cleanup eval() functions on our const types

Author: RalfJung

compiler/rustc_codegen_cranelift/src/base.rs

@@ -733,11 +733,7 @@ fn codegen_stmt<'tcx>(
                 }
                 Rvalue::Repeat(ref operand, times) => {
                     let operand = codegen_operand(fx, operand);
-                    let times = fx
-                        .monomorphize(times)
-                        .eval(fx.tcx, ParamEnv::reveal_all())
-                        .try_to_bits(fx.tcx.data_layout.pointer_size)
-                        .unwrap();
+                    let times = fx.monomorphize(times).try_to_target_usize(fx.tcx).unwrap();
                     if operand.layout().size.bytes() == 0 {
                         // Do nothing for ZST's
                     } else if fx.clif_type(operand.layout().ty) == Some(types::I8) {

compiler/rustc_codegen_cranelift/src/constant.rs

@@ -67,34 +67,12 @@ pub(crate) fn eval_mir_constant<'tcx>(
     fx: &FunctionCx<'_, '_, 'tcx>,
     constant: &Constant<'tcx>,
 ) -> (ConstValue<'tcx>, Ty<'tcx>) {
-    let constant_kind = fx.monomorphize(constant.literal);
-    let uv = match constant_kind {
-        ConstantKind::Ty(const_) => match const_.kind() {
-            ty::ConstKind::Unevaluated(uv) => uv.expand(),
-            ty::ConstKind::Value(val) => {
-                return (fx.tcx.valtree_to_const_val((const_.ty(), val)), const_.ty());
-            }
-            err => span_bug!(
-                constant.span,
-                "encountered bad ConstKind after monomorphizing: {:?}",
-                err
-            ),
-        },
-        ConstantKind::Unevaluated(mir::UnevaluatedConst { def, .. }, _)
-            if fx.tcx.is_static(def) =>
-        {
-            span_bug!(constant.span, "MIR constant refers to static");
-        }
-        ConstantKind::Unevaluated(uv, _) => uv,
-        ConstantKind::Val(val, _) => return (val, constant_kind.ty()),
-    };
-
     // This cannot fail because we checked all required_consts in advance.
     let val = fx
-        .tcx
-        .const_eval_resolve(ty::ParamEnv::reveal_all(), uv, Some(constant.span))
+        .monomorphize(constant.literal)
+        .eval(fx.tcx, ty::ParamEnv::reveal_all(), Some(constant.span))
         .expect("erroneous constant not captured by required_consts");
-    (val, constant_kind.ty())
+    (val, constant.ty())
 }
 
 pub(crate) fn codegen_constant_operand<'tcx>(

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -670,10 +670,8 @@ 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());
-                    hcx.while_hashing_spans(false, |hcx| {
-                        ct.to_valtree().hash_stable(hcx, &mut hasher)
-                    });
+                    let ct = ct.eval(tcx, ty::ParamEnv::reveal_all(), None);
+                    hcx.while_hashing_spans(false, |hcx| ct.hash_stable(hcx, &mut hasher));
                     hasher.finish::<Hash64>()
                 });
 

compiler/rustc_codegen_ssa/src/mir/constant.rs

@@ -21,33 +21,17 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     }
 
     pub fn eval_mir_constant(&self, constant: &mir::Constant<'tcx>) -> ConstValue<'tcx> {
-        let ct = self.monomorphize(constant.literal);
-        let uv = match ct {
-            mir::ConstantKind::Ty(ct) => match ct.kind() {
-                ty::ConstKind::Unevaluated(uv) => uv.expand(),
-                ty::ConstKind::Value(val) => {
-                    return self.cx.tcx().valtree_to_const_val((ct.ty(), val));
-                }
-                err => span_bug!(
-                    constant.span,
-                    "encountered bad ConstKind after monomorphizing: {:?}",
-                    err
-                ),
-            },
-            mir::ConstantKind::Unevaluated(uv, _) => uv,
-            mir::ConstantKind::Val(val, _) => return val,
-        };
-
         // This cannot fail because we checked all required_consts in advance.
-        self.cx
-            .tcx()
-            .const_eval_resolve(ty::ParamEnv::reveal_all(), uv, None)
+        self.monomorphize(constant.literal)
+            .eval(self.cx.tcx(), ty::ParamEnv::reveal_all(), Some(constant.span))
             .expect("erroneous constant not captured by required_consts")
     }
 
     /// This is a convenience helper for `simd_shuffle_indices`. It has the precondition
     /// that the given `constant` is an `ConstantKind::Unevaluated` and must be convertible to
     /// a `ValTree`. If you want a more general version of this, talk to `wg-const-eval` on zulip.
+    ///
+    /// Note that this function is cursed, since usually MIR consts should not be evaluated to valtrees!
     pub fn eval_unevaluated_mir_constant_to_valtree(
         &self,
         constant: &mir::Constant<'tcx>,
@@ -67,7 +51,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             // `simd_shuffle` call without wrapping the constant argument in a `const {}` block, but
             // the user pass through arbitrary expressions.
             // FIXME(oli-obk): replace the magic const generic argument of `simd_shuffle` with a real
-            // const generic.
+            // const generic, and get rid of this entire function.
             other => span_bug!(constant.span, "{other:#?}"),
         };
         let uv = self.monomorphize(uv);

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -3,7 +3,7 @@
 use crate::errors::MaxNumNodesInConstErr;
 use crate::interpret::{intern_const_alloc_recursive, ConstValue, InternKind, InterpCx, Scalar};
 use rustc_middle::mir;
-use rustc_middle::mir::interpret::{EvalToValTreeResult, GlobalId};
+use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult, GlobalId};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
 
@@ -70,15 +70,19 @@ pub(crate) fn eval_to_valtree<'tcx>(
         Ok(valtree) => Ok(Some(valtree)),
         Err(err) => {
             let did = cid.instance.def_id();
+            let span = tcx.hir().span_if_local(did);
             let global_const_id = cid.display(tcx);
             match err {
                 ValTreeCreationError::NodesOverflow => {
-                    let span = tcx.hir().span_if_local(did);
-                    tcx.sess.emit_err(MaxNumNodesInConstErr { span, global_const_id });
-
+                    let g = tcx.sess.emit_err(MaxNumNodesInConstErr { span, global_const_id });
+                    Err(ErrorHandled::Reported(g.into(), span.unwrap_or(DUMMY_SP)))
+                }
+                ValTreeCreationError::NonSupportedType | ValTreeCreationError::Other => {
+                    // Sadly we cannot report an error or `delay_span_bug` here; pattern
+                    // construction calls this function speculatively needs the `None` to fall back
+                    // to MIR constant value.
                     Ok(None)
                 }
-                ValTreeCreationError::NonSupportedType | ValTreeCreationError::Other => Ok(None),
             }
         }
     }

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -20,9 +20,9 @@ use rustc_span::Span;
 use rustc_target::abi::{call::FnAbi, Align, HasDataLayout, Size, TargetDataLayout};
 
 use super::{
-    AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace,
-    MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, Pointer, PointerArithmetic,
-    Projectable, Provenance, Scalar, StackPopJump,
+    AllocId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta,
+    Memory, MemoryKind, OpTy, Operand, Place, PlaceTy, Pointer, PointerArithmetic, Projectable,
+    Provenance, Scalar, StackPopJump,
 };
 use crate::errors::{self, ErroneousConstUsed};
 use crate::util;
@@ -1078,23 +1078,14 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         })
     }
 
-    pub fn eval_global(
+    pub fn eval_mir_constant(
         &self,
-        gid: GlobalId<'tcx>,
+        val: &mir::ConstantKind<'tcx>,
         span: Option<Span>,
-    ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
-        // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics
-        // and thus don't care about the parameter environment. While we could just use
-        // `self.param_env`, that would mean we invoke the query to evaluate the static
-        // with different parameter environments, thus causing the static to be evaluated
-        // multiple times.
-        let param_env = if self.tcx.is_static(gid.instance.def_id()) {
-            ty::ParamEnv::reveal_all()
-        } else {
-            self.param_env
-        };
-        let val = self.ctfe_query(span, |tcx| tcx.eval_to_allocation_raw(param_env.and(gid)))?;
-        self.raw_const_to_mplace(val)
+        layout: Option<TyAndLayout<'tcx>>,
+    ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
+        let const_val = self.ctfe_query(span, |tcx| val.eval(*tcx, self.param_env, span))?;
+        self.const_val_to_op(const_val, val.ty(), layout)
     }
 
     #[must_use]

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -8,15 +8,14 @@ use either::{Either, Left, Right};
 use rustc_hir::def::Namespace;
 use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
 use rustc_middle::ty::print::{FmtPrinter, PrettyPrinter};
-use rustc_middle::ty::{ConstInt, Ty, ValTree};
+use rustc_middle::ty::{ConstInt, Ty};
 use rustc_middle::{mir, ty};
-use rustc_span::Span;
 use rustc_target::abi::{self, Abi, Align, HasDataLayout, Size};
 
 use super::{
-    alloc_range, from_known_layout, mir_assign_valid_types, AllocId, ConstValue, Frame, GlobalId,
-    InterpCx, InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta, PlaceTy, Pointer,
-    Projectable, Provenance, Scalar,
+    alloc_range, from_known_layout, mir_assign_valid_types, AllocId, ConstValue, Frame, InterpCx,
+    InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta, PlaceTy, Pointer, Projectable,
+    Provenance, Scalar,
 };
 
 /// An `Immediate` represents a single immediate self-contained Rust value.
@@ -693,54 +692,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         Ok(op)
     }
 
-    fn eval_ty_constant(
-        &self,
-        val: ty::Const<'tcx>,
-        span: Option<Span>,
-    ) -> InterpResult<'tcx, ValTree<'tcx>> {
-        Ok(match val.kind() {
-            ty::ConstKind::Param(_) | ty::ConstKind::Placeholder(..) => {
-                throw_inval!(TooGeneric)
-            }
-            // FIXME(generic_const_exprs): `ConstKind::Expr` should be able to be evaluated
-            ty::ConstKind::Expr(_) => throw_inval!(TooGeneric),
-            ty::ConstKind::Error(reported) => {
-                throw_inval!(AlreadyReported(reported.into()))
-            }
-            ty::ConstKind::Unevaluated(uv) => {
-                let instance = self.resolve(uv.def, uv.args)?;
-                let cid = GlobalId { instance, promoted: None };
-                self.ctfe_query(span, |tcx| tcx.eval_to_valtree(self.param_env.and(cid)))?
-                    .unwrap_or_else(|| bug!("unable to create ValTree for {uv:?}"))
-            }
-            ty::ConstKind::Bound(..) | ty::ConstKind::Infer(..) => {
-                span_bug!(self.cur_span(), "unexpected ConstKind in ctfe: {val:?}")
-            }
-            ty::ConstKind::Value(valtree) => valtree,
-        })
-    }
-
-    pub fn eval_mir_constant(
-        &self,
-        val: &mir::ConstantKind<'tcx>,
-        span: Option<Span>,
-        layout: Option<TyAndLayout<'tcx>>,
-    ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
-        match *val {
-            mir::ConstantKind::Ty(ct) => {
-                let ty = ct.ty();
-                let valtree = self.eval_ty_constant(ct, span)?;
-                let const_val = self.tcx.valtree_to_const_val((ty, valtree));
-                self.const_val_to_op(const_val, ty, layout)
-            }
-            mir::ConstantKind::Val(val, ty) => self.const_val_to_op(val, ty, layout),
-            mir::ConstantKind::Unevaluated(uv, _) => {
-                let instance = self.resolve(uv.def, uv.args)?;
-                Ok(self.eval_global(GlobalId { instance, promoted: uv.promoted }, span)?.into())
-            }
-        }
-    }
-
     pub(crate) fn const_val_to_op(
         &self,
         val_val: ConstValue<'tcx>,

compiler/rustc_infer/src/infer/mod.rs

@@ -6,7 +6,6 @@ pub use self::RegionVariableOrigin::*;
 pub use self::SubregionOrigin::*;
 pub use self::ValuePairs::*;
 pub use combine::ObligationEmittingRelation;
-use rustc_data_structures::undo_log::UndoLogs;
 
 use self::opaque_types::OpaqueTypeStorage;
 pub(crate) use self::undo_log::{InferCtxtUndoLogs, Snapshot, UndoLog};
@@ -17,6 +16,7 @@ use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::undo_log::Rollback;
+use rustc_data_structures::undo_log::UndoLogs;
 use rustc_data_structures::unify as ut;
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -36,7 +36,7 @@ use rustc_middle::ty::{self, GenericParamDefKind, InferConst, InferTy, Ty, TyCtx
 use rustc_middle::ty::{ConstVid, FloatVid, IntVid, TyVid};
 use rustc_middle::ty::{GenericArg, GenericArgKind, GenericArgs, GenericArgsRef};
 use rustc_span::symbol::Symbol;
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 
 use std::cell::{Cell, RefCell};
 use std::fmt;
@@ -1552,15 +1552,15 @@ impl<'tcx> InferCtxt<'tcx> {
         // variables
         let tcx = self.tcx;
         if args.has_non_region_infer() {
-            if let Some(ct) = tcx.thir_abstract_const(unevaluated.def)? {
+            if let Some(ct) = tcx
+                .thir_abstract_const(unevaluated.def)
+                .map_err(|e| ErrorHandled::Reported(e.into(), DUMMY_SP))?
+            {
                 let ct = tcx.expand_abstract_consts(ct.instantiate(tcx, args));
                 if let Err(e) = ct.error_reported() {
-                    return Err(ErrorHandled::Reported(
-                        e.into(),
-                        span.unwrap_or(rustc_span::DUMMY_SP),
-                    ));
+                    return Err(ErrorHandled::Reported(e.into(), span.unwrap_or(DUMMY_SP)));
                 } else if ct.has_non_region_infer() || ct.has_non_region_param() {
-                    return Err(ErrorHandled::TooGeneric(span.unwrap_or(rustc_span::DUMMY_SP)));
+                    return Err(ErrorHandled::TooGeneric(span.unwrap_or(DUMMY_SP)));
                 } else {
                     args = replace_param_and_infer_args_with_placeholder(tcx, args);
                 }

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -11,7 +11,7 @@ use rustc_errors::{
 };
 use rustc_macros::HashStable;
 use rustc_session::CtfeBacktrace;
-use rustc_span::{def_id::DefId, Span, DUMMY_SP};
+use rustc_span::{def_id::DefId, Span};
 use rustc_target::abi::{call, Align, Size, VariantIdx, WrappingRange};
 
 use std::borrow::Cow;
@@ -27,13 +27,6 @@ pub enum ErrorHandled {
     TooGeneric(Span),
 }
 
-impl From<ErrorGuaranteed> for ErrorHandled {
-    #[inline]
-    fn from(error: ErrorGuaranteed) -> ErrorHandled {
-        ErrorHandled::Reported(error.into(), DUMMY_SP)
-    }
-}
-
 impl ErrorHandled {
     pub fn with_span(self, span: Span) -> Self {
         match self {
@@ -80,6 +73,8 @@ TrivialTypeTraversalAndLiftImpls! { ErrorHandled }
 
 pub type EvalToAllocationRawResult<'tcx> = Result<ConstAlloc<'tcx>, ErrorHandled>;
 pub type EvalToConstValueResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>;
+/// `Ok(None)` indicates the constant was fine, but the valtree couldn't be constructed.
+/// This is needed in `thir::pattern::lower_inline_const`.
 pub type EvalToValTreeResult<'tcx> = Result<Option<ValTree<'tcx>>, ErrorHandled>;
 
 pub fn struct_error<'tcx>(