TypeId implements_trait

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -24,7 +24,7 @@ use crate::interpret::{
     self, AllocId, AllocInit, AllocRange, ConstAllocation, CtfeProvenance, FnArg, Frame,
     GlobalAlloc, ImmTy, InterpCx, InterpResult, OpTy, PlaceTy, RangeSet, Scalar,
     compile_time_machine, err_inval, interp_ok, throw_exhaust, throw_inval, throw_ub,
-    throw_ub_custom, throw_unsup, throw_unsup_format,
+    throw_ub_custom, throw_unsup, throw_unsup_format, type_implements_dyn_trait,
 };
 
 /// When hitting this many interpreted terminators we emit a deny by default lint
@@ -586,6 +586,16 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
                 }
             }
 
+            sym::type_id_implements_trait => {
+                let type_from_type_id = ecx.read_type_id(&args[0])?;
+                let trait_from_type_id = ecx.read_type_id(&args[1])?;
+
+                let (implements, _) =
+                    type_implements_dyn_trait(ecx, type_from_type_id, trait_from_type_id)?;
+
+                ecx.write_scalar(Scalar::from_bool(implements), dest)?;
+            }
+
             sym::type_of => {
                 let ty = ecx.read_type_id(&args[0])?;
                 ecx.write_type_info(ty, dest)?;

compiler/rustc_const_eval/src/const_eval/type_info.rs

@@ -172,6 +172,9 @@ impl<'tcx> InterpCx<'tcx, CompileTimeMachine<'tcx>> {
                     };
                     self.write_discriminant(variant_index, &field_dest)?;
                 }
+                sym::id => {
+                    self.write_type_id(ty, &field_dest)?;
+                }
                 other => span_bug!(self.tcx.span, "unknown `Type` field {other}"),
             }
         }

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -7,15 +7,12 @@ mod simd;
 use rustc_abi::{FIRST_VARIANT, FieldIdx, HasDataLayout, Size, VariantIdx};
 use rustc_apfloat::ieee::{Double, Half, Quad, Single};
 use rustc_data_structures::assert_matches;
-use rustc_hir::def_id::CRATE_DEF_ID;
-use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::mir::interpret::{CTFE_ALLOC_SALT, read_target_uint, write_target_uint};
 use rustc_middle::mir::{self, BinOp, ConstValue, NonDivergingIntrinsic};
 use rustc_middle::ty::layout::TyAndLayout;
-use rustc_middle::ty::{FloatTy, PolyExistentialPredicate, Ty, TyCtxt};
+use rustc_middle::ty::{FloatTy, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug, ty};
 use rustc_span::{Symbol, sym};
-use rustc_trait_selection::traits::{Obligation, ObligationCause, ObligationCtxt};
 use tracing::trace;
 
 use super::memory::MemoryKind;
@@ -27,6 +24,7 @@ use super::{
 };
 use crate::fluent_generated as fluent;
 use crate::interpret::Writeable;
+use crate::interpret::util::type_implements_dyn_trait;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 enum MulAddType {
@@ -226,32 +224,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let tp_ty = instance.args.type_at(0);
                 let result_ty = instance.args.type_at(1);
 
-                ensure_monomorphic_enough(tcx, tp_ty)?;
-                ensure_monomorphic_enough(tcx, result_ty)?;
-                let ty::Dynamic(preds, _) = result_ty.kind() else {
-                    span_bug!(
-                        self.find_closest_untracked_caller_location(),
-                        "Invalid type provided to vtable_for::<T, U>. U must be dyn Trait, got {result_ty}."
-                    );
-                };
+                let (implements_trait, preds) = type_implements_dyn_trait(self, tp_ty, result_ty)?;
 
-                let (infcx, param_env) =
-                    self.tcx.infer_ctxt().build_with_typing_env(self.typing_env);
-
-                let ocx = ObligationCtxt::new(&infcx);
-                ocx.register_obligations(preds.iter().map(|pred: PolyExistentialPredicate<'_>| {
-                    let pred = pred.with_self_ty(tcx, tp_ty);
-                    // Lifetimes can only be 'static because of the bound on T
-                    let pred = ty::fold_regions(tcx, pred, |r, _| {
-                        if r == tcx.lifetimes.re_erased { tcx.lifetimes.re_static } else { r }
-                    });
-                    Obligation::new(tcx, ObligationCause::dummy(), param_env, pred)
-                }));
-                let type_impls_trait = ocx.evaluate_obligations_error_on_ambiguity().is_empty();
-                // Since `assumed_wf_tys=[]` the choice of LocalDefId is irrelevant, so using the "default"
-                let regions_are_valid = ocx.resolve_regions(CRATE_DEF_ID, param_env, []).is_empty();
-
-                if regions_are_valid && type_impls_trait {
+                if implements_trait {
                     let vtable_ptr = self.get_vtable_ptr(tp_ty, preds)?;
                     // Writing a non-null pointer into an `Option<NonNull>` will automatically make it `Some`.
                     self.write_pointer(vtable_ptr, dest)?;

compiler/rustc_const_eval/src/interpret/mod.rs

@@ -38,6 +38,6 @@ use self::place::{MemPlace, Place};
 pub use self::projection::{OffsetMode, Projectable};
 pub use self::stack::{Frame, FrameInfo, LocalState, ReturnContinuation, StackPopInfo};
 pub use self::util::EnteredTraceSpan;
-pub(crate) use self::util::create_static_alloc;
+pub(crate) use self::util::{create_static_alloc, type_implements_dyn_trait};
 pub use self::validity::{CtfeValidationMode, RangeSet, RefTracking};
 pub use self::visitor::ValueVisitor;

compiler/rustc_const_eval/src/interpret/util.rs

@@ -1,12 +1,51 @@
-use rustc_hir::def_id::LocalDefId;
-use rustc_middle::mir;
+use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_middle::mir::interpret::{AllocInit, Allocation, GlobalAlloc, InterpResult, Pointer};
 use rustc_middle::ty::layout::TyAndLayout;
-use rustc_middle::ty::{TyCtxt, TypeVisitable, TypeVisitableExt};
+use rustc_middle::ty::{PolyExistentialPredicate, Ty, TyCtxt, TypeVisitable, TypeVisitableExt};
+use rustc_middle::{mir, span_bug, ty};
+use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::debug;
 
 use super::{InterpCx, MPlaceTy, MemoryKind, interp_ok, throw_inval};
 use crate::const_eval::{CompileTimeInterpCx, CompileTimeMachine, InterpretationResult};
+use crate::interpret::Machine;
+
+/// Checks if a type implements predicates.
+/// Calls `ensure_monomorphic_enough` on `ty` and `trait_ty` for you.
+pub(crate) fn type_implements_dyn_trait<'tcx, M: Machine<'tcx>>(
+    ecx: &mut InterpCx<'tcx, M>,
+    ty: Ty<'tcx>,
+    trait_ty: Ty<'tcx>,
+) -> InterpResult<'tcx, (bool, &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>)> {
+    ensure_monomorphic_enough(ecx.tcx.tcx, ty)?;
+    ensure_monomorphic_enough(ecx.tcx.tcx, trait_ty)?;
+
+    let ty::Dynamic(preds, _) = trait_ty.kind() else {
+        span_bug!(
+            ecx.find_closest_untracked_caller_location(),
+            "Invalid type provided to type_implements_predicates. U must be dyn Trait, got {trait_ty}."
+        );
+    };
+
+    let (infcx, param_env) = ecx.tcx.infer_ctxt().build_with_typing_env(ecx.typing_env);
+
+    let ocx = ObligationCtxt::new(&infcx);
+    ocx.register_obligations(preds.iter().map(|pred: PolyExistentialPredicate<'_>| {
+        let pred = pred.with_self_ty(ecx.tcx.tcx, ty);
+        // Lifetimes can only be 'static because of the bound on T
+        let pred = rustc_middle::ty::fold_regions(ecx.tcx.tcx, pred, |r, _| {
+            if r == ecx.tcx.tcx.lifetimes.re_erased { ecx.tcx.tcx.lifetimes.re_static } else { r }
+        });
+        Obligation::new(ecx.tcx.tcx, ObligationCause::dummy(), param_env, pred)
+    }));
+    let type_impls_trait = ocx.evaluate_obligations_error_on_ambiguity().is_empty();
+    // Since `assumed_wf_tys=[]` the choice of LocalDefId is irrelevant, so using the "default"
+    let regions_are_valid = ocx.resolve_regions(CRATE_DEF_ID, param_env, []).is_empty();
+
+    interp_ok((regions_are_valid && type_impls_trait, preds))
+}
 
 /// Checks whether a type contains generic parameters which must be instantiated.
 ///

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -213,6 +213,7 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
         | sym::truncf128
         | sym::type_id
         | sym::type_id_eq
+        | sym::type_id_implements_trait
         | sym::type_name
         | sym::type_of
         | sym::ub_checks
@@ -322,6 +323,12 @@ pub(crate) fn check_intrinsic_type(
             let type_id = tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap();
             (0, 0, vec![type_id, type_id], tcx.types.bool)
         }
+        sym::type_id_implements_trait => (
+            0,
+            0,
+            vec![tcx.type_of(tcx.lang_items().type_id().unwrap()).no_bound_vars().unwrap(); 2],
+            tcx.types.bool,
+        ),
         sym::type_of => (
             0,
             0,

compiler/rustc_span/src/symbol.rs

@@ -1239,6 +1239,7 @@ symbols! {
         i128_legacy_fn_min_value,
         i128_legacy_mod,
         i128_type,
+        id,
         ident,
         if_let,
         if_let_guard,
@@ -2339,6 +2340,7 @@ symbols! {
         type_const,
         type_id,
         type_id_eq,
+        type_id_implements_trait,
         type_info,
         type_ir,
         type_ir_infer_ctxt_like,

library/core/src/intrinsics/mod.rs

@@ -2852,6 +2852,15 @@ pub const unsafe fn size_of_val<T: ?Sized>(ptr: *const T) -> usize;
 #[rustc_intrinsic_const_stable_indirect]
 pub const unsafe fn align_of_val<T: ?Sized>(ptr: *const T) -> usize;
 
+/// Check if a type represented by a `TypeId` implements a trait represented by a `TypeId`.
+/// It can only be called at compile time, the backends do
+/// not implement it.
+#[rustc_intrinsic]
+#[unstable(feature = "core_intrinsics", issue = "none")]
+pub const fn type_id_implements_trait(_id: crate::any::TypeId, _trait: crate::any::TypeId) -> bool {
+    panic!("`TypeId::implements_trait` can only be called at compile-time")
+}
+
 /// Compute the type information of a concrete type.
 /// It can only be called at compile time, the backends do
 /// not implement it.

library/core/src/mem/type_info.rs

@@ -2,7 +2,8 @@
 //! runtime or const-eval processable way.
 
 use crate::any::TypeId;
-use crate::intrinsics::type_of;
+use crate::intrinsics::{type_id_implements_trait, type_of};
+use crate::ptr;
 
 /// Compile-time type information.
 #[derive(Debug)]
@@ -14,6 +15,8 @@ pub struct Type {
     pub kind: TypeKind,
     /// Size of the type. `None` if it is unsized
     pub size: Option<usize>,
+    /// `TypeId` that the type was gathered from.
+    pub id: TypeId,
 }
 
 impl TypeId {
@@ -34,6 +37,30 @@ impl Type {
     pub const fn of<T: ?Sized + 'static>() -> Self {
         const { TypeId::of::<T>().info() }
     }
+
+    /// Checks if the type has the trait.
+    /// It can only be called at compile time.
+    pub const fn has_trait<T: ptr::Pointee<Metadata = ptr::DynMetadata<T>> + ?Sized + 'static>(
+        self,
+    ) -> bool {
+        type_id_implements_trait(self.id, TypeId::of::<T>())
+    }
+
+    /// Checks if the type has the trait represented by the `TypeId`.
+    /// Returns `None` if the `trait_represented_by_type_id` is not a trait represented by type id.
+    /// It can only be called at compile time.
+    #[unstable(feature = "type_info", issue = "146922")]
+    #[rustc_const_unstable(feature = "type_info", issue = "146922")]
+    pub const fn has_trait_represented_by_type_id(
+        self,
+        trait_represented_by_type_id: TypeId,
+    ) -> Option<bool> {
+        if matches!(trait_represented_by_type_id.info().kind, TypeKind::DynTrait(_)) {
+            Some(type_id_implements_trait(self.id, trait_represented_by_type_id))
+        } else {
+            None
+        }
+    }
 }
 
 /// Compile-time type information.

library/coretests/tests/mem/type_info.rs

@@ -292,3 +292,16 @@ fn test_dynamic_traits() {
         assert!(sync.trait_ty.is_auto);
     }
 }
+
+#[test]
+fn test_implements_trait() {
+    struct Garlic;
+    trait Blah {}
+    impl Blah for Garlic {}
+
+    const {
+        assert!(TypeId::of::<Garlic>().info().has_trait::<dyn Blah>());
+        assert!(TypeId::of::<Garlic>().info().has_trait::<dyn Blah + Send>());
+        assert!(!TypeId::of::<*const Box<Garlic>>().info().has_trait::<dyn Sync>());
+    }
+}