Rollup merge of #124957 - compiler-errors:builtin-deref, r=michaelwoe…

…rister

Make `Ty::builtin_deref` just return a `Ty`

Nowhere in the compiler are we using the mutability part of the `TyAndMut` that we used to return.

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1483,10 +1483,9 @@ fn suggest_ampmut<'tcx>(
     } else {
         // otherwise, suggest that the user annotates the binding; we provide the
         // type of the local.
-        let ty_mut = decl_ty.builtin_deref(true).unwrap();
-        assert_eq!(ty_mut.mutbl, hir::Mutability::Not);
+        let ty = decl_ty.builtin_deref(true).unwrap();
 
-        (false, span, format!("{}mut {}", if decl_ty.is_ref() { "&" } else { "*" }, ty_mut.ty))
+        (false, span, format!("{}mut {}", if decl_ty.is_ref() { "&" } else { "*" }, ty))
     }
 }
 

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -400,7 +400,7 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
             } else if let Some(static_def_id) = constant.check_static_ptr(tcx) {
                 let unnormalized_ty = tcx.type_of(static_def_id).instantiate_identity();
                 let normalized_ty = self.cx.normalize(unnormalized_ty, locations);
-                let literal_ty = constant.const_.ty().builtin_deref(true).unwrap().ty;
+                let literal_ty = constant.const_.ty().builtin_deref(true).unwrap();
 
                 if let Err(terr) = self.cx.eq_types(
                     literal_ty,
@@ -637,7 +637,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         match pi {
             ProjectionElem::Deref => {
                 let deref_ty = base_ty.builtin_deref(true);
-                PlaceTy::from_ty(deref_ty.map(|t| t.ty).unwrap_or_else(|| {
+                PlaceTy::from_ty(deref_ty.unwrap_or_else(|| {
                     span_mirbug_and_err!(self, place, "deref of non-pointer {:?}", base_ty)
                 }))
             }

compiler/rustc_codegen_cranelift/src/base.rs

@@ -670,11 +670,8 @@ fn codegen_stmt<'tcx>(
                     let to_ty = fx.monomorphize(to_ty);
 
                     fn is_fat_ptr<'tcx>(fx: &FunctionCx<'_, '_, 'tcx>, ty: Ty<'tcx>) -> bool {
-                        ty.builtin_deref(true).is_some_and(
-                            |ty::TypeAndMut { ty: pointee_ty, mutbl: _ }| {
-                                has_ptr_meta(fx.tcx, pointee_ty)
-                            },
-                        )
+                        ty.builtin_deref(true)
+                            .is_some_and(|pointee_ty| has_ptr_meta(fx.tcx, pointee_ty))
                     }
 
                     if is_fat_ptr(fx, from_ty) {

compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs

@@ -586,7 +586,7 @@ fn codegen_regular_intrinsic_call<'tcx>(
             intrinsic_args!(fx, args => (base, offset); intrinsic);
             let offset = offset.load_scalar(fx);
 
-            let pointee_ty = base.layout().ty.builtin_deref(true).unwrap().ty;
+            let pointee_ty = base.layout().ty.builtin_deref(true).unwrap();
             let pointee_size = fx.layout_of(pointee_ty).size.bytes();
             let ptr_diff = if pointee_size != 1 {
                 fx.bcx.ins().imul_imm(offset, pointee_size as i64)
@@ -610,7 +610,7 @@ fn codegen_regular_intrinsic_call<'tcx>(
             let val = val.load_scalar(fx);
             let count = count.load_scalar(fx);
 
-            let pointee_ty = dst.layout().ty.builtin_deref(true).unwrap().ty;
+            let pointee_ty = dst.layout().ty.builtin_deref(true).unwrap();
             let pointee_size = fx.layout_of(pointee_ty).size.bytes();
             let count = if pointee_size != 1 {
                 fx.bcx.ins().imul_imm(count, pointee_size as i64)
@@ -715,7 +715,7 @@ fn codegen_regular_intrinsic_call<'tcx>(
 
             // Cranelift treats loads as volatile by default
             // FIXME correctly handle unaligned_volatile_load
-            let inner_layout = fx.layout_of(ptr.layout().ty.builtin_deref(true).unwrap().ty);
+            let inner_layout = fx.layout_of(ptr.layout().ty.builtin_deref(true).unwrap());
             let val = CValue::by_ref(Pointer::new(ptr.load_scalar(fx)), inner_layout);
             ret.write_cvalue(fx, val);
         }

compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs

@@ -974,7 +974,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
             intrinsic_args!(fx, args => (ptr, offset); intrinsic);
 
             let (lane_count, ptr_lane_ty) = ptr.layout().ty.simd_size_and_type(fx.tcx);
-            let pointee_ty = ptr_lane_ty.builtin_deref(true).unwrap().ty;
+            let pointee_ty = ptr_lane_ty.builtin_deref(true).unwrap();
             let pointee_size = fx.layout_of(pointee_ty).size.bytes();
             let (ret_lane_count, ret_lane_ty) = ret.layout().ty.simd_size_and_type(fx.tcx);
             let ret_lane_layout = fx.layout_of(ret_lane_ty);

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -95,7 +95,7 @@ mod prelude {
     pub(crate) use rustc_middle::mir::{self, *};
     pub(crate) use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
     pub(crate) use rustc_middle::ty::{
-        self, FloatTy, Instance, InstanceDef, IntTy, ParamEnv, Ty, TyCtxt, TypeAndMut, UintTy,
+        self, FloatTy, Instance, InstanceDef, IntTy, ParamEnv, Ty, TyCtxt, UintTy,
     };
     pub(crate) use rustc_span::Span;
     pub(crate) use rustc_target::abi::{Abi, FieldIdx, Scalar, Size, VariantIdx, FIRST_VARIANT};

compiler/rustc_codegen_cranelift/src/num.rs

@@ -388,12 +388,8 @@ pub(crate) fn codegen_ptr_binop<'tcx>(
     in_lhs: CValue<'tcx>,
     in_rhs: CValue<'tcx>,
 ) -> CValue<'tcx> {
-    let is_thin_ptr = in_lhs
-        .layout()
-        .ty
-        .builtin_deref(true)
-        .map(|TypeAndMut { ty, mutbl: _ }| !has_ptr_meta(fx.tcx, ty))
-        .unwrap_or(true);
+    let is_thin_ptr =
+        in_lhs.layout().ty.builtin_deref(true).map(|ty| !has_ptr_meta(fx.tcx, ty)).unwrap_or(true);
 
     if is_thin_ptr {
         match bin_op {
@@ -404,7 +400,7 @@ pub(crate) fn codegen_ptr_binop<'tcx>(
                 codegen_compare_bin_op(fx, bin_op, false, lhs, rhs)
             }
             BinOp::Offset => {
-                let pointee_ty = in_lhs.layout().ty.builtin_deref(true).unwrap().ty;
+                let pointee_ty = in_lhs.layout().ty.builtin_deref(true).unwrap();
                 let (base, offset) = (in_lhs, in_rhs.load_scalar(fx));
                 let pointee_size = fx.layout_of(pointee_ty).size.bytes();
                 let ptr_diff = fx.bcx.ins().imul_imm(offset, pointee_size as i64);

compiler/rustc_codegen_cranelift/src/unsize.rs

@@ -127,7 +127,7 @@ pub(crate) fn coerce_unsized_into<'tcx>(
     let dst_ty = dst.layout().ty;
     let mut coerce_ptr = || {
         let (base, info) =
-            if fx.layout_of(src.layout().ty.builtin_deref(true).unwrap().ty).is_unsized() {
+            if fx.layout_of(src.layout().ty.builtin_deref(true).unwrap()).is_unsized() {
                 let (old_base, old_info) = src.load_scalar_pair(fx);
                 unsize_ptr(fx, old_base, src.layout(), dst.layout(), Some(old_info))
             } else {

compiler/rustc_codegen_cranelift/src/value_and_place.rs

@@ -819,7 +819,7 @@ impl<'tcx> CPlace<'tcx> {
     }
 
     pub(crate) fn place_deref(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> CPlace<'tcx> {
-        let inner_layout = fx.layout_of(self.layout().ty.builtin_deref(true).unwrap().ty);
+        let inner_layout = fx.layout_of(self.layout().ty.builtin_deref(true).unwrap());
         if has_ptr_meta(fx.tcx, inner_layout.ty) {
             let (addr, extra) = self.to_cvalue(fx).load_scalar_pair(fx);
             CPlace::for_ptr_with_extra(Pointer::new(addr), extra, inner_layout)

compiler/rustc_codegen_cranelift/src/vtable.rs

@@ -59,7 +59,7 @@ pub(crate) fn get_ptr_and_method_ref<'tcx>(
 
         if let ty::Ref(_, ty, _) = arg.layout().ty.kind() {
             if ty.is_dyn_star() {
-                let inner_layout = fx.layout_of(arg.layout().ty.builtin_deref(true).unwrap().ty);
+                let inner_layout = fx.layout_of(arg.layout().ty.builtin_deref(true).unwrap());
                 let dyn_star = CPlace::for_ptr(Pointer::new(arg.load_scalar(fx)), inner_layout);
                 let ptr = dyn_star.place_field(fx, FieldIdx::ZERO).to_ptr();
                 let vtable =

compiler/rustc_codegen_llvm/src/abi.rs

@@ -583,7 +583,7 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
         let element_type_index = unsafe { llvm::LLVMRustGetElementTypeArgIndex(callsite) };
         if element_type_index >= 0 {
             let arg_ty = self.args[element_type_index as usize].layout.ty;
-            let pointee_ty = arg_ty.builtin_deref(true).expect("Must be pointer argument").ty;
+            let pointee_ty = arg_ty.builtin_deref(true).expect("Must be pointer argument");
             let element_type_attr = unsafe {
                 llvm::LLVMRustCreateElementTypeAttr(bx.llcx, bx.layout_of(pointee_ty).llvm_type(bx))
             };

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -2383,7 +2383,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
         let pointee = in_elem.builtin_deref(true).unwrap_or_else(|| {
             span_bug!(span, "must be called with a vector of pointer types as first argument")
         });
-        let layout = bx.layout_of(pointee.ty);
+        let layout = bx.layout_of(pointee);
         let ptrs = args[0].immediate();
         // The second argument must be a ptr-sized integer.
         // (We don't care about the signedness, this is wrapping anyway.)

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1060,7 +1060,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
                         // Make sure that we've actually unwrapped the rcvr down
                         // to a pointer or ref to `dyn* Trait`.
-                        if !op.layout.ty.builtin_deref(true).unwrap().ty.is_dyn_star() {
+                        if !op.layout.ty.builtin_deref(true).unwrap().is_dyn_star() {
                             span_bug!(span, "can't codegen a virtual call on {:#?}", op);
                         }
                         let place = op.deref(bx.cx());

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -120,7 +120,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> DebugInfoOffsetLocation<'tcx, Bx>
 {
     fn deref(&self, bx: &mut Bx) -> Self {
         bx.cx().layout_of(
-            self.ty.builtin_deref(true).unwrap_or_else(|| bug!("cannot deref `{}`", self.ty)).ty,
+            self.ty.builtin_deref(true).unwrap_or_else(|| bug!("cannot deref `{}`", self.ty)),
         )
     }
 

compiler/rustc_codegen_ssa/src/mir/operand.rs

@@ -215,8 +215,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
             .layout
             .ty
             .builtin_deref(true)
-            .unwrap_or_else(|| bug!("deref of non-pointer {:?}", self))
-            .ty;
+            .unwrap_or_else(|| bug!("deref of non-pointer {:?}", self));
 
         let (llptr, llextra) = match self.val {
             OperandValue::Immediate(llptr) => (llptr, None),
@@ -455,8 +454,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandValue<V> {
             .layout
             .ty
             .builtin_deref(true)
-            .unwrap_or_else(|| bug!("indirect_dest has non-pointer type: {:?}", indirect_dest))
-            .ty;
+            .unwrap_or_else(|| bug!("indirect_dest has non-pointer type: {:?}", indirect_dest));
 
         let OperandValue::Ref(PlaceValue { llval: llptr, llextra: Some(llextra), .. }) = self
         else {

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -870,8 +870,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             mir::BinOp::Offset => {
                 let pointee_type = input_ty
                     .builtin_deref(true)
-                    .unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty))
-                    .ty;
+                    .unwrap_or_else(|| bug!("deref of non-pointer {:?}", input_ty));
                 let pointee_layout = bx.cx().layout_of(pointee_type);
                 if pointee_layout.is_zst() {
                     // `Offset` works in terms of the size of pointee,

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -222,7 +222,7 @@ pub(super) fn op_to_const<'tcx>(
                 // This codepath solely exists for `valtree_to_const_value` to not need to generate
                 // a `ConstValue::Indirect` for wide references, so it is tightly restricted to just
                 // that case.
-                let pointee_ty = imm.layout.ty.builtin_deref(false).unwrap().ty; // `false` = no raw ptrs
+                let pointee_ty = imm.layout.ty.builtin_deref(false).unwrap(); // `false` = no raw ptrs
                 debug_assert!(
                     matches!(
                         ecx.tcx.struct_tail_without_normalization(pointee_ty).kind(),

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -605,7 +605,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         nonoverlapping: bool,
     ) -> InterpResult<'tcx> {
         let count = self.read_target_usize(count)?;
-        let layout = self.layout_of(src.layout.ty.builtin_deref(true).unwrap().ty)?;
+        let layout = self.layout_of(src.layout.ty.builtin_deref(true).unwrap())?;
         let (size, align) = (layout.size, layout.align.abi);
         // `checked_mul` enforces a too small bound (the correct one would probably be target_isize_max),
         // but no actual allocation can be big enough for the difference to be noticeable.
@@ -649,7 +649,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         byte: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
         count: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
     ) -> InterpResult<'tcx> {
-        let layout = self.layout_of(dst.layout.ty.builtin_deref(true).unwrap().ty)?;
+        let layout = self.layout_of(dst.layout.ty.builtin_deref(true).unwrap())?;
 
         let dst = self.read_pointer(dst)?;
         let byte = self.read_scalar(byte)?.to_u8()?;
@@ -688,7 +688,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         lhs: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
         rhs: &OpTy<'tcx, <M as Machine<'mir, 'tcx>>::Provenance>,
     ) -> InterpResult<'tcx, Scalar<M::Provenance>> {
-        let layout = self.layout_of(lhs.layout.ty.builtin_deref(true).unwrap().ty)?;
+        let layout = self.layout_of(lhs.layout.ty.builtin_deref(true).unwrap())?;
         assert!(layout.is_sized());
 
         let get_bytes = |this: &InterpCx<'mir, 'tcx, M>,

compiler/rustc_const_eval/src/interpret/operator.rs

@@ -357,7 +357,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             Offset => {
                 let ptr = left.to_scalar().to_pointer(self)?;
                 let offset_count = right.to_scalar().to_target_isize(self)?;
-                let pointee_ty = left.layout.ty.builtin_deref(true).unwrap().ty;
+                let pointee_ty = left.layout.ty.builtin_deref(true).unwrap();
 
                 // We cannot overflow i64 as a type's size must be <= isize::MAX.
                 let pointee_size = i64::try_from(self.layout_of(pointee_ty)?.size.bytes()).unwrap();

compiler/rustc_const_eval/src/interpret/place.rs

@@ -415,7 +415,7 @@ where
         val: &ImmTy<'tcx, M::Provenance>,
     ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
         let pointee_type =
-            val.layout.ty.builtin_deref(true).expect("`ref_to_mplace` called on non-ptr type").ty;
+            val.layout.ty.builtin_deref(true).expect("`ref_to_mplace` called on non-ptr type");
         let layout = self.layout_of(pointee_type)?;
         let (ptr, meta) = val.to_scalar_and_meta();
 

compiler/rustc_const_eval/src/transform/validate.rs

@@ -1291,7 +1291,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             )) => {
                 let src_ty = src.ty(&self.body.local_decls, self.tcx);
                 let op_src_ty = if let Some(src_deref) = src_ty.builtin_deref(true) {
-                    src_deref.ty
+                    src_deref
                 } else {
                     self.fail(
                         location,
@@ -1301,7 +1301,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 };
                 let dst_ty = dst.ty(&self.body.local_decls, self.tcx);
                 let op_dst_ty = if let Some(dst_deref) = dst_ty.builtin_deref(true) {
-                    dst_deref.ty
+                    dst_deref
                 } else {
                     self.fail(
                         location,

compiler/rustc_const_eval/src/util/check_validity_requirement.rs

@@ -115,7 +115,7 @@ fn might_permit_raw_init_lax<'tcx>(
 
     // Special magic check for references and boxes (i.e., special pointer types).
     if let Some(pointee) = this.ty.builtin_deref(false) {
-        let pointee = cx.layout_of(pointee.ty)?;
+        let pointee = cx.layout_of(pointee)?;
         // We need to ensure that the LLVM attributes `aligned` and `dereferenceable(size)` are satisfied.
         if pointee.align.abi.bytes() > 1 {
             // 0x01-filling is not aligned.

compiler/rustc_hir_analysis/src/autoderef.rs

@@ -68,28 +68,27 @@ impl<'a, 'tcx> Iterator for Autoderef<'a, 'tcx> {
         }
 
         // Otherwise, deref if type is derefable:
-        let (kind, new_ty) = if let Some(ty::TypeAndMut { ty, .. }) =
-            self.state.cur_ty.builtin_deref(self.include_raw_pointers)
-        {
-            debug_assert_eq!(ty, self.infcx.resolve_vars_if_possible(ty));
-            // NOTE: we may still need to normalize the built-in deref in case
-            // we have some type like `&<Ty as Trait>::Assoc`, since users of
-            // autoderef expect this type to have been structurally normalized.
-            if self.infcx.next_trait_solver()
-                && let ty::Alias(..) = ty.kind()
-            {
-                let (normalized_ty, obligations) = self.structurally_normalize(ty)?;
-                self.state.obligations.extend(obligations);
-                (AutoderefKind::Builtin, normalized_ty)
+        let (kind, new_ty) =
+            if let Some(ty) = self.state.cur_ty.builtin_deref(self.include_raw_pointers) {
+                debug_assert_eq!(ty, self.infcx.resolve_vars_if_possible(ty));
+                // NOTE: we may still need to normalize the built-in deref in case
+                // we have some type like `&<Ty as Trait>::Assoc`, since users of
+                // autoderef expect this type to have been structurally normalized.
+                if self.infcx.next_trait_solver()
+                    && let ty::Alias(..) = ty.kind()
+                {
+                    let (normalized_ty, obligations) = self.structurally_normalize(ty)?;
+                    self.state.obligations.extend(obligations);
+                    (AutoderefKind::Builtin, normalized_ty)
+                } else {
+                    (AutoderefKind::Builtin, ty)
+                }
+            } else if let Some(ty) = self.overloaded_deref_ty(self.state.cur_ty) {
+                // The overloaded deref check already normalizes the pointee type.
+                (AutoderefKind::Overloaded, ty)
             } else {
-                (AutoderefKind::Builtin, ty)
-            }
-        } else if let Some(ty) = self.overloaded_deref_ty(self.state.cur_ty) {
-            // The overloaded deref check already normalizes the pointee type.
-            (AutoderefKind::Overloaded, ty)
-        } else {
-            return None;
-        };
+                return None;
+            };
 
         self.state.steps.push((self.state.cur_ty, kind));
         debug!(

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -624,10 +624,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// returns a type of `&T`, but the actual type we assign to the
     /// *expression* is `T`. So this function just peels off the return
     /// type by one layer to yield `T`.
-    pub(crate) fn make_overloaded_place_return_type(
-        &self,
-        method: MethodCallee<'tcx>,
-    ) -> ty::TypeAndMut<'tcx> {
+    pub(crate) fn make_overloaded_place_return_type(&self, method: MethodCallee<'tcx>) -> Ty<'tcx> {
         // extract method return type, which will be &T;
         let ret_ty = method.sig.output();
 

compiler/rustc_hir_typeck/src/mem_categorization.rs

@@ -207,7 +207,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
                     // but what we want here is the type of the underlying value being borrowed.
                     // So peel off one-level, turning the &T into T.
                     match base_ty.builtin_deref(false) {
-                        Some(t) => Ok(t.ty),
+                        Some(ty) => Ok(ty),
                         None => {
                             debug!("By-ref binding of non-derefable type");
                             Err(())
@@ -485,7 +485,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
     ) -> McResult<PlaceWithHirId<'tcx>> {
         let base_curr_ty = base_place.place.ty();
         let deref_ty = match base_curr_ty.builtin_deref(true) {
-            Some(mt) => mt.ty,
+            Some(pointee_ty) => pointee_ty,
             None => {
                 debug!("explicit deref of non-derefable type: {:?}", base_curr_ty);
                 return Err(());