path<'_>) -> Option<String> {
     match &path.res {
         Res::Def(_, def_id) => {
             if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(*def_id) {
@@ -244,13 +248,17 @@ fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, path: &Path<'_>) -> Option<String> {
     None
 }
 
-fn gen_args(segment: &PathSegment<'_>) -> String {
+fn gen_args(segment: &hir::PathSegment<'_>) -> String {
     if let Some(args) = &segment.args {
         let lifetimes = args
             .args
             .iter()
             .filter_map(|arg| {
-                if let GenericArg::Lifetime(lt) = arg { Some(lt.ident.to_string()) } else { None }
+                if let hir::GenericArg::Lifetime(lt) = arg {
+                    Some(lt.ident.to_string())
+                } else {
+                    None
+                }
             })
             .collect::<Vec<_>>();
 
@@ -272,7 +280,7 @@ declare_tool_lint! {
 }
 
 declare_tool_lint! {
-    /// The `usage_of_type_ir_inherent` lint detects usage `rustc_type_ir::inherent`.
+    /// The `usage_of_type_ir_inherent` lint detects usage of `rustc_type_ir::inherent`.
     ///
     /// This module should only be used within the trait solver.
     pub rustc::USAGE_OF_TYPE_IR_INHERENT,
@@ -281,10 +289,43 @@ declare_tool_lint! {
     report_in_external_macro: true
 }
 
-declare_lint_pass!(TypeIr => [NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT, USAGE_OF_TYPE_IR_INHERENT]);
+declare_tool_lint! {
+    /// The `usage_of_type_ir_traits` lint detects usage of `rustc_type_ir::Interner`,
+    /// or `rustc_infer::InferCtxtLike`.
+    ///
+    /// Methods of this trait should only be used within the type system abstraction layer,
+    /// and in the generic next trait solver implementation. Look for an analogously named
+    /// method on `TyCtxt` or `InferCtxt` (respectively).
+    pub rustc::USAGE_OF_TYPE_IR_TRAITS,
+    Allow,
+    "usage `rustc_type_ir`-specific abstraction traits outside of trait system",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(TypeIr => [NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT, USAGE_OF_TYPE_IR_INHERENT, USAGE_OF_TYPE_IR_TRAITS]);
 
 impl<'tcx> LateLintPass<'tcx> for TypeIr {
-    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
+        let res_def_id = match expr.kind {
+            hir::ExprKind::Path(hir::QPath::Resolved(_, path)) => path.res.opt_def_id(),
+            hir::ExprKind::Path(hir::QPath::TypeRelative(..)) | hir::ExprKind::MethodCall(..) => {
+                cx.typeck_results().type_dependent_def_id(expr.hir_id)
+            }
+            _ => return,
+        };
+        let Some(res_def_id) = res_def_id else {
+            return;
+        };
+        if let Some(assoc_item) = cx.tcx.opt_associated_item(res_def_id)
+            && let Some(trait_def_id) = assoc_item.trait_container(cx.tcx)
+            && (cx.tcx.is_diagnostic_item(sym::type_ir_interner, trait_def_id)
+                | cx.tcx.is_diagnostic_item(sym::type_ir_infer_ctxt_like, trait_def_id))
+        {
+            cx.emit_span_lint(USAGE_OF_TYPE_IR_TRAITS, expr.span, TypeIrTraitUsage);
+        }
+    }
+
+    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'tcx>) {
         let rustc_hir::ItemKind::Use(path, kind) = item.kind else { return };
 
         let is_mod_inherent = |def_id| cx.tcx.is_diagnostic_item(sym::type_ir_inherent, def_id);
@@ -394,23 +435,23 @@ declare_tool_lint! {
 declare_lint_pass!(Diagnostics => [UNTRANSLATABLE_DIAGNOSTIC, DIAGNOSTIC_OUTSIDE_OF_IMPL]);
 
 impl LateLintPass<'_> for Diagnostics {
-    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
-        let collect_args_tys_and_spans = |args: &[Expr<'_>], reserve_one_extra: bool| {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
+        let collect_args_tys_and_spans = |args: &[hir::Expr<'_>], reserve_one_extra: bool| {
             let mut result = Vec::with_capacity(args.len() + usize::from(reserve_one_extra));
             result.extend(args.iter().map(|arg| (cx.typeck_results().expr_ty(arg), arg.span)));
             result
         };
         // Only check function calls and method calls.
         let (span, def_id, fn_gen_args, arg_tys_and_spans) = match expr.kind {
-            ExprKind::Call(callee, args) => {
+            hir::ExprKind::Call(callee, args) => {
                 match cx.typeck_results().node_type(callee.hir_id).kind() {
                     &ty::FnDef(def_id, fn_gen_args) => {
                         (callee.span, def_id, fn_gen_args, collect_args_tys_and_spans(args, false))
                     }
                     _ => return, // occurs for fns passed as args
                 }
             }
-            ExprKind::MethodCall(_segment, _recv, args, _span) => {
+            hir::ExprKind::MethodCall(_segment, _recv, args, _span) => {
                 let Some((span, def_id, fn_gen_args)) = typeck_results_of_method_fn(cx, expr)
                 else {
                     return;
@@ -514,8 +555,8 @@ impl Diagnostics {
         let mut is_inside_appropriate_impl = false;
         for (_hir_id, parent) in cx.tcx.hir_parent_iter(current_id) {
             debug!(?parent);
-            if let Node::Item(Item { kind: ItemKind::Impl(impl_), .. }) = parent
-                && let Impl { of_trait: Some(of_trait), .. } = impl_
+            if let hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(impl_), .. }) = parent
+                && let hir::Impl { of_trait: Some(of_trait), .. } = impl_
                 && let Some(def_id) = of_trait.trait_def_id()
                 && let Some(name) = cx.tcx.get_diagnostic_name(def_id)
                 && matches!(name, sym::Diagnostic | sym::Subdiagnostic | sym::LintDiagnostic)
@@ -543,8 +584,8 @@ declare_tool_lint! {
 declare_lint_pass!(BadOptAccess => [BAD_OPT_ACCESS]);
 
 impl LateLintPass<'_> for BadOptAccess {
-    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
-        let ExprKind::Field(base, target) = expr.kind else { return };
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
+        let hir::ExprKind::Field(base, target) = expr.kind else { return };
         let Some(adt_def) = cx.typeck_results().expr_ty(base).ty_adt_def() else { return };
         // Skip types without `#[rustc_lint_opt_ty]` - only so that the rest of the lint can be
         // avoided.
@@ -581,9 +622,12 @@ declare_tool_lint! {
 declare_lint_pass!(SpanUseEqCtxt => [SPAN_USE_EQ_CTXT]);
 
 impl<'tcx> LateLintPass<'tcx> for SpanUseEqCtxt {
-    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'_>) {
-        if let ExprKind::Binary(BinOp { node: BinOpKind::Eq | BinOpKind::Ne, .. }, lhs, rhs) =
-            expr.kind
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) {
+        if let hir::ExprKind::Binary(
+            hir::BinOp { node: hir::BinOpKind::Eq | hir::BinOpKind::Ne, .. },
+            lhs,
+            rhs,
+        ) = expr.kind
         {
             if is_span_ctxt_call(cx, lhs) && is_span_ctxt_call(cx, rhs) {
                 cx.emit_span_lint(SPAN_USE_EQ_CTXT, expr.span, SpanUseEqCtxtDiag);
@@ -592,9 +636,9 @@ impl<'tcx> LateLintPass<'tcx> for SpanUseEqCtxt {
     }
 }
 
-fn is_span_ctxt_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+fn is_span_ctxt_call(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
     match &expr.kind {
-        ExprKind::MethodCall(..) => cx
+        hir::ExprKind::MethodCall(..) => cx
             .typeck_results()
             .type_dependent_def_id(expr.hir_id)
             .is_some_and(|call_did| cx.tcx.is_diagnostic_item(sym::SpanCtxt, call_did)),
@@ -617,11 +661,11 @@ declare_lint_pass!(SymbolInternStringLiteral => [SYMBOL_INTERN_STRING_LITERAL]);
 
 impl<'tcx> LateLintPass<'tcx> for SymbolInternStringLiteral {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) {
-        if let ExprKind::Call(path, [arg]) = expr.kind
-            && let ExprKind::Path(ref qpath) = path.kind
+        if let hir::ExprKind::Call(path, [arg]) = expr.kind
+            && let hir::ExprKind::Path(ref qpath) = path.kind
             && let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
             && cx.tcx.is_diagnostic_item(sym::SymbolIntern, def_id)
-            && let ExprKind::Lit(kind) = arg.kind
+            && let hir::ExprKind::Lit(kind) = arg.kind
             && let rustc_ast::LitKind::Str(_, _) = kind.node
         {
             cx.emit_span_lint(

compiler/rustc_lint/src/lib.rs

@@ -645,6 +645,7 @@ fn register_internals(store: &mut LintStore) {
             LintId::of(USAGE_OF_QUALIFIED_TY),
             LintId::of(NON_GLOB_IMPORT_OF_TYPE_IR_INHERENT),
             LintId::of(USAGE_OF_TYPE_IR_INHERENT),
+            LintId::of(USAGE_OF_TYPE_IR_TRAITS),
             LintId::of(BAD_OPT_ACCESS),
             LintId::of(SPAN_USE_EQ_CTXT),
         ],

compiler/rustc_lint/src/lints.rs

@@ -943,6 +943,11 @@ pub(crate) struct TyQualified {
 #[note]
 pub(crate) struct TypeIrInherentUsage;
 
+#[derive(LintDiagnostic)]
+#[diag(lint_type_ir_trait_usage)]
+#[note]
+pub(crate) struct TypeIrTraitUsage;
+
 #[derive(LintDiagnostic)]
 #[diag(lint_non_glob_import_type_ir_inherent)]
 pub(crate) struct NonGlobImportTypeIrInherent {

compiler/rustc_monomorphize/src/collector.rs

@@ -225,8 +225,8 @@ use rustc_middle::ty::adjustment::{CustomCoerceUnsized, PointerCoercion};
 use rustc_middle::ty::layout::ValidityRequirement;
 use rustc_middle::ty::print::{shrunk_instance_name, with_no_trimmed_paths};
 use rustc_middle::ty::{
-    self, GenericArgs, GenericParamDefKind, Instance, InstanceKind, Interner, Ty, TyCtxt,
-    TypeFoldable, TypeVisitableExt, VtblEntry,
+    self, GenericArgs, GenericParamDefKind, Instance, InstanceKind, Ty, TyCtxt, TypeFoldable,
+    TypeVisitableExt, VtblEntry,
 };
 use rustc_middle::util::Providers;
 use rustc_middle::{bug, span_bug};
@@ -967,7 +967,7 @@ fn should_codegen_locally<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) ->
     {
         // `#[rustc_force_inline]` items should never be codegened. This should be caught by
         // the MIR validator.
-        tcx.delay_bug("attempt to codegen `#[rustc_force_inline]` item");
+        tcx.dcx().delayed_bug("attempt to codegen `#[rustc_force_inline]` item");
     }
 
     if def_id.is_local() {

compiler/rustc_next_trait_solver/src/lib.rs

@@ -6,6 +6,7 @@
 
 // tidy-alphabetical-start
 #![allow(rustc::usage_of_type_ir_inherent)]
+#![cfg_attr(not(bootstrap), allow(rustc::usage_of_type_ir_traits))]
 // tidy-alphabetical-end
 
 pub mod canonicalizer;

compiler/rustc_span/src/symbol.rs

@@ -2118,7 +2118,9 @@ symbols! {
         type_changing_struct_update,
         type_const,
         type_id,
+        type_ir_infer_ctxt_like,
         type_ir_inherent,
+        type_ir_interner,
         type_length_limit,
         type_macros,
         type_name,

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -16,7 +16,7 @@ use rustc_infer::traits::{Obligation, PolyTraitObligation, SelectionError};
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::{self, Ty, TypeVisitableExt, TypingMode};
 use rustc_middle::{bug, span_bug};
-use rustc_type_ir::{Interner, elaborate};
+use rustc_type_ir::elaborate;
 use tracing::{debug, instrument, trace};
 
 use super::SelectionCandidate::*;
@@ -802,7 +802,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 | ty::UnsafeBinder(_) => {
                     // Only consider auto impls of unsafe traits when there are
                     // no unsafe fields.
-                    if self.tcx().trait_is_unsafe(def_id) && self_ty.has_unsafe_fields() {
+                    if self.tcx().trait_def(def_id).safety.is_unsafe()
+                        && self_ty.has_unsafe_fields()
+                    {
                         return;
                     }
 

compiler/rustc_type_ir/src/infer_ctxt.rs

@@ -102,6 +102,7 @@ impl<I: Interner> TypingMode<I> {
     }
 }
 
+#[cfg_attr(feature = "nightly", rustc_diagnostic_item = "type_ir_infer_ctxt_like")]
 pub trait InferCtxtLike: Sized {
     type Interner: Interner;
     fn cx(&self) -> Self::Interner;

compiler/rustc_type_ir/src/interner.rs

@@ -15,6 +15,7 @@ use crate::solve::{CanonicalInput, ExternalConstraintsData, PredefinedOpaquesDat
 use crate::visit::{Flags, TypeSuperVisitable, TypeVisitable};
 use crate::{self as ty, search_graph};
 
+#[cfg_attr(feature = "nightly", rustc_diagnostic_item = "type_ir_interner")]
 pub trait Interner:
     Sized
     + Copy