Remove FeedConstTy

mu001999 · mu001999 · commit d0247c8ad1cb · 2026-01-11T19:23:49.000+08:00
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
@@ -47,9 +47,7 @@ use rustc_trait_selection::traits::{
 use tracing::{debug, instrument};
 
 use crate::errors;
-use crate::hir_ty_lowering::{
-    FeedConstTy, HirTyLowerer, InherentAssocCandidate, RegionInferReason,
-};
+use crate::hir_ty_lowering::{HirTyLowerer, InherentAssocCandidate, RegionInferReason};
 
 pub(crate) mod dump;
 mod generics_of;
@@ -1499,7 +1497,7 @@ fn const_param_default<'tcx>(
 
     let ct = icx
         .lowerer()
-        .lower_const_arg(default_ct, FeedConstTy::with_type_of(tcx, def_id, identity_args));
+        .lower_const_arg(default_ct, tcx.type_of(def_id).instantiate(tcx, identity_args));
     ty::EarlyBinder::bind(ct)
 }
 
@@ -1557,7 +1555,7 @@ fn const_of_item<'tcx>(
     let identity_args = ty::GenericArgs::identity_for_item(tcx, def_id);
     let ct = icx
         .lowerer()
-        .lower_const_arg(ct_arg, FeedConstTy::with_type_of(tcx, def_id.to_def_id(), identity_args));
+        .lower_const_arg(ct_arg, tcx.type_of(def_id.to_def_id()).instantiate(tcx, identity_args));
     if let Err(e) = icx.check_tainted_by_errors()
         && !ct.references_error()
     {
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
@@ -20,7 +20,7 @@ use tracing::{debug, instrument};
 
 use crate::errors;
 use crate::hir_ty_lowering::{
-    AssocItemQSelf, FeedConstTy, GenericsArgsErrExtend, HirTyLowerer, ImpliedBoundsContext,
+    AssocItemQSelf, GenericsArgsErrExtend, HirTyLowerer, ImpliedBoundsContext,
     OverlappingAsssocItemConstraints, PredicateFilter, RegionInferReason,
 };
 
@@ -543,7 +543,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 let term = match term {
                     hir::Term::Ty(ty) => self.lower_ty(ty).into(),
                     hir::Term::Const(ct) => {
-                        // Provide the resolved type of the associated constant
                         let ty = projection_term.map_bound(|alias| {
                             tcx.type_of(alias.def_id).instantiate(tcx, alias.args)
                         });
@@ -554,7 +553,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                             constraint.hir_id,
                         );
 
-                        self.lower_const_arg(ct, FeedConstTy::WithTy(ty)).into()
+                        self.lower_const_arg(ct, ty).into()
                     }
                 };
 
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -253,35 +253,6 @@ impl AssocItemQSelf {
     }
 }
 
-/// In some cases, [`hir::ConstArg`]s that are being used in the type system
-/// through const generics need to have their type "fed" to them
-/// using the query system.
-///
-/// Use this enum with `<dyn HirTyLowerer>::lower_const_arg` to instruct it with the
-/// desired behavior.
-#[derive(Debug, Clone, Copy)]
-pub enum FeedConstTy<'tcx> {
-    /// Feed the type to the (anno) const arg.
-    WithTy(Ty<'tcx>),
-    /// Don't feed the type.
-    No,
-}
-
-impl<'tcx> FeedConstTy<'tcx> {
-    /// The `DefId` belongs to the const param that we are supplying
-    /// this (anon) const arg to.
-    ///
-    /// The list of generic args is used to instantiate the parameters
-    /// used by the type of the const param specified by `DefId`.
-    pub fn with_type_of(
-        tcx: TyCtxt<'tcx>,
-        def_id: DefId,
-        generic_args: &[ty::GenericArg<'tcx>],
-    ) -> Self {
-        Self::WithTy(tcx.type_of(def_id).instantiate(tcx, generic_args))
-    }
-}
-
 #[derive(Debug, Clone, Copy)]
 enum LowerTypeRelativePathMode {
     Type(PermitVariants),
@@ -733,7 +704,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         // Ambig portions of `ConstArg` are handled in the match arm below
                         .lower_const_arg(
                             ct.as_unambig_ct(),
-                            FeedConstTy::with_type_of(tcx, param.def_id, preceding_args),
+                            tcx.type_of(param.def_id).instantiate(tcx, preceding_args),
                         )
                         .into(),
                     (&GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => {
@@ -1322,7 +1293,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                                             constraint.hir_id,
                                         );
 
-                                        self.lower_const_arg(ct, FeedConstTy::WithTy(ty)).into()
+                                        self.lower_const_arg(ct, ty).into()
                                     }
                                 };
                                 if term.references_error() {
@@ -2347,16 +2318,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
     /// Lower a [`hir::ConstArg`] to a (type-level) [`ty::Const`](Const).
     #[instrument(skip(self), level = "debug")]
-    pub fn lower_const_arg(
-        &self,
-        const_arg: &hir::ConstArg<'tcx>,
-        feed: FeedConstTy<'tcx>,
-    ) -> Const<'tcx> {
+    pub fn lower_const_arg(&self, const_arg: &hir::ConstArg<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
         let tcx = self.tcx();
 
-        if let FeedConstTy::WithTy(anon_const_type) = feed
-            && let hir::ConstArgKind::Anon(anon) = &const_arg.kind
-        {
+        if let hir::ConstArgKind::Anon(anon) = &const_arg.kind {
             // FIXME(generic_const_parameter_types): Ideally we remove these errors below when
             // we have the ability to intermix typeck of anon const const args with the parent
             // bodies typeck.
@@ -2366,7 +2331,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             // hir typeck was using equality but mir borrowck wound up using subtyping as that could
             // result in a non-infer in hir typeck but a region variable in borrowck.
             if tcx.features().generic_const_parameter_types()
-                && (anon_const_type.has_free_regions() || anon_const_type.has_erased_regions())
+                && (ty.has_free_regions() || ty.has_erased_regions())
             {
                 let e = self.dcx().span_err(
                     const_arg.span,
@@ -2378,7 +2343,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             // We must error if the instantiated type has any inference variables as we will
             // use this type to feed the `type_of` and query results must not contain inference
             // variables otherwise we will ICE.
-            if anon_const_type.has_non_region_infer() {
+            if ty.has_non_region_infer() {
                 let e = self.dcx().span_err(
                     const_arg.span,
                     "anonymous constants with inferred types are not yet supported",
@@ -2388,7 +2353,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
             // We error when the type contains unsubstituted generics since we do not currently
             // give the anon const any of the generics from the parent.
-            if anon_const_type.has_non_region_param() {
+            if ty.has_non_region_param() {
                 let e = self.dcx().span_err(
                     const_arg.span,
                     "anonymous constants referencing generics are not yet supported",
@@ -2397,12 +2362,12 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 return ty::Const::new_error(tcx, e);
             }
 
-            tcx.feed_anon_const_type(anon.def_id, ty::EarlyBinder::bind(anon_const_type));
+            tcx.feed_anon_const_type(anon.def_id, ty::EarlyBinder::bind(ty));
         }
 
         let hir_id = const_arg.hir_id;
         match const_arg.kind {
-            hir::ConstArgKind::Tup(exprs) => self.lower_const_arg_tup(exprs, feed, const_arg.span),
+            hir::ConstArgKind::Tup(exprs) => self.lower_const_arg_tup(exprs, ty, const_arg.span),
             hir::ConstArgKind::Path(hir::QPath::Resolved(maybe_qself, path)) => {
                 debug!(?maybe_qself, ?path);
                 let opt_self_ty = maybe_qself.as_ref().map(|qself| self.lower_ty(qself));
@@ -2429,12 +2394,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             hir::ConstArgKind::Anon(anon) => self.lower_const_arg_anon(anon),
             hir::ConstArgKind::Infer(()) => self.ct_infer(None, const_arg.span),
             hir::ConstArgKind::Error(e) => ty::Const::new_error(tcx, e),
-            hir::ConstArgKind::Literal(kind) if let FeedConstTy::WithTy(anon_const_type) = feed => {
-                self.lower_const_arg_literal(&kind, anon_const_type, const_arg.span)
-            }
-            hir::ConstArgKind::Literal(..) => {
-                let e = self.dcx().span_err(const_arg.span, "literal of unknown type");
-                ty::Const::new_error(tcx, e)
+            hir::ConstArgKind::Literal(kind) => {
+                self.lower_const_arg_literal(&kind, ty, const_arg.span)
             }
         }
     }
@@ -2514,7 +2475,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             .iter()
             .zip(args)
             .map(|(field_def, arg)| {
-                self.lower_const_arg(arg, FeedConstTy::with_type_of(tcx, field_def.did, adt_args))
+                self.lower_const_arg(arg, tcx.type_of(field_def.did).instantiate(tcx, adt_args))
             })
             .collect::<Vec<_>>();
 
@@ -2533,23 +2494,19 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     fn lower_const_arg_tup(
         &self,
         exprs: &'tcx [&'tcx hir::ConstArg<'tcx>],
-        feed: FeedConstTy<'tcx>,
+        ty: Ty<'tcx>,
         span: Span,
     ) -> Const<'tcx> {
         let tcx = self.tcx();
 
-        let FeedConstTy::WithTy(ty) = feed else {
-            return Const::new_error_with_message(tcx, span, "unsupported const tuple");
-        };
-
         let ty::Tuple(tys) = ty.kind() else {
             return Const::new_error_with_message(tcx, span, "const tuple must have a tuple type");
         };
 
         let exprs = exprs
             .iter()
             .zip(tys.iter())
-            .map(|(expr, ty)| self.lower_const_arg(expr, FeedConstTy::WithTy(ty)))
+            .map(|(expr, ty)| self.lower_const_arg(expr, ty))
             .collect::<Vec<_>>();
 
         let valtree = ty::ValTree::from_branches(tcx, exprs);
@@ -2636,7 +2593,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
                         self.lower_const_arg(
                             expr.expr,
-                            FeedConstTy::with_type_of(tcx, field_def.did, adt_args),
+                            tcx.type_of(field_def.did).instantiate(tcx, adt_args),
                         )
                     }
                     None => {
@@ -2998,7 +2955,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 .unwrap_or_else(|guar| Ty::new_error(tcx, guar))
             }
             hir::TyKind::Array(ty, length) => {
-                let length = self.lower_const_arg(length, FeedConstTy::WithTy(tcx.types.usize));
+                let length = self.lower_const_arg(length, tcx.types.usize);
                 Ty::new_array_with_const_len(tcx, self.lower_ty(ty), length)
             }
             hir::TyKind::Infer(()) => {
@@ -3038,8 +2995,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     // Keep this list of types in sync with the list of types that
                     // the `RangePattern` trait is implemented for.
                     ty::Int(_) | ty::Uint(_) | ty::Char => {
-                        let start = self.lower_const_arg(start, FeedConstTy::WithTy(ty));
-                        let end = self.lower_const_arg(end, FeedConstTy::WithTy(ty));
+                        let start = self.lower_const_arg(start, ty);
+                        let end = self.lower_const_arg(end, ty);
                         Ok(ty::PatternKind::Range { start, end })
                     }
                     _ => Err(self
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
@@ -101,7 +101,7 @@ use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::traits;
 
 pub use crate::collect::suggest_impl_trait;
-use crate::hir_ty_lowering::{FeedConstTy, HirTyLowerer};
+use crate::hir_ty_lowering::HirTyLowerer;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
@@ -301,8 +301,8 @@ pub fn lower_ty<'tcx>(tcx: TyCtxt<'tcx>, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
 pub fn lower_const_arg_for_rustdoc<'tcx>(
     tcx: TyCtxt<'tcx>,
     hir_ct: &hir::ConstArg<'tcx>,
-    feed: FeedConstTy<'tcx>,
+    ty: Ty<'tcx>,
 ) -> Const<'tcx> {
     let env_def_id = tcx.hir_get_parent_item(hir_ct.hir_id);
-    collect::ItemCtxt::new(tcx, env_def_id.def_id).lowerer().lower_const_arg(hir_ct, feed)
+    collect::ItemCtxt::new(tcx, env_def_id.def_id).lowerer().lower_const_arg(hir_ct, ty)
 }
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
@@ -21,7 +21,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{ExprKind, HirId, QPath, find_attr, is_range_literal};
 use rustc_hir_analysis::NoVariantNamed;
-use rustc_hir_analysis::hir_ty_lowering::{FeedConstTy, HirTyLowerer as _};
+use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer as _;
 use rustc_infer::infer::{self, DefineOpaqueTypes, InferOk, RegionVariableOrigin};
 use rustc_infer::traits::query::NoSolution;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AllowTwoPhase};
@@ -1749,10 +1749,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let count_span = count.span;
         let count = self.try_structurally_resolve_const(
             count_span,
-            self.normalize(
-                count_span,
-                self.lower_const_arg(count, FeedConstTy::WithTy(tcx.types.usize)),
-            ),
+            self.normalize(count_span, self.lower_const_arg(count, tcx.types.usize)),
         );
 
         if let Some(count) = count.try_to_target_usize(tcx) {
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -14,8 +14,8 @@ use rustc_hir_analysis::hir_ty_lowering::generics::{
     check_generic_arg_count_for_call, lower_generic_args,
 };
 use rustc_hir_analysis::hir_ty_lowering::{
-    ExplicitLateBound, FeedConstTy, GenericArgCountMismatch, GenericArgCountResult,
-    GenericArgsLowerer, GenericPathSegment, HirTyLowerer, IsMethodCall, RegionInferReason,
+    ExplicitLateBound, GenericArgCountMismatch, GenericArgCountResult, GenericArgsLowerer,
+    GenericPathSegment, HirTyLowerer, IsMethodCall, RegionInferReason,
 };
 use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
 use rustc_infer::infer::{DefineOpaqueTypes, InferResult};
@@ -525,9 +525,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     pub(crate) fn lower_const_arg(
         &self,
         const_arg: &'tcx hir::ConstArg<'tcx>,
-        feed: FeedConstTy<'tcx>,
+        ty: Ty<'tcx>,
     ) -> ty::Const<'tcx> {
-        let ct = self.lowerer().lower_const_arg(const_arg, feed);
+        let ct = self.lowerer().lower_const_arg(const_arg, ty);
         self.register_wf_obligation(
             ct.into(),
             self.tcx.hir_span(const_arg.hir_id),
@@ -1228,7 +1228,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // Ambiguous parts of `ConstArg` are handled in the match arms below
                         .lower_const_arg(
                             ct.as_unambig_ct(),
-                            FeedConstTy::with_type_of(self.fcx.tcx, param.def_id, preceding_args),
+                            self.fcx
+                                .tcx
+                                .type_of(param.def_id)
+                                .instantiate(self.fcx.tcx, preceding_args),
                         )
                         .into(),
                     (&GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => {
diff --git a/compiler/rustc_hir_typeck/src/method/confirm.rs b/compiler/rustc_hir_typeck/src/method/confirm.rs
@@ -7,7 +7,7 @@ use rustc_hir_analysis::hir_ty_lowering::generics::{
     check_generic_arg_count_for_call, lower_generic_args,
 };
 use rustc_hir_analysis::hir_ty_lowering::{
-    FeedConstTy, GenericArgsLowerer, HirTyLowerer, IsMethodCall, RegionInferReason,
+    GenericArgsLowerer, HirTyLowerer, IsMethodCall, RegionInferReason,
 };
 use rustc_infer::infer::{
     BoundRegionConversionTime, DefineOpaqueTypes, InferOk, RegionVariableOrigin,
@@ -447,7 +447,10 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                         // We handle the ambig portions of `ConstArg` in the match arms below
                         .lower_const_arg(
                             ct.as_unambig_ct(),
-                            FeedConstTy::with_type_of(self.cfcx.tcx, param.def_id, preceding_args),
+                            self.cfcx
+                                .tcx
+                                .type_of(param.def_id)
+                                .instantiate(self.cfcx.tcx, preceding_args),
                         )
                         .into(),
                     (GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => {
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
