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Replace two BottomUpFolders with fold_regions.

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Because these folders only change regions.

Note: `BottomUpFolder` folds all regions, while `fold_regions` skips
some bound regions. But that's ok because these two folders only modify
`ReVar`s.
This commit is contained in:
Nicholas Nethercote 2026-01-09 10:42:48 +11:00
parent 7c41ee66db
commit 2ae298711f
2 changed files with 9 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

11
compiler/rustc_const_eval/src/interpret/intrinsics.rs
View file

@ -13,7 +13,7 @@ use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::mir::interpret::{CTFE_ALLOC_SALT, read_target_uint, write_target_uint};
use rustc_middle::mir::{self, BinOp, ConstValue, NonDivergingIntrinsic};
use rustc_middle::ty::layout::TyAndLayout;
use rustc_middle::ty::{FloatTy, PolyExistentialPredicate, Ty, TyCtxt, TypeFoldable};
use rustc_middle::ty::{FloatTy, PolyExistentialPredicate, Ty, TyCtxt};
use rustc_middle::{bug, span_bug, ty};
use rustc_span::{Symbol, sym};
use rustc_trait_selection::traits::{Obligation, ObligationCause, ObligationCtxt};
@ -243,13 +243,8 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
ocx.register_obligations(preds.iter().map(|pred: PolyExistentialPredicate<'_>| {
let pred = pred.with_self_ty(tcx, tp_ty);
// Lifetimes can only be 'static because of the bound on T
let pred = pred.fold_with(&mut ty::BottomUpFolder {
tcx,
ty_op: |ty| ty,
lt_op: |lt| {
if lt == tcx.lifetimes.re_erased { tcx.lifetimes.re_static } else { lt }
},
ct_op: |ct| ct,
let pred = ty::fold_regions(tcx, pred, |r, _| {
if r == tcx.lifetimes.re_erased { tcx.lifetimes.re_static } else { r }
});
Obligation::new(tcx, ObligationCause::dummy(), param_env, pred)
}));

17
compiler/rustc_hir_analysis/src/check/check.rs
View file

@ -508,23 +508,18 @@ fn sanity_check_found_hidden_type<'tcx>(
return Ok(());
}
}
let strip_vars = |ty: Ty<'tcx>| {
ty.fold_with(&mut BottomUpFolder {
tcx,
ty_op: |t| t,
ct_op: |c| c,
lt_op: |l| match l.kind() {
RegionKind::ReVar(_) => tcx.lifetimes.re_erased,
_ => l,
},
let erase_re_vars = |ty: Ty<'tcx>| {
fold_regions(tcx, ty, |r, _| match r.kind() {
RegionKind::ReVar(_) => tcx.lifetimes.re_erased,
_ => r,
})
};
// Closures frequently end up containing erased lifetimes in their final representation.
// These correspond to lifetime variables that never got resolved, so we patch this up here.
ty.ty = strip_vars(ty.ty);
ty.ty = erase_re_vars(ty.ty);
// Get the hidden type.
let hidden_ty = tcx.type_of(key.def_id).instantiate(tcx, key.args);
let hidden_ty = strip_vars(hidden_ty);
let hidden_ty = erase_re_vars(hidden_ty);
// If the hidden types differ, emit a type mismatch diagnostic.
if hidden_ty == ty.ty {