Rollup merge of rust-lang#63495 - eddyb:mir-constant-ty, r=oli-obk

 Remove redundant `ty` fields from `mir::Constant` and `hair::pattern::PatternRange`.

Fixes rust-lang#56137.

As a side-effect, associated const literals have the correct type now, which should make things easier for rust-lang#61041.

r? @oli-obk / @matthewjasper cc @davidtwco @varkor

src/librustc/mir/mod.rs

@@ -2197,7 +2197,6 @@ impl<'tcx> Operand<'tcx> {
         let ty = tcx.type_of(def_id).subst(tcx, substs);
         Operand::Constant(box Constant {
             span,
-            ty,
             user_ty: None,
             literal: ty::Const::zero_sized(tcx, ty),
         })
@@ -2476,7 +2475,6 @@ impl<'tcx> Debug for Rvalue<'tcx> {
 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
 pub struct Constant<'tcx> {
     pub span: Span,
-    pub ty: Ty<'tcx>,
 
     /// Optional user-given type: for something like
     /// `collect::<Vec<_>>`, this would be present and would
@@ -3385,12 +3383,11 @@ impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
         Constant {
             span: self.span.clone(),
-            ty: self.ty.fold_with(folder),
             user_ty: self.user_ty.fold_with(folder),
             literal: self.literal.fold_with(folder),
         }
     }
     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
-        self.ty.visit_with(visitor) || self.literal.visit_with(visitor)
+        self.literal.visit_with(visitor)
     }
 }

src/librustc/mir/tcx.rs

@@ -252,7 +252,7 @@ impl<'tcx> Operand<'tcx> {
         match self {
             &Operand::Copy(ref l) |
             &Operand::Move(ref l) => l.ty(local_decls, tcx).ty,
-            &Operand::Constant(ref c) => c.ty,
+            &Operand::Constant(ref c) => c.literal.ty,
         }
     }
 }

src/librustc/mir/visit.rs

@@ -782,13 +782,11 @@ macro_rules! make_mir_visitor {
                               location: Location) {
                 let Constant {
                     span,
-                    ty,
                     user_ty,
                     literal,
                 } = constant;
 
                 self.visit_span(span);
-                self.visit_ty(ty, TyContext::Location(location));
                 drop(user_ty); // no visit method for this
                 self.visit_const(literal, location);
             }

src/librustc_codegen_ssa/mir/analyze.rs

@@ -221,7 +221,7 @@ impl<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> Visitor<'tcx>
             mir::TerminatorKind::Call {
                 func: mir::Operand::Constant(ref c),
                 ref args, ..
-            } => match c.ty.sty {
+            } => match c.literal.ty.sty {
                 ty::FnDef(did, _) => Some((did, args)),
                 _ => None,
             },

src/librustc_codegen_ssa/mir/block.rs

@@ -651,7 +651,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             let (llval, ty) = self.simd_shuffle_indices(
                                 &bx,
                                 constant.span,
-                                constant.ty,
+                                constant.literal.ty,
                                 c,
                             );
                             return OperandRef {

src/librustc_codegen_ssa/mir/operand.rs

@@ -466,7 +466,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             }
 
             mir::Operand::Constant(ref constant) => {
-                let ty = self.monomorphize(&constant.ty);
                 self.eval_mir_constant(constant)
                     .map(|c| OperandRef::from_const(bx, c))
                     .unwrap_or_else(|err| {
@@ -481,6 +480,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         // the above error (or silence it under some conditions) will not cause UB
                         bx.abort();
                         // We've errored, so we don't have to produce working code.
+                        let ty = self.monomorphize(&constant.literal.ty);
                         let layout = bx.cx().layout_of(ty);
                         bx.load_operand(PlaceRef::new_sized(
                             bx.cx().const_undef(bx.cx().type_ptr_to(bx.cx().backend_type(layout))),

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -272,12 +272,11 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
 
     fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
         self.super_constant(constant, location);
-        self.sanitize_constant(constant, location);
-        self.sanitize_type(constant, constant.ty);
+        self.sanitize_type(constant, constant.literal.ty);
 
         if let Some(annotation_index) = constant.user_ty {
             if let Err(terr) = self.cx.relate_type_and_user_type(
-                constant.ty,
+                constant.literal.ty,
                 ty::Variance::Invariant,
                 &UserTypeProjection { base: annotation_index, projs: vec![], },
                 location.to_locations(),
@@ -289,7 +288,7 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
                     constant,
                     "bad constant user type {:?} vs {:?}: {:?}",
                     annotation,
-                    constant.ty,
+                    constant.literal.ty,
                     terr,
                 );
             }
@@ -299,7 +298,7 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
                     location.to_locations(),
                     ConstraintCategory::Boring,
                     self.cx.param_env.and(type_op::ascribe_user_type::AscribeUserType::new(
-                        constant.ty, def_id, UserSubsts { substs, user_self_ty: None },
+                        constant.literal.ty, def_id, UserSubsts { substs, user_self_ty: None },
                     )),
                 ) {
                     span_mirbug!(
@@ -403,41 +402,6 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
         }
     }
 
-    /// Checks that the constant's `ty` field matches up with what would be
-    /// expected from its literal. Unevaluated constants and well-formed
-    /// constraints are checked by `visit_constant`.
-    fn sanitize_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
-        debug!(
-            "sanitize_constant(constant={:?}, location={:?})",
-            constant, location
-        );
-
-        let literal = constant.literal;
-
-        if let ConstValue::Unevaluated(..) = literal.val {
-            return;
-        }
-
-        debug!("sanitize_constant: expected_ty={:?}", literal.ty);
-
-        if let Err(terr) = self.cx.eq_types(
-            literal.ty,
-            constant.ty,
-            location.to_locations(),
-            ConstraintCategory::Boring,
-        ) {
-            span_mirbug!(
-                self,
-                constant,
-                "constant {:?} should have type {:?} but has {:?} ({:?})",
-                constant,
-                literal.ty,
-                constant.ty,
-                terr,
-            );
-        }
-    }
-
     /// Checks that the types internal to the `place` match up with
     /// what would be expected.
     fn sanitize_place(

src/librustc_mir/build/expr/as_constant.rs

@@ -38,9 +38,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         inferred_ty: ty,
                     })
                 });
+                assert_eq!(literal.ty, ty);
                 Constant {
                     span,
-                    ty,
                     user_ty,
                     literal,
                 }

src/librustc_mir/build/expr/as_rvalue.rs

@@ -591,7 +591,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let n = (!0u128) >> (128 - bits);
         let literal = ty::Const::from_bits(self.hir.tcx(), n, param_ty);
 
-        self.literal_operand(span, ty, literal)
+        self.literal_operand(span, literal)
     }
 
     // Helper to get the minimum value of the appropriate type
@@ -602,6 +602,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let n = 1 << (bits - 1);
         let literal = ty::Const::from_bits(self.hir.tcx(), n, param_ty);
 
-        self.literal_operand(span, ty, literal)
+        self.literal_operand(span, literal)
     }
 }

src/librustc_mir/build/expr/into.rs

@@ -114,7 +114,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     destination,
                     Constant {
                         span: expr_span,
-                        ty: this.hir.bool_ty(),
                         user_ty: None,
                         literal: this.hir.true_literal(),
                     },
@@ -126,7 +125,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     destination,
                     Constant {
                         span: expr_span,
-                        ty: this.hir.bool_ty(),
                         user_ty: None,
                         literal: this.hir.false_literal(),
                     },

src/librustc_mir/build/matches/simplify.rs

@@ -108,8 +108,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 Err(match_pair)
             }
 
-            PatternKind::Range(PatternRange { lo, hi, ty, end }) => {
-                let (range, bias) = match ty.sty {
+            PatternKind::Range(PatternRange { lo, hi, end }) => {
+                let (range, bias) = match lo.ty.sty {
                     ty::Char => {
                         (Some(('\u{0000}' as u128, '\u{10FFFF}' as u128, Size::from_bits(32))), 0)
                     }

src/librustc_mir/build/matches/test.rs

@@ -63,7 +63,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
 
             PatternKind::Range(range) => {
-                assert!(range.ty == match_pair.pattern.ty);
+                assert_eq!(range.lo.ty, match_pair.pattern.ty);
+                assert_eq!(range.hi.ty, match_pair.pattern.ty);
                 Test {
                     span: match_pair.pattern.span,
                     kind: TestKind::Range(range),
@@ -270,22 +271,23 @@ 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 val = Operand::Copy(place.clone());
-                        let expect = self.literal_operand(test.span, ty, value);
                         self.compare(block, success, fail, source_info, BinOp::Eq, expect, val);
                     } else {
                         bug!("`TestKind::Eq` should have two target blocks");
                     }
                 }
             }
 
-            TestKind::Range(PatternRange { ref lo, ref hi, ty, ref end }) => {
+            TestKind::Range(PatternRange { ref lo, ref hi, ref end }) => {
                 let lower_bound_success = self.cfg.start_new_block();
                 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, ty, lo);
-                let hi = self.literal_operand(test.span, ty, hi);
+                let lo = self.literal_operand(test.span, lo);
+                let hi = self.literal_operand(test.span, hi);
                 let val = Operand::Copy(place.clone());
 
                 if let [success, fail] = *target_blocks {
@@ -387,7 +389,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     ) {
         use rustc::middle::lang_items::EqTraitLangItem;
 
-        let mut expect = self.literal_operand(source_info.span, value.ty, value);
+        let mut expect = self.literal_operand(source_info.span, value);
         let mut val = Operand::Copy(place.clone());
 
         // If we're using `b"..."` as a pattern, we need to insert an
@@ -440,7 +442,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         };
 
         let eq_def_id = self.hir.tcx().require_lang_item(EqTraitLangItem);
-        let (mty, method) = self.hir.trait_method(eq_def_id, sym::eq, deref_ty, &[deref_ty.into()]);
+        let method = self.hir.trait_method(eq_def_id, sym::eq, deref_ty, &[deref_ty.into()]);
 
         let bool_ty = self.hir.bool_ty();
         let eq_result = self.temp(bool_ty, source_info.span);
@@ -449,7 +451,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.terminate(block, source_info, TerminatorKind::Call {
             func: Operand::Constant(box Constant {
                 span: source_info.span,
-                ty: mty,
 
                 // FIXME(#54571): This constant comes from user input (a
                 // constant in a pattern).  Are there forms where users can add
@@ -656,8 +657,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                     let tcx = self.hir.tcx();
 
-                    let lo = compare_const_vals(tcx, test.lo, pat.hi, self.hir.param_env, test.ty)?;
-                    let hi = compare_const_vals(tcx, test.hi, pat.lo, self.hir.param_env, test.ty)?;
+                    let test_ty = test.lo.ty;
+                    let lo = compare_const_vals(tcx, test.lo, pat.hi, self.hir.param_env, test_ty)?;
+                    let hi = compare_const_vals(tcx, test.hi, pat.lo, self.hir.param_env, test_ty)?;
 
                     match (test.end, pat.end, lo, hi) {
                         // pat < test
@@ -774,8 +776,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
         let tcx = self.hir.tcx();
 
-        let a = compare_const_vals(tcx, range.lo, value, self.hir.param_env, range.ty)?;
-        let b = compare_const_vals(tcx, value, range.hi, self.hir.param_env, range.ty)?;
+        let a = compare_const_vals(tcx, range.lo, value, self.hir.param_env, range.lo.ty)?;
+        let b = compare_const_vals(tcx, value, range.hi, self.hir.param_env, range.lo.ty)?;
 
         match (b, range.end) {
             (Less, _) |

src/librustc_mir/build/misc.rs

@@ -26,12 +26,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// without any user type annotation.
     pub fn literal_operand(&mut self,
                            span: Span,
-                           ty: Ty<'tcx>,
                            literal: &'tcx ty::Const<'tcx>)
                            -> Operand<'tcx> {
         let constant = box Constant {
             span,
-            ty,
             user_ty: None,
             literal,
         };
@@ -47,7 +45,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub fn zero_literal(&mut self, span: Span, ty: Ty<'tcx>) -> Operand<'tcx> {
         let literal = ty::Const::from_bits(self.hir.tcx(), 0, ty::ParamEnv::empty().and(ty));
 
-        self.literal_operand(span, ty, literal)
+        self.literal_operand(span, literal)
     }
 
     pub fn push_usize(&mut self,
@@ -61,7 +59,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             block, source_info, &temp,
             Constant {
                 span: source_info.span,
-                ty: self.hir.usize_ty(),
                 user_ty: None,
                 literal: self.hir.usize_literal(value),
             });

src/librustc_mir/hair/cx/expr.rs

@@ -927,7 +927,7 @@ fn convert_path_expr<'a, 'tcx>(
             ExprKind::Literal {
                 literal: cx.tcx.mk_const(ty::Const {
                     val: ConstValue::Unevaluated(def_id, substs),
-                    ty: cx.tcx.type_of(def_id),
+                    ty: cx.tables().node_type(expr.hir_id),
                 }),
                 user_ty,
             }

src/librustc_mir/hair/cx/mod.rs

@@ -170,13 +170,13 @@ impl<'a, 'tcx> Cx<'a, 'tcx> {
                         method_name: Symbol,
                         self_ty: Ty<'tcx>,
                         params: &[Kind<'tcx>])
-                        -> (Ty<'tcx>, &'tcx ty::Const<'tcx>) {
+                        -> &'tcx ty::Const<'tcx> {
         let substs = self.tcx.mk_substs_trait(self_ty, params);
         for item in self.tcx.associated_items(trait_def_id) {
             if item.kind == ty::AssocKind::Method && item.ident.name == method_name {
                 let method_ty = self.tcx.type_of(item.def_id);
                 let method_ty = method_ty.subst(self.tcx, substs);
-                return (method_ty, ty::Const::zero_sized(self.tcx, method_ty));
+                return ty::Const::zero_sized(self.tcx, method_ty);
             }
         }