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Avoid doing redundant work in receiver_is_valid #127473

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Avoid doing redundant work in receiver_is_valid #127473

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compiler-errors Jul 8, 2024
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compiler-errors Jul 8, 2024
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Add it back
compiler-errors Jul 16, 2024
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21 changes: 2 additions & 19 deletions compiler/rustc_hir_analysis/src/check/wfcheck.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1713,24 +1713,13 @@ fn receiver_is_valid<'tcx>(
let cause =
ObligationCause::new(span, wfcx.body_def_id, traits::ObligationCauseCode::MethodReceiver);

// Special case `receiver == self_ty`, which doesn't necessarily require the `Receiver` lang item.
if let Ok(()) = wfcx.infcx.commit_if_ok(|_| {
let ocx = ObligationCtxt::new(wfcx.infcx);
ocx.eq(&cause, wfcx.param_env, self_ty, receiver_ty)?;
if ocx.select_all_or_error().is_empty() { Ok(()) } else { Err(NoSolution) }
}) {
return true;
}

let mut autoderef = Autoderef::new(infcx, wfcx.param_env, wfcx.body_def_id, span, receiver_ty);

// The `arbitrary_self_types` feature allows raw pointer receivers like `self: *const Self`.
if arbitrary_self_types_enabled {
autoderef = autoderef.include_raw_pointers();
}

let receiver_trait_def_id = tcx.require_lang_item(LangItem::Receiver, Some(span));

// Keep dereferencing `receiver_ty` until we get to `self_ty`.
while let Some((potential_self_ty, _)) = autoderef.next() {
debug!(
Expand All @@ -1752,6 +1741,8 @@ fn receiver_is_valid<'tcx>(
// Without `feature(arbitrary_self_types)`, we require that each step in the
// deref chain implement `receiver`.
if !arbitrary_self_types_enabled {
let receiver_trait_def_id = tcx.require_lang_item(LangItem::Receiver, Some(span));

if !receiver_is_implemented(
wfcx,
receiver_trait_def_id,
Expand All @@ -1761,14 +1752,6 @@ fn receiver_is_valid<'tcx>(
// We cannot proceed.
break;
}

// Register the bound, in case it has any region side-effects.
wfcx.register_bound(
cause.clone(),
wfcx.param_env,
potential_self_ty,
receiver_trait_def_id,
);
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This may have been perf negative, since we now have trait goals to process... If this is the problem, then we probably need to accept this for soundness reasons if we ever want to stabilize receiver lol

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so this means we only check T: Receiver ignoring regions? 🤔

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As we were previously. Let me try adding it back and seeing what happens still...

}
}

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