do use ty::Const in patterns and abstract consts

Author: b-naber

compiler/rustc_middle/src/thir.rs

@@ -661,7 +661,7 @@ pub enum PatKind<'tcx> {
     /// * Opaque constants, that must not be matched structurally. So anything that does not derive
     ///   `PartialEq` and `Eq`.
     Constant {
-        value: mir::ConstantKind<'tcx>,
+        value: ty::Const<'tcx>,
     },
 
     Range(PatRange<'tcx>),
@@ -691,8 +691,8 @@ pub enum PatKind<'tcx> {
 
 #[derive(Copy, Clone, Debug, PartialEq, HashStable)]
 pub struct PatRange<'tcx> {
-    pub lo: mir::ConstantKind<'tcx>,
-    pub hi: mir::ConstantKind<'tcx>,
+    pub lo: ty::Const<'tcx>,
+    pub hi: ty::Const<'tcx>,
     pub end: RangeEnd,
 }
 
@@ -736,7 +736,11 @@ impl<'tcx> fmt::Display for Pat<'tcx> {
                         Some(adt_def.variant(variant_index))
                     }
                     _ => self.ty.ty_adt_def().and_then(|adt| {
-                        if !adt.is_enum() { Some(adt.non_enum_variant()) } else { None }
+                        if !adt.is_enum() {
+                            Some(adt.non_enum_variant())
+                        } else {
+                            None
+                        }
                     }),
                 };
 

compiler/rustc_middle/src/thir/abstract_const.rs

@@ -22,7 +22,7 @@ pub enum CastKind {
 /// A node of an `AbstractConst`.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
 pub enum Node<'tcx> {
-    Leaf(mir::ConstantKind<'tcx>),
+    Leaf(ty::Const<'tcx>),
     Binop(mir::BinOp, NodeId, NodeId),
     UnaryOp(mir::UnOp, NodeId),
     FunctionCall(NodeId, &'tcx [NodeId]),

compiler/rustc_middle/src/thir/visit.rs

@@ -94,13 +94,8 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
                 visitor.visit_expr(&visitor.thir()[value])
             }
         }
-<<<<<<< HEAD
         ConstBlock { did: _, substs: _ } => {}
         Repeat { value, count: _ } => {
-=======
-        ConstBlock { value } => visitor.visit_constant(value),
-        Repeat { value, count } => {
->>>>>>> 6064f16d846 (change thir to use mir::ConstantKind instead of ty::Const)
             visitor.visit_expr(&visitor.thir()[value]);
         }
         Array { ref fields } | Tuple { ref fields } => {

compiler/rustc_middle/src/ty/consts/kind.rs

@@ -76,7 +76,11 @@ static_assert_size!(ConstKind<'_>, 40);
 impl<'tcx> ConstKind<'tcx> {
     #[inline]
     pub fn try_to_value(self) -> Option<ConstValue<'tcx>> {
-        if let ConstKind::Value(val) = self { Some(val) } else { None }
+        if let ConstKind::Value(val) = self {
+            Some(val)
+        } else {
+            None
+        }
     }
 
     #[inline]
@@ -126,6 +130,7 @@ impl<'tcx> ConstKind<'tcx> {
     #[inline]
     /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary
     /// return `None`.
+    // FIXME(@lcnr): Completely rework the evaluation/normalization system for `ty::Const` once valtrees are merged.
     pub fn try_eval(
         self,
         tcx: TyCtxt<'tcx>,

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -964,13 +964,13 @@ enum TestKind<'tcx> {
         ///
         /// For `bool` we always generate two edges, one for `true` and one for
         /// `false`.
-        options: FxIndexMap<ConstantKind<'tcx>, u128>,
+        options: FxIndexMap<ty::Const<'tcx>, u128>,
     },
 
     /// Test for equality with value, possibly after an unsizing coercion to
     /// `ty`,
     Eq {
-        value: ConstantKind<'tcx>,
+        value: ty::Const<'tcx>,
         // Integer types are handled by `SwitchInt`, and constants with ADT
         // types are converted back into patterns, so this can only be `&str`,
         // `&[T]`, `f32` or `f64`.

compiler/rustc_mir_build/src/build/matches/simplify.rs

@@ -228,7 +228,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     _ => (None, 0),
                 };
                 if let Some((min, max, sz)) = range {
-                    if let (Some(lo), Some(hi)) = (lo.try_to_bits(sz), hi.try_to_bits(sz)) {
+                    if let (Some(lo), Some(hi)) =
+                        (lo.val().try_to_bits(sz), hi.val().try_to_bits(sz))
+                    {
                         // We want to compare ranges numerically, but the order of the bitwise
                         // representation of signed integers does not match their numeric order.
                         // Thus, to correct the ordering, we need to shift the range of signed

compiler/rustc_mir_build/src/build/matches/test.rs

@@ -86,7 +86,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         test_place: &PlaceBuilder<'tcx>,
         candidate: &Candidate<'pat, 'tcx>,
         switch_ty: Ty<'tcx>,
-        options: &mut FxIndexMap<ConstantKind<'tcx>, u128>,
+        options: &mut FxIndexMap<ty::Const<'tcx>, u128>,
     ) -> bool {
         let Some(match_pair) = candidate.match_pairs.iter().find(|mp| mp.place == *test_place) else {
             return false;
@@ -264,7 +264,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     );
                 } else if let [success, fail] = *make_target_blocks(self) {
                     assert_eq!(value.ty(), ty);
-                    let expect = self.literal_operand(test.span, value);
+                    let expect = self.literal_operand(test.span, value.into());
                     let val = Operand::Copy(place);
                     self.compare(block, success, fail, source_info, BinOp::Eq, expect, val);
                 } else {
@@ -277,8 +277,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let target_blocks = make_target_blocks(self);
 
                 // Test `val` by computing `lo <= val && val <= hi`, using primitive comparisons.
-                let lo = self.literal_operand(test.span, lo);
-                let hi = self.literal_operand(test.span, hi);
+                let lo = self.literal_operand(test.span, lo.into());
+                let hi = self.literal_operand(test.span, hi.into());
                 let val = Operand::Copy(place);
 
                 let [success, fail] = *target_blocks else {
@@ -366,11 +366,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         block: BasicBlock,
         make_target_blocks: impl FnOnce(&mut Self) -> Vec<BasicBlock>,
         source_info: SourceInfo,
-        value: ConstantKind<'tcx>,
+        value: ty::Const<'tcx>,
         place: Place<'tcx>,
         mut ty: Ty<'tcx>,
     ) {
-        let mut expect = self.literal_operand(source_info.span, value);
+        let mut expect = self.literal_operand(source_info.span, value.into());
         let mut val = Operand::Copy(place);
 
         // If we're using `b"..."` as a pattern, we need to insert an
@@ -760,11 +760,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         span_bug!(match_pair.pattern.span, "simplifyable pattern found: {:?}", match_pair.pattern)
     }
 
-    fn const_range_contains(
-        &self,
-        range: PatRange<'tcx>,
-        value: ConstantKind<'tcx>,
-    ) -> Option<bool> {
+    fn const_range_contains(&self, range: PatRange<'tcx>, value: ty::Const<'tcx>) -> Option<bool> {
         use std::cmp::Ordering::*;
 
         let tcx = self.tcx;
@@ -781,7 +777,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     fn values_not_contained_in_range(
         &self,
         range: PatRange<'tcx>,
-        options: &FxIndexMap<ConstantKind<'tcx>, u128>,
+        options: &FxIndexMap<ty::Const<'tcx>, u128>,
     ) -> Option<bool> {
         for &val in options.keys() {
             if self.const_range_contains(range, val)? {

compiler/rustc_mir_build/src/build/misc.rs

@@ -3,6 +3,7 @@
 
 use crate::build::Builder;
 
+use rustc_middle::mir;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, Ty};
 use rustc_span::{Span, DUMMY_SP};
@@ -25,7 +26,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
     /// Convenience function for creating a literal operand, one
     /// without any user type annotation.
-    crate fn literal_operand(&mut self, span: Span, literal: ConstantKind<'tcx>) -> Operand<'tcx> {
+    crate fn literal_operand(
+        &mut self,
+        span: Span,
+        literal: mir::ConstantKind<'tcx>,
+    ) -> Operand<'tcx> {
         let constant = Box::new(Constant { span, user_ty: None, literal });
         Operand::Constant(constant)
     }

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -1,7 +1,7 @@
 use rustc_hir as hir;
 use rustc_index::vec::Idx;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
-use rustc_middle::mir::{self, Field};
+use rustc_middle::mir::Field;
 use rustc_middle::thir::{FieldPat, Pat, PatKind};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
@@ -22,7 +22,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
     #[instrument(level = "debug", skip(self))]
     pub(super) fn const_to_pat(
         &self,
-        cv: mir::ConstantKind<'tcx>,
+        cv: ty::Const<'tcx>,
         id: hir::HirId,
         span: Span,
         mir_structural_match_violation: bool,
@@ -152,11 +152,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
         ty.is_structural_eq_shallow(self.infcx.tcx)
     }
 
-    fn to_pat(
-        &mut self,
-        cv: mir::ConstantKind<'tcx>,
-        mir_structural_match_violation: bool,
-    ) -> Pat<'tcx> {
+    fn to_pat(&mut self, cv: ty::Const<'tcx>, mir_structural_match_violation: bool) -> Pat<'tcx> {
         trace!(self.treat_byte_string_as_slice);
         // This method is just a wrapper handling a validity check; the heavy lifting is
         // performed by the recursive `recur` method, which is not meant to be
@@ -250,7 +246,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
 
     fn field_pats(
         &self,
-        vals: impl Iterator<Item = mir::ConstantKind<'tcx>>,
+        vals: impl Iterator<Item = ty::Const<'tcx>>,
     ) -> Result<Vec<FieldPat<'tcx>>, FallbackToConstRef> {
         vals.enumerate()
             .map(|(idx, val)| {
@@ -263,7 +259,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
     // Recursive helper for `to_pat`; invoke that (instead of calling this directly).
     fn recur(
         &self,
-        cv: mir::ConstantKind<'tcx>,
+        cv: ty::Const<'tcx>,
         mir_structural_match_violation: bool,
     ) -> Result<Pat<'tcx>, FallbackToConstRef> {
         let id = self.id;
@@ -369,7 +365,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 PatKind::Wild
             }
             ty::Adt(adt_def, substs) if adt_def.is_enum() => {
-                let destructured = tcx.destructure_mir_constant(param_env.and(cv));
+                let destructured = tcx.destructure_const(param_env.and(cv));
                 PatKind::Variant {
                     adt_def: *adt_def,
                     substs,
@@ -380,12 +376,12 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 }
             }
             ty::Tuple(_) | ty::Adt(_, _) => {
-                let destructured = tcx.destructure_mir_constant(param_env.and(cv));
+                let destructured = tcx.destructure_const(param_env.and(cv));
                 PatKind::Leaf { subpatterns: self.field_pats(destructured.fields.iter().copied())? }
             }
             ty::Array(..) => PatKind::Array {
                 prefix: tcx
-                    .destructure_mir_constant(param_env.and(cv))
+                    .destructure_const(param_env.and(cv))
                     .fields
                     .iter()
                     .map(|val| self.recur(*val, false))
@@ -416,12 +412,12 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 // arrays.
                 ty::Array(..) if !self.treat_byte_string_as_slice => {
                     let old = self.behind_reference.replace(true);
-                    let array = tcx.deref_mir_constant(self.param_env.and(cv));
+                    let array = tcx.deref_const(self.param_env.and(cv));
                     let val = PatKind::Deref {
                         subpattern: Pat {
                             kind: Box::new(PatKind::Array {
                                 prefix: tcx
-                                    .destructure_mir_constant(param_env.and(array))
+                                    .destructure_const(param_env.and(array))
                                     .fields
                                     .iter()
                                     .map(|val| self.recur(*val, false))
@@ -442,12 +438,12 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                 // pattern.
                 ty::Slice(elem_ty) => {
                     let old = self.behind_reference.replace(true);
-                    let array = tcx.deref_mir_constant(self.param_env.and(cv));
+                    let array = tcx.deref_const(self.param_env.and(cv));
                     let val = PatKind::Deref {
                         subpattern: Pat {
                             kind: Box::new(PatKind::Slice {
                                 prefix: tcx
-                                    .destructure_mir_constant(param_env.and(array))
+                                    .destructure_const(param_env.and(array))
                                     .fields
                                     .iter()
                                     .map(|val| self.recur(*val, false))
@@ -516,7 +512,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
                         // we fall back to a const pattern. If we do not do this, we may end up with
                         // a !structural-match constant that is not of reference type, which makes it
                         // very hard to invoke `PartialEq::eq` on it as a fallback.
-                        let val = match self.recur(tcx.deref_mir_constant(self.param_env.and(cv)), false) {
+                        let val = match self.recur(tcx.deref_const(self.param_env.and(cv)), false) {
                             Ok(subpattern) => PatKind::Deref { subpattern },
                             Err(_) => PatKind::Constant { value: cv },
                         };

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

@@ -52,7 +52,7 @@ use rustc_data_structures::captures::Captures;
 use rustc_index::vec::Idx;
 
 use rustc_hir::{HirId, RangeEnd};
-use rustc_middle::mir::{self, Field};
+use rustc_middle::mir::Field;
 use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
@@ -136,30 +136,20 @@ impl IntRange {
     fn from_const<'tcx>(
         tcx: TyCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
-        value: mir::ConstantKind<'tcx>,
+        value: ty::Const<'tcx>,
     ) -> Option<IntRange> {
         let ty = value.ty();
         if let Some((target_size, bias)) = Self::integral_size_and_signed_bias(tcx, ty) {
             let val = (|| {
-                match value {
-                    mir::ConstantKind::Val(ConstValue::Scalar(scalar), _) => {
-                        // For this specific pattern we can skip a lot of effort and go
-                        // straight to the result, after doing a bit of checking. (We
-                        // could remove this branch and just fall through, which
-                        // is more general but much slower.)
-                        if let Ok(bits) = scalar.to_bits_or_ptr_internal(target_size) {
-                            return Some(bits);
-                        }
+                if let ty::ConstKind::Value(ConstValue::Scalar(scalar)) = value.val() {
+                    // For this specific pattern we can skip a lot of effort and go
+                    // straight to the result, after doing a bit of checking. (We
+                    // could remove this branch and just fall through, which
+                    // is more general but much slower.)
+                    if let Ok(bits) = scalar.to_bits_or_ptr_internal(target_size) {
+                        return Some(bits);
                     }
-                    mir::ConstantKind::Ty(c) => match c.val() {
-                        ty::ConstKind::Value(_) => bug!(
-                            "encountered ConstValue in mir::ConstantKind::Ty, whereas this is expected to be in ConstantKind::Val"
-                        ),
-                        _ => {}
-                    },
-                    _ => {}
                 }
-
                 // This is a more general form of the previous case.
                 value.try_eval_bits(tcx, param_env, ty)
             })()?;
@@ -244,8 +234,8 @@ impl IntRange {
         let (lo, hi) = (lo ^ bias, hi ^ bias);
 
         let env = ty::ParamEnv::empty().and(ty);
-        let lo_const = mir::ConstantKind::from_bits(tcx, lo, env);
-        let hi_const = mir::ConstantKind::from_bits(tcx, hi, env);
+        let lo_const = ty::Const::from_bits(tcx, lo, env);
+        let hi_const = ty::Const::from_bits(tcx, hi, env);
 
         let kind = if lo == hi {
             PatKind::Constant { value: lo_const }
@@ -640,9 +630,9 @@ pub(super) enum Constructor<'tcx> {
     /// Ranges of integer literal values (`2`, `2..=5` or `2..5`).
     IntRange(IntRange),
     /// Ranges of floating-point literal values (`2.0..=5.2`).
-    FloatRange(mir::ConstantKind<'tcx>, mir::ConstantKind<'tcx>, RangeEnd),
+    FloatRange(ty::Const<'tcx>, ty::Const<'tcx>, RangeEnd),
     /// String literals. Strings are not quite the same as `&[u8]` so we treat them separately.
-    Str(mir::ConstantKind<'tcx>),
+    Str(ty::Const<'tcx>),
     /// Array and slice patterns.
     Slice(Slice),
     /// Constants that must not be matched structurally. They are treated as black
@@ -839,7 +829,8 @@ impl<'tcx> Constructor<'tcx> {
                 }
             }
             (Str(self_val), Str(other_val)) => {
-                // FIXME: there's probably a more direct way of comparing for equality
+                // FIXME Once valtrees are available we can directly use the bytes
+                // in the `Str` variant of the valtree for the comparison here.
                 match compare_const_vals(
                     pcx.cx.tcx,
                     *self_val,