Move `mir::Field` → `abi::FieldIdx`

The first PR for https://github.com/rust-lang/compiler-team/issues/606

This is just the move-and-rename, because it's plenty big-and-bitrotty already.  Future PRs will start using `FieldIdx` more broadly, and concomitantly removing `FieldIdx::new`s.

9 files changed, 31 insertions, 26 deletions

diff --git a/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs b/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
index bf58b3090fb..77a5017b363 100644
--- a/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
+++ b/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
@@ -3,7 +3,7 @@ use rustc_middle::mir::tcx::PlaceTy;
 use rustc_middle::ty::cast::mir_cast_kind;
 use rustc_middle::{mir::*, thir::*, ty};
 use rustc_span::Span;
-use rustc_target::abi::VariantIdx;
+use rustc_target::abi::{FieldIdx, VariantIdx};
 
 use crate::build::custom::ParseError;
 use crate::build::expr::as_constant::as_constant_inner;
@@ -223,7 +223,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
         let (parent, proj) = parse_by_kind!(self, expr_id, expr, "place",
             @call("mir_field", args) => {
                 let (parent, ty) = self.parse_place_inner(args[0])?;
-                let field = Field::from_u32(self.parse_integer_literal(args[1])? as u32);
+                let field = FieldIdx::from_u32(self.parse_integer_literal(args[1])? as u32);
                 let field_ty = ty.field_ty(self.tcx, field);
                 let proj = PlaceElem::Field(field, field_ty);
                 let place = parent.project_deeper(&[proj], self.tcx);
diff --git a/compiler/rustc_mir_build/src/build/expr/as_place.rs b/compiler/rustc_mir_build/src/build/expr/as_place.rs
index e112bf9829b..0fc99e57d12 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_place.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_place.rs
@@ -13,7 +13,7 @@ use rustc_middle::thir::*;
 use rustc_middle::ty::AdtDef;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, Variance};
 use rustc_span::Span;
-use rustc_target::abi::{VariantIdx, FIRST_VARIANT};
+use rustc_target::abi::{FieldIdx, VariantIdx, FIRST_VARIANT};
 
 use std::assert_matches::assert_matches;
 use std::iter;
@@ -293,7 +293,7 @@ impl<'tcx> PlaceBuilder<'tcx> {
         &self.projection
     }
 
-    pub(crate) fn field(self, f: Field, ty: Ty<'tcx>) -> Self {
+    pub(crate) fn field(self, f: FieldIdx, ty: Ty<'tcx>) -> Self {
         self.project(PlaceElem::Field(f, ty))
     }
 
diff --git a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
index 7fff801b169..d1878bf77ef 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
@@ -17,6 +17,7 @@ use rustc_middle::thir::*;
 use rustc_middle::ty::cast::{mir_cast_kind, CastTy};
 use rustc_middle::ty::{self, Ty, UpvarSubsts};
 use rustc_span::Span;
+use rustc_target::abi::FieldIdx;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Returns an rvalue suitable for use until the end of the current
@@ -553,8 +554,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     result_value,
                     Rvalue::CheckedBinaryOp(op, Box::new((lhs.to_copy(), rhs.to_copy()))),
                 );
-                let val_fld = Field::new(0);
-                let of_fld = Field::new(1);
+                let val_fld = FieldIdx::new(0);
+                let of_fld = FieldIdx::new(1);
 
                 let tcx = self.tcx;
                 let val = tcx.mk_place_field(result_value, val_fld, ty);
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index ebe8ea25ad3..b8260c719c8 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -10,6 +10,7 @@ use rustc_index::vec::Idx;
 use rustc_middle::mir::*;
 use rustc_middle::thir::*;
 use rustc_middle::ty::CanonicalUserTypeAnnotation;
+use rustc_target::abi::FieldIdx;
 use std::iter;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
@@ -344,7 +345,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     .collect();
 
                 let field_names: Vec<_> =
-                    (0..adt_def.variant(variant_index).fields.len()).map(Field::new).collect();
+                    (0..adt_def.variant(variant_index).fields.len()).map(FieldIdx::new).collect();
 
                 let fields: Vec<_> = if let Some(FruInfo { base, field_types }) = base {
                     let place_builder =
diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs
index 1923e10ddb5..e87e38fd04c 100644
--- a/compiler/rustc_mir_build/src/build/mod.rs
+++ b/compiler/rustc_mir_build/src/build/mod.rs
@@ -25,6 +25,7 @@ use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 use rustc_span::Symbol;
+use rustc_target::abi::FieldIdx;
 use rustc_target::spec::abi::Abi;
 
 use super::lints;
@@ -793,7 +794,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let mutability = captured_place.mutability;
 
                 let mut projs = closure_env_projs.clone();
-                projs.push(ProjectionElem::Field(Field::new(i), ty));
+                projs.push(ProjectionElem::Field(FieldIdx::new(i), ty));
                 match capture {
                     ty::UpvarCapture::ByValue => {}
                     ty::UpvarCapture::ByRef(..) => {
diff --git a/compiler/rustc_mir_build/src/thir/cx/expr.rs b/compiler/rustc_mir_build/src/thir/cx/expr.rs
index 04e9273fc46..2a0b5d04733 100644
--- a/compiler/rustc_mir_build/src/thir/cx/expr.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/expr.rs
@@ -10,7 +10,7 @@ use rustc_middle::hir::place::Place as HirPlace;
 use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
 use rustc_middle::hir::place::ProjectionKind as HirProjectionKind;
 use rustc_middle::middle::region;
-use rustc_middle::mir::{self, BinOp, BorrowKind, Field, UnOp};
+use rustc_middle::mir::{self, BinOp, BorrowKind, UnOp};
 use rustc_middle::thir::*;
 use rustc_middle::ty::adjustment::{
     Adjust, Adjustment, AutoBorrow, AutoBorrowMutability, PointerCast,
@@ -20,7 +20,7 @@ use rustc_middle::ty::{
     self, AdtKind, InlineConstSubsts, InlineConstSubstsParts, ScalarInt, Ty, UpvarSubsts, UserType,
 };
 use rustc_span::{sym, Span};
-use rustc_target::abi::FIRST_VARIANT;
+use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
 
 impl<'tcx> Cx<'tcx> {
     pub(crate) fn mirror_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) -> ExprId {
@@ -379,7 +379,7 @@ impl<'tcx> Cx<'tcx> {
                             .iter()
                             .enumerate()
                             .map(|(idx, e)| FieldExpr {
-                                name: Field::new(idx),
+                                name: FieldIdx::new(idx),
                                 expr: self.mirror_expr(e),
                             })
                             .collect();
@@ -733,7 +733,7 @@ impl<'tcx> Cx<'tcx> {
             hir::ExprKind::Field(ref source, ..) => ExprKind::Field {
                 lhs: self.mirror_expr(source),
                 variant_index: FIRST_VARIANT,
-                name: Field::new(self.typeck_results.field_index(expr.hir_id)),
+                name: FieldIdx::new(self.typeck_results.field_index(expr.hir_id)),
             },
             hir::ExprKind::Cast(ref source, ref cast_ty) => {
                 // Check for a user-given type annotation on this `cast`
@@ -1053,7 +1053,7 @@ impl<'tcx> Cx<'tcx> {
                 HirProjectionKind::Field(field, variant_index) => ExprKind::Field {
                     lhs: self.thir.exprs.push(captured_place_expr),
                     variant_index,
-                    name: Field::new(field as usize),
+                    name: FieldIdx::new(field as usize),
                 },
                 HirProjectionKind::Index | HirProjectionKind::Subslice => {
                     // We don't capture these projections, so we can ignore them here
@@ -1107,7 +1107,7 @@ impl<'tcx> Cx<'tcx> {
         fields
             .iter()
             .map(|field| FieldExpr {
-                name: Field::new(self.typeck_results.field_index(field.hir_id)),
+                name: FieldIdx::new(self.typeck_results.field_index(field.hir_id)),
                 expr: self.mirror_expr(field.expr),
             })
             .collect()
diff --git a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
index 274c2f06137..2dbef740d1a 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
@@ -2,11 +2,12 @@ use rustc_hir as hir;
 use rustc_index::vec::Idx;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::Obligation;
-use rustc_middle::mir::{self, Field};
+use rustc_middle::mir;
 use rustc_middle::thir::{FieldPat, Pat, PatKind};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::lint;
 use rustc_span::Span;
+use rustc_target::abi::FieldIdx;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{self, ObligationCause};
 
@@ -218,7 +219,7 @@ impl<'tcx> ConstToPat<'tcx> {
     ) -> Result<Vec<FieldPat<'tcx>>, FallbackToConstRef> {
         vals.enumerate()
             .map(|(idx, val)| {
-                let field = Field::new(idx);
+                let field = FieldIdx::new(idx);
                 Ok(FieldPat { field, pattern: self.recur(val, false)? })
             })
             .collect()
diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
index 8a7b1fce51d..e619e095496 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
@@ -53,14 +53,14 @@ use smallvec::{smallvec, SmallVec};
 use rustc_data_structures::captures::Captures;
 use rustc_hir::{HirId, RangeEnd};
 use rustc_index::vec::Idx;
-use rustc_middle::mir::{self, Field};
+use rustc_middle::mir;
 use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
 use rustc_middle::{middle::stability::EvalResult, mir::interpret::ConstValue};
 use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
-use rustc_target::abi::{Integer, Size, VariantIdx, FIRST_VARIANT};
+use rustc_target::abi::{FieldIdx, Integer, Size, VariantIdx, FIRST_VARIANT};
 
 use self::Constructor::*;
 use self::SliceKind::*;
@@ -1126,7 +1126,7 @@ impl<'tcx> SplitWildcard<'tcx> {
 /// Note that the number of fields of a constructor may not match the fields declared in the
 /// original struct/variant. This happens if a private or `non_exhaustive` field is uninhabited,
 /// because the code mustn't observe that it is uninhabited. In that case that field is not
-/// included in `fields`. For that reason, when you have a `mir::Field` you must use
+/// included in `fields`. For that reason, when you have a `FieldIdx` you must use
 /// `index_with_declared_idx`.
 #[derive(Debug, Clone, Copy)]
 pub(super) struct Fields<'p, 'tcx> {
@@ -1165,7 +1165,7 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
         cx: &'a MatchCheckCtxt<'p, 'tcx>,
         ty: Ty<'tcx>,
         variant: &'a VariantDef,
-    ) -> impl Iterator<Item = (Field, Ty<'tcx>)> + Captures<'a> + Captures<'p> {
+    ) -> impl Iterator<Item = (FieldIdx, Ty<'tcx>)> + Captures<'a> + Captures<'p> {
         let ty::Adt(adt, substs) = ty.kind() else { bug!() };
         // Whether we must not match the fields of this variant exhaustively.
         let is_non_exhaustive = variant.is_field_list_non_exhaustive() && !adt.did().is_local();
@@ -1180,7 +1180,7 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
             if is_uninhabited && (!is_visible || is_non_exhaustive) {
                 None
             } else {
-                Some((Field::new(i), ty))
+                Some((FieldIdx::new(i), ty))
             }
         })
     }
@@ -1438,7 +1438,7 @@ impl<'p, 'tcx> DeconstructedPat<'p, 'tcx> {
                 ty::Tuple(..) => PatKind::Leaf {
                     subpatterns: subpatterns
                         .enumerate()
-                        .map(|(i, pattern)| FieldPat { field: Field::new(i), pattern })
+                        .map(|(i, pattern)| FieldPat { field: FieldIdx::new(i), pattern })
                         .collect(),
                 },
                 ty::Adt(adt_def, _) if adt_def.is_box() => {
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index f356c8a6838..72b4041aa1b 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -21,12 +21,13 @@ use rustc_middle::mir::interpret::{
     ConstValue, ErrorHandled, LitToConstError, LitToConstInput, Scalar,
 };
 use rustc_middle::mir::{self, UserTypeProjection};
-use rustc_middle::mir::{BorrowKind, Field, Mutability};
+use rustc_middle::mir::{BorrowKind, Mutability};
 use rustc_middle::thir::{Ascription, BindingMode, FieldPat, LocalVarId, Pat, PatKind, PatRange};
 use rustc_middle::ty::subst::{GenericArg, SubstsRef};
 use rustc_middle::ty::CanonicalUserTypeAnnotation;
 use rustc_middle::ty::{self, AdtDef, ConstKind, Region, Ty, TyCtxt, UserType};
 use rustc_span::{Span, Symbol};
+use rustc_target::abi::FieldIdx;
 
 use std::cmp::Ordering;
 
@@ -356,7 +357,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                 let subpatterns = fields
                     .iter()
                     .map(|field| FieldPat {
-                        field: Field::new(self.typeck_results.field_index(field.hir_id)),
+                        field: FieldIdx::new(self.typeck_results.field_index(field.hir_id)),
                         pattern: self.lower_pattern(&field.pat),
                     })
                     .collect();
@@ -379,7 +380,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         pats.iter()
             .enumerate_and_adjust(expected_len, gap_pos)
             .map(|(i, subpattern)| FieldPat {
-                field: Field::new(i),
+                field: FieldIdx::new(i),
                 pattern: self.lower_pattern(subpattern),
             })
             .collect()
@@ -723,7 +724,7 @@ macro_rules! ClonePatternFoldableImpls {
 }
 
 ClonePatternFoldableImpls! { <'tcx>
-    Span, Field, Mutability, Symbol, LocalVarId, usize,
+    Span, FieldIdx, Mutability, Symbol, LocalVarId, usize,
     Region<'tcx>, Ty<'tcx>, BindingMode, AdtDef<'tcx>,
     SubstsRef<'tcx>, &'tcx GenericArg<'tcx>, UserType<'tcx>,
     UserTypeProjection, CanonicalUserTypeAnnotation<'tcx>