Rollup merge of rust-lang#124957 - compiler-errors:builtin-deref, r=michaelwoerister

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.

Author: matthiaskrgr

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) {

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);
         }

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);

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};

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);

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 {

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)

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 =