Rollup merge of #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``

Author: matthiaskrgr

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -110,7 +110,7 @@ pub(crate) fn codegen_const_value<'tcx>(
                 if fx.clif_type(layout.ty).is_some() {
                     return CValue::const_val(fx, layout, int);
                 } else {
-                    let raw_val = int.size().truncate(int.assert_bits(int.size()));
+                    let raw_val = int.size().truncate(int.to_bits(int.size()));
                     let val = match int.size().bytes() {
                         1 => fx.bcx.ins().iconst(types::I8, raw_val as i64),
                         2 => fx.bcx.ins().iconst(types::I16, raw_val as i64),
@@ -501,12 +501,12 @@ pub(crate) fn mir_operand_get_const_val<'tcx>(
                                             Ordering::Equal => scalar_int,
                                             Ordering::Less => match ty.kind() {
                                                 ty::Uint(_) => ScalarInt::try_from_uint(
-                                                    scalar_int.assert_uint(scalar_int.size()),
+                                                    scalar_int.to_uint(scalar_int.size()),
                                                     fx.layout_of(*ty).size,
                                                 )
                                                 .unwrap(),
                                                 ty::Int(_) => ScalarInt::try_from_int(
-                                                    scalar_int.assert_int(scalar_int.size()),
+                                                    scalar_int.to_int(scalar_int.size()),
                                                     fx.layout_of(*ty).size,
                                                 )
                                                 .unwrap(),

compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs

@@ -902,7 +902,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
                         .span_fatal(span, "Index argument for `_mm_cmpestri` is not a constant");
                 };
 
-            let imm8 = imm8.try_to_u8().unwrap_or_else(|_| panic!("kind not scalar: {:?}", imm8));
+            let imm8 = imm8.to_u8();
 
             codegen_inline_asm_inner(
                 fx,
@@ -955,7 +955,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
                         .span_fatal(span, "Index argument for `_mm_cmpestrm` is not a constant");
                 };
 
-            let imm8 = imm8.try_to_u8().unwrap_or_else(|_| panic!("kind not scalar: {:?}", imm8));
+            let imm8 = imm8.to_u8();
 
             codegen_inline_asm_inner(
                 fx,
@@ -1003,7 +1003,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
                     );
                 };
 
-            let imm8 = imm8.try_to_u8().unwrap_or_else(|_| panic!("kind not scalar: {:?}", imm8));
+            let imm8 = imm8.to_u8();
 
             codegen_inline_asm_inner(
                 fx,
@@ -1040,7 +1040,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
                     );
                 };
 
-            let imm8 = imm8.try_to_u8().unwrap_or_else(|_| panic!("kind not scalar: {:?}", imm8));
+            let imm8 = imm8.to_u8();
 
             codegen_inline_asm_inner(
                 fx,
@@ -1195,7 +1195,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
                     .span_fatal(span, "Func argument for `_mm_sha1rnds4_epu32` is not a constant");
             };
 
-            let func = func.try_to_u8().unwrap_or_else(|_| panic!("kind not scalar: {:?}", func));
+            let func = func.to_u8();
 
             codegen_inline_asm_inner(
                 fx,

compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs

@@ -147,8 +147,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
 
             let total_len = lane_count * 2;
 
-            let indexes =
-                idx.iter().map(|idx| idx.unwrap_leaf().try_to_u32().unwrap()).collect::<Vec<u32>>();
+            let indexes = idx.iter().map(|idx| idx.unwrap_leaf().to_u32()).collect::<Vec<u32>>();
 
             for &idx in &indexes {
                 assert!(u64::from(idx) < total_len, "idx {} out of range 0..{}", idx, total_len);
@@ -282,9 +281,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                 fx.tcx.dcx().span_fatal(span, "Index argument for `simd_insert` is not a constant");
             };
 
-            let idx: u32 = idx_const
-                .try_to_u32()
-                .unwrap_or_else(|_| panic!("kind not scalar: {:?}", idx_const));
+            let idx: u32 = idx_const.to_u32();
             let (lane_count, _lane_ty) = base.layout().ty.simd_size_and_type(fx.tcx);
             if u64::from(idx) >= lane_count {
                 fx.tcx.dcx().span_fatal(
@@ -330,9 +327,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                 return;
             };
 
-            let idx = idx_const
-                .try_to_u32()
-                .unwrap_or_else(|_| panic!("kind not scalar: {:?}", idx_const));
+            let idx = idx_const.to_u32();
             let (lane_count, _lane_ty) = v.layout().ty.simd_size_and_type(fx.tcx);
             if u64::from(idx) >= lane_count {
                 fx.tcx.dcx().span_fatal(

compiler/rustc_codegen_cranelift/src/value_and_place.rs

@@ -327,7 +327,7 @@ impl<'tcx> CValue<'tcx> {
 
         let val = match layout.ty.kind() {
             ty::Uint(UintTy::U128) | ty::Int(IntTy::I128) => {
-                let const_val = const_val.assert_bits(layout.size);
+                let const_val = const_val.to_bits(layout.size);
                 let lsb = fx.bcx.ins().iconst(types::I64, const_val as u64 as i64);
                 let msb = fx.bcx.ins().iconst(types::I64, (const_val >> 64) as u64 as i64);
                 fx.bcx.ins().iconcat(lsb, msb)
@@ -339,7 +339,7 @@ impl<'tcx> CValue<'tcx> {
             | ty::Ref(..)
             | ty::RawPtr(..)
             | ty::FnPtr(..) => {
-                let raw_val = const_val.size().truncate(const_val.assert_bits(layout.size));
+                let raw_val = const_val.size().truncate(const_val.to_bits(layout.size));
                 fx.bcx.ins().iconst(clif_ty, raw_val as i64)
             }
             ty::Float(FloatTy::F32) => {

compiler/rustc_codegen_gcc/src/common.rs

@@ -166,7 +166,7 @@ impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
             Scalar::Int(int) => {
-                let data = int.assert_bits(layout.size(self));
+                let data = int.to_bits(layout.size(self));
 
                 // FIXME(antoyo): there's some issues with using the u128 code that follows, so hard-code
                 // the paths for floating-point values.

compiler/rustc_codegen_llvm/src/common.rs

@@ -244,7 +244,7 @@ impl<'ll, 'tcx> ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
             Scalar::Int(int) => {
-                let data = int.assert_bits(layout.size(self));
+                let data = int.to_bits(layout.size(self));
                 let llval = self.const_uint_big(self.type_ix(bitsize), data);
                 if matches!(layout.primitive(), Pointer(_)) {
                     unsafe { llvm::LLVMConstIntToPtr(llval, llty) }

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -1223,7 +1223,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
             .iter()
             .enumerate()
             .map(|(arg_idx, val)| {
-                let idx = val.unwrap_leaf().try_to_i32().unwrap();
+                let idx = val.unwrap_leaf().to_i32();
                 if idx >= i32::try_from(total_len).unwrap() {
                     bx.sess().dcx().emit_err(InvalidMonomorphization::SimdIndexOutOfBounds {
                         span,

compiler/rustc_codegen_ssa/src/common.rs

@@ -163,7 +163,7 @@ pub fn asm_const_to_str<'tcx>(
     let mir::ConstValue::Scalar(scalar) = const_value else {
         span_bug!(sp, "expected Scalar for promoted asm const, but got {:#?}", const_value)
     };
-    let value = scalar.assert_bits(ty_and_layout.size);
+    let value = scalar.assert_scalar_int().to_bits(ty_and_layout.size);
     match ty_and_layout.ty.kind() {
         ty::Uint(_) => value.to_string(),
         ty::Int(int_ty) => match int_ty.normalize(tcx.sess.target.pointer_width) {

compiler/rustc_const_eval/src/const_eval/valtrees.rs

@@ -95,10 +95,10 @@ fn const_to_valtree_inner<'tcx>(
         }
         ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
             let val = ecx.read_immediate(place)?;
-            let val = val.to_scalar();
+            let val = val.to_scalar_int().unwrap();
             *num_nodes += 1;
 
-            Ok(ty::ValTree::Leaf(val.assert_int()))
+            Ok(ty::ValTree::Leaf(val))
         }
 
         ty::Pat(base, ..) => {
@@ -125,7 +125,7 @@ fn const_to_valtree_inner<'tcx>(
             let val = val.to_scalar();
             // We are in the CTFE machine, so ptr-to-int casts will fail.
             // This can only be `Ok` if `val` already is an integer.
-            let Ok(val) = val.try_to_int() else {
+            let Ok(val) = val.try_to_scalar_int() else {
                 return Err(ValTreeCreationError::NonSupportedType);
             };
             // It's just a ScalarInt!
@@ -411,7 +411,7 @@ fn valtree_into_mplace<'tcx>(
                 ty::Adt(def, _) if def.is_enum() => {
                     // First element of valtree corresponds to variant
                     let scalar_int = branches[0].unwrap_leaf();
-                    let variant_idx = VariantIdx::from_u32(scalar_int.try_to_u32().unwrap());
+                    let variant_idx = VariantIdx::from_u32(scalar_int.to_u32());
                     let variant = def.variant(variant_idx);
                     debug!(?variant);
 

compiler/rustc_const_eval/src/interpret/discriminant.rs

@@ -123,14 +123,14 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 // (`tag_bits` itself is only used for error messages below.)
                 let tag_bits = tag_val
                     .to_scalar()
-                    .try_to_int()
+                    .try_to_scalar_int()
                     .map_err(|dbg_val| err_ub!(InvalidTag(dbg_val)))?
-                    .assert_bits(tag_layout.size);
+                    .to_bits(tag_layout.size);
                 // Cast bits from tag layout to discriminant layout.
                 // After the checks we did above, this cannot fail, as
                 // discriminants are int-like.
                 let discr_val = self.int_to_int_or_float(&tag_val, discr_layout).unwrap();
-                let discr_bits = discr_val.to_scalar().assert_bits(discr_layout.size);
+                let discr_bits = discr_val.to_scalar().to_bits(discr_layout.size)?;
                 // Convert discriminant to variant index, and catch invalid discriminants.
                 let index = match *ty.kind() {
                     ty::Adt(adt, _) => {
@@ -152,7 +152,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 // discriminant (encoded in niche/tag) and variant index are the same.
                 let variants_start = niche_variants.start().as_u32();
                 let variants_end = niche_variants.end().as_u32();
-                let variant = match tag_val.try_to_int() {
+                let variant = match tag_val.try_to_scalar_int() {
                     Err(dbg_val) => {
                         // So this is a pointer then, and casting to an int failed.
                         // Can only happen during CTFE.
@@ -167,15 +167,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                         untagged_variant
                     }
                     Ok(tag_bits) => {
-                        let tag_bits = tag_bits.assert_bits(tag_layout.size);
+                        let tag_bits = tag_bits.to_bits(tag_layout.size);
                         // We need to use machine arithmetic to get the relative variant idx:
                         // variant_index_relative = tag_val - niche_start_val
                         let tag_val = ImmTy::from_uint(tag_bits, tag_layout);
                         let niche_start_val = ImmTy::from_uint(niche_start, tag_layout);
                         let variant_index_relative_val =
                             self.binary_op(mir::BinOp::Sub, &tag_val, &niche_start_val)?;
                         let variant_index_relative =
-                            variant_index_relative_val.to_scalar().assert_bits(tag_val.layout.size);
+                            variant_index_relative_val.to_scalar().to_bits(tag_val.layout.size)?;
                         // Check if this is in the range that indicates an actual discriminant.
                         if variant_index_relative <= u128::from(variants_end - variants_start) {
                             let variant_index_relative = u32::try_from(variant_index_relative)
@@ -294,8 +294,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                     ImmTy::from_uint(variant_index_relative, tag_layout);
                 let tag = self
                     .binary_op(mir::BinOp::Add, &variant_index_relative_val, &niche_start_val)?
-                    .to_scalar()
-                    .assert_int();
+                    .to_scalar_int()?;
                 Ok(Some((tag, tag_field)))
             }
         }

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -519,7 +519,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         // `x % y != 0` or `y == 0` or `x == T::MIN && y == -1`.
         // First, check x % y != 0 (or if that computation overflows).
         let rem = self.binary_op(BinOp::Rem, a, b)?;
-        if rem.to_scalar().assert_bits(a.layout.size) != 0 {
+        if rem.to_scalar().to_bits(a.layout.size)? != 0 {
             throw_ub_custom!(
                 fluent::const_eval_exact_div_has_remainder,
                 a = format!("{a}"),

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -1344,7 +1344,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     /// Test if this value might be null.
     /// If the machine does not support ptr-to-int casts, this is conservative.
     pub fn scalar_may_be_null(&self, scalar: Scalar<M::Provenance>) -> InterpResult<'tcx, bool> {
-        Ok(match scalar.try_to_int() {
+        Ok(match scalar.try_to_scalar_int() {
             Ok(int) => int.is_null(),
             Err(_) => {
                 // Can only happen during CTFE.

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -87,6 +87,12 @@ impl<Prov: Provenance> Immediate<Prov> {
         }
     }
 
+    #[inline]
+    #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
+    pub fn to_scalar_int(self) -> ScalarInt {
+        self.to_scalar().try_to_scalar_int().unwrap()
+    }
+
     #[inline]
     #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980)
     pub fn to_scalar_pair(self) -> (Scalar<Prov>, Scalar<Prov>) {
@@ -219,19 +225,11 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
         Self::from_scalar(Scalar::from(s), layout)
     }
 
-    #[inline]
-    pub fn try_from_uint(i: impl Into<u128>, layout: TyAndLayout<'tcx>) -> Option<Self> {
-        Some(Self::from_scalar(Scalar::try_from_uint(i, layout.size)?, layout))
-    }
     #[inline]
     pub fn from_uint(i: impl Into<u128>, layout: TyAndLayout<'tcx>) -> Self {
         Self::from_scalar(Scalar::from_uint(i, layout.size), layout)
     }
 
-    #[inline]
-    pub fn try_from_int(i: impl Into<i128>, layout: TyAndLayout<'tcx>) -> Option<Self> {
-        Some(Self::from_scalar(Scalar::try_from_int(i, layout.size)?, layout))
-    }
     #[inline]
     pub fn from_int(i: impl Into<i128>, layout: TyAndLayout<'tcx>) -> Self {
         Self::from_scalar(Scalar::from_int(i, layout.size), layout)
@@ -276,7 +274,8 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
     #[inline]
     pub fn to_const_int(self) -> ConstInt {
         assert!(self.layout.ty.is_integral());
-        let int = self.to_scalar().assert_int();
+        let int = self.imm.to_scalar_int();
+        assert_eq!(int.size(), self.layout.size);
         ConstInt::new(int, self.layout.ty.is_signed(), self.layout.ty.is_ptr_sized_integral())
     }
 

compiler/rustc_const_eval/src/interpret/operator.rs

@@ -95,10 +95,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let l = left.to_scalar_int()?;
         let r = right.to_scalar_int()?;
         // Prepare to convert the values to signed or unsigned form.
-        let l_signed = || l.assert_int(left.layout.size);
-        let l_unsigned = || l.assert_uint(left.layout.size);
-        let r_signed = || r.assert_int(right.layout.size);
-        let r_unsigned = || r.assert_uint(right.layout.size);
+        let l_signed = || l.to_int(left.layout.size);
+        let l_unsigned = || l.to_uint(left.layout.size);
+        let r_signed = || r.to_int(right.layout.size);
+        let r_unsigned = || r.to_uint(right.layout.size);
 
         let throw_ub_on_overflow = match bin_op {
             AddUnchecked => Some(sym::unchecked_add),

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -653,8 +653,8 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
         let WrappingRange { start, end } = valid_range;
         let max_value = size.unsigned_int_max();
         assert!(end <= max_value);
-        let bits = match scalar.try_to_int() {
-            Ok(int) => int.assert_bits(size),
+        let bits = match scalar.try_to_scalar_int() {
+            Ok(int) => int.to_bits(size),
             Err(_) => {
                 // So this is a pointer then, and casting to an int failed.
                 // Can only happen during CTFE.

compiler/rustc_hir_typeck/src/pat.rs

@@ -2385,11 +2385,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         min_len: u64,
     ) -> (Option<Ty<'tcx>>, Ty<'tcx>) {
         let len = match len.eval(self.tcx, self.param_env, span) {
-            // FIXME(BoxyUwU): Assert the `Ty` is a `usize`?
             Ok((_, val)) => val
                 .try_to_scalar()
-                .and_then(|scalar| scalar.try_to_int().ok())
-                .and_then(|int| int.try_to_target_usize(self.tcx).ok()),
+                .and_then(|scalar| scalar.try_to_scalar_int().ok())
+                .map(|int| int.to_target_usize(self.tcx)),
             Err(ErrorHandled::Reported(..)) => {
                 let guar = self.error_scrutinee_unfixed_length(span);
                 return (Some(Ty::new_error(self.tcx, guar)), arr_ty);