From ba87be05cfa8f9a02d673a64aa2ee83976d80e60 Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Tue, 18 Jan 2022 17:01:52 -0800 Subject: Short-circuit some trivially const Drop types --- .../src/transform/check_consts/qualifs.rs | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) (limited to 'compiler/rustc_const_eval/src') diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs index 1269f2207d5..8dfdbf5d9dd 100644 --- a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs +++ b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs @@ -146,15 +146,10 @@ impl Qualif for NeedsNonConstDrop { qualifs.needs_non_const_drop } - fn in_any_value_of_ty<'tcx>(cx: &ConstCx<'_, 'tcx>, mut ty: Ty<'tcx>) -> bool { - // Avoid selecting for simple cases. - match ty::util::needs_drop_components(ty, &cx.tcx.data_layout).as_deref() { - Ok([]) => return false, - Err(ty::util::AlwaysRequiresDrop) => return true, - // If we've got a single component, select with that - // to increase the chance that we hit the selection cache. - Ok([t]) => ty = t, - Ok([..]) => {} + fn in_any_value_of_ty<'tcx>(cx: &ConstCx<'_, 'tcx>, ty: Ty<'tcx>) -> bool { + // Avoid selecting for simple cases, such as builtin types. + if ty::util::trivial_const_drop(ty) { + return false; } let Some(drop_trait) = cx.tcx.lang_items().drop_trait() else { @@ -187,11 +182,15 @@ impl Qualif for NeedsNonConstDrop { impl_src, ImplSource::ConstDrop(_) | ImplSource::Param(_, ty::BoundConstness::ConstIfConst) ) { - // If our const drop candidate is not ConstDrop or implied by param, + // If our const drop candidate is not ConstDrop or implied by the param env, // then it's bad return true; } + if impl_src.borrow_nested_obligations().is_empty() { + return false; + } + // If we successfully found one, then select all of the predicates // implied by our const drop impl. let mut fcx = FulfillmentContext::new(); -- cgit 1.4.1-3-g733a5