From de940fc72553065cdf213a55c2d8bc7059e414ff Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Sat, 2 Oct 2021 19:02:22 +0100
Subject: [PATCH] Use Ancestory to check default fn in const impl instead of
comparing idents
---
compiler/rustc_passes/src/check_const.rs | 42 ++++++++++++++----------
1 file changed, 25 insertions(+), 17 deletions(-)
diff --git a/compiler/rustc_passes/src/check_const.rs b/compiler/rustc_passes/src/check_const.rs
index 4a82252a32b..a0ceb567f25 100644
--- a/compiler/rustc_passes/src/check_const.rs
+++ b/compiler/rustc_passes/src/check_const.rs
@@ -8,7 +8,6 @@
//! through, but errors for structured control flow in a `const` should be emitted here.
use rustc_attr as attr;
-use rustc_data_structures::stable_set::FxHashSet;
use rustc_errors::struct_span_err;
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
@@ -83,32 +82,41 @@ impl<'tcx> hir::itemlikevisit::ItemLikeVisitor<'tcx> for CheckConstTraitVisitor<
let _: Option<_> = try {
if let hir::ItemKind::Impl(ref imp) = item.kind {
if let hir::Constness::Const = imp.constness {
- let did = imp.of_trait.as_ref()?.trait_def_id()?;
- let mut to_implement = FxHashSet::default();
+ let trait_def_id = imp.of_trait.as_ref()?.trait_def_id()?;
+ let ancestors = self
+ .tcx
+ .trait_def(trait_def_id)
+ .ancestors(self.tcx, item.def_id.to_def_id())
+ .ok()?;
+ let mut to_implement = Vec::new();
- for did in self.tcx.associated_item_def_ids(did) {
+ for trait_item in self.tcx.associated_items(trait_def_id).in_definition_order()
+ {
if let ty::AssocItem {
kind: ty::AssocKind::Fn, ident, defaultness, ..
- } = self.tcx.associated_item(*did)
+ } = trait_item
{
// we can ignore functions that do not have default bodies:
// if those are unimplemented it will be catched by typeck.
- if defaultness.has_value()
- && !self.tcx.has_attr(*did, sym::default_method_body_is_const)
+ if !defaultness.has_value()
+ || self
+ .tcx
+ .has_attr(trait_item.def_id, sym::default_method_body_is_const)
{
- to_implement.insert(ident);
+ continue;
+ }
+
+ let is_implemented = ancestors
+ .leaf_def(self.tcx, trait_item.ident, trait_item.kind)
+ .map(|node_item| !node_item.defining_node.is_from_trait())
+ .unwrap_or(false);
+
+ if !is_implemented {
+ to_implement.push(ident.to_string());
}
}
}
- for it in imp
- .items
- .iter()
- .filter(|it| matches!(it.kind, hir::AssocItemKind::Fn { .. }))
- {
- to_implement.remove(&it.ident);
- }
-
// all nonconst trait functions (not marked with #[default_method_body_is_const])
// must be implemented
if !to_implement.is_empty() {
@@ -118,7 +126,7 @@ impl<'tcx> hir::itemlikevisit::ItemLikeVisitor<'tcx> for CheckConstTraitVisitor<
item.span,
"const trait implementations may not use non-const default functions",
)
- .note(&format!("`{}` not implemented", to_implement.into_iter().map(|id| id.to_string()).collect::<Vec<_>>().join("`, `")))
+ .note(&format!("`{}` not implemented", to_implement.join("`, `")))
.emit();
}
}