Remove some superfluous type parameters from layout.rs.

Specifically remove V, which can always be VariantIdx, and F, which can
always be Layout.

compiler/rustc_abi/src/lib.rs

@@ -8,6 +8,7 @@ use std::ops::{Add, AddAssign, Mul, RangeInclusive, Sub};
 use std::str::FromStr;
 
 use bitflags::bitflags;
+use rustc_data_structures::intern::Interned;
 #[cfg(feature = "nightly")]
 use rustc_data_structures::stable_hasher::StableOrd;
 use rustc_index::vec::{Idx, IndexVec};
@@ -1257,9 +1258,9 @@ impl Abi {
 
 #[derive(PartialEq, Eq, Hash, Clone, Debug)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-pub enum Variants<V: Idx> {
+pub enum Variants {
     /// Single enum variants, structs/tuples, unions, and all non-ADTs.
-    Single { index: V },
+    Single { index: VariantIdx },
 
     /// Enum-likes with more than one inhabited variant: each variant comes with
     /// a *discriminant* (usually the same as the variant index but the user can
@@ -1269,15 +1270,15 @@ pub enum Variants<V: Idx> {
     /// For enums, the tag is the sole field of the layout.
     Multiple {
         tag: Scalar,
-        tag_encoding: TagEncoding<V>,
+        tag_encoding: TagEncoding,
         tag_field: usize,
-        variants: IndexVec<V, LayoutS<V>>,
+        variants: IndexVec<VariantIdx, LayoutS>,
     },
 }
 
 #[derive(PartialEq, Eq, Hash, Clone, Debug)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-pub enum TagEncoding<V: Idx> {
+pub enum TagEncoding {
     /// The tag directly stores the discriminant, but possibly with a smaller layout
     /// (so converting the tag to the discriminant can require sign extension).
     Direct,
@@ -1292,7 +1293,11 @@ pub enum TagEncoding<V: Idx> {
     /// For example, `Option<(usize, &T)>`  is represented such that
     /// `None` has a null pointer for the second tuple field, and
     /// `Some` is the identity function (with a non-null reference).
-    Niche { untagged_variant: V, niche_variants: RangeInclusive<V>, niche_start: u128 },
+    Niche {
+        untagged_variant: VariantIdx,
+        niche_variants: RangeInclusive<VariantIdx>,
+        niche_start: u128,
+    },
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
@@ -1379,9 +1384,14 @@ impl Niche {
     }
 }
 
+rustc_index::newtype_index! {
+    #[derive(HashStable_Generic)]
+    pub struct VariantIdx {}
+}
+
 #[derive(PartialEq, Eq, Hash, Clone)]
 #[cfg_attr(feature = "nightly", derive(HashStable_Generic))]
-pub struct LayoutS<V: Idx> {
+pub struct LayoutS {
     /// Says where the fields are located within the layout.
     pub fields: FieldsShape,
 
@@ -1392,7 +1402,7 @@ pub struct LayoutS<V: Idx> {
     ///
     /// To access all fields of this layout, both `fields` and the fields of the active variant
     /// must be taken into account.
-    pub variants: Variants<V>,
+    pub variants: Variants,
 
     /// The `abi` defines how this data is passed between functions, and it defines
     /// value restrictions via `valid_range`.
@@ -1411,13 +1421,13 @@ pub struct LayoutS<V: Idx> {
     pub size: Size,
 }
 
-impl<V: Idx> LayoutS<V> {
+impl LayoutS {
     pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
         let largest_niche = Niche::from_scalar(cx, Size::ZERO, scalar);
         let size = scalar.size(cx);
         let align = scalar.align(cx);
         LayoutS {
-            variants: Variants::Single { index: V::new(0) },
+            variants: Variants::Single { index: VariantIdx::new(0) },
             fields: FieldsShape::Primitive,
             abi: Abi::Scalar(scalar),
             largest_niche,
@@ -1427,7 +1437,7 @@ impl<V: Idx> LayoutS<V> {
     }
 }
 
-impl<V: Idx> fmt::Debug for LayoutS<V> {
+impl fmt::Debug for LayoutS {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // This is how `Layout` used to print before it become
         // `Interned<LayoutS>`. We print it like this to avoid having to update
@@ -1444,6 +1454,43 @@ impl<V: Idx> fmt::Debug for LayoutS<V> {
     }
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
+#[rustc_pass_by_value]
+pub struct Layout<'a>(pub Interned<'a, LayoutS>);
+
+impl<'a> fmt::Debug for Layout<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // See comment on `<LayoutS as Debug>::fmt` above.
+        self.0.0.fmt(f)
+    }
+}
+
+impl<'a> Layout<'a> {
+    pub fn fields(self) -> &'a FieldsShape {
+        &self.0.0.fields
+    }
+
+    pub fn variants(self) -> &'a Variants {
+        &self.0.0.variants
+    }
+
+    pub fn abi(self) -> Abi {
+        self.0.0.abi
+    }
+
+    pub fn largest_niche(self) -> Option<Niche> {
+        self.0.0.largest_niche
+    }
+
+    pub fn align(self) -> AbiAndPrefAlign {
+        self.0.0.align
+    }
+
+    pub fn size(self) -> Size {
+        self.0.0.size
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum PointerKind {
     /// Most general case, we know no restrictions to tell LLVM.
@@ -1479,7 +1526,7 @@ pub enum InitKind {
     UninitMitigated0x01Fill,
 }
 
-impl<V: Idx> LayoutS<V> {
+impl LayoutS {
     /// Returns `true` if the layout corresponds to an unsized type.
     pub fn is_unsized(&self) -> bool {
         self.abi.is_unsized()

compiler/rustc_middle/src/arena.rs

@@ -8,7 +8,7 @@
 macro_rules! arena_types {
     ($macro:path) => (
         $macro!([
-            [] layout: rustc_target::abi::LayoutS<rustc_target::abi::VariantIdx>,
+            [] layout: rustc_target::abi::LayoutS,
             [] fn_abi: rustc_target::abi::call::FnAbi<'tcx, rustc_middle::ty::Ty<'tcx>>,
             // AdtDef are interned and compared by address
             [decode] adt_def: rustc_middle::ty::AdtDefData,

compiler/rustc_middle/src/ty/context.rs

@@ -142,7 +142,7 @@ pub struct CtxtInterners<'tcx> {
     const_: InternedSet<'tcx, ConstData<'tcx>>,
     const_allocation: InternedSet<'tcx, Allocation>,
     bound_variable_kinds: InternedSet<'tcx, List<ty::BoundVariableKind>>,
-    layout: InternedSet<'tcx, LayoutS<VariantIdx>>,
+    layout: InternedSet<'tcx, LayoutS>,
     adt_def: InternedSet<'tcx, AdtDefData>,
 }
 
@@ -1586,7 +1586,7 @@ direct_interners! {
     region: mk_region(RegionKind<'tcx>): Region -> Region<'tcx>,
     const_: mk_const_internal(ConstData<'tcx>): Const -> Const<'tcx>,
     const_allocation: intern_const_alloc(Allocation): ConstAllocation -> ConstAllocation<'tcx>,
-    layout: intern_layout(LayoutS<VariantIdx>): Layout -> Layout<'tcx>,
+    layout: intern_layout(LayoutS): Layout -> Layout<'tcx>,
     adt_def: intern_adt_def(AdtDefData): AdtDef -> AdtDef<'tcx>,
 }
 

compiler/rustc_target/src/abi/mod.rs

@@ -3,10 +3,8 @@ pub use Primitive::*;
 
 use crate::json::{Json, ToJson};
 
-use std::fmt;
 use std::ops::Deref;
 
-use rustc_data_structures::intern::Interned;
 use rustc_macros::HashStable_Generic;
 
 pub mod call;
@@ -19,48 +17,6 @@ impl ToJson for Endian {
     }
 }
 
-rustc_index::newtype_index! {
-    #[derive(HashStable_Generic)]
-    pub struct VariantIdx {}
-}
-
-#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
-#[rustc_pass_by_value]
-pub struct Layout<'a>(pub Interned<'a, LayoutS<VariantIdx>>);
-
-impl<'a> fmt::Debug for Layout<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        // See comment on `<LayoutS as Debug>::fmt` above.
-        self.0.0.fmt(f)
-    }
-}
-
-impl<'a> Layout<'a> {
-    pub fn fields(self) -> &'a FieldsShape {
-        &self.0.0.fields
-    }
-
-    pub fn variants(self) -> &'a Variants<VariantIdx> {
-        &self.0.0.variants
-    }
-
-    pub fn abi(self) -> Abi {
-        self.0.0.abi
-    }
-
-    pub fn largest_niche(self) -> Option<Niche> {
-        self.0.0.largest_niche
-    }
-
-    pub fn align(self) -> AbiAndPrefAlign {
-        self.0.0.align
-    }
-
-    pub fn size(self) -> Size {
-        self.0.0.size
-    }
-}
-
 /// The layout of a type, alongside the type itself.
 /// Provides various type traversal APIs (e.g., recursing into fields).
 ///
@@ -75,8 +31,8 @@ pub struct TyAndLayout<'a, Ty> {
 }
 
 impl<'a, Ty> Deref for TyAndLayout<'a, Ty> {
-    type Target = &'a LayoutS<VariantIdx>;
-    fn deref(&self) -> &&'a LayoutS<VariantIdx> {
+    type Target = &'a LayoutS;
+    fn deref(&self) -> &&'a LayoutS {
         &self.layout.0.0
     }
 }

compiler/rustc_ty_utils/src/layout.rs

@@ -78,10 +78,10 @@ fn invert_mapping(map: &[u32]) -> Vec<u32> {
 fn univariant_uninterned<'tcx>(
     cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
     ty: Ty<'tcx>,
-    fields: &[TyAndLayout<'_>],
+    fields: &[Layout<'_>],
     repr: &ReprOptions,
     kind: StructKind,
-) -> Result<LayoutS<VariantIdx>, LayoutError<'tcx>> {
+) -> Result<LayoutS, LayoutError<'tcx>> {
     let dl = cx.data_layout();
     let pack = repr.pack;
     if pack.is_some() && repr.align.is_some() {
@@ -106,7 +106,7 @@ fn layout_of_uncached<'tcx>(
     };
     let scalar = |value: Primitive| tcx.intern_layout(LayoutS::scalar(cx, scalar_unit(value)));
 
-    let univariant = |fields: &[TyAndLayout<'_>], repr: &ReprOptions, kind| {
+    let univariant = |fields: &[Layout<'_>], repr: &ReprOptions, kind| {
         Ok(tcx.intern_layout(univariant_uninterned(cx, ty, fields, repr, kind)?))
     };
     debug_assert!(!ty.has_non_region_infer());
@@ -272,7 +272,7 @@ fn layout_of_uncached<'tcx>(
         ty::Closure(_, ref substs) => {
             let tys = substs.as_closure().upvar_tys();
             univariant(
-                &tys.map(|ty| cx.layout_of(ty)).collect::<Result<Vec<_>, _>>()?,
+                &tys.map(|ty| Ok(cx.layout_of(ty)?.layout)).collect::<Result<Vec<_>, _>>()?,
                 &ReprOptions::default(),
                 StructKind::AlwaysSized,
             )?
@@ -283,7 +283,7 @@ fn layout_of_uncached<'tcx>(
                 if tys.len() == 0 { StructKind::AlwaysSized } else { StructKind::MaybeUnsized };
 
             univariant(
-                &tys.iter().map(|k| cx.layout_of(k)).collect::<Result<Vec<_>, _>>()?,
+                &tys.iter().map(|k| Ok(cx.layout_of(k)?.layout)).collect::<Result<Vec<_>, _>>()?,
                 &ReprOptions::default(),
                 kind,
             )?
@@ -412,7 +412,7 @@ fn layout_of_uncached<'tcx>(
                 .map(|v| {
                     v.fields
                         .iter()
-                        .map(|field| cx.layout_of(field.ty(tcx, substs)))
+                        .map(|field| Ok(cx.layout_of(field.ty(tcx, substs))?.layout))
                         .collect::<Result<Vec<_>, _>>()
                 })
                 .collect::<Result<IndexVec<VariantIdx, _>, _>>()?;
@@ -630,23 +630,21 @@ fn generator_layout<'tcx>(
     // `info.variant_fields` already accounts for the reserved variants, so no need to add them.
     let max_discr = (info.variant_fields.len() - 1) as u128;
     let discr_int = Integer::fit_unsigned(max_discr);
-    let discr_int_ty = discr_int.to_ty(tcx, false);
     let tag = Scalar::Initialized {
         value: Primitive::Int(discr_int, false),
         valid_range: WrappingRange { start: 0, end: max_discr },
     };
     let tag_layout = cx.tcx.intern_layout(LayoutS::scalar(cx, tag));
-    let tag_layout = TyAndLayout { ty: discr_int_ty, layout: tag_layout };
 
     let promoted_layouts = ineligible_locals
         .iter()
         .map(|local| subst_field(info.field_tys[local]))
         .map(|ty| tcx.mk_maybe_uninit(ty))
-        .map(|ty| cx.layout_of(ty));
+        .map(|ty| Ok(cx.layout_of(ty)?.layout));
     let prefix_layouts = substs
         .as_generator()
         .prefix_tys()
-        .map(|ty| cx.layout_of(ty))
+        .map(|ty| Ok(cx.layout_of(ty)?.layout))
         .chain(iter::once(Ok(tag_layout)))
         .chain(promoted_layouts)
         .collect::<Result<Vec<_>, _>>()?;
@@ -715,7 +713,9 @@ fn generator_layout<'tcx>(
             let mut variant = univariant_uninterned(
                 cx,
                 ty,
-                &variant_only_tys.map(|ty| cx.layout_of(ty)).collect::<Result<Vec<_>, _>>()?,
+                &variant_only_tys
+                    .map(|ty| Ok(cx.layout_of(ty)?.layout))
+                    .collect::<Result<Vec<_>, _>>()?,
                 &ReprOptions::default(),
                 StructKind::Prefixed(prefix_size, prefix_align.abi),
             )?;

src/librustdoc/html/render/print_item.rs

@@ -10,7 +10,7 @@ use rustc_middle::ty::layout::LayoutError;
 use rustc_middle::ty::{self, Adt, TyCtxt};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::{kw, sym, Symbol};
-use rustc_target::abi::{LayoutS, Primitive, TagEncoding, VariantIdx, Variants};
+use rustc_target::abi::{LayoutS, Primitive, TagEncoding, Variants};
 use std::cmp::Ordering;
 use std::fmt;
 use std::rc::Rc;
@@ -1887,7 +1887,7 @@ fn document_non_exhaustive(w: &mut Buffer, item: &clean::Item) {
 }
 
 fn document_type_layout(w: &mut Buffer, cx: &Context<'_>, ty_def_id: DefId) {
-    fn write_size_of_layout(w: &mut Buffer, layout: &LayoutS<VariantIdx>, tag_size: u64) {
+    fn write_size_of_layout(w: &mut Buffer, layout: &LayoutS, tag_size: u64) {
         if layout.abi.is_unsized() {
             write!(w, "(unsized)");
         } else {