Auto merge of #130950 - compiler-errors:yeet-eval, r=BoxyUwU

Continue to get rid of `ty::Const::{try_}eval*`

This PR mostly does:

* Removes all of the `try_eval_*` and `eval_*` helpers from `ty::Const`, and replace their usages with `try_to_*`.
* Remove `ty::Const::eval`.
* Rename `ty::Const::normalize` to `ty::Const::normalize_internal`. This function is still used in the normalization code itself.
* Fix some weirdness around the `TransmuteFrom` goal.

I'm happy to split it out further; for example, I could probably land the first part which removes the helpers, or the changes to codegen which are more obvious than the changes to tools.

r? BoxyUwU

Part of #130704

compiler/rustc_borrowck/src/lib.rs

@@ -187,10 +187,10 @@ fn do_mir_borrowck<'tcx>(
 
     let location_table = LocationTable::new(body);
 
-    let move_data = MoveData::gather_moves(body, tcx, param_env, |_| true);
+    let move_data = MoveData::gather_moves(body, tcx, |_| true);
     let promoted_move_data = promoted
         .iter_enumerated()
-        .map(|(idx, body)| (idx, MoveData::gather_moves(body, tcx, param_env, |_| true)));
+        .map(|(idx, body)| (idx, MoveData::gather_moves(body, tcx, |_| true)));
 
     let mut flow_inits = MaybeInitializedPlaces::new(tcx, body, &move_data)
         .into_engine(tcx, body)

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1128,7 +1128,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             }
             let projected_ty = curr_projected_ty.projection_ty_core(
                 tcx,
-                self.param_env,
                 proj,
                 |this, field, ()| {
                     let ty = this.field_ty(tcx, field);
@@ -1919,7 +1918,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 // than 1.
                 // If the length is larger than 1, the repeat expression will need to copy the
                 // element, so we require the `Copy` trait.
-                if len.try_eval_target_usize(tcx, self.param_env).map_or(true, |len| len > 1) {
+                if len.try_to_target_usize(tcx).is_none_or(|len| len > 1) {
                     match operand {
                         Operand::Copy(..) | Operand::Constant(..) => {
                             // These are always okay: direct use of a const, or a value that can evidently be copied.

compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs

@@ -133,6 +133,7 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                 .expect_const()
                 .try_to_valtree()
                 .expect("expected monomorphic const in codegen")
+                .0
                 .unwrap_branch();
 
             assert_eq!(x.layout(), y.layout());
@@ -806,8 +807,10 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                 ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => m.load_scalar(fx),
                 ty::Array(elem, len)
                     if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
-                        && len.try_eval_target_usize(fx.tcx, ty::ParamEnv::reveal_all())
-                            == Some(expected_bytes) =>
+                        && len
+                            .try_to_target_usize(fx.tcx)
+                            .expect("expected monomorphic const in codegen")
+                            == expected_bytes =>
                 {
                     m.force_stack(fx).0.load(
                         fx,
@@ -907,8 +910,10 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
                 ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => {}
                 ty::Array(elem, len)
                     if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
-                        && len.try_eval_target_usize(fx.tcx, ty::ParamEnv::reveal_all())
-                            == Some(expected_bytes) => {}
+                        && len
+                            .try_to_target_usize(fx.tcx)
+                            .expect("expected monomorphic const in codegen")
+                            == expected_bytes => {}
                 _ => {
                     fx.tcx.dcx().span_fatal(
                         span,

compiler/rustc_codegen_gcc/src/intrinsic/simd.rs

@@ -76,8 +76,10 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(
             ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => args[0].immediate(),
             ty::Array(elem, len)
                 if matches!(*elem.kind(), ty::Uint(ty::UintTy::U8))
-                    && len.try_eval_target_usize(bx.tcx, ty::ParamEnv::reveal_all())
-                        == Some(expected_bytes) =>
+                    && len
+                        .try_to_target_usize(bx.tcx)
+                        .expect("expected monomorphic const in codegen")
+                        == expected_bytes =>
             {
                 let place = PlaceRef::alloca(bx, args[0].layout);
                 args[0].val.store(bx, place);
@@ -696,8 +698,10 @@ pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(
             }
             ty::Array(elem, len)
                 if matches!(*elem.kind(), ty::Uint(ty::UintTy::U8))
-                    && len.try_eval_target_usize(bx.tcx, ty::ParamEnv::reveal_all())
-                        == Some(expected_bytes) =>
+                    && len
+                        .try_to_target_usize(bx.tcx)
+                        .expect("expected monomorphic const in codegen")
+                        == expected_bytes =>
             {
                 // Zero-extend iN to the array length:
                 let ze = bx.zext(result, bx.type_ix(expected_bytes * 8));

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -1179,8 +1179,10 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
             ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => args[0].immediate(),
             ty::Array(elem, len)
                 if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
-                    && len.try_eval_target_usize(bx.tcx, ty::ParamEnv::reveal_all())
-                        == Some(expected_bytes) =>
+                    && len
+                        .try_to_target_usize(bx.tcx)
+                        .expect("expected monomorphic const in codegen")
+                        == expected_bytes =>
             {
                 let place = PlaceRef::alloca(bx, args[0].layout);
                 args[0].val.store(bx, place);
@@ -1245,12 +1247,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
     }
 
     if name == sym::simd_shuffle_generic {
-        let idx = fn_args[2]
-            .expect_const()
-            .eval(tcx, ty::ParamEnv::reveal_all(), span)
-            .unwrap()
-            .1
-            .unwrap_branch();
+        let idx = fn_args[2].expect_const().try_to_valtree().unwrap().0.unwrap_branch();
         let n = idx.len() as u64;
 
         let (out_len, out_ty) = require_simd!(ret_ty, SimdReturn);
@@ -1469,8 +1466,10 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
             }
             ty::Array(elem, len)
                 if matches!(elem.kind(), ty::Uint(ty::UintTy::U8))
-                    && len.try_eval_target_usize(bx.tcx, ty::ParamEnv::reveal_all())
-                        == Some(expected_bytes) =>
+                    && len
+                        .try_to_target_usize(bx.tcx)
+                        .expect("expected monomorphic const in codegen")
+                        == expected_bytes =>
             {
                 // Zero-extend iN to the array length:
                 let ze = bx.zext(i_, bx.type_ix(expected_bytes * 8));

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -23,7 +23,6 @@ use rustc_middle::ty::layout::{IntegerExt, TyAndLayout};
 use rustc_middle::ty::{
     self, ExistentialProjection, GenericArgKind, GenericArgsRef, ParamEnv, Ty, TyCtxt,
 };
-use rustc_span::DUMMY_SP;
 use rustc_target::abi::Integer;
 use smallvec::SmallVec;
 
@@ -685,21 +684,25 @@ fn push_const_param<'tcx>(tcx: TyCtxt<'tcx>, ct: ty::Const<'tcx>, output: &mut S
         ty::ConstKind::Param(param) => {
             write!(output, "{}", param.name)
         }
-        ty::ConstKind::Value(ty, _) => {
+        ty::ConstKind::Value(ty, valtree) => {
             match ty.kind() {
                 ty::Int(ity) => {
                     // FIXME: directly extract the bits from a valtree instead of evaluating an
                     // already evaluated `Const` in order to get the bits.
-                    let bits = ct.eval_bits(tcx, ty::ParamEnv::reveal_all());
+                    let bits = ct
+                        .try_to_bits(tcx, ty::ParamEnv::reveal_all())
+                        .expect("expected monomorphic const in codegen");
                     let val = Integer::from_int_ty(&tcx, *ity).size().sign_extend(bits) as i128;
                     write!(output, "{val}")
                 }
                 ty::Uint(_) => {
-                    let val = ct.eval_bits(tcx, ty::ParamEnv::reveal_all());
+                    let val = ct
+                        .try_to_bits(tcx, ty::ParamEnv::reveal_all())
+                        .expect("expected monomorphic const in codegen");
                     write!(output, "{val}")
                 }
                 ty::Bool => {
-                    let val = ct.try_eval_bool(tcx, ty::ParamEnv::reveal_all()).unwrap();
+                    let val = ct.try_to_bool().expect("expected monomorphic const in codegen");
                     write!(output, "{val}")
                 }
                 _ => {
@@ -711,8 +714,9 @@ fn push_const_param<'tcx>(tcx: TyCtxt<'tcx>, ct: ty::Const<'tcx>, output: &mut S
                     // avoiding collisions and will make the emitted type names shorter.
                     let hash_short = tcx.with_stable_hashing_context(|mut hcx| {
                         let mut hasher = StableHasher::new();
-                        let ct = ct.eval(tcx, ty::ParamEnv::reveal_all(), DUMMY_SP).unwrap();
-                        hcx.while_hashing_spans(false, |hcx| ct.hash_stable(hcx, &mut hasher));
+                        hcx.while_hashing_spans(false, |hcx| {
+                            (ty, valtree).hash_stable(hcx, &mut hasher)
+                        });
                         hasher.finish::<Hash64>()
                     });
 

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -43,7 +43,7 @@ pub(crate) fn try_destructure_mir_constant_for_user_output<'tcx>(
 
     // We go to `usize` as we cannot allocate anything bigger anyway.
     let (field_count, variant, down) = match ty.kind() {
-        ty::Array(_, len) => (len.eval_target_usize(tcx.tcx, param_env) as usize, None, op),
+        ty::Array(_, len) => (len.try_to_target_usize(tcx.tcx)? as usize, None, op),
         ty::Adt(def, _) if def.variants().is_empty() => {
             return None;
         }

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -391,7 +391,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let ptr = self.read_pointer(src)?;
                 let val = Immediate::new_slice(
                     ptr,
-                    length.eval_target_usize(*self.tcx, self.param_env),
+                    length
+                        .try_to_target_usize(*self.tcx)
+                        .expect("expected monomorphic const in const eval"),
                     self,
                 );
                 self.write_immediate(val, dest)

compiler/rustc_hir_analysis/src/check/check.rs

@@ -1037,7 +1037,11 @@ fn check_simd(tcx: TyCtxt<'_>, sp: Span, def_id: LocalDefId) {
             return;
         }
 
-        if let Some(len) = len_const.try_eval_target_usize(tcx, tcx.param_env(def.did())) {
+        // FIXME(repr_simd): This check is nice, but perhaps unnecessary due to the fact
+        // we do not expect users to implement their own `repr(simd)` types. If they could,
+        // this check is easily side-steppable by hiding the const behind normalization.
+        // The consequence is that the error is, in general, only observable post-mono.
+        if let Some(len) = len_const.try_to_target_usize(tcx) {
             if len == 0 {
                 struct_span_code_err!(tcx.dcx(), sp, E0075, "SIMD vector cannot be empty").emit();
                 return;

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -76,9 +76,7 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
 
                 let (size, ty) = match elem_ty.kind() {
                     ty::Array(ty, len) => {
-                        if let Some(len) =
-                            len.try_eval_target_usize(self.tcx, self.tcx.param_env(adt.did()))
-                        {
+                        if let Some(len) = len.try_to_target_usize(self.tcx) {
                             (len, *ty)
                         } else {
                             return None;

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -1487,7 +1487,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
             }
         } else if self.tcx.features().generic_const_exprs {
-            ct.normalize(self.tcx, self.param_env)
+            ct.normalize_internal(self.tcx, self.param_env)
         } else {
             ct
         }

compiler/rustc_lint/src/builtin.rs

@@ -2601,7 +2601,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                     ty.tuple_fields().iter().find_map(|field| ty_find_init_error(cx, field, init))
                 }
                 Array(ty, len) => {
-                    if matches!(len.try_eval_target_usize(cx.tcx, cx.param_env), Some(v) if v > 0) {
+                    if matches!(len.try_to_target_usize(cx.tcx), Some(v) if v > 0) {
                         // Array length known at array non-empty -- recurse.
                         ty_find_init_error(cx, *ty, init)
                     } else {

compiler/rustc_lint/src/unused.rs

@@ -346,7 +346,7 @@ impl<'tcx> LateLintPass<'tcx> for UnusedResults {
                         None
                     }
                 }
-                ty::Array(ty, len) => match len.try_eval_target_usize(cx.tcx, cx.param_env) {
+                ty::Array(ty, len) => match len.try_to_target_usize(cx.tcx) {
                     // If the array is empty we don't lint, to avoid false positives
                     Some(0) | None => None,
                     // If the array is definitely non-empty, we can do `#[must_use]` checking.

compiler/rustc_middle/src/mir/consts.rs

@@ -1,5 +1,6 @@
 use std::fmt::{self, Debug, Display, Formatter};
 
+use either::Either;
 use rustc_hir::def_id::DefId;
 use rustc_macros::{HashStable, Lift, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
 use rustc_session::RemapFileNameExt;
@@ -320,8 +321,14 @@ impl<'tcx> Const<'tcx> {
             Const::Ty(_, c) => {
                 // We want to consistently have a "clean" value for type system constants (i.e., no
                 // data hidden in the padding), so we always go through a valtree here.
-                let (ty, val) = c.eval(tcx, param_env, span)?;
-                Ok(tcx.valtree_to_const_val((ty, val)))
+                match c.eval_valtree(tcx, param_env, span) {
+                    Ok((ty, val)) => Ok(tcx.valtree_to_const_val((ty, val))),
+                    Err(Either::Left(_bad_ty)) => Err(tcx
+                        .dcx()
+                        .delayed_bug("`mir::Const::eval` called on a non-valtree-compatible type")
+                        .into()),
+                    Err(Either::Right(e)) => Err(e),
+                }
             }
             Const::Unevaluated(uneval, _) => {
                 // FIXME: We might want to have a `try_eval`-like function on `Unevaluated`

compiler/rustc_middle/src/mir/tcx.rs

@@ -55,7 +55,7 @@ impl<'tcx> PlaceTy<'tcx> {
     /// `PlaceElem`, where we can just use the `Ty` that is already
     /// stored inline on field projection elems.
     pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: PlaceElem<'tcx>) -> PlaceTy<'tcx> {
-        self.projection_ty_core(tcx, ty::ParamEnv::empty(), &elem, |_, _, ty| ty, |_, ty| ty)
+        self.projection_ty_core(tcx, &elem, |_, _, ty| ty, |_, ty| ty)
     }
 
     /// `place_ty.projection_ty_core(tcx, elem, |...| { ... })`
@@ -66,7 +66,6 @@ impl<'tcx> PlaceTy<'tcx> {
     pub fn projection_ty_core<V, T>(
         self,
         tcx: TyCtxt<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
         elem: &ProjectionElem<V, T>,
         mut handle_field: impl FnMut(&Self, FieldIdx, T) -> Ty<'tcx>,
         mut handle_opaque_cast_and_subtype: impl FnMut(&Self, T) -> Ty<'tcx>,
@@ -93,7 +92,9 @@ impl<'tcx> PlaceTy<'tcx> {
                     ty::Slice(..) => self.ty,
                     ty::Array(inner, _) if !from_end => Ty::new_array(tcx, *inner, to - from),
                     ty::Array(inner, size) if from_end => {
-                        let size = size.eval_target_usize(tcx, param_env);
+                        let size = size
+                            .try_to_target_usize(tcx)
+                            .expect("expected subslice projection on fixed-size array");
                         let len = size - from - to;
                         Ty::new_array(tcx, *inner, len)
                     }