rust-analyzer

diff --git a/crates/hir-ty/src/db.rs b/crates/hir-ty/src/db.rs
index ebbe8a448c..ce5a821ea2 100644
--- a/crates/hir-ty/src/db.rs
+++ b/crates/hir-ty/src/db.rs

@@ -154,6 +154,9 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {

#[salsa::invoke(crate::lower::generic_predicates_query)]

fn generic_predicates(&self, def: GenericDefId) -> GenericPredicates;

+ #[salsa::invoke(crate::lower::generic_predicates_without_parent_query)]

+ fn generic_predicates_without_parent(&self, def: GenericDefId) -> GenericPredicates;

#[salsa::invoke(crate::lower::trait_environment_for_body_query)]

#[salsa::transparent]

fn trait_environment_for_body(&self, def: DefWithBodyId) -> Arc<TraitEnvironment>;

diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs
index 841e0216ae..213400d04a 100644
--- a/crates/hir-ty/src/lower.rs
+++ b/crates/hir-ty/src/lower.rs

@@ -1700,6 +1700,28 @@ pub(crate) fn generic_predicates_query(

db: &dyn HirDatabase,

def: GenericDefId,

) -> GenericPredicates {

+ generic_predicates_filtered_by(db, def, |_, _| true)

+/// Resolve the where clause(s) of an item with generics,

+/// except the ones inherited from the parent

+pub(crate) fn generic_predicates_without_parent_query(

+ db: &dyn HirDatabase,

+ def: GenericDefId,

+) -> GenericPredicates {

+ generic_predicates_filtered_by(db, def, |_, d| *d == def)

+/// Resolve the where clause(s) of an item with generics,

+/// except the ones inherited from the parent

+fn generic_predicates_filtered_by<F>(

+ db: &dyn HirDatabase,

+ def: GenericDefId,

+ filter: F,

+) -> GenericPredicates

+where

+ F: Fn(&WherePredicate, &GenericDefId) -> bool,

let resolver = def.resolver(db.upcast());

let (impl_trait_lowering, param_lowering) = match def {

GenericDefId::FunctionId(_) => {

@@ -1714,6 +1736,7 @@ pub(crate) fn generic_predicates_query(

let mut predicates = resolver

.where_predicates_in_scope()

+ .filter(|(pred, def)| filter(pred, def))

.flat_map(|(pred, def)| {

ctx.lower_where_predicate(pred, def, false).map(|p| make_binders(db, &generics, p))

})

diff --git a/crates/hir-ty/src/object_safety.rs b/crates/hir-ty/src/object_safety.rs
index f3bbb6b04f..89bf3619a0 100644
--- a/crates/hir-ty/src/object_safety.rs
+++ b/crates/hir-ty/src/object_safety.rs

@@ -12,7 +12,7 @@ use hir_def::{

lang_item::LangItem, AssocItemId, ConstId, FunctionId, GenericDefId, HasModule, TraitId,

TypeAliasId,

};

-use rustc_hash::{FxHashMap, FxHashSet};

+use rustc_hash::FxHashSet;

use smallvec::SmallVec;

use crate::{

@@ -417,30 +417,11 @@ where

cb(MethodViolationCode::UndispatchableReceiver)?;

}

- let predicates = &*db.generic_predicates(func.into());

- let mut parent_predicates = (*db.generic_predicates(trait_.into()))

- .iter()

- .map(|b| b.skip_binders().skip_binders().clone())

- .fold(FxHashMap::default(), |mut acc, item| {

- acc.entry(item)

- .and_modify(|cnt| {

- *cnt += 1;

- })

- .or_insert(1);

- acc

- });

+ let predicates = &*db.generic_predicates_without_parent(func.into());

let trait_self_idx = trait_self_param_idx(db.upcast(), func.into());

for pred in predicates {

let pred = pred.skip_binders().skip_binders();

- // Skip predicates from parent, i.e. the trait that contains this method

- if let Some(cnt) = parent_predicates.get_mut(pred) {

- if *cnt > 0 {

- *cnt -= 1;

- continue;

- }

if matches!(pred, WhereClause::TypeOutlives(_)) {

continue;

}

diff --git a/crates/hir-ty/src/object_safety/tests.rs b/crates/hir-ty/src/object_safety/tests.rs
index 585313e5b9..3dc08c4619 100644
--- a/crates/hir-ty/src/object_safety/tests.rs
+++ b/crates/hir-ty/src/object_safety/tests.rs

@@ -361,3 +361,20 @@ pub trait Trait {

[("Trait", vec![])],

);

}

+#[test]

+fn std_error_is_object_safe() {

+ check_object_safety(

+ r#"

+//- minicore: fmt, dispatch_from_dyn

+trait Erased<'a>: 'a {}

+pub struct Request<'a>(dyn Erased<'a> + 'a);

+pub trait Error: core::fmt::Debug + core::fmt::Display {

+ fn provide<'a>(&'a self, request: &mut Request<'a>);

+"#,

+ [("Error", vec![])],

+ );