From ca581f91614dacabe1f6629435b9c74720e469cd Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Mon, 5 Jun 2023 15:57:21 +0000
Subject: [PATCH] Don't require associated types with `Self: Sized` bounds in
`dyn Trait` objects
---
compiler/rustc_hir_analysis/src/astconv/mod.rs | 10 ++++++++++
compiler/rustc_middle/src/query/mod.rs | 4 ++++
.../src/traits/object_safety.rs | 7 ++++++-
tests/ui/object-safety/assoc_type_bounds_sized.rs | 4 +++-
.../ui/object-safety/assoc_type_bounds_sized.stderr | 12 ------------
5 files changed, 23 insertions(+), 14 deletions(-)
delete mode 100644 tests/ui/object-safety/assoc_type_bounds_sized.stderr
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 752c5ad535a..6291d124ab4 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -1131,6 +1131,16 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
}
}
+ for def_ids in associated_types.values_mut() {
+ for def_id in def_ids.clone() {
+ // If the associated type has a `where Self: Sized` bound, we do not need to constrain the associated
+ // type in the `dyn Trait`.
+ if tcx.generics_require_sized_self(def_id) {
+ def_ids.remove(&def_id);
+ }
+ }
+ }
+
self.complain_about_missing_associated_types(
associated_types,
potential_assoc_types,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 6f942e0bc86..0e1c6d19e31 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -2197,6 +2197,10 @@ rustc_queries! {
desc { "getting cfg-ed out item names" }
separate_provide_extern
}
+
+ query generics_require_sized_self(def_id: DefId) -> bool {
+ desc { "check whether the item has a `where Self: Sized` bound" }
+ }
}
rustc_query_append! { define_callbacks! }
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index 08be60c65d4..6a9f0ffc425 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -922,5 +922,10 @@ pub fn contains_illegal_impl_trait_in_trait<'tcx>(
}
pub fn provide(providers: &mut Providers) {
- *providers = Providers { object_safety_violations, check_is_object_safe, ..*providers };
+ *providers = Providers {
+ object_safety_violations,
+ check_is_object_safe,
+ generics_require_sized_self,
+ ..*providers
+ };
}
diff --git a/tests/ui/object-safety/assoc_type_bounds_sized.rs b/tests/ui/object-safety/assoc_type_bounds_sized.rs
index 61ad3cf9dc6..546cde37f63 100644
--- a/tests/ui/object-safety/assoc_type_bounds_sized.rs
+++ b/tests/ui/object-safety/assoc_type_bounds_sized.rs
@@ -1,9 +1,11 @@
+// check-pass
+
trait Foo {
type Bar
where
Self: Sized;
}
-fn foo(_: &dyn Foo) {} //~ ERROR: the value of the associated type `Bar` (from trait `Foo`) must be specified
+fn foo(_: &dyn Foo) {}
fn main() {}
diff --git a/tests/ui/object-safety/assoc_type_bounds_sized.stderr b/tests/ui/object-safety/assoc_type_bounds_sized.stderr
deleted file mode 100644
index 49d624f9b1d..00000000000
--- a/tests/ui/object-safety/assoc_type_bounds_sized.stderr
+++ /dev/null
@@ -1,12 +0,0 @@
-error[E0191]: the value of the associated type `Bar` (from trait `Foo`) must be specified
- --> $DIR/assoc_type_bounds_sized.rs:7:16
- |
-LL | type Bar
- | -------- `Bar` defined here
-...
-LL | fn foo(_: &dyn Foo) {}
- | ^^^ help: specify the associated type: `Foo<Bar = Type>`
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0191`.