Rollup merge of rust-lang#126159 - RalfJung:scalarint-size-mismatch, …

…r=oli-obk

ScalarInt: size mismatches are a bug, do not delay the panic

Cc [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/146212-t-compiler.2Fconst-eval/topic/Why.20are.20ScalarInt.20to.20iN.2FuN.20methods.20fallible.3F)

r? ``@oli-obk``

clippy_lints/src/large_const_arrays.rs

@@ -55,7 +55,7 @@ impl<'tcx> LateLintPass<'tcx> for LargeConstArrays {
             && let ty = cx.tcx.type_of(item.owner_id).instantiate_identity()
             && let ty::Array(element_type, cst) = ty.kind()
             && let ConstKind::Value(_, ty::ValTree::Leaf(element_count)) = cst.kind()
-            && let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
+            && let element_count = element_count.to_target_usize(cx.tcx)
             && let Ok(element_size) = cx.layout_of(*element_type).map(|l| l.size.bytes())
             && self.maximum_allowed_size < u128::from(element_count) * u128::from(element_size)
         {

clippy_lints/src/large_stack_arrays.rs

@@ -65,7 +65,7 @@ impl<'tcx> LateLintPass<'tcx> for LargeStackArrays {
             && !self.is_from_vec_macro(cx, expr.span)
             && let ty::Array(element_type, cst) = cx.typeck_results().expr_ty(expr).kind()
             && let ConstKind::Value(_, ty::ValTree::Leaf(element_count)) = cst.kind()
-            && let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
+            && let element_count = element_count.to_target_usize(cx.tcx)
             && let Ok(element_size) = cx.layout_of(*element_type).map(|l| l.size.bytes())
             && !cx.tcx.hir().parent_iter(expr.hir_id).any(|(_, node)| {
                 matches!(

clippy_lints/src/non_copy_const.rs

@@ -199,7 +199,7 @@ impl<'tcx> NonCopyConst<'tcx> {
                 .any(|field| Self::is_value_unfrozen_raw_inner(cx, *field, ty)),
             ty::Adt(def, args) if def.is_enum() => {
                 let (&variant_index, fields) = val.unwrap_branch().split_first().unwrap();
-                let variant_index = VariantIdx::from_u32(variant_index.unwrap_leaf().try_to_u32().ok().unwrap());
+                let variant_index = VariantIdx::from_u32(variant_index.unwrap_leaf().to_u32());
                 fields
                     .iter()
                     .copied()

clippy_lints/src/zero_repeat_side_effects.rs

@@ -56,8 +56,7 @@ impl LateLintPass<'_> for ZeroRepeatSideEffects {
         } else if let ExprKind::Repeat(inner_expr, _) = expr.kind
             && let ty::Array(_, cst) = cx.typeck_results().expr_ty(expr).kind()
             && let ConstKind::Value(_, ty::ValTree::Leaf(element_count)) = cst.kind()
-            && let Ok(element_count) = element_count.try_to_target_usize(cx.tcx)
-            && element_count == 0
+            && element_count.to_target_usize(cx.tcx) == 0
         {
             inner_check(cx, expr, inner_expr, false);
         }

clippy_utils/src/consts.rs

@@ -810,14 +810,14 @@ pub fn mir_to_const<'tcx>(lcx: &LateContext<'tcx>, result: mir::Const<'tcx>) ->
         (ConstValue::Scalar(Scalar::Int(int)), _) => match result.ty().kind() {
             ty::Adt(adt_def, _) if adt_def.is_struct() => Some(Constant::Adt(result)),
             ty::Bool => Some(Constant::Bool(int == ScalarInt::TRUE)),
-            ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.assert_bits(int.size()))),
+            ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.to_bits(int.size()))),
             ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(
                 int.try_into().expect("invalid f32 bit representation"),
             ))),
             ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(
                 int.try_into().expect("invalid f64 bit representation"),
             ))),
-            ty::RawPtr(_, _) => Some(Constant::RawPtr(int.assert_bits(int.size()))),
+            ty::RawPtr(_, _) => Some(Constant::RawPtr(int.to_bits(int.size()))),
             _ => None,
         },
         (_, ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Str) => {

clippy_utils/src/ty.rs

@@ -23,7 +23,7 @@ use rustc_middle::ty::{
 };
 use rustc_span::symbol::Ident;
 use rustc_span::{sym, Span, Symbol, DUMMY_SP};
-use rustc_target::abi::{Size, VariantIdx};
+use rustc_target::abi::VariantIdx;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
 use rustc_trait_selection::traits::{Obligation, ObligationCause};
@@ -865,22 +865,8 @@ impl core::ops::Add<u32> for EnumValue {
 pub fn read_explicit_enum_value(tcx: TyCtxt<'_>, id: DefId) -> Option<EnumValue> {
     if let Ok(ConstValue::Scalar(Scalar::Int(value))) = tcx.const_eval_poly(id) {
         match tcx.type_of(id).instantiate_identity().kind() {
-            ty::Int(_) => Some(EnumValue::Signed(match value.size().bytes() {
-                1 => i128::from(value.assert_bits(Size::from_bytes(1)) as u8 as i8),
-                2 => i128::from(value.assert_bits(Size::from_bytes(2)) as u16 as i16),
-                4 => i128::from(value.assert_bits(Size::from_bytes(4)) as u32 as i32),
-                8 => i128::from(value.assert_bits(Size::from_bytes(8)) as u64 as i64),
-                16 => value.assert_bits(Size::from_bytes(16)) as i128,
-                _ => return None,
-            })),
-            ty::Uint(_) => Some(EnumValue::Unsigned(match value.size().bytes() {
-                1 => value.assert_bits(Size::from_bytes(1)),
-                2 => value.assert_bits(Size::from_bytes(2)),
-                4 => value.assert_bits(Size::from_bytes(4)),
-                8 => value.assert_bits(Size::from_bytes(8)),
-                16 => value.assert_bits(Size::from_bytes(16)),
-                _ => return None,
-            })),
+            ty::Int(_) => Some(EnumValue::Signed(value.to_int(value.size()))),
+            ty::Uint(_) => Some(EnumValue::Unsigned(value.to_uint(value.size()))),
             _ => None,
         }
     } else {