Rename Receiver -> LegacyReceiver

As part of the "arbitrary self types v2" project, we are going to
replace the current `Receiver` trait with a new mechanism based on a
new, different `Receiver` trait.

This PR renames the old trait to get it out the way. Naming is hard.
Options considered included:
* HardCodedReceiver (because it should only be used for things in the
  standard library, and hence is sort-of hard coded)
* LegacyReceiver
* TargetLessReceiver
* OldReceiver

These are all bad names, but fortunately this will be temporary.
Assuming the new mechanism proceeds to stabilization as intended, the
legacy trait will be removed altogether.

Although we expect this trait to be used only in the standard library,
we suspect it may be in use elsehwere, so we're landing this change
separately to identify any surprising breakages.

It's known that this trait is used within the Rust for Linux project; a
patch is in progress to remove their dependency.

This is a part of the arbitrary self types v2 project,
https://github.com/rust-lang/rfcs/pull/3519
https://github.com/rust-lang/rust/issues/44874

r? @wesleywiser

5 files changed, 13 insertions, 13 deletions

diff --git a/compiler/rustc_codegen_cranelift/example/mini_core.rs b/compiler/rustc_codegen_cranelift/example/mini_core.rs
index 9fc0318df5d..42c7f5f0dc6 100644
--- a/compiler/rustc_codegen_cranelift/example/mini_core.rs
+++ b/compiler/rustc_codegen_cranelift/example/mini_core.rs
@@ -47,12 +47,12 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<*const U> for *const T {}
 impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<*mut U> for *mut T {}
 impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T> {}
 
-#[lang = "receiver"]
-pub trait Receiver {}
+#[lang = "legacy_receiver"]
+pub trait LegacyReceiver {}
 
-impl<T: ?Sized> Receiver for &T {}
-impl<T: ?Sized> Receiver for &mut T {}
-impl<T: ?Sized> Receiver for Box<T> {}
+impl<T: ?Sized> LegacyReceiver for &T {}
+impl<T: ?Sized> LegacyReceiver for &mut T {}
+impl<T: ?Sized> LegacyReceiver for Box<T> {}
 
 #[lang = "copy"]
 pub unsafe trait Copy {}
diff --git a/compiler/rustc_codegen_gcc/example/mini_core.rs b/compiler/rustc_codegen_gcc/example/mini_core.rs
index f47bfdad131..0576b64ef6f 100644
--- a/compiler/rustc_codegen_gcc/example/mini_core.rs
+++ b/compiler/rustc_codegen_gcc/example/mini_core.rs
@@ -44,12 +44,12 @@ impl<T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<*const U> for *const T {}
 impl<T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<*mut U> for *mut T {}
 impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U, ()>> for Box<T, ()> {}
 
-#[lang = "receiver"]
-pub trait Receiver {}
+#[lang = "legacy_receiver"]
+pub trait LegacyReceiver {}
 
-impl<T: ?Sized> Receiver for &T {}
-impl<T: ?Sized> Receiver for &mut T {}
-impl<T: ?Sized, A: Allocator> Receiver for Box<T, A> {}
+impl<T: ?Sized> LegacyReceiver for &T {}
+impl<T: ?Sized> LegacyReceiver for &mut T {}
+impl<T: ?Sized, A: Allocator> LegacyReceiver for Box<T, A> {}
 
 #[lang = "copy"]
 pub unsafe trait Copy {}
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index b161e6ba0fa..ae046c09ebe 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -241,7 +241,7 @@ language_item_table! {
     DerefMut,                sym::deref_mut,           deref_mut_trait,            Target::Trait,          GenericRequirement::Exact(0);
     DerefPure,               sym::deref_pure,          deref_pure_trait,           Target::Trait,          GenericRequirement::Exact(0);
     DerefTarget,             sym::deref_target,        deref_target,               Target::AssocTy,        GenericRequirement::None;
-    Receiver,                sym::receiver,            receiver_trait,             Target::Trait,          GenericRequirement::None;
+    LegacyReceiver,          sym::legacy_receiver,     legacy_receiver_trait,      Target::Trait,          GenericRequirement::None;
 
     Fn,                      kw::Fn,                   fn_trait,                   Target::Trait,          GenericRequirement::Exact(1);
     FnMut,                   sym::fn_mut,              fn_mut_trait,               Target::Trait,          GenericRequirement::Exact(1);
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index f788456d4e9..ee46a1ffc7b 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -1801,7 +1801,7 @@ fn receiver_is_valid<'tcx>(
         autoderef = autoderef.include_raw_pointers();
     }
 
-    let receiver_trait_def_id = tcx.require_lang_item(LangItem::Receiver, Some(span));
+    let receiver_trait_def_id = tcx.require_lang_item(LangItem::LegacyReceiver, Some(span));
 
     // Keep dereferencing `receiver_ty` until we get to `self_ty`.
     while let Some((potential_self_ty, _)) = autoderef.next() {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 3ab482072b8..aa05b88ea0c 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1133,6 +1133,7 @@ symbols! {
         lazy_normalization_consts,
         lazy_type_alias,
         le,
+        legacy_receiver,
         len,
         let_chains,
         let_else,
@@ -1573,7 +1574,6 @@ symbols! {
         readonly,
         realloc,
         reason,
-        receiver,
         recursion_limit,
         reexport_test_harness_main,
         ref_pat_eat_one_layer_2024,