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Refactor: VariantIdx::from_u32(0) -> FIRST_VARIANT

Since structs are always `VariantIdx(0)`, there's a bunch of files where the only reason they had `VariantIdx` or `vec::Idx` imported at all was to get the first variant.

So this uses a constant for that, and adds some doc-comments to `VariantIdx` while I'm there, since it doesn't have any today.
This commit is contained in:
Scott McMurray 2023-03-25 18:43:03 -07:00
parent 96bd50dd47
commit 0439d13176
25 changed files with 80 additions and 78 deletions

View file

@ -58,7 +58,6 @@ use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdSet, CRATE_DEF_ID};
use rustc_hir::intravisit::FnKind as HirFnKind;
use rustc_hir::{Body, FnDecl, ForeignItemKind, GenericParamKind, Node, PatKind, PredicateOrigin};
use rustc_index::vec::Idx;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::layout::{LayoutError, LayoutOf};
use rustc_middle::ty::print::with_no_trimmed_paths;
@ -69,7 +68,7 @@ use rustc_span::edition::Edition;
use rustc_span::source_map::Spanned;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, InnerSpan, Span};
use rustc_target::abi::{Abi, VariantIdx};
use rustc_target::abi::{Abi, FIRST_VARIANT};
use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
use rustc_trait_selection::traits::{self, misc::type_allowed_to_implement_copy};
@ -2788,7 +2787,7 @@ impl ClashingExternDeclarations {
);
if is_transparent && !is_non_null {
debug_assert_eq!(def.variants().len(), 1);
let v = &def.variant(VariantIdx::new(0));
let v = &def.variant(FIRST_VARIANT);
// continue with `ty`'s non-ZST field,
// otherwise `ty` is a ZST and we can return
if let Some(field) = transparent_newtype_field(tcx, v) {