Change `tag_field` to `FieldIdx` in `Variants::Multiple`

It was already available as a generic parameter anyway, and it's not like we'll ever put a tag in the 5-billionth field.

3 files changed, 5 insertions, 5 deletions

diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs
index 42250aa173b..21fd6be39fa 100644
--- a/compiler/rustc_abi/src/layout.rs
+++ b/compiler/rustc_abi/src/layout.rs
@@ -758,7 +758,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                         niche_variants,
                         niche_start,
                     },
-                    tag_field: 0,
+                    tag_field: FieldIdx::new(0),
                     variants: IndexVec::new(),
                 },
                 fields: FieldsShape::Arbitrary {
@@ -1072,7 +1072,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             variants: Variants::Multiple {
                 tag,
                 tag_encoding: TagEncoding::Direct,
-                tag_field: 0,
+                tag_field: FieldIdx::new(0),
                 variants: IndexVec::new(),
             },
             fields: FieldsShape::Arbitrary {
diff --git a/compiler/rustc_abi/src/layout/coroutine.rs b/compiler/rustc_abi/src/layout/coroutine.rs
index 27e704d538c..2b22276d4ae 100644
--- a/compiler/rustc_abi/src/layout/coroutine.rs
+++ b/compiler/rustc_abi/src/layout/coroutine.rs
@@ -158,7 +158,7 @@ pub(super) fn layout<
     // Build a prefix layout, including "promoting" all ineligible
     // locals as part of the prefix. We compute the layout of all of
     // these fields at once to get optimal packing.
-    let tag_index = prefix_layouts.len();
+    let tag_index = prefix_layouts.next_index();
 
     // `variant_fields` already accounts for the reserved variants, so no need to add them.
     let max_discr = (variant_fields.len() - 1) as u128;
@@ -187,7 +187,7 @@ pub(super) fn layout<
 
             // "a" (`0..b_start`) and "b" (`b_start..`) correspond to
             // "outer" and "promoted" fields respectively.
-            let b_start = FieldIdx::new(tag_index + 1);
+            let b_start = tag_index.plus(1);
             let offsets_b = IndexVec::from_raw(offsets.raw.split_off(b_start.index()));
             let offsets_a = offsets;
 
diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index b806d0aba31..46b7a0c1e77 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -1573,7 +1573,7 @@ pub enum Variants<FieldIdx: Idx, VariantIdx: Idx> {
     Multiple {
         tag: Scalar,
         tag_encoding: TagEncoding<VariantIdx>,
-        tag_field: usize,
+        tag_field: FieldIdx,
         variants: IndexVec<VariantIdx, LayoutData<FieldIdx, VariantIdx>>,
     },
 }