rebase and use ty::Const in patterns again

Author: b-naber

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -184,13 +184,13 @@ pub(crate) fn destructure_mir_constant<'tcx>(
     // We go to `usize` as we cannot allocate anything bigger anyway.
     let (field_count, variant, down) = match val.ty().kind() {
         ty::Array(_, len) => (usize::try_from(len.eval_usize(tcx, param_env)).unwrap(), None, op),
-        ty::Adt(def, _) if def.variants.is_empty() => {
+        ty::Adt(def, _) if def.variants().is_empty() => {
             return mir::DestructuredMirConstant { variant: None, fields: &[] };
         }
         ty::Adt(def, _) => {
             let variant = ecx.read_discriminant(&op).unwrap().1;
             let down = ecx.operand_downcast(&op, variant).unwrap();
-            (def.variants[variant].fields.len(), Some(variant), down)
+            (def.variants()[variant].fields.len(), Some(variant), down)
         }
         ty::Tuple(substs) => (substs.len(), None, op),
         _ => bug!("cannot destructure constant {:?}", val),
@@ -253,7 +253,7 @@ pub(crate) fn deref_mir_constant<'tcx>(
     let mplace = ecx.deref_operand(&op).unwrap();
     if let Some(alloc_id) = mplace.ptr.provenance {
         assert_eq!(
-            tcx.get_global_alloc(alloc_id).unwrap().unwrap_memory().mutability,
+            tcx.get_global_alloc(alloc_id).unwrap().unwrap_memory().0.0.mutability,
             Mutability::Not,
             "deref_const cannot be used with mutable allocations as \
             that could allow pattern matching to observe mutable statics",

compiler/rustc_middle/src/mir/mod.rs

@@ -2711,7 +2711,7 @@ impl<'tcx> ConstantKind<'tcx> {
                 if let Some(val) = c.val().try_eval(tcx, param_env) {
                     match val {
                         Ok(val) => Self::Val(val, c.ty()),
-                        Err(ErrorReported) => Self::Ty(tcx.const_error(self.ty())),
+                        Err(_) => Self::Ty(tcx.const_error(self.ty())),
                     }
                 } else {
                     self

compiler/rustc_middle/src/thir.rs

@@ -193,7 +193,7 @@ pub enum StmtKind<'tcx> {
 
 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Expr<'_>, 144);
+rustc_data_structures::static_assert_size!(Expr<'_>, 104);
 
 /// A THIR expression.
 #[derive(Debug, HashStable)]
@@ -736,11 +736,7 @@ 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/visit.rs

@@ -2,7 +2,6 @@ use super::{
     Arm, Block, Expr, ExprKind, Guard, InlineAsmOperand, Pat, PatKind, Stmt, StmtKind, Thir,
 };
 use crate::mir::ConstantKind;
-use crate::ty::Const;
 
 pub trait Visitor<'a, 'tcx: 'a>: Sized {
     fn thir(&self) -> &'a Thir<'tcx>;

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

@@ -76,11 +76,7 @@ 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]

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -1,17 +1,12 @@
 //! See docs in build/expr/mod.rs
 
 use crate::build::Builder;
-use crate::thir::constant::parse_float;
-use rustc_ast::ast;
 use rustc_hir::def_id::DefId;
-use rustc_middle::mir::interpret::{
-    Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar,
-};
+use rustc_middle::mir::interpret::{ConstValue, LitToConstError, LitToConstInput, Scalar};
 use rustc_middle::mir::*;
 use rustc_middle::thir::*;
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt};
-use rustc_target::abi::Size;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Compile `expr`, yielding a compile-time constant. Assumes that
@@ -32,11 +27,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
             ExprKind::Literal { lit, neg } => {
                 let literal =
-                    match lit_to_constant(tcx, LitToConstInput { lit: &lit.node, ty, neg }) {
+                    match tcx.lit_to_mir_constant(LitToConstInput { lit: &lit.node, ty, neg }) {
                         Ok(c) => c,
                         Err(LitToConstError::Reported) => ConstantKind::Ty(tcx.const_error(ty)),
                         Err(LitToConstError::TypeError) => {
-                            bug!("encountered type error in `lit_to_constant")
+                            bug!("encountered type error in `lit_to_mir_constant")
                         }
                     };
 
@@ -85,60 +80,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                 Constant { span, user_ty: None, literal }
             }
-            ExprKind::ConstBlock { value } => {
-                Constant { span: span, user_ty: None, literal: value }
-            }
             _ => span_bug!(span, "expression is not a valid constant {:?}", kind),
         }
     }
 }
-
-crate fn lit_to_constant<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    lit_input: LitToConstInput<'tcx>,
-) -> Result<ConstantKind<'tcx>, LitToConstError> {
-    let LitToConstInput { lit, ty, neg } = lit_input;
-    let trunc = |n| {
-        let param_ty = ty::ParamEnv::reveal_all().and(ty);
-        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
-        trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
-        let result = width.truncate(n);
-        trace!("trunc result: {}", result);
-        Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
-    };
-
-    let value = match (lit, &ty.kind()) {
-        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
-            let s = s.as_str();
-            let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
-            let allocation = tcx.intern_const_alloc(allocation);
-            ConstValue::Slice { data: allocation, start: 0, end: s.len() }
-        }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
-            if matches!(inner_ty.kind(), ty::Slice(_)) =>
-        {
-            let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
-            let allocation = tcx.intern_const_alloc(allocation);
-            ConstValue::Slice { data: allocation, start: 0, end: data.len() }
-        }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
-            let id = tcx.allocate_bytes(data);
-            ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
-        }
-        (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
-            ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
-        }
-        (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
-            trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
-        }
-        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
-            parse_float(*n, *fty, neg).ok_or(LitToConstError::Reported)?
-        }
-        (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
-        (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
-        (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
-        _ => return Err(LitToConstError::TypeError),
-    };
-
-    Ok(ConstantKind::Val(value, ty))
-}

compiler/rustc_mir_build/src/thir/constant.rs

@@ -59,6 +59,56 @@ crate fn lit_to_const<'tcx>(
     Ok(ty::Const::from_value(tcx, lit, ty))
 }
 
+crate fn lit_to_mir_constant<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    lit_input: LitToConstInput<'tcx>,
+) -> Result<ConstantKind<'tcx>, LitToConstError> {
+    let LitToConstInput { lit, ty, neg } = lit_input;
+    let trunc = |n| {
+        let param_ty = ty::ParamEnv::reveal_all().and(ty);
+        let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
+        trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
+        let result = width.truncate(n);
+        trace!("trunc result: {}", result);
+        Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
+    };
+
+    let value = match (lit, &ty.kind()) {
+        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
+            let s = s.as_str();
+            let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
+            let allocation = tcx.intern_const_alloc(allocation);
+            ConstValue::Slice { data: allocation, start: 0, end: s.len() }
+        }
+        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
+            if matches!(inner_ty.kind(), ty::Slice(_)) =>
+        {
+            let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
+            let allocation = tcx.intern_const_alloc(allocation);
+            ConstValue::Slice { data: allocation, start: 0, end: data.len() }
+        }
+        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
+            let id = tcx.allocate_bytes(data);
+            ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
+        }
+        (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
+            ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
+        }
+        (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
+            trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
+        }
+        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
+            parse_float(*n, *fty, neg).ok_or(LitToConstError::Reported)?
+        }
+        (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
+        (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
+        (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
+        _ => return Err(LitToConstError::TypeError),
+    };
+
+    Ok(ConstantKind::Val(value, ty))
+}
+
 // FIXME move this to rustc_mir_build::build
 pub(crate) fn parse_float<'tcx>(
     num: Symbol,

compiler/rustc_mir_build/src/thir/cx/mod.rs

@@ -5,6 +5,7 @@
 use crate::thir::pattern::pat_from_hir;
 use crate::thir::util::UserAnnotatedTyHelpers;
 
+use rustc_ast::ast;
 use rustc_data_structures::steal::Steal;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
@@ -15,7 +16,7 @@ use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
 use rustc_middle::mir::ConstantKind;
 use rustc_middle::thir::*;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
 
 crate fn thir_body<'tcx>(

compiler/rustc_trait_selection/src/traits/const_evaluatable.rs

@@ -377,10 +377,6 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
                 }
             }
 
-            fn visit_const(&mut self, ct: ty::Const<'tcx>) {
-                self.is_poly |= ct.has_param_types_or_consts();
-            }
-
             fn visit_constant(&mut self, ct: mir::ConstantKind<'tcx>) {
                 self.is_poly |= ct.has_param_types_or_consts();
             }
@@ -815,51 +811,3 @@ impl<'tcx> ConstUnifyCtxt<'tcx> {
         }
     }
 }
-
-/* Think I need these changes
-=======
-            match (a_ct, b_ct) {
-                (mir::ConstantKind::Ty(a_ct), mir::ConstantKind::Ty(b_ct)) => {
-                    match (a_ct.val(), b_ct.val()) {
-                        // We can just unify errors with everything to reduce the amount of
-                        // emitted errors here.
-                        (ty::ConstKind::Error(_), _) | (_, ty::ConstKind::Error(_)) => true,
-                        (ty::ConstKind::Param(a_param), ty::ConstKind::Param(b_param)) => {
-                            a_param == b_param
-                        }
-                        (ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => {
-                            a_val == b_val
-                        }
-
-                        // If we have `fn a<const N: usize>() -> [u8; N + 1]` and `fn b<const M: usize>() -> [u8; 1 + M]`
-                        // we do not want to use `assert_eq!(a(), b())` to infer that `N` and `M` have to be `1`. This
-                        // means that we only allow inference variables if they are equal.
-                        (ty::ConstKind::Infer(a_val), ty::ConstKind::Infer(b_val)) => {
-                            a_val == b_val
-                        }
-                        // We expand generic anonymous constants at the start of this function, so this
-                        // branch should only be taking when dealing with associated constants, at
-                        // which point directly comparing them seems like the desired behavior.
-                        //
-                        // FIXME(generic_const_exprs): This isn't actually the case.
-                        // We also take this branch for concrete anonymous constants and
-                        // expand generic anonymous constants with concrete substs.
-                        (ty::ConstKind::Unevaluated(a_uv), ty::ConstKind::Unevaluated(b_uv)) => {
-                            a_uv == b_uv
-                        }
-                        // FIXME(generic_const_exprs): We may want to either actually try
-                        // to evaluate `a_ct` and `b_ct` if they are are fully concrete or something like
-                        // this, for now we just return false here.
-                        _ => false,
-                    }
-                }
-                (mir::ConstantKind::Val(a_val, a_ty), mir::ConstantKind::Val(b_val, b_ty)) => {
-                    a_val == b_val && a_ty == b_ty
-                }
-                _ => {
-                    // FIXME Can it happen that we need to compare ConstantKind::Ty(ConstKind::Value)
-                    // with a ConstantKind::Val and vice versa?
-                    false
->>>>>>> 6064f16d846 (change thir to use mir::ConstantKind instead of ty::Const)
-
- */

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -407,7 +407,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
                     let pred =
                         ty::Binder::dummy(infcx.replace_bound_vars_with_placeholders(binder));
                     ProcessResult::Changed(mk_pending(vec![
-                        obligation.with(pred.to_predicate(self.selcx.tcx()))
+                        obligation.with(pred.to_predicate(self.selcx.tcx())),
                     ]))
                 }
                 ty::PredicateKind::TypeWellFormedFromEnv(..) => {