Auto merge of #94733 - nnethercote:fix-AdtDef-interning, r=fee1-dead

Improve `AdtDef` interning.

This commit makes `AdtDef` use `Interned`. Much of the commit is tedious
changes to introduce getter functions. The interesting changes are in
`compiler/rustc_middle/src/ty/adt.rs`.

r? `@fee1-dead`

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -105,13 +105,13 @@ fn const_to_valtree_inner<'tcx>(
         ty::Array(_, len) => branches(usize::try_from(len.eval_usize(ecx.tcx.tcx, ecx.param_env)).unwrap(), None),
 
         ty::Adt(def, _) => {
-            if def.variants.is_empty() {
+            if def.variants().is_empty() {
                 bug!("uninhabited types should have errored and never gotten converted to valtree")
             }
 
             let variant = ecx.read_discriminant(&place.into()).unwrap().1;
 
-            branches(def.variants[variant].fields.len(), def.is_enum().then_some(variant))
+            branches(def.variant(variant).fields.len(), def.is_enum().then_some(variant))
         }
 
         ty::Never
@@ -150,11 +150,11 @@ pub(crate) fn try_destructure_const<'tcx>(
         // Checks if we have any variants, to avoid downcasting to a non-existing variant (when
         // there are no variants `read_discriminant` successfully returns a non-existing variant
         // index).
-        ty::Adt(def, _) if def.variants.is_empty() => throw_ub!(Unreachable),
+        ty::Adt(def, _) if def.variants().is_empty() => throw_ub!(Unreachable),
         ty::Adt(def, _) => {
             let variant = ecx.read_discriminant(&op)?.1;
             let down = ecx.operand_downcast(&op, variant)?;
-            (def.variants[variant].fields.len(), Some(variant), down)
+            (def.variant(variant).fields.len(), Some(variant), down)
         }
         ty::Tuple(substs) => (substs.len(), None, op),
         _ => bug!("cannot destructure constant {:?}", val),

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -174,7 +174,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: CompileTimeMachine<'mir, 'tcx, const_eval::Memory
         }
 
         if let Some(def) = mplace.layout.ty.ty_adt_def() {
-            if Some(def.did) == self.ecx.tcx.lang_items().unsafe_cell_type() {
+            if Some(def.did()) == self.ecx.tcx.lang_items().unsafe_cell_type() {
                 // We are crossing over an `UnsafeCell`, we can mutate again. This means that
                 // References we encounter inside here are interned as pointing to mutable
                 // allocations.

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -73,7 +73,9 @@ crate fn eval_nullary_intrinsic<'tcx>(
         }
         sym::variant_count => match tp_ty.kind() {
             // Correctly handles non-monomorphic calls, so there is no need for ensure_monomorphic_enough.
-            ty::Adt(ref adt, _) => ConstValue::from_machine_usize(adt.variants.len() as u64, &tcx),
+            ty::Adt(ref adt, _) => {
+                ConstValue::from_machine_usize(adt.variants().len() as u64, &tcx)
+            }
             ty::Projection(_)
             | ty::Opaque(_, _)
             | ty::Param(_)

compiler/rustc_const_eval/src/interpret/intrinsics/type_name.rs

@@ -1,3 +1,4 @@
+use rustc_data_structures::intern::Interned;
 use rustc_hir::def_id::CrateNum;
 use rustc_hir::definitions::DisambiguatedDefPathData;
 use rustc_middle::mir::interpret::{Allocation, ConstAllocation};
@@ -56,7 +57,7 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
             }
 
             // Types with identity (print the module path).
-            ty::Adt(&ty::AdtDef { did: def_id, .. }, substs)
+            ty::Adt(ty::AdtDef(Interned(&ty::AdtDefData { did: def_id, .. }, _)), substs)
             | ty::FnDef(def_id, substs)
             | ty::Opaque(def_id, substs)
             | ty::Projection(ty::ProjectionTy { item_def_id: def_id, substs })

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -759,7 +759,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                                 .ty
                                 .ty_adt_def()
                                 .expect("tagged layout for non adt")
-                                .variants
+                                .variants()
                                 .len();
                             assert!(usize::try_from(variant_index).unwrap() < variants_len);
                             VariantIdx::from_u32(variant_index)

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -267,7 +267,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                 match layout.variants {
                     Variants::Single { index } => {
                         // Inside a variant
-                        PathElem::Field(def.variants[index].fields[field].name)
+                        PathElem::Field(def.variant(index).fields[field].name)
                     }
                     Variants::Multiple { .. } => bug!("we handled variants above"),
                 }
@@ -734,7 +734,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
         new_op: &OpTy<'tcx, M::PointerTag>,
     ) -> InterpResult<'tcx> {
         let name = match old_op.layout.ty.kind() {
-            ty::Adt(adt, _) => PathElem::Variant(adt.variants[variant_id].name),
+            ty::Adt(adt, _) => PathElem::Variant(adt.variant(variant_id).name),
             // Generators also have variants
             ty::Generator(..) => PathElem::GeneratorState(variant_id),
             _ => bug!("Unexpected type with variant: {:?}", old_op.layout.ty),
@@ -771,7 +771,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
         // Special check preventing `UnsafeCell` in the inner part of constants
         if let Some(def) = op.layout.ty.ty_adt_def() {
             if matches!(self.ctfe_mode, Some(CtfeValidationMode::Const { inner: true, .. }))
-                && Some(def.did) == self.ecx.tcx.lang_items().unsafe_cell_type()
+                && Some(def.did()) == self.ecx.tcx.lang_items().unsafe_cell_type()
             {
                 throw_validation_failure!(self.path, { "`UnsafeCell` in a `const`" });
             }

compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs

@@ -71,7 +71,7 @@ pub trait Qualif {
     /// Returning `true` for `in_adt_inherently` but `false` for `in_any_value_of_ty` is unsound.
     fn in_adt_inherently<'tcx>(
         cx: &ConstCx<'_, 'tcx>,
-        adt: &'tcx AdtDef,
+        adt: AdtDef<'tcx>,
         substs: SubstsRef<'tcx>,
     ) -> bool;
 }
@@ -96,12 +96,12 @@ impl Qualif for HasMutInterior {
 
     fn in_adt_inherently<'tcx>(
         cx: &ConstCx<'_, 'tcx>,
-        adt: &'tcx AdtDef,
+        adt: AdtDef<'tcx>,
         _: SubstsRef<'tcx>,
     ) -> bool {
         // Exactly one type, `UnsafeCell`, has the `HasMutInterior` qualif inherently.
         // It arises structurally for all other types.
-        Some(adt.did) == cx.tcx.lang_items().unsafe_cell_type()
+        Some(adt.did()) == cx.tcx.lang_items().unsafe_cell_type()
     }
 }
 
@@ -126,7 +126,7 @@ impl Qualif for NeedsDrop {
 
     fn in_adt_inherently<'tcx>(
         cx: &ConstCx<'_, 'tcx>,
-        adt: &'tcx AdtDef,
+        adt: AdtDef<'tcx>,
         _: SubstsRef<'tcx>,
     ) -> bool {
         adt.has_dtor(cx.tcx)
@@ -205,7 +205,7 @@ impl Qualif for NeedsNonConstDrop {
 
     fn in_adt_inherently<'tcx>(
         cx: &ConstCx<'_, 'tcx>,
-        adt: &'tcx AdtDef,
+        adt: AdtDef<'tcx>,
         _: SubstsRef<'tcx>,
     ) -> bool {
         adt.has_non_const_dtor(cx.tcx)
@@ -233,7 +233,7 @@ impl Qualif for CustomEq {
 
     fn in_adt_inherently<'tcx>(
         cx: &ConstCx<'_, 'tcx>,
-        adt: &'tcx AdtDef,
+        adt: AdtDef<'tcx>,
         substs: SubstsRef<'tcx>,
     ) -> bool {
         let ty = cx.tcx.mk_ty(ty::Adt(adt, substs));

compiler/rustc_const_eval/src/util/alignment.rs

@@ -55,7 +55,7 @@ where
             ProjectionElem::Field(..) => {
                 let ty = place_base.ty(local_decls, tcx).ty;
                 match ty.kind() {
-                    ty::Adt(def, _) => return def.repr.pack,
+                    ty::Adt(def, _) => return def.repr().pack,
                     _ => {}
                 }
             }

compiler/rustc_const_eval/src/util/call_kind.rs

@@ -132,7 +132,7 @@ pub fn call_kind<'tcx>(
             .parent(method_did)
             .filter(|did| tcx.def_kind(*did) == rustc_hir::def::DefKind::Impl)
             .and_then(|did| match tcx.type_of(did).kind() {
-                ty::Adt(def, ..) => Some(def.did),
+                ty::Adt(def, ..) => Some(def.did()),
                 _ => None,
             });
         let is_option_or_result = parent_self_ty.map_or(false, |def_id| {