Rollup merge of #86726 - sexxi-goose:use-diagnostic-item-for-rfc2229-migration, r=nikomatsakis

Use diagnostic items instead of lang items for rfc2229 migrations

This PR removes the `Send`, `UnwindSafe` and `RefUnwindSafe` lang items introduced in #84730, and uses diagnostic items instead to check for `Send`, `UnwindSafe` and `RefUnwindSafe` traits for RFC2229 migrations.

r? ```@nikomatsakis```

Author: GuillaumeGomez

compiler/rustc_hir/src/lang_items.rs

@@ -348,7 +348,4 @@ language_item_table! {
     Range,                   sym::Range,               range_struct,               Target::Struct;
     RangeToInclusive,        sym::RangeToInclusive,    range_to_inclusive_struct,  Target::Struct;
     RangeTo,                 sym::RangeTo,             range_to_struct,            Target::Struct;
-    Send,                    sym::send,                send_trait,                 Target::Trait;
-    UnwindSafe,              sym::unwind_safe,         unwind_safe_trait,          Target::Trait;
-    RefUnwindSafe,           sym::ref_unwind_safe,     ref_unwind_safe_trait,      Target::Trait;
 }

compiler/rustc_passes/src/lang_items.rs

@@ -257,9 +257,6 @@ impl LanguageItemCollector<'tcx> {
             | LangItem::Unpin
             | LangItem::Termination
             | LangItem::Try
-            | LangItem::Send
-            | LangItem::UnwindSafe
-            | LangItem::RefUnwindSafe
                 => Some(0),
 
             // Not a trait

compiler/rustc_span/src/symbol.rs

@@ -947,7 +947,7 @@ symbols! {
         receiver,
         recursion_limit,
         reexport_test_harness_main,
-        ref_unwind_safe,
+        ref_unwind_safe_trait,
         reference,
         reflect,
         reg,
@@ -1073,7 +1073,6 @@ symbols! {
         self_in_typedefs,
         self_struct_ctor,
         semitransparent,
-        send,
         send_trait,
         shl,
         shl_assign,
@@ -1299,7 +1298,7 @@ symbols! {
         unused_qualifications,
         unwind,
         unwind_attributes,
-        unwind_safe,
+        unwind_safe_trait,
         unwrap,
         unwrap_or,
         use_extern_macros,

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -688,15 +688,17 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             return false;
         }
 
-        // Blacklist traits for which it would be nonsensical to suggest borrowing.
+        // List of traits for which it would be nonsensical to suggest borrowing.
         // For instance, immutable references are always Copy, so suggesting to
         // borrow would always succeed, but it's probably not what the user wanted.
-        let blacklist: Vec<_> =
-            [LangItem::Copy, LangItem::Clone, LangItem::Unpin, LangItem::Sized, LangItem::Send]
+        let mut never_suggest_borrow: Vec<_> =
+            [LangItem::Copy, LangItem::Clone, LangItem::Unpin, LangItem::Sized]
                 .iter()
                 .filter_map(|lang_item| self.tcx.lang_items().require(*lang_item).ok())
                 .collect();
 
+        never_suggest_borrow.push(self.tcx.get_diagnostic_item(sym::send_trait).unwrap());
+
         let span = obligation.cause.span;
         let param_env = obligation.param_env;
         let trait_ref = trait_ref.skip_binder();
@@ -798,15 +800,15 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 ty::TraitRef::new(trait_ref.def_id, imm_substs),
                 trait_ref,
                 false,
-                &blacklist[..],
+                &never_suggest_borrow[..],
             ) {
                 return true;
             } else {
                 return try_borrowing(
                     ty::TraitRef::new(trait_ref.def_id, mut_substs),
                     trait_ref,
                     true,
-                    &blacklist[..],
+                    &never_suggest_borrow[..],
                 );
             }
         } else {

compiler/rustc_typeck/src/check/upvar.rs

@@ -670,7 +670,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         if self.need_2229_migrations_for_trait(
             min_captures,
             var_hir_id,
-            tcx.lang_items().send_trait(),
+            tcx.get_diagnostic_item(sym::send_trait),
         ) {
             auto_trait_reasons.insert("`Send`");
         }
@@ -686,15 +686,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         if self.need_2229_migrations_for_trait(
             min_captures,
             var_hir_id,
-            tcx.lang_items().unwind_safe_trait(),
+            tcx.get_diagnostic_item(sym::unwind_safe_trait),
         ) {
             auto_trait_reasons.insert("`UnwindSafe`");
         }
 
         if self.need_2229_migrations_for_trait(
             min_captures,
             var_hir_id,
-            tcx.lang_items().ref_unwind_safe_trait(),
+            tcx.get_diagnostic_item(sym::ref_unwind_safe_trait),
         ) {
             auto_trait_reasons.insert("`RefUnwindSafe`");
         }

library/core/src/marker.rs

@@ -31,7 +31,6 @@ use crate::hash::Hasher;
 /// [ub]: ../../reference/behavior-considered-undefined.html
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "send_trait")]
-#[lang = "send"]
 #[rustc_on_unimplemented(
     message = "`{Self}` cannot be sent between threads safely",
     label = "`{Self}` cannot be sent between threads safely"

library/std/src/panic.rs

@@ -133,7 +133,7 @@ pub fn panic_any<M: 'static + Any + Send>(msg: M) -> ! {
 /// [`AssertUnwindSafe`] wrapper struct can be used to force this trait to be
 /// implemented for any closed over variables passed to `catch_unwind`.
 #[stable(feature = "catch_unwind", since = "1.9.0")]
-#[cfg_attr(not(test), lang = "unwind_safe")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "unwind_safe_trait")]
 #[rustc_on_unimplemented(
     message = "the type `{Self}` may not be safely transferred across an unwind boundary",
     label = "`{Self}` may not be safely transferred across an unwind boundary"
@@ -149,7 +149,7 @@ pub auto trait UnwindSafe {}
 /// This is a "helper marker trait" used to provide impl blocks for the
 /// [`UnwindSafe`] trait, for more information see that documentation.
 #[stable(feature = "catch_unwind", since = "1.9.0")]
-#[cfg_attr(not(test), lang = "ref_unwind_safe")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "ref_unwind_safe_trait")]
 #[rustc_on_unimplemented(
     message = "the type `{Self}` may contain interior mutability and a reference may not be safely \
                transferrable across a catch_unwind boundary",