diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 7bad9d33e7d31..ca439460adc11 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1317,11 +1317,9 @@ fn link_sanitizer_runtime(
     name: &str,
 ) {
     fn find_sanitizer_runtime(sess: &Session, filename: &str) -> PathBuf {
-        let session_tlib =
-            filesearch::make_target_lib_path(&sess.sysroot, sess.opts.target_triple.triple());
-        let path = session_tlib.join(filename);
+        let path = sess.target_tlib_path.dir.join(filename);
         if path.exists() {
-            return session_tlib;
+            return sess.target_tlib_path.dir.clone();
         } else {
             let default_sysroot =
                 filesearch::get_or_default_sysroot().expect("Failed finding sysroot");
@@ -1612,19 +1610,18 @@ fn print_native_static_libs(
 }
 
 fn get_object_file_path(sess: &Session, name: &str, self_contained: bool) -> PathBuf {
-    let fs = sess.target_filesearch(PathKind::Native);
-    let file_path = fs.get_lib_path().join(name);
+    let file_path = sess.target_tlib_path.dir.join(name);
     if file_path.exists() {
         return file_path;
     }
     // Special directory with objects used only in self-contained linkage mode
     if self_contained {
-        let file_path = fs.get_self_contained_lib_path().join(name);
+        let file_path = sess.target_tlib_path.dir.join("self-contained").join(name);
         if file_path.exists() {
             return file_path;
         }
     }
-    for search_path in fs.search_paths() {
+    for search_path in sess.target_filesearch(PathKind::Native).search_paths() {
         let file_path = search_path.dir.join(name);
         if file_path.exists() {
             return file_path;
@@ -2131,7 +2128,7 @@ fn add_library_search_dirs(
             | LinkSelfContainedComponents::UNWIND
             | LinkSelfContainedComponents::MINGW,
     ) {
-        let lib_path = sess.target_filesearch(PathKind::Native).get_self_contained_lib_path();
+        let lib_path = sess.target_tlib_path.dir.join("self-contained");
         cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
     }
 
@@ -2146,8 +2143,7 @@ fn add_library_search_dirs(
         || sess.target.os == "fuchsia"
         || sess.target.is_like_osx && !sess.opts.unstable_opts.sanitizer.is_empty()
     {
-        let lib_path = sess.target_filesearch(PathKind::Native).get_lib_path();
-        cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
+        cmd.include_path(&fix_windows_verbatim_for_gcc(&sess.target_tlib_path.dir));
     }
 
     // Mac Catalyst uses the macOS SDK, but to link to iOS-specific frameworks
@@ -2859,15 +2855,14 @@ fn add_upstream_native_libraries(
 //
 // The returned path will always have `fix_windows_verbatim_for_gcc()` applied to it.
 fn rehome_sysroot_lib_dir(sess: &Session, lib_dir: &Path) -> PathBuf {
-    let sysroot_lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
+    let sysroot_lib_path = &sess.target_tlib_path.dir;
     let canonical_sysroot_lib_path =
-        { try_canonicalize(&sysroot_lib_path).unwrap_or_else(|_| sysroot_lib_path.clone()) };
+        { try_canonicalize(sysroot_lib_path).unwrap_or_else(|_| sysroot_lib_path.clone()) };
 
     let canonical_lib_dir = try_canonicalize(lib_dir).unwrap_or_else(|_| lib_dir.to_path_buf());
     if canonical_lib_dir == canonical_sysroot_lib_path {
-        // This path, returned by `target_filesearch().get_lib_path()`, has
-        // already had `fix_windows_verbatim_for_gcc()` applied if needed.
-        sysroot_lib_path
+        // This path already had `fix_windows_verbatim_for_gcc()` applied if needed.
+        sysroot_lib_path.clone()
     } else {
         fix_windows_verbatim_for_gcc(lib_dir)
     }
diff --git a/compiler/rustc_hir_analysis/src/variance/dump.rs b/compiler/rustc_hir_analysis/src/variance/dump.rs
index 1a17dabb677ac..ace183986bd00 100644
--- a/compiler/rustc_hir_analysis/src/variance/dump.rs
+++ b/compiler/rustc_hir_analysis/src/variance/dump.rs
@@ -1,18 +1,36 @@
+use std::fmt::Write;
+
 use rustc_hir::def::DefKind;
-use rustc_hir::def_id::CRATE_DEF_ID;
-use rustc_middle::ty::TyCtxt;
+use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
+use rustc_middle::ty::{GenericArgs, TyCtxt};
 use rustc_span::symbol::sym;
 
+fn format_variances(tcx: TyCtxt<'_>, def_id: LocalDefId) -> String {
+    let variances = tcx.variances_of(def_id);
+    let generics = GenericArgs::identity_for_item(tcx, def_id);
+    // 7 = 2-letter parameter + ": " + 1-letter variance + ", "
+    let mut ret = String::with_capacity(2 + 7 * variances.len());
+    ret.push('[');
+    for (arg, variance) in generics.iter().zip(variances.iter()) {
+        write!(ret, "{arg}: {variance:?}, ").unwrap();
+    }
+    // Remove trailing `, `.
+    if !variances.is_empty() {
+        ret.pop();
+        ret.pop();
+    }
+    ret.push(']');
+    ret
+}
+
 pub(crate) fn variances(tcx: TyCtxt<'_>) {
     if tcx.has_attr(CRATE_DEF_ID, sym::rustc_variance_of_opaques) {
         for id in tcx.hir().items() {
             let DefKind::OpaqueTy = tcx.def_kind(id.owner_id) else { continue };
 
-            let variances = tcx.variances_of(id.owner_id);
-
             tcx.dcx().emit_err(crate::errors::VariancesOf {
                 span: tcx.def_span(id.owner_id),
-                variances: format!("{variances:?}"),
+                variances: format_variances(tcx, id.owner_id.def_id),
             });
         }
     }
@@ -22,11 +40,9 @@ pub(crate) fn variances(tcx: TyCtxt<'_>) {
             continue;
         }
 
-        let variances = tcx.variances_of(id.owner_id);
-
         tcx.dcx().emit_err(crate::errors::VariancesOf {
             span: tcx.def_span(id.owner_id),
-            variances: format!("{variances:?}"),
+            variances: format_variances(tcx, id.owner_id.def_id),
         });
     }
 }
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
index fec6efdc0f71b..91778a366684b 100644
--- a/compiler/rustc_hir_typeck/src/expr.rs
+++ b/compiler/rustc_hir_typeck/src/expr.rs
@@ -841,6 +841,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let ret_ty = ret_coercion.borrow().expected_ty();
         let return_expr_ty = self.check_expr_with_hint(return_expr, ret_ty);
         let mut span = return_expr.span;
+        let mut hir_id = return_expr.hir_id;
         // Use the span of the trailing expression for our cause,
         // not the span of the entire function
         if !explicit_return
@@ -848,6 +849,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             && let Some(last_expr) = body.expr
         {
             span = last_expr.span;
+            hir_id = last_expr.hir_id;
         }
         ret_coercion.borrow_mut().coerce(
             self,
@@ -864,6 +866,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             self.select_obligations_where_possible(|errors| {
                 self.point_at_return_for_opaque_ty_error(
                     errors,
+                    hir_id,
                     span,
                     return_expr_ty,
                     return_expr.span,
@@ -921,6 +924,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     fn point_at_return_for_opaque_ty_error(
         &self,
         errors: &mut Vec<traits::FulfillmentError<'tcx>>,
+        hir_id: HirId,
         span: Span,
         return_expr_ty: Ty<'tcx>,
         return_span: Span,
@@ -935,7 +939,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 let new_cause = ObligationCause::new(
                     cause.span,
                     cause.body_id,
-                    ObligationCauseCode::OpaqueReturnType(Some((return_expr_ty, span))),
+                    ObligationCauseCode::OpaqueReturnType(Some((return_expr_ty, hir_id))),
                 );
                 *cause = new_cause;
             }
diff --git a/compiler/rustc_index/src/lib.rs b/compiler/rustc_index/src/lib.rs
index b5e4f02a8d15c..b9d2a43206b1e 100644
--- a/compiler/rustc_index/src/lib.rs
+++ b/compiler/rustc_index/src/lib.rs
@@ -2,6 +2,7 @@
 #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
 #![cfg_attr(feature = "nightly", feature(extend_one, new_uninit, step_trait, test))]
+#![cfg_attr(feature = "nightly", feature(new_zeroed_alloc))]
 // tidy-alphabetical-end
 
 pub mod bit_set;
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 28aef9055ef44..08a50050a36d5 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -361,6 +361,11 @@ lint_improper_ctypes_box = box cannot be represented as a single pointer
 lint_improper_ctypes_char_help = consider using `u32` or `libc::wchar_t` instead
 
 lint_improper_ctypes_char_reason = the `char` type has no C equivalent
+
+lint_improper_ctypes_cstr_help =
+    consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+lint_improper_ctypes_cstr_reason = `CStr`/`CString` do not have a guaranteed layout
+
 lint_improper_ctypes_dyn = trait objects have no C equivalent
 
 lint_improper_ctypes_enum_repr_help =
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index cb7a07116ced8..f1da14bb1f382 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -985,6 +985,14 @@ struct ImproperCTypesVisitor<'a, 'tcx> {
     mode: CItemKind,
 }
 
+/// Accumulator for recursive ffi type checking
+struct CTypesVisitorState<'tcx> {
+    cache: FxHashSet<Ty<'tcx>>,
+    /// The original type being checked, before we recursed
+    /// to any other types it contains.
+    base_ty: Ty<'tcx>,
+}
+
 enum FfiResult<'tcx> {
     FfiSafe,
     FfiPhantom(Ty<'tcx>),
@@ -1213,7 +1221,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
     /// Checks if the given field's type is "ffi-safe".
     fn check_field_type_for_ffi(
         &self,
-        cache: &mut FxHashSet<Ty<'tcx>>,
+        acc: &mut CTypesVisitorState<'tcx>,
         field: &ty::FieldDef,
         args: GenericArgsRef<'tcx>,
     ) -> FfiResult<'tcx> {
@@ -1223,13 +1231,13 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
             .tcx
             .try_normalize_erasing_regions(self.cx.param_env, field_ty)
             .unwrap_or(field_ty);
-        self.check_type_for_ffi(cache, field_ty)
+        self.check_type_for_ffi(acc, field_ty)
     }
 
     /// Checks if the given `VariantDef`'s field types are "ffi-safe".
     fn check_variant_for_ffi(
         &self,
-        cache: &mut FxHashSet<Ty<'tcx>>,
+        acc: &mut CTypesVisitorState<'tcx>,
         ty: Ty<'tcx>,
         def: ty::AdtDef<'tcx>,
         variant: &ty::VariantDef,
@@ -1239,7 +1247,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
         let transparent_with_all_zst_fields = if def.repr().transparent() {
             if let Some(field) = transparent_newtype_field(self.cx.tcx, variant) {
                 // Transparent newtypes have at most one non-ZST field which needs to be checked..
-                match self.check_field_type_for_ffi(cache, field, args) {
+                match self.check_field_type_for_ffi(acc, field, args) {
                     FfiUnsafe { ty, .. } if ty.is_unit() => (),
                     r => return r,
                 }
@@ -1257,7 +1265,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
         // We can't completely trust `repr(C)` markings, so make sure the fields are actually safe.
         let mut all_phantom = !variant.fields.is_empty();
         for field in &variant.fields {
-            all_phantom &= match self.check_field_type_for_ffi(cache, field, args) {
+            all_phantom &= match self.check_field_type_for_ffi(acc, field, args) {
                 FfiSafe => false,
                 // `()` fields are FFI-safe!
                 FfiUnsafe { ty, .. } if ty.is_unit() => false,
@@ -1277,7 +1285,11 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
 
     /// Checks if the given type is "ffi-safe" (has a stable, well-defined
     /// representation which can be exported to C code).
-    fn check_type_for_ffi(&self, cache: &mut FxHashSet<Ty<'tcx>>, ty: Ty<'tcx>) -> FfiResult<'tcx> {
+    fn check_type_for_ffi(
+        &self,
+        acc: &mut CTypesVisitorState<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> FfiResult<'tcx> {
         use FfiResult::*;
 
         let tcx = self.cx.tcx;
@@ -1286,7 +1298,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
         // `struct S(*mut S);`.
         // FIXME: A recursion limit is necessary as well, for irregular
         // recursive types.
-        if !cache.insert(ty) {
+        if !acc.cache.insert(ty) {
             return FfiSafe;
         }
 
@@ -1308,6 +1320,17 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                 }
                 match def.adt_kind() {
                     AdtKind::Struct | AdtKind::Union => {
+                        if let Some(sym::cstring_type | sym::cstr_type) =
+                            tcx.get_diagnostic_name(def.did())
+                            && !acc.base_ty.is_mutable_ptr()
+                        {
+                            return FfiUnsafe {
+                                ty,
+                                reason: fluent::lint_improper_ctypes_cstr_reason,
+                                help: Some(fluent::lint_improper_ctypes_cstr_help),
+                            };
+                        }
+
                         if !def.repr().c() && !def.repr().transparent() {
                             return FfiUnsafe {
                                 ty,
@@ -1354,7 +1377,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                             };
                         }
 
-                        self.check_variant_for_ffi(cache, ty, def, def.non_enum_variant(), args)
+                        self.check_variant_for_ffi(acc, ty, def, def.non_enum_variant(), args)
                     }
                     AdtKind::Enum => {
                         if def.variants().is_empty() {
@@ -1378,7 +1401,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                             if let Some(ty) =
                                 repr_nullable_ptr(self.cx.tcx, self.cx.param_env, ty, self.mode)
                             {
-                                return self.check_type_for_ffi(cache, ty);
+                                return self.check_type_for_ffi(acc, ty);
                             }
 
                             return FfiUnsafe {
@@ -1399,7 +1422,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                                 };
                             }
 
-                            match self.check_variant_for_ffi(cache, ty, def, variant, args) {
+                            match self.check_variant_for_ffi(acc, ty, def, variant, args) {
                                 FfiSafe => (),
                                 r => return r,
                             }
@@ -1469,9 +1492,9 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                 FfiSafe
             }
 
-            ty::RawPtr(ty, _) | ty::Ref(_, ty, _) => self.check_type_for_ffi(cache, ty),
+            ty::RawPtr(ty, _) | ty::Ref(_, ty, _) => self.check_type_for_ffi(acc, ty),
 
-            ty::Array(inner_ty, _) => self.check_type_for_ffi(cache, inner_ty),
+            ty::Array(inner_ty, _) => self.check_type_for_ffi(acc, inner_ty),
 
             ty::FnPtr(sig_tys, hdr) => {
                 let sig = sig_tys.with(hdr);
@@ -1485,7 +1508,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
 
                 let sig = tcx.instantiate_bound_regions_with_erased(sig);
                 for arg in sig.inputs() {
-                    match self.check_type_for_ffi(cache, *arg) {
+                    match self.check_type_for_ffi(acc, *arg) {
                         FfiSafe => {}
                         r => return r,
                     }
@@ -1496,7 +1519,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                     return FfiSafe;
                 }
 
-                self.check_type_for_ffi(cache, ret_ty)
+                self.check_type_for_ffi(acc, ret_ty)
             }
 
             ty::Foreign(..) => FfiSafe,
@@ -1619,7 +1642,8 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
             return;
         }
 
-        match self.check_type_for_ffi(&mut FxHashSet::default(), ty) {
+        let mut acc = CTypesVisitorState { cache: FxHashSet::default(), base_ty: ty };
+        match self.check_type_for_ffi(&mut acc, ty) {
             FfiResult::FfiSafe => {}
             FfiResult::FfiPhantom(ty) => {
                 self.emit_ffi_unsafe_type_lint(
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index d54e2ca0a74f7..a3277fb96d229 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -353,7 +353,7 @@ pub enum ObligationCauseCode<'tcx> {
     ReturnValue(HirId),
 
     /// Opaque return type of this function
-    OpaqueReturnType(Option<(Ty<'tcx>, Span)>),
+    OpaqueReturnType(Option<(Ty<'tcx>, HirId)>),
 
     /// Block implicit return
     BlockTailExpression(HirId, hir::MatchSource),
diff --git a/compiler/rustc_session/src/filesearch.rs b/compiler/rustc_session/src/filesearch.rs
index 63ca5fefd9faf..d78f4a78de732 100644
--- a/compiler/rustc_session/src/filesearch.rs
+++ b/compiler/rustc_session/src/filesearch.rs
@@ -5,14 +5,11 @@ use std::{env, fs};
 
 use rustc_fs_util::{fix_windows_verbatim_for_gcc, try_canonicalize};
 use smallvec::{smallvec, SmallVec};
-use tracing::debug;
 
 use crate::search_paths::{PathKind, SearchPath};
 
 #[derive(Clone)]
 pub struct FileSearch<'a> {
-    sysroot: &'a Path,
-    triple: &'a str,
     cli_search_paths: &'a [SearchPath],
     tlib_path: &'a SearchPath,
     kind: PathKind,
@@ -32,23 +29,12 @@ impl<'a> FileSearch<'a> {
             .chain(std::iter::once(self.tlib_path))
     }
 
-    pub fn get_lib_path(&self) -> PathBuf {
-        make_target_lib_path(self.sysroot, self.triple)
-    }
-
-    pub fn get_self_contained_lib_path(&self) -> PathBuf {
-        self.get_lib_path().join("self-contained")
-    }
-
     pub fn new(
-        sysroot: &'a Path,
-        triple: &'a str,
         cli_search_paths: &'a [SearchPath],
         tlib_path: &'a SearchPath,
         kind: PathKind,
     ) -> FileSearch<'a> {
-        debug!("using sysroot = {}, triple = {}", sysroot.display(), triple);
-        FileSearch { sysroot, triple, cli_search_paths, tlib_path, kind }
+        FileSearch { cli_search_paths, tlib_path, kind }
     }
 }
 
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 693867c3853da..b073950a750b4 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -439,22 +439,10 @@ impl Session {
     }
 
     pub fn target_filesearch(&self, kind: PathKind) -> filesearch::FileSearch<'_> {
-        filesearch::FileSearch::new(
-            &self.sysroot,
-            self.opts.target_triple.triple(),
-            &self.opts.search_paths,
-            &self.target_tlib_path,
-            kind,
-        )
+        filesearch::FileSearch::new(&self.opts.search_paths, &self.target_tlib_path, kind)
     }
     pub fn host_filesearch(&self, kind: PathKind) -> filesearch::FileSearch<'_> {
-        filesearch::FileSearch::new(
-            &self.sysroot,
-            config::host_triple(),
-            &self.opts.search_paths,
-            &self.host_tlib_path,
-            kind,
-        )
+        filesearch::FileSearch::new(&self.opts.search_paths, &self.host_tlib_path, kind)
     }
 
     /// Returns a list of directories where target-specific tool binaries are located. Some fallback
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index a2e94492f8c23..b16951a186893 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -673,6 +673,7 @@ symbols! {
         crate_visibility_modifier,
         crt_dash_static: "crt-static",
         csky_target_feature,
+        cstr_type,
         cstring_type,
         ctlz,
         ctlz_nonzero,
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 80f89a0ab2be0..41afe8ccb8a4f 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -1695,6 +1695,8 @@ supported_targets! {
     ("armv7r-none-eabihf", armv7r_none_eabihf),
     ("armv8r-none-eabihf", armv8r_none_eabihf),
 
+    ("armv7-rtems-eabihf", armv7_rtems_eabihf),
+
     ("x86_64-pc-solaris", x86_64_pc_solaris),
     ("sparcv9-sun-solaris", sparcv9_sun_solaris),
 
diff --git a/compiler/rustc_target/src/spec/targets/armv7_rtems_eabihf.rs b/compiler/rustc_target/src/spec/targets/armv7_rtems_eabihf.rs
new file mode 100644
index 0000000000000..12e94665c3d61
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/armv7_rtems_eabihf.rs
@@ -0,0 +1,35 @@
+use crate::spec::{cvs, Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "armv7-unknown-none-eabihf".into(),
+        metadata: crate::spec::TargetMetadata {
+            description: Some("Armv7 RTEMS (Requires RTEMS toolchain and kernel".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
+        pointer_width: 32,
+        data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),
+        arch: "arm".into(),
+
+        options: TargetOptions {
+            os: "rtems".into(),
+            families: cvs!["unix"],
+            abi: "eabihf".into(),
+            linker_flavor: LinkerFlavor::Gnu(Cc::Yes, Lld::No),
+            linker: None,
+            relocation_model: RelocModel::Static,
+            panic_strategy: PanicStrategy::Abort,
+            features: "+thumb2,+neon,+vfp3".into(),
+            max_atomic_width: Some(64),
+            emit_debug_gdb_scripts: false,
+            // GCC defaults to 8 for arm-none here.
+            c_enum_min_bits: Some(8),
+            eh_frame_header: false,
+            no_default_libraries: false,
+            env: "newlib".into(),
+            ..Default::default()
+        },
+    }
+}
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
index a962be54c3d88..228b75cd73ca6 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -2727,6 +2727,20 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
         let tcx = self.tcx;
         let predicate = predicate.upcast(tcx);
+        let suggest_remove_deref = |err: &mut Diag<'_, G>, expr: &hir::Expr<'_>| {
+            if let Some(pred) = predicate.as_trait_clause()
+                && tcx.is_lang_item(pred.def_id(), LangItem::Sized)
+                && let hir::ExprKind::Unary(hir::UnOp::Deref, inner) = expr.kind
+            {
+                err.span_suggestion_verbose(
+                    expr.span.until(inner.span),
+                    "references are always `Sized`, even if they point to unsized data; consider \
+                     not dereferencing the expression",
+                    String::new(),
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        };
         match *cause_code {
             ObligationCauseCode::ExprAssignable
             | ObligationCauseCode::MatchExpressionArm { .. }
@@ -2773,6 +2787,19 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             | ObligationCauseCode::WhereClauseInExpr(item_def_id, span, ..)
                 if !span.is_dummy() =>
             {
+                if let ObligationCauseCode::WhereClauseInExpr(_, _, hir_id, pos) = &cause_code {
+                    if let Node::Expr(expr) = tcx.parent_hir_node(*hir_id)
+                        && let hir::ExprKind::Call(_, args) = expr.kind
+                        && let Some(expr) = args.get(*pos)
+                    {
+                        suggest_remove_deref(err, &expr);
+                    } else if let Node::Expr(expr) = self.tcx.hir_node(*hir_id)
+                        && let hir::ExprKind::MethodCall(_, _, args, _) = expr.kind
+                        && let Some(expr) = args.get(*pos)
+                    {
+                        suggest_remove_deref(err, &expr);
+                    }
+                }
                 let item_name = tcx.def_path_str(item_def_id);
                 let short_item_name = with_forced_trimmed_paths!(tcx.def_path_str(item_def_id));
                 let mut multispan = MultiSpan::from(span);
@@ -2970,6 +2997,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     ));
                     err.downgrade_to_delayed_bug();
                 }
+                let mut local = true;
                 match tcx.parent_hir_node(hir_id) {
                     Node::LetStmt(hir::LetStmt { ty: Some(ty), .. }) => {
                         err.span_suggestion_verbose(
@@ -2978,7 +3006,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             "&",
                             Applicability::MachineApplicable,
                         );
-                        err.note("all local variables must have a statically known size");
                     }
                     Node::LetStmt(hir::LetStmt {
                         init: Some(hir::Expr { kind: hir::ExprKind::Index(..), span, .. }),
@@ -2993,7 +3020,11 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             "&",
                             Applicability::MachineApplicable,
                         );
-                        err.note("all local variables must have a statically known size");
+                    }
+                    Node::LetStmt(hir::LetStmt { init: Some(expr), .. }) => {
+                        // When encountering an assignment of an unsized trait, like `let x = *"";`,
+                        // we check if the RHS is a deref operation, to suggest removing it.
+                        suggest_remove_deref(err, &expr);
                     }
                     Node::Param(param) => {
                         err.span_suggestion_verbose(
@@ -3003,10 +3034,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             "&",
                             Applicability::MachineApplicable,
                         );
+                        local = false;
                     }
-                    _ => {
-                        err.note("all local variables must have a statically known size");
-                    }
+                    _ => {}
+                }
+                if local {
+                    err.note("all local variables must have a statically known size");
                 }
                 if !tcx.features().unsized_locals {
                     err.help("unsized locals are gated as an unstable feature");
@@ -3529,14 +3562,16 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 );
             }
             ObligationCauseCode::OpaqueReturnType(expr_info) => {
-                if let Some((expr_ty, expr_span)) = expr_info {
+                if let Some((expr_ty, hir_id)) = expr_info {
                     let expr_ty = self.tcx.short_ty_string(expr_ty, &mut long_ty_file);
+                    let expr = self.infcx.tcx.hir().expect_expr(hir_id);
                     err.span_label(
-                        expr_span,
+                        expr.span,
                         with_forced_trimmed_paths!(format!(
                             "return type was inferred to be `{expr_ty}` here",
                         )),
                     );
+                    suggest_remove_deref(err, &expr);
                 }
             }
         }
diff --git a/library/Cargo.lock b/library/Cargo.lock
index f2f446b61085d..aa22181a4639a 100644
--- a/library/Cargo.lock
+++ b/library/Cargo.lock
@@ -58,9 +58,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.120"
+version = "0.1.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "38c44e9c76d996d8049dee591a997eab801069ad86ed892ed3039f68b73d301c"
+checksum = "ce956e6dc07082ec481f0935a51e83b343f8ca51be560452c0ebf830d0bdf5a5"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",
diff --git a/library/alloc/Cargo.toml b/library/alloc/Cargo.toml
index 43799acc02736..a39a0a6ce0ea2 100644
--- a/library/alloc/Cargo.toml
+++ b/library/alloc/Cargo.toml
@@ -10,7 +10,7 @@ edition = "2021"
 
 [dependencies]
 core = { path = "../core" }
-compiler_builtins = { version = "0.1.120", features = ['rustc-dep-of-std'] }
+compiler_builtins = { version = "0.1.121", features = ['rustc-dep-of-std'] }
 
 [dev-dependencies]
 rand = { version = "0.8.5", default-features = false, features = ["alloc"] }
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 7de412595993a..c8e8d2a22ca48 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -293,6 +293,7 @@ impl<T> Box<T> {
     ///
     /// ```
     /// #![feature(new_uninit)]
+    /// #![feature(new_zeroed_alloc)]
     ///
     /// let zero = Box::<u32>::new_zeroed();
     /// let zero = unsafe { zero.assume_init() };
@@ -303,7 +304,7 @@ impl<T> Box<T> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
     #[must_use]
     pub fn new_zeroed() -> Box<mem::MaybeUninit<T>> {
         Self::new_zeroed_in(Global)
@@ -684,6 +685,7 @@ impl<T> Box<[T]> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(new_zeroed_alloc)]
     /// #![feature(new_uninit)]
     ///
     /// let values = Box::<[u32]>::new_zeroed_slice(3);
@@ -694,7 +696,7 @@ impl<T> Box<[T]> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
     #[must_use]
     pub fn new_zeroed_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
         unsafe { RawVec::with_capacity_zeroed(len).into_box(len) }
@@ -955,6 +957,7 @@ impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(box_uninit_write)]
     /// #![feature(new_uninit)]
     ///
     /// let big_box = Box::<[usize; 1024]>::new_uninit();
@@ -972,7 +975,7 @@ impl<T, A: Allocator> Box<mem::MaybeUninit<T>, A> {
     ///     assert_eq!(*x, i);
     /// }
     /// ```
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "box_uninit_write", issue = "129397")]
     #[inline]
     pub fn write(mut boxed: Self, value: T) -> Box<T, A> {
         unsafe {
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index bdee06154faec..f153aa6d3be9a 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -539,6 +539,7 @@ impl<T> Rc<T> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(new_zeroed_alloc)]
     /// #![feature(new_uninit)]
     ///
     /// use std::rc::Rc;
@@ -551,7 +552,7 @@ impl<T> Rc<T> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
     #[must_use]
     pub fn new_zeroed() -> Rc<mem::MaybeUninit<T>> {
         unsafe {
@@ -1000,6 +1001,7 @@ impl<T> Rc<[T]> {
     ///
     /// ```
     /// #![feature(new_uninit)]
+    /// #![feature(new_zeroed_alloc)]
     ///
     /// use std::rc::Rc;
     ///
@@ -1011,7 +1013,7 @@ impl<T> Rc<[T]> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
     #[must_use]
     pub fn new_zeroed_slice(len: usize) -> Rc<[mem::MaybeUninit<T>]> {
         unsafe {
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index 2c0d19b0ada09..4a3522f1a641b 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -542,6 +542,7 @@ impl<T> Arc<T> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(new_zeroed_alloc)]
     /// #![feature(new_uninit)]
     ///
     /// use std::sync::Arc;
@@ -555,7 +556,7 @@ impl<T> Arc<T> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
     #[must_use]
     pub fn new_zeroed() -> Arc<mem::MaybeUninit<T>> {
         unsafe {
@@ -1134,6 +1135,7 @@ impl<T> Arc<[T]> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(new_zeroed_alloc)]
     /// #![feature(new_uninit)]
     ///
     /// use std::sync::Arc;
@@ -1147,7 +1149,7 @@ impl<T> Arc<[T]> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
     #[must_use]
     pub fn new_zeroed_slice(len: usize) -> Arc<[mem::MaybeUninit<T>]> {
         unsafe {
@@ -1191,7 +1193,7 @@ impl<T, A: Allocator> Arc<[T], A> {
     /// assert_eq!(*values, [1, 2, 3])
     /// ```
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "allocator_api", issue = "32838")]
     #[inline]
     pub fn new_uninit_slice_in(len: usize, alloc: A) -> Arc<[mem::MaybeUninit<T>], A> {
         unsafe { Arc::from_ptr_in(Arc::allocate_for_slice_in(len, &alloc), alloc) }
@@ -1220,7 +1222,7 @@ impl<T, A: Allocator> Arc<[T], A> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_uninit", issue = "63291")]
+    #[unstable(feature = "allocator_api", issue = "32838")]
     #[inline]
     pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Arc<[mem::MaybeUninit<T>], A> {
         unsafe {
diff --git a/library/core/Cargo.toml b/library/core/Cargo.toml
index cace4582b489a..94f343d06705e 100644
--- a/library/core/Cargo.toml
+++ b/library/core/Cargo.toml
@@ -43,6 +43,8 @@ check-cfg = [
     'cfg(bootstrap)',
     'cfg(no_fp_fmt_parse)',
     'cfg(stdarch_intel_sde)',
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
     # core use #[path] imports to portable-simd `core_simd` crate
     # and to stdarch `core_arch` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index 22084dcff8f88..7808d42ab5de4 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -91,6 +91,7 @@ use crate::{fmt, intrinsics, ops, slice, str};
 /// [str]: prim@str "str"
 #[derive(PartialEq, Eq, Hash)]
 #[stable(feature = "core_c_str", since = "1.64.0")]
+#[rustc_diagnostic_item = "cstr_type"]
 #[rustc_has_incoherent_inherent_impls]
 #[lang = "CStr"]
 // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies
diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs
index ec1f9052a1564..dc107c5d22cdd 100644
--- a/library/core/src/ffi/mod.rs
+++ b/library/core/src/ffi/mod.rs
@@ -110,7 +110,7 @@ mod c_char_definition {
             all(target_os = "android", any(target_arch = "aarch64", target_arch = "arm")),
             all(target_os = "l4re", target_arch = "x86_64"),
             all(
-                any(target_os = "freebsd", target_os = "openbsd"),
+                any(target_os = "freebsd", target_os = "openbsd", target_os = "rtems"),
                 any(
                     target_arch = "aarch64",
                     target_arch = "arm",
diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs
index 0569b8b762433..0f9e6061c32da 100644
--- a/library/core/src/pin.rs
+++ b/library/core/src/pin.rs
@@ -1291,8 +1291,8 @@ impl<Ptr: Deref> Pin<Ptr> {
     ///     // Now, if `x` was the only reference, we have a mutable reference to
     ///     // data that we pinned above, which we could use to move it as we have
     ///     // seen in the previous example. We have violated the pinning API contract.
-    ///  }
-    ///  ```
+    /// }
+    /// ```
     ///
     /// ## Pinning of closure captures
     ///
@@ -1370,33 +1370,6 @@ impl<Ptr: Deref> Pin<Ptr> {
         unsafe { Pin::new_unchecked(&*self.__pointer) }
     }
 
-    /// Unwraps this `Pin<Ptr>`, returning the underlying `Ptr`.
-    ///
-    /// # Safety
-    ///
-    /// This function is unsafe. You must guarantee that you will continue to
-    /// treat the pointer `Ptr` as pinned after you call this function, so that
-    /// the invariants on the `Pin` type can be upheld. If the code using the
-    /// resulting `Ptr` does not continue to maintain the pinning invariants that
-    /// is a violation of the API contract and may lead to undefined behavior in
-    /// later (safe) operations.
-    ///
-    /// Note that you must be able to guarantee that the data pointed to by `Ptr`
-    /// will be treated as pinned all the way until its `drop` handler is complete!
-    ///
-    /// *For more information, see the [`pin` module docs][self]*
-    ///
-    /// If the underlying data is [`Unpin`], [`Pin::into_inner`] should be used
-    /// instead.
-    #[inline(always)]
-    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
-    #[stable(feature = "pin_into_inner", since = "1.39.0")]
-    pub const unsafe fn into_inner_unchecked(pin: Pin<Ptr>) -> Ptr {
-        pin.__pointer
-    }
-}
-
-impl<Ptr: DerefMut> Pin<Ptr> {
     /// Gets a mutable reference to the pinned value this `Pin<Ptr>` points to.
     ///
     /// This is a generic method to go from `&mut Pin<Pointer<T>>` to `Pin<&mut T>`.
@@ -1428,11 +1401,55 @@ impl<Ptr: DerefMut> Pin<Ptr> {
     /// ```
     #[stable(feature = "pin", since = "1.33.0")]
     #[inline(always)]
-    pub fn as_mut(&mut self) -> Pin<&mut Ptr::Target> {
+    pub fn as_mut(&mut self) -> Pin<&mut Ptr::Target>
+    where
+        Ptr: DerefMut,
+    {
         // SAFETY: see documentation on this function
         unsafe { Pin::new_unchecked(&mut *self.__pointer) }
     }
 
+    /// Gets `Pin<&mut T>` to the underlying pinned value from this nested `Pin`-pointer.
+    ///
+    /// This is a generic method to go from `Pin<&mut Pin<Pointer<T>>>` to `Pin<&mut T>`. It is
+    /// safe because the existence of a `Pin<Pointer<T>>` ensures that the pointee, `T`, cannot
+    /// move in the future, and this method does not enable the pointee to move. "Malicious"
+    /// implementations of `Ptr::DerefMut` are likewise ruled out by the contract of
+    /// `Pin::new_unchecked`.
+    #[unstable(feature = "pin_deref_mut", issue = "86918")]
+    #[must_use = "`self` will be dropped if the result is not used"]
+    #[inline(always)]
+    pub fn as_deref_mut(self: Pin<&mut Pin<Ptr>>) -> Pin<&mut Ptr::Target>
+    where
+        Ptr: DerefMut,
+    {
+        // SAFETY: What we're asserting here is that going from
+        //
+        //     Pin<&mut Pin<Ptr>>
+        //
+        // to
+        //
+        //     Pin<&mut Ptr::Target>
+        //
+        // is safe.
+        //
+        // We need to ensure that two things hold for that to be the case:
+        //
+        // 1) Once we give out a `Pin<&mut Ptr::Target>`, a `&mut Ptr::Target` will not be given out.
+        // 2) By giving out a `Pin<&mut Ptr::Target>`, we do not risk violating
+        // `Pin<&mut Pin<Ptr>>`
+        //
+        // The existence of `Pin<Ptr>` is sufficient to guarantee #1: since we already have a
+        // `Pin<Ptr>`, it must already uphold the pinning guarantees, which must mean that
+        // `Pin<&mut Ptr::Target>` does as well, since `Pin::as_mut` is safe. We do not have to rely
+        // on the fact that `Ptr` is _also_ pinned.
+        //
+        // For #2, we need to ensure that code given a `Pin<&mut Ptr::Target>` cannot cause the
+        // `Pin<Ptr>` to move? That is not possible, since `Pin<&mut Ptr::Target>` no longer retains
+        // any access to the `Ptr` itself, much less the `Pin<Ptr>`.
+        unsafe { self.get_unchecked_mut() }.as_mut()
+    }
+
     /// Assigns a new value to the memory location pointed to by the `Pin<Ptr>`.
     ///
     /// This overwrites pinned data, but that is okay: the original pinned value's destructor gets
@@ -1457,10 +1474,36 @@ impl<Ptr: DerefMut> Pin<Ptr> {
     #[inline(always)]
     pub fn set(&mut self, value: Ptr::Target)
     where
+        Ptr: DerefMut,
         Ptr::Target: Sized,
     {
         *(self.__pointer) = value;
     }
+
+    /// Unwraps this `Pin<Ptr>`, returning the underlying `Ptr`.
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe. You must guarantee that you will continue to
+    /// treat the pointer `Ptr` as pinned after you call this function, so that
+    /// the invariants on the `Pin` type can be upheld. If the code using the
+    /// resulting `Ptr` does not continue to maintain the pinning invariants that
+    /// is a violation of the API contract and may lead to undefined behavior in
+    /// later (safe) operations.
+    ///
+    /// Note that you must be able to guarantee that the data pointed to by `Ptr`
+    /// will be treated as pinned all the way until its `drop` handler is complete!
+    ///
+    /// *For more information, see the [`pin` module docs][self]*
+    ///
+    /// If the underlying data is [`Unpin`], [`Pin::into_inner`] should be used
+    /// instead.
+    #[inline(always)]
+    #[rustc_const_unstable(feature = "const_pin", issue = "76654")]
+    #[stable(feature = "pin_into_inner", since = "1.39.0")]
+    pub const unsafe fn into_inner_unchecked(pin: Pin<Ptr>) -> Ptr {
+        pin.__pointer
+    }
 }
 
 impl<'a, T: ?Sized> Pin<&'a T> {
@@ -1613,46 +1656,6 @@ impl<T: ?Sized> Pin<&'static T> {
     }
 }
 
-impl<'a, Ptr: DerefMut> Pin<&'a mut Pin<Ptr>> {
-    /// Gets `Pin<&mut T>` to the underlying pinned value from this nested `Pin`-pointer.
-    ///
-    /// This is a generic method to go from `Pin<&mut Pin<Pointer<T>>>` to `Pin<&mut T>`. It is
-    /// safe because the existence of a `Pin<Pointer<T>>` ensures that the pointee, `T`, cannot
-    /// move in the future, and this method does not enable the pointee to move. "Malicious"
-    /// implementations of `Ptr::DerefMut` are likewise ruled out by the contract of
-    /// `Pin::new_unchecked`.
-    #[unstable(feature = "pin_deref_mut", issue = "86918")]
-    #[must_use = "`self` will be dropped if the result is not used"]
-    #[inline(always)]
-    pub fn as_deref_mut(self) -> Pin<&'a mut Ptr::Target> {
-        // SAFETY: What we're asserting here is that going from
-        //
-        //     Pin<&mut Pin<Ptr>>
-        //
-        // to
-        //
-        //     Pin<&mut Ptr::Target>
-        //
-        // is safe.
-        //
-        // We need to ensure that two things hold for that to be the case:
-        //
-        // 1) Once we give out a `Pin<&mut Ptr::Target>`, a `&mut Ptr::Target` will not be given out.
-        // 2) By giving out a `Pin<&mut Ptr::Target>`, we do not risk violating
-        // `Pin<&mut Pin<Ptr>>`
-        //
-        // The existence of `Pin<Ptr>` is sufficient to guarantee #1: since we already have a
-        // `Pin<Ptr>`, it must already uphold the pinning guarantees, which must mean that
-        // `Pin<&mut Ptr::Target>` does as well, since `Pin::as_mut` is safe. We do not have to rely
-        // on the fact that `Ptr` is _also_ pinned.
-        //
-        // For #2, we need to ensure that code given a `Pin<&mut Ptr::Target>` cannot cause the
-        // `Pin<Ptr>` to move? That is not possible, since `Pin<&mut Ptr::Target>` no longer retains
-        // any access to the `Ptr` itself, much less the `Pin<Ptr>`.
-        unsafe { self.get_unchecked_mut() }.as_mut()
-    }
-}
-
 impl<T: ?Sized> Pin<&'static mut T> {
     /// Gets a pinning mutable reference from a static mutable reference.
     ///
diff --git a/library/panic_unwind/Cargo.toml b/library/panic_unwind/Cargo.toml
index f830808d19648..6d1f9764efbfd 100644
--- a/library/panic_unwind/Cargo.toml
+++ b/library/panic_unwind/Cargo.toml
@@ -20,3 +20,10 @@ cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2", default-features = false }
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
+]
diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs
index 2d174f4b1a4a2..4552fb68d26d5 100644
--- a/library/panic_unwind/src/lib.rs
+++ b/library/panic_unwind/src/lib.rs
@@ -48,7 +48,7 @@ cfg_if::cfg_if! {
         target_os = "psp",
         target_os = "xous",
         target_os = "solid_asp3",
-        all(target_family = "unix", not(target_os = "espidf")),
+        all(target_family = "unix", not(any(target_os = "espidf", target_os = "rtems"))),
         all(target_vendor = "fortanix", target_env = "sgx"),
         target_family = "wasm",
     ))] {
diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index dca42a3e98ec1..a533e104aa20d 100644
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -17,7 +17,7 @@ cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
 panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
 core = { path = "../core", public = true }
-compiler_builtins = { version = "0.1.120" }
+compiler_builtins = { version = "0.1.121" }
 profiler_builtins = { path = "../profiler_builtins", optional = true }
 unwind = { path = "../unwind" }
 hashbrown = { version = "0.14", default-features = false, features = [
@@ -146,4 +146,6 @@ check-cfg = [
     # and to the `backtrace` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg
     'cfg(feature, values(any()))',
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
 ]
diff --git a/library/std/build.rs b/library/std/build.rs
index 35a5977b6ebaf..172cf50e37df7 100644
--- a/library/std/build.rs
+++ b/library/std/build.rs
@@ -53,6 +53,7 @@ fn main() {
         || target_os == "uefi"
         || target_os == "teeos"
         || target_os == "zkvm"
+        || target_os == "rtems"
 
         // See src/bootstrap/src/core/build_steps/synthetic_targets.rs
         || env::var("RUSTC_BOOTSTRAP_SYNTHETIC_TARGET").is_ok()
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 2530a37638757..f65e9bc8d8b5a 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -363,6 +363,7 @@
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]
 #![feature(new_uninit)]
+#![feature(new_zeroed_alloc)]
 #![feature(slice_concat_trait)]
 #![feature(thin_box)]
 #![feature(try_reserve_kind)]
diff --git a/library/std/src/os/mod.rs b/library/std/src/os/mod.rs
index 020a8b324f410..a2496baa63fb1 100644
--- a/library/std/src/os/mod.rs
+++ b/library/std/src/os/mod.rs
@@ -143,6 +143,8 @@ pub mod nto;
 pub mod openbsd;
 #[cfg(target_os = "redox")]
 pub mod redox;
+#[cfg(target_os = "rtems")]
+pub mod rtems;
 #[cfg(target_os = "solaris")]
 pub mod solaris;
 #[cfg(target_os = "solid_asp3")]
diff --git a/library/std/src/os/rtems/fs.rs b/library/std/src/os/rtems/fs.rs
new file mode 100644
index 0000000000000..bec0d41e42d81
--- /dev/null
+++ b/library/std/src/os/rtems/fs.rs
@@ -0,0 +1,374 @@
+#![stable(feature = "metadata_ext", since = "1.1.0")]
+
+use crate::fs::Metadata;
+use crate::sys_common::AsInner;
+
+/// OS-specific extensions to [`fs::Metadata`].
+///
+/// [`fs::Metadata`]: crate::fs::Metadata
+#[stable(feature = "metadata_ext", since = "1.1.0")]
+pub trait MetadataExt {
+    /// Returns the device ID on which this file resides.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_dev());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_dev(&self) -> u64;
+
+    /// Returns the inode number.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_ino());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_ino(&self) -> u64;
+
+    /// Returns the file type and mode.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_mode());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_mode(&self) -> u32;
+
+    /// Returns the number of hard links to file.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_nlink());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_nlink(&self) -> u64;
+
+    /// Returns the user ID of the file owner.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_uid());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_uid(&self) -> u32;
+
+    /// Returns the group ID of the file owner.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_gid());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_gid(&self) -> u32;
+
+    /// Returns the device ID that this file represents. Only relevant for special file.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_rdev());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_rdev(&self) -> u64;
+
+    /// Returns the size of the file (if it is a regular file or a symbolic link) in bytes.
+    ///
+    /// The size of a symbolic link is the length of the pathname it contains,
+    /// without a terminating null byte.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_size());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_size(&self) -> u64;
+
+    /// Returns the last access time of the file, in seconds since Unix Epoch.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_atime());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_atime(&self) -> i64;
+
+    /// Returns the last access time of the file, in nanoseconds since [`st_atime`].
+    ///
+    /// [`st_atime`]: Self::st_atime
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_atime_nsec());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_atime_nsec(&self) -> i64;
+
+    /// Returns the last modification time of the file, in seconds since Unix Epoch.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_mtime());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_mtime(&self) -> i64;
+
+    /// Returns the last modification time of the file, in nanoseconds since [`st_mtime`].
+    ///
+    /// [`st_mtime`]: Self::st_mtime
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_mtime_nsec());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_mtime_nsec(&self) -> i64;
+
+    /// Returns the last status change time of the file, in seconds since Unix Epoch.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_ctime());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_ctime(&self) -> i64;
+
+    /// Returns the last status change time of the file, in nanoseconds since [`st_ctime`].
+    ///
+    /// [`st_ctime`]: Self::st_ctime
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_ctime_nsec());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_ctime_nsec(&self) -> i64;
+
+    /// Returns the "preferred" block size for efficient filesystem I/O.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_blksize());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_blksize(&self) -> u64;
+
+    /// Returns the number of blocks allocated to the file, 512-byte units.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::fs;
+    /// use std::io;
+    /// use std::os::rtems::fs::MetadataExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let meta = fs::metadata("some_file")?;
+    ///     println!("{}", meta.st_blocks());
+    ///     Ok(())
+    /// }
+    /// ```
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_blocks(&self) -> u64;
+}
+
+#[stable(feature = "metadata_ext", since = "1.1.0")]
+impl MetadataExt for Metadata {
+    fn st_dev(&self) -> u64 {
+        self.as_inner().as_inner().st_dev as u64
+    }
+
+    fn st_ino(&self) -> u64 {
+        self.as_inner().as_inner().st_ino as u64
+    }
+
+    fn st_mode(&self) -> u32 {
+        self.as_inner().as_inner().st_mode as u32
+    }
+
+    fn st_nlink(&self) -> u64 {
+        self.as_inner().as_inner().st_nlink as u64
+    }
+
+    fn st_uid(&self) -> u32 {
+        self.as_inner().as_inner().st_uid as u32
+    }
+
+    fn st_gid(&self) -> u32 {
+        self.as_inner().as_inner().st_gid as u32
+    }
+
+    fn st_rdev(&self) -> u64 {
+        self.as_inner().as_inner().st_rdev as u64
+    }
+
+    fn st_size(&self) -> u64 {
+        self.as_inner().as_inner().st_size as u64
+    }
+
+    fn st_atime(&self) -> i64 {
+        self.as_inner().as_inner().st_atime as i64
+    }
+
+    fn st_atime_nsec(&self) -> i64 {
+        0
+    }
+
+    fn st_mtime(&self) -> i64 {
+        self.as_inner().as_inner().st_mtime as i64
+    }
+
+    fn st_mtime_nsec(&self) -> i64 {
+        0
+    }
+
+    fn st_ctime(&self) -> i64 {
+        self.as_inner().as_inner().st_ctime as i64
+    }
+
+    fn st_ctime_nsec(&self) -> i64 {
+        0
+    }
+
+    fn st_blksize(&self) -> u64 {
+        self.as_inner().as_inner().st_blksize as u64
+    }
+
+    fn st_blocks(&self) -> u64 {
+        self.as_inner().as_inner().st_blocks as u64
+    }
+}
diff --git a/library/std/src/os/rtems/mod.rs b/library/std/src/os/rtems/mod.rs
new file mode 100644
index 0000000000000..7275bfd1765d5
--- /dev/null
+++ b/library/std/src/os/rtems/mod.rs
@@ -0,0 +1,4 @@
+#![stable(feature = "raw_ext", since = "1.1.0")]
+#![forbid(unsafe_op_in_unsafe_fn)]
+pub mod fs;
+pub(crate) mod raw;
diff --git a/library/std/src/os/rtems/raw.rs b/library/std/src/os/rtems/raw.rs
new file mode 100644
index 0000000000000..113079cf4abdc
--- /dev/null
+++ b/library/std/src/os/rtems/raw.rs
@@ -0,0 +1,33 @@
+//! rtems raw type definitions
+
+#![stable(feature = "raw_ext", since = "1.1.0")]
+#![deprecated(
+    since = "1.8.0",
+    note = "these type aliases are no longer supported by \
+            the standard library, the `libc` crate on \
+            crates.io should be used instead for the correct \
+            definitions"
+)]
+#![allow(deprecated)]
+
+#[stable(feature = "pthread_t", since = "1.8.0")]
+pub type pthread_t = libc::pthread_t;
+
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type blkcnt_t = libc::blkcnt_t;
+
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type blksize_t = libc::blksize_t;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type dev_t = libc::dev_t;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type ino_t = libc::ino_t;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type mode_t = libc::mode_t;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type nlink_t = libc::nlink_t;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type off_t = libc::off_t;
+
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type time_t = libc::time_t;
diff --git a/library/std/src/os/unix/mod.rs b/library/std/src/os/unix/mod.rs
index c6581b9c4c8c8..7d2f0bd4efea7 100644
--- a/library/std/src/os/unix/mod.rs
+++ b/library/std/src/os/unix/mod.rs
@@ -73,6 +73,8 @@ mod platform {
     pub use crate::os::openbsd::*;
     #[cfg(target_os = "redox")]
     pub use crate::os::redox::*;
+    #[cfg(target_os = "rtems")]
+    pub use crate::os::rtems::*;
     #[cfg(target_os = "solaris")]
     pub use crate::os::solaris::*;
     #[cfg(target_os = "vita")]
diff --git a/library/std/src/sys/pal/unix/args.rs b/library/std/src/sys/pal/unix/args.rs
index 9a37e1a0346d7..a943e3a581a83 100644
--- a/library/std/src/sys/pal/unix/args.rs
+++ b/library/std/src/sys/pal/unix/args.rs
@@ -112,6 +112,7 @@ impl DoubleEndedIterator for Args {
     target_os = "aix",
     target_os = "nto",
     target_os = "hurd",
+    target_os = "rtems",
 ))]
 mod imp {
     use crate::ffi::c_char;
diff --git a/library/std/src/sys/pal/unix/env.rs b/library/std/src/sys/pal/unix/env.rs
index fb1f868644d48..b2d399b8791b5 100644
--- a/library/std/src/sys/pal/unix/env.rs
+++ b/library/std/src/sys/pal/unix/env.rs
@@ -240,6 +240,17 @@ pub mod os {
     pub const EXE_EXTENSION: &str = "";
 }
 
+#[cfg(target_os = "rtems")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "rtems";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
 #[cfg(target_os = "vxworks")]
 pub mod os {
     pub const FAMILY: &str = "unix";
diff --git a/library/std/src/sys/pal/unix/fs.rs b/library/std/src/sys/pal/unix/fs.rs
index fc9d7e988835e..b6ce3497b5143 100644
--- a/library/std/src/sys/pal/unix/fs.rs
+++ b/library/std/src/sys/pal/unix/fs.rs
@@ -478,6 +478,7 @@ impl FileAttr {
         target_os = "horizon",
         target_os = "vita",
         target_os = "hurd",
+        target_os = "rtems",
     )))]
     pub fn modified(&self) -> io::Result<SystemTime> {
         #[cfg(target_pointer_width = "32")]
@@ -490,7 +491,12 @@ impl FileAttr {
         SystemTime::new(self.stat.st_mtime as i64, self.stat.st_mtime_nsec as i64)
     }
 
-    #[cfg(any(target_os = "vxworks", target_os = "espidf", target_os = "vita"))]
+    #[cfg(any(
+        target_os = "vxworks",
+        target_os = "espidf",
+        target_os = "vita",
+        target_os = "rtems",
+    ))]
     pub fn modified(&self) -> io::Result<SystemTime> {
         SystemTime::new(self.stat.st_mtime as i64, 0)
     }
@@ -506,6 +512,7 @@ impl FileAttr {
         target_os = "horizon",
         target_os = "vita",
         target_os = "hurd",
+        target_os = "rtems",
     )))]
     pub fn accessed(&self) -> io::Result<SystemTime> {
         #[cfg(target_pointer_width = "32")]
@@ -518,7 +525,12 @@ impl FileAttr {
         SystemTime::new(self.stat.st_atime as i64, self.stat.st_atime_nsec as i64)
     }
 
-    #[cfg(any(target_os = "vxworks", target_os = "espidf", target_os = "vita"))]
+    #[cfg(any(
+        target_os = "vxworks",
+        target_os = "espidf",
+        target_os = "vita",
+        target_os = "rtems"
+    ))]
     pub fn accessed(&self) -> io::Result<SystemTime> {
         SystemTime::new(self.stat.st_atime as i64, 0)
     }
@@ -853,6 +865,7 @@ impl Drop for Dir {
             target_os = "fuchsia",
             target_os = "horizon",
             target_os = "vxworks",
+            target_os = "rtems",
         )))]
         {
             let fd = unsafe { libc::dirfd(self.0) };
@@ -970,6 +983,7 @@ impl DirEntry {
         target_os = "aix",
         target_os = "nto",
         target_os = "hurd",
+        target_os = "rtems",
         target_vendor = "apple",
     ))]
     pub fn ino(&self) -> u64 {
diff --git a/library/std/src/sys/pal/unix/mod.rs b/library/std/src/sys/pal/unix/mod.rs
index 10df3306f9251..f0265125aa6b6 100644
--- a/library/std/src/sys/pal/unix/mod.rs
+++ b/library/std/src/sys/pal/unix/mod.rs
@@ -80,6 +80,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8, sigpipe: u8) {
             target_os = "l4re",
             target_os = "horizon",
             target_os = "vita",
+            target_os = "rtems",
             // The poll on Darwin doesn't set POLLNVAL for closed fds.
             target_vendor = "apple",
         )))]
diff --git a/library/std/src/sys/pal/unix/os.rs b/library/std/src/sys/pal/unix/os.rs
index a785b97ac8dc5..503f8915256ee 100644
--- a/library/std/src/sys/pal/unix/os.rs
+++ b/library/std/src/sys/pal/unix/os.rs
@@ -31,7 +31,7 @@ cfg_if::cfg_if! {
 }
 
 extern "C" {
-    #[cfg(not(any(target_os = "dragonfly", target_os = "vxworks")))]
+    #[cfg(not(any(target_os = "dragonfly", target_os = "vxworks", target_os = "rtems")))]
     #[cfg_attr(
         any(
             target_os = "linux",
@@ -61,13 +61,14 @@ extern "C" {
 }
 
 /// Returns the platform-specific value of errno
-#[cfg(not(any(target_os = "dragonfly", target_os = "vxworks")))]
+#[cfg(not(any(target_os = "dragonfly", target_os = "vxworks", target_os = "rtems")))]
 pub fn errno() -> i32 {
     unsafe { (*errno_location()) as i32 }
 }
 
 /// Sets the platform-specific value of errno
-#[cfg(all(not(target_os = "dragonfly"), not(target_os = "vxworks")))] // needed for readdir and syscall!
+// needed for readdir and syscall!
+#[cfg(all(not(target_os = "dragonfly"), not(target_os = "vxworks"), not(target_os = "rtems")))]
 #[allow(dead_code)] // but not all target cfgs actually end up using it
 pub fn set_errno(e: i32) {
     unsafe { *errno_location() = e as c_int }
@@ -78,6 +79,16 @@ pub fn errno() -> i32 {
     unsafe { libc::errnoGet() }
 }
 
+#[cfg(target_os = "rtems")]
+pub fn errno() -> i32 {
+    extern "C" {
+        #[thread_local]
+        static _tls_errno: c_int;
+    }
+
+    unsafe { _tls_errno as i32 }
+}
+
 #[cfg(target_os = "dragonfly")]
 pub fn errno() -> i32 {
     extern "C" {
@@ -472,7 +483,7 @@ pub fn current_exe() -> io::Result<PathBuf> {
     }
 }
 
-#[cfg(target_os = "redox")]
+#[cfg(any(target_os = "redox", target_os = "rtems"))]
 pub fn current_exe() -> io::Result<PathBuf> {
     crate::fs::read_to_string("sys:exe").map(PathBuf::from)
 }
diff --git a/library/std/src/sys/pal/unix/process/process_unix.rs b/library/std/src/sys/pal/unix/process/process_unix.rs
index 5552e9ac97753..1db319347a222 100644
--- a/library/std/src/sys/pal/unix/process/process_unix.rs
+++ b/library/std/src/sys/pal/unix/process/process_unix.rs
@@ -1086,13 +1086,13 @@ fn signal_string(signal: i32) -> &'static str {
         libc::SIGURG => " (SIGURG)",
         #[cfg(not(target_os = "l4re"))]
         libc::SIGXCPU => " (SIGXCPU)",
-        #[cfg(not(target_os = "l4re"))]
+        #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
         libc::SIGXFSZ => " (SIGXFSZ)",
-        #[cfg(not(target_os = "l4re"))]
+        #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
         libc::SIGVTALRM => " (SIGVTALRM)",
         #[cfg(not(target_os = "l4re"))]
         libc::SIGPROF => " (SIGPROF)",
-        #[cfg(not(target_os = "l4re"))]
+        #[cfg(not(any(target_os = "l4re", target_os = "rtems")))]
         libc::SIGWINCH => " (SIGWINCH)",
         #[cfg(not(any(target_os = "haiku", target_os = "l4re")))]
         libc::SIGIO => " (SIGIO)",
diff --git a/library/std/src/sys/personality/mod.rs b/library/std/src/sys/personality/mod.rs
index 1a6ea1dafcb53..68085d026c40a 100644
--- a/library/std/src/sys/personality/mod.rs
+++ b/library/std/src/sys/personality/mod.rs
@@ -31,7 +31,7 @@ cfg_if::cfg_if! {
         target_os = "psp",
         target_os = "xous",
         target_os = "solid_asp3",
-        all(target_family = "unix", not(target_os = "espidf"), not(target_os = "l4re")),
+        all(target_family = "unix", not(target_os = "espidf"), not(target_os = "l4re"), not(target_os = "rtems")),
         all(target_vendor = "fortanix", target_env = "sgx"),
     ))] {
         mod gcc;
diff --git a/library/unwind/Cargo.toml b/library/unwind/Cargo.toml
index bbd1db8dfa57f..590de31a678ca 100644
--- a/library/unwind/Cargo.toml
+++ b/library/unwind/Cargo.toml
@@ -34,3 +34,10 @@ llvm-libunwind = []
 # If crt-static is enabled, static link to `libunwind.a` provided by system
 # If crt-static is disabled, dynamic link to `libunwind.so` provided by system
 system-llvm-libunwind = []
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+check-cfg = [
+    # #[cfg(bootstrap)] rtems
+    'cfg(target_os, values("rtems"))',
+]
diff --git a/library/unwind/src/lib.rs b/library/unwind/src/lib.rs
index b3de71f29f394..2656e62ad6bd8 100644
--- a/library/unwind/src/lib.rs
+++ b/library/unwind/src/lib.rs
@@ -22,6 +22,7 @@ cfg_if::cfg_if! {
         target_os = "l4re",
         target_os = "none",
         target_os = "espidf",
+        target_os = "rtems",
     ))] {
         // These "unix" family members do not have unwinder.
     } else if #[cfg(any(
diff --git a/src/bootstrap/src/core/sanity.rs b/src/bootstrap/src/core/sanity.rs
index c42d4c56c3816..157cd2989ba93 100644
--- a/src/bootstrap/src/core/sanity.rs
+++ b/src/bootstrap/src/core/sanity.rs
@@ -37,6 +37,7 @@ pub struct Finder {
 #[cfg(not(feature = "bootstrap-self-test"))]
 const STAGE0_MISSING_TARGETS: &[&str] = &[
     // just a dummy comment so the list doesn't get onelined
+    "armv7-rtems-eabihf",
 ];
 
 /// Minimum version threshold for libstdc++ required when using prebuilt LLVM
diff --git a/src/ci/docker/scripts/rfl-build.sh b/src/ci/docker/scripts/rfl-build.sh
index d690aac27fae6..389abb2fdd38c 100755
--- a/src/ci/docker/scripts/rfl-build.sh
+++ b/src/ci/docker/scripts/rfl-build.sh
@@ -2,7 +2,7 @@
 
 set -euo pipefail
 
-LINUX_VERSION=v6.11-rc1
+LINUX_VERSION=4c7864e81d8bbd51036dacf92fb0a400e13aaeee
 
 # Build rustc, rustdoc and cargo
 ../x.py build --stage 1 library rustdoc
@@ -28,7 +28,7 @@ rm -rf linux || true
 # Download Linux at a specific commit
 mkdir -p linux
 git -C linux init
-git -C linux remote add origin https://github.com/torvalds/linux.git
+git -C linux remote add origin https://github.com/Rust-for-Linux/linux.git
 git -C linux fetch --depth 1 origin ${LINUX_VERSION}
 git -C linux checkout FETCH_HEAD
 
diff --git a/src/doc/rustc/src/SUMMARY.md b/src/doc/rustc/src/SUMMARY.md
index 4e34e2667cfc0..5416254084fcd 100644
--- a/src/doc/rustc/src/SUMMARY.md
+++ b/src/doc/rustc/src/SUMMARY.md
@@ -40,6 +40,7 @@
       - [thumbv8m.base-none-eabi](./platform-support/thumbv8m.base-none-eabi.md)
       - [thumbv8m.main-none-eabi\*](./platform-support/thumbv8m.main-none-eabi.md)
     - [armv6k-nintendo-3ds](platform-support/armv6k-nintendo-3ds.md)
+    - [armv7-rtems-eabihf](platform-support/armv7-rtems-eabihf.md)
     - [armv7-sony-vita-newlibeabihf](platform-support/armv7-sony-vita-newlibeabihf.md)
     - [armv7-unknown-linux-uclibceabi](platform-support/armv7-unknown-linux-uclibceabi.md)
     - [armv7-unknown-linux-uclibceabihf](platform-support/armv7-unknown-linux-uclibceabihf.md)
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index dd478e9df379e..0c3046930ad78 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -278,6 +278,7 @@ target | std | host | notes
 `armv6-unknown-freebsd` | ✓ | ✓ | Armv6 FreeBSD
 [`armv6-unknown-netbsd-eabihf`](platform-support/netbsd.md) | ✓ | ✓ | Armv6 NetBSD w/hard-float
 [`armv6k-nintendo-3ds`](platform-support/armv6k-nintendo-3ds.md) | ? |  | Armv6k Nintendo 3DS, Horizon (Requires devkitARM toolchain)
+[`armv7-rtems-eabihf`](platform-support/armv7-rtems-eabihf.md) | ✓ |  | RTEMS OS for ARM BSPs
 [`armv7-sony-vita-newlibeabihf`](platform-support/armv7-sony-vita-newlibeabihf.md) | ✓ |  | Armv7-A Cortex-A9 Sony PlayStation Vita (requires VITASDK toolchain)
 [`armv7-unknown-linux-uclibceabi`](platform-support/armv7-unknown-linux-uclibceabi.md) | ✓ | ✓ | Armv7-A Linux with uClibc, softfloat
 [`armv7-unknown-linux-uclibceabihf`](platform-support/armv7-unknown-linux-uclibceabihf.md) | ✓ | ? | Armv7-A Linux with uClibc, hardfloat
diff --git a/src/doc/rustc/src/platform-support/armv7-rtems-eabihf.md b/src/doc/rustc/src/platform-support/armv7-rtems-eabihf.md
new file mode 100644
index 0000000000000..2791c21ee453b
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/armv7-rtems-eabihf.md
@@ -0,0 +1,52 @@
+# `armv7-rtems-eabihf`
+
+**Tier: 3**
+
+ARM targets for the [RTEMS realtime operating system](https://www.rtems.org)  using the RTEMS gcc cross-compiler for linking against the libraries of a specified Board Support Package (BSP).
+
+## Target maintainers
+
+- [@thesummer](https://github.com/thesummer)
+
+## Requirements
+
+The target does not support host tools. Only cross-compilation is possible.
+The cross-compiler toolchain can be obtained by following the installation instructions
+of the [RTEMS Documentation](https://docs.rtems.org/branches/master/user/index.html). Additionally to the cross-compiler also a compiled BSP
+for a board fitting the architecture needs to be available on the host.
+Currently tested has been the BSP `xilinx_zynq_a9_qemu` of RTEMS 6.
+
+`std` support is available, but not yet fully tested. Do NOT use in flight software!
+
+The target follows the EABI calling convention for `extern "C"`.
+
+The resulting binaries are in ELF format.
+
+## Building the target
+
+The target can be built by the standard compiler of Rust.
+
+## Building Rust programs
+
+Rust does not yet ship pre-compiled artifacts for this target. To compile for
+this target, you will either need to build Rust with the target enabled (see
+"Building the target" above), or build your own copy of `core` by using
+`build-std` or similar.
+
+In order to build an RTEMS executable it is also necessary to have a basic RTEMS configuration (in C) compiled to link against as this configures the operating system.
+An example can be found at this [`rtems-sys`](https://github.com/thesummer/rtems-sys) crate which could be added as an dependency to your application.
+
+## Testing
+
+The resulting binaries run fine on an emulated target (possibly also on a real Zedboard or similar).
+For example, on qemu the following command can execute the binary:
+```sh
+qemu-system-arm -no-reboot -serial null -serial mon:stdio -net none -nographic -M xilinx-zynq-a9 -m 512M -kernel <binary file>
+```
+
+While basic execution of the unit test harness seems to work. However, running the Rust testsuite on the (emulated) hardware has not yet been tested.
+
+## Cross-compilation toolchains and C code
+
+Compatible C-code can be built with the RTEMS cross-compiler toolchain `arm-rtems6-gcc`.
+For more information how to build the toolchain, RTEMS itself and RTEMS applications please have a look at the [RTEMS Documentation](https://docs.rtems.org/branches/master/user/index.html).
diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 4e3b532ae08ae..be0ec425946c2 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -1393,6 +1393,7 @@ function initSearch(rawSearchIndex) {
          */
         async function sortResults(results, isType, preferredCrate) {
             const userQuery = parsedQuery.userQuery;
+            const casedUserQuery = parsedQuery.original;
             const result_list = [];
             for (const result of results.values()) {
                 result.item = searchIndex[result.id];
@@ -1403,6 +1404,13 @@ function initSearch(rawSearchIndex) {
             result_list.sort((aaa, bbb) => {
                 let a, b;
 
+                // sort by exact case-sensitive match
+                a = (aaa.item.name !== casedUserQuery);
+                b = (bbb.item.name !== casedUserQuery);
+                if (a !== b) {
+                    return a - b;
+                }
+
                 // sort by exact match with regard to the last word (mismatch goes later)
                 a = (aaa.word !== userQuery);
                 b = (bbb.word !== userQuery);
diff --git a/tests/assembly/targets/targets-elf.rs b/tests/assembly/targets/targets-elf.rs
index c3a083321e229..9a22efbe1e8c8 100644
--- a/tests/assembly/targets/targets-elf.rs
+++ b/tests/assembly/targets/targets-elf.rs
@@ -123,6 +123,9 @@
 //@ revisions: armv7_linux_androideabi
 //@ [armv7_linux_androideabi] compile-flags: --target armv7-linux-androideabi
 //@ [armv7_linux_androideabi] needs-llvm-components: arm
+//@ revisions: armv7_rtems_eabihf
+//@ [armv7_rtems_eabihf] compile-flags: --target armv7-rtems-eabihf
+//@ [armv7_rtems_eabihf] needs-llvm-components: arm
 //@ revisions: armv7_sony_vita_newlibeabihf
 //@ [armv7_sony_vita_newlibeabihf] compile-flags: --target armv7-sony-vita-newlibeabihf
 //@ [armv7_sony_vita_newlibeabihf] needs-llvm-components: arm
diff --git a/tests/rustdoc-js-std/exact-case.js b/tests/rustdoc-js-std/exact-case.js
new file mode 100644
index 0000000000000..d9faff22fff70
--- /dev/null
+++ b/tests/rustdoc-js-std/exact-case.js
@@ -0,0 +1,7 @@
+const EXPECTED = {
+    'query': 'Copy',
+    'others': [
+        { 'path': 'std::marker', 'name': 'Copy' },
+        { 'path': 'std::fs', 'name': 'copy' },
+    ],
+}
diff --git a/tests/ui/check-cfg/well-known-values.stderr b/tests/ui/check-cfg/well-known-values.stderr
index d780e04e729a2..7078bda8a8f0b 100644
--- a/tests/ui/check-cfg/well-known-values.stderr
+++ b/tests/ui/check-cfg/well-known-values.stderr
@@ -201,7 +201,7 @@ warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
 LL |     target_os = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: expected values for `target_os` are: `aix`, `android`, `cuda`, `dragonfly`, `emscripten`, `espidf`, `freebsd`, `fuchsia`, `haiku`, `hermit`, `horizon`, `hurd`, `illumos`, `ios`, `l4re`, `linux`, `macos`, `netbsd`, `none`, `nto`, `nuttx`, `openbsd`, `psp`, `redox`, `solaris`, `solid_asp3`, `teeos`, `tvos`, `uefi`, `unknown`, `visionos`, `vita`, `vxworks`, `wasi`, `watchos`, `windows`, `xous`, and `zkvm`
+   = note: expected values for `target_os` are: `aix`, `android`, `cuda`, `dragonfly`, `emscripten`, `espidf`, `freebsd`, `fuchsia`, `haiku`, `hermit`, `horizon`, `hurd`, `illumos`, `ios`, `l4re`, `linux`, `macos`, `netbsd`, `none`, `nto`, `nuttx`, `openbsd`, `psp`, `redox`, `rtems`, `solaris`, `solid_asp3`, `teeos`, `tvos`, `uefi`, `unknown`, `visionos`, `vita`, `vxworks`, `wasi`, `watchos`, `windows`, `xous`, and `zkvm`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
@@ -285,7 +285,7 @@ LL | #[cfg(target_os = "linuz")] // testing that we suggest `linux`
    |                   |
    |                   help: there is a expected value with a similar name: `"linux"`
    |
-   = note: expected values for `target_os` are: `aix`, `android`, `cuda`, `dragonfly`, `emscripten`, `espidf`, `freebsd`, `fuchsia`, `haiku`, `hermit`, `horizon`, `hurd`, `illumos`, `ios`, `l4re`, `linux`, `macos`, `netbsd`, `none`, `nto`, `nuttx`, `openbsd`, `psp`, `redox`, `solaris`, `solid_asp3`, `teeos`, `tvos`, `uefi`, `unknown`, `visionos`, `vita`, `vxworks`, `wasi`, `watchos`, `windows`, `xous`, and `zkvm`
+   = note: expected values for `target_os` are: `aix`, `android`, `cuda`, `dragonfly`, `emscripten`, `espidf`, `freebsd`, `fuchsia`, `haiku`, `hermit`, `horizon`, `hurd`, `illumos`, `ios`, `l4re`, `linux`, `macos`, `netbsd`, `none`, `nto`, `nuttx`, `openbsd`, `psp`, `redox`, `rtems`, `solaris`, `solid_asp3`, `teeos`, `tvos`, `uefi`, `unknown`, `visionos`, `vita`, `vxworks`, `wasi`, `watchos`, `windows`, `xous`, and `zkvm`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
 
 warning: 29 warnings emitted
diff --git a/tests/ui/dst/dst-rvalue.stderr b/tests/ui/dst/dst-rvalue.stderr
index 8d0a82b707dda..d8c529617f75f 100644
--- a/tests/ui/dst/dst-rvalue.stderr
+++ b/tests/ui/dst/dst-rvalue.stderr
@@ -9,6 +9,11 @@ LL |     let _x: Box<str> = Box::new(*"hello world");
    = help: the trait `Sized` is not implemented for `str`
 note: required by a bound in `Box::<T>::new`
   --> $SRC_DIR/alloc/src/boxed.rs:LL:COL
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     let _x: Box<str> = Box::new(*"hello world");
+LL +     let _x: Box<str> = Box::new("hello world");
+   |
 
 error[E0277]: the size for values of type `[isize]` cannot be known at compilation time
   --> $DIR/dst-rvalue.rs:8:37
@@ -21,6 +26,11 @@ LL |     let _x: Box<[isize]> = Box::new(*array);
    = help: the trait `Sized` is not implemented for `[isize]`
 note: required by a bound in `Box::<T>::new`
   --> $SRC_DIR/alloc/src/boxed.rs:LL:COL
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     let _x: Box<[isize]> = Box::new(*array);
+LL +     let _x: Box<[isize]> = Box::new(array);
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/error-codes/E0208.rs b/tests/ui/error-codes/E0208.rs
index 74c138af483c1..2713ba6ed6cb5 100644
--- a/tests/ui/error-codes/E0208.rs
+++ b/tests/ui/error-codes/E0208.rs
@@ -1,7 +1,7 @@
 #![feature(rustc_attrs)]
 
 #[rustc_variance]
-struct Foo<'a, T> { //~ ERROR [+, o]
+struct Foo<'a, T> { //~ ERROR ['a: +, T: o]
     t: &'a mut T,
 }
 
diff --git a/tests/ui/error-codes/E0208.stderr b/tests/ui/error-codes/E0208.stderr
index 77b6ceae4dcee..a39e93afab3e1 100644
--- a/tests/ui/error-codes/E0208.stderr
+++ b/tests/ui/error-codes/E0208.stderr
@@ -1,4 +1,4 @@
-error: [+, o]
+error: ['a: +, T: o]
   --> $DIR/E0208.rs:4:1
    |
 LL | struct Foo<'a, T> {
diff --git a/tests/ui/extern/extern-C-non-FFI-safe-arg-ice-52334.stderr b/tests/ui/extern/extern-C-non-FFI-safe-arg-ice-52334.stderr
index 8349298847918..044c1ae2dd42f 100644
--- a/tests/ui/extern/extern-C-non-FFI-safe-arg-ice-52334.stderr
+++ b/tests/ui/extern/extern-C-non-FFI-safe-arg-ice-52334.stderr
@@ -1,21 +1,21 @@
-warning: `extern` fn uses type `[i8 or u8 (arch dependant)]`, which is not FFI-safe
+warning: `extern` fn uses type `CStr`, which is not FFI-safe
   --> $DIR/extern-C-non-FFI-safe-arg-ice-52334.rs:7:12
    |
 LL | type Foo = extern "C" fn(::std::ffi::CStr);
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
    |
-   = help: consider using a raw pointer instead
-   = note: slices have no C equivalent
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
    = note: `#[warn(improper_ctypes_definitions)]` on by default
 
-warning: `extern` block uses type `[i8 or u8 (arch dependant)]`, which is not FFI-safe
+warning: `extern` block uses type `CStr`, which is not FFI-safe
   --> $DIR/extern-C-non-FFI-safe-arg-ice-52334.rs:10:18
    |
 LL |     fn meh(blah: Foo);
    |                  ^^^ not FFI-safe
    |
-   = help: consider using a raw pointer instead
-   = note: slices have no C equivalent
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
    = note: `#[warn(improper_ctypes)]` on by default
 
 warning: 2 warnings emitted
diff --git a/tests/ui/impl-trait/capture-lifetime-not-in-hir.rs b/tests/ui/impl-trait/capture-lifetime-not-in-hir.rs
index 9c067cb693444..2fde0f200c0e5 100644
--- a/tests/ui/impl-trait/capture-lifetime-not-in-hir.rs
+++ b/tests/ui/impl-trait/capture-lifetime-not-in-hir.rs
@@ -6,13 +6,13 @@ trait Bar<'a> {
 }
 
 fn foo<'a, T: Bar<'a>>() -> impl Into<T::Assoc> {
-    //~^ ERROR [o, o]
+    //~^ ERROR ['a: o, T: o]
     // captures both T and 'a invariantly
     ()
 }
 
 fn foo2<'a, T: Bar<'a>>() -> impl Into<T::Assoc> + 'a {
-    //~^ ERROR [o, o, o]
+    //~^ ERROR ['a: o, T: o, 'a: o]
     // captures both T and 'a invariantly, and also duplicates `'a`
     // i.e. the opaque looks like `impl Into<<T as Bar<'a>>::Assoc> + 'a_duplicated`
     ()
diff --git a/tests/ui/impl-trait/capture-lifetime-not-in-hir.stderr b/tests/ui/impl-trait/capture-lifetime-not-in-hir.stderr
index 9d52001b02460..fe8a2772a00b1 100644
--- a/tests/ui/impl-trait/capture-lifetime-not-in-hir.stderr
+++ b/tests/ui/impl-trait/capture-lifetime-not-in-hir.stderr
@@ -1,10 +1,10 @@
-error: [o, o]
+error: ['a: o, T: o]
   --> $DIR/capture-lifetime-not-in-hir.rs:8:29
    |
 LL | fn foo<'a, T: Bar<'a>>() -> impl Into<T::Assoc> {
    |                             ^^^^^^^^^^^^^^^^^^^
 
-error: [o, o, o]
+error: ['a: o, T: o, 'a: o]
   --> $DIR/capture-lifetime-not-in-hir.rs:14:30
    |
 LL | fn foo2<'a, T: Bar<'a>>() -> impl Into<T::Assoc> + 'a {
diff --git a/tests/ui/impl-trait/implicit-capture-late.stderr b/tests/ui/impl-trait/implicit-capture-late.stderr
index 080750f849767..3adf78322d2e5 100644
--- a/tests/ui/impl-trait/implicit-capture-late.stderr
+++ b/tests/ui/impl-trait/implicit-capture-late.stderr
@@ -10,7 +10,7 @@ note: lifetime declared here
 LL | fn foo(x: Vec<i32>) -> Box<dyn for<'a> Deref<Target = impl ?Sized>> {
    |                                    ^^
 
-error: [o]
+error: ['a: o]
   --> $DIR/implicit-capture-late.rs:10:55
    |
 LL | fn foo(x: Vec<i32>) -> Box<dyn for<'a> Deref<Target = impl ?Sized>> {
diff --git a/tests/ui/impl-trait/in-trait/variance.rs b/tests/ui/impl-trait/in-trait/variance.rs
index 65565dcc2a6f4..0ac44bf7546c2 100644
--- a/tests/ui/impl-trait/in-trait/variance.rs
+++ b/tests/ui/impl-trait/in-trait/variance.rs
@@ -7,14 +7,16 @@ impl<T> Captures<'_> for T {}
 
 trait Foo<'i> {
     fn implicit_capture_early<'a: 'a>() -> impl Sized {}
-    //~^ [o, *, *, o, o]
-    // Self, 'i, 'a, 'i_duplicated, 'a_duplicated
+    //~^ [Self: o, 'i: *, 'a: *, 'a: o, 'i: o]
 
-    fn explicit_capture_early<'a: 'a>() -> impl Sized + Captures<'a> {} //~ [o, *, *, o, o]
+    fn explicit_capture_early<'a: 'a>() -> impl Sized + Captures<'a> {}
+    //~^ [Self: o, 'i: *, 'a: *, 'a: o, 'i: o]
 
-    fn implicit_capture_late<'a>(_: &'a ()) -> impl Sized {} //~ [o, *, o, o]
+    fn implicit_capture_late<'a>(_: &'a ()) -> impl Sized {}
+    //~^ [Self: o, 'i: *, 'a: o, 'i: o]
 
-    fn explicit_capture_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {} //~ [o, *, o, o]
+    fn explicit_capture_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
+    //~^ [Self: o, 'i: *, 'a: o, 'i: o]
 }
 
 fn main() {}
diff --git a/tests/ui/impl-trait/in-trait/variance.stderr b/tests/ui/impl-trait/in-trait/variance.stderr
index 8cae5a92f0dd5..54e0afbaa950d 100644
--- a/tests/ui/impl-trait/in-trait/variance.stderr
+++ b/tests/ui/impl-trait/in-trait/variance.stderr
@@ -1,23 +1,23 @@
-error: [o, *, *, o, o]
+error: [Self: o, 'i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:9:44
    |
 LL |     fn implicit_capture_early<'a: 'a>() -> impl Sized {}
    |                                            ^^^^^^^^^^
 
-error: [o, *, *, o, o]
-  --> $DIR/variance.rs:13:44
+error: [Self: o, 'i: *, 'a: *, 'a: o, 'i: o]
+  --> $DIR/variance.rs:12:44
    |
 LL |     fn explicit_capture_early<'a: 'a>() -> impl Sized + Captures<'a> {}
    |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o, *, o, o]
+error: [Self: o, 'i: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:15:48
    |
 LL |     fn implicit_capture_late<'a>(_: &'a ()) -> impl Sized {}
    |                                                ^^^^^^^^^^
 
-error: [o, *, o, o]
-  --> $DIR/variance.rs:17:48
+error: [Self: o, 'i: *, 'a: o, 'i: o]
+  --> $DIR/variance.rs:18:48
    |
 LL |     fn explicit_capture_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
    |                                                ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/impl-trait/variance.e2024.stderr b/tests/ui/impl-trait/variance.e2024.stderr
index 1724505574413..011ab3259c477 100644
--- a/tests/ui/impl-trait/variance.e2024.stderr
+++ b/tests/ui/impl-trait/variance.e2024.stderr
@@ -1,22 +1,22 @@
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:14:36
    |
 LL | fn not_captured_early<'a: 'a>() -> impl Sized {}
    |                                    ^^^^^^^^^^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:19:32
    |
 LL | fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {}
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o]
+error: ['a: o]
   --> $DIR/variance.rs:21:40
    |
 LL | fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
    |                                        ^^^^^^^^^^
 
-error: [o]
+error: ['a: o]
   --> $DIR/variance.rs:26:36
    |
 LL | fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
diff --git a/tests/ui/impl-trait/variance.new.stderr b/tests/ui/impl-trait/variance.new.stderr
index 1724505574413..011ab3259c477 100644
--- a/tests/ui/impl-trait/variance.new.stderr
+++ b/tests/ui/impl-trait/variance.new.stderr
@@ -1,22 +1,22 @@
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:14:36
    |
 LL | fn not_captured_early<'a: 'a>() -> impl Sized {}
    |                                    ^^^^^^^^^^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:19:32
    |
 LL | fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {}
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o]
+error: ['a: o]
   --> $DIR/variance.rs:21:40
    |
 LL | fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
    |                                        ^^^^^^^^^^
 
-error: [o]
+error: ['a: o]
   --> $DIR/variance.rs:26:36
    |
 LL | fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
diff --git a/tests/ui/impl-trait/variance.old.stderr b/tests/ui/impl-trait/variance.old.stderr
index 9410b54b491a8..ac3bcd2723fb3 100644
--- a/tests/ui/impl-trait/variance.old.stderr
+++ b/tests/ui/impl-trait/variance.old.stderr
@@ -1,10 +1,10 @@
-error: [*]
+error: ['a: *]
   --> $DIR/variance.rs:14:36
    |
 LL | fn not_captured_early<'a: 'a>() -> impl Sized {}
    |                                    ^^^^^^^^^^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:19:32
    |
 LL | fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {}
@@ -16,7 +16,7 @@ error: []
 LL | fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
    |                                        ^^^^^^^^^^
 
-error: [o]
+error: ['a: o]
   --> $DIR/variance.rs:26:36
    |
 LL | fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {}
diff --git a/tests/ui/impl-trait/variance.rs b/tests/ui/impl-trait/variance.rs
index 72b4a831badcb..43f7207a90423 100644
--- a/tests/ui/impl-trait/variance.rs
+++ b/tests/ui/impl-trait/variance.rs
@@ -12,17 +12,17 @@ trait Captures<'a> {}
 impl<T> Captures<'_> for T {}
 
 fn not_captured_early<'a: 'a>() -> impl Sized {}
-//[old]~^ [*]
-//[new]~^^ [*, o]
-//[e2024]~^^^ [*, o]
+//[old]~^ ['a: *]
+//[new]~^^ ['a: *, 'a: o]
+//[e2024]~^^^ ['a: *, 'a: o]
 
-fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {} //~ [*, o]
+fn captured_early<'a: 'a>() -> impl Sized + Captures<'a> {} //~ ['a: *, 'a: o]
 
 fn not_captured_late<'a>(_: &'a ()) -> impl Sized {}
 //[old]~^ []
-//[new]~^^ [o]
-//[e2024]~^^^ [o]
+//[new]~^^ ['a: o]
+//[e2024]~^^^ ['a: o]
 
-fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {} //~ [o]
+fn captured_late<'a>(_: &'a ()) -> impl Sized + Captures<'a> {} //~ ['a: o]
 
 fn main() {}
diff --git a/tests/ui/issues/issue-17651.stderr b/tests/ui/issues/issue-17651.stderr
index 0c95a3c0c40d8..9519507320d82 100644
--- a/tests/ui/issues/issue-17651.stderr
+++ b/tests/ui/issues/issue-17651.stderr
@@ -9,6 +9,11 @@ LL |     (|| Box::new(*(&[0][..])))();
    = help: the trait `Sized` is not implemented for `[{integer}]`
 note: required by a bound in `Box::<T>::new`
   --> $SRC_DIR/alloc/src/boxed.rs:LL:COL
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     (|| Box::new(*(&[0][..])))();
+LL +     (|| Box::new((&[0][..])))();
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/lint/lint-ctypes-cstr.rs b/tests/ui/lint/lint-ctypes-cstr.rs
new file mode 100644
index 0000000000000..b04decd0bcacc
--- /dev/null
+++ b/tests/ui/lint/lint-ctypes-cstr.rs
@@ -0,0 +1,36 @@
+#![crate_type = "lib"]
+#![deny(improper_ctypes, improper_ctypes_definitions)]
+
+use std::ffi::{CStr, CString};
+
+extern "C" {
+    fn take_cstr(s: CStr);
+    //~^ ERROR `extern` block uses type `CStr`, which is not FFI-safe
+    //~| HELP consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+    fn take_cstr_ref(s: &CStr);
+    //~^ ERROR `extern` block uses type `CStr`, which is not FFI-safe
+    //~| HELP consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+    fn take_cstring(s: CString);
+    //~^ ERROR `extern` block uses type `CString`, which is not FFI-safe
+    //~| HELP consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+    fn take_cstring_ref(s: &CString);
+    //~^ ERROR `extern` block uses type `CString`, which is not FFI-safe
+    //~| HELP consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+
+    fn no_special_help_for_mut_cstring(s: *mut CString);
+    //~^ ERROR `extern` block uses type `CString`, which is not FFI-safe
+    //~| HELP consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
+
+    fn no_special_help_for_mut_cstring_ref(s: &mut CString);
+    //~^ ERROR `extern` block uses type `CString`, which is not FFI-safe
+    //~| HELP consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
+}
+
+extern "C" fn rust_take_cstr_ref(s: &CStr) {}
+//~^ ERROR `extern` fn uses type `CStr`, which is not FFI-safe
+//~| HELP consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+extern "C" fn rust_take_cstring(s: CString) {}
+//~^ ERROR `extern` fn uses type `CString`, which is not FFI-safe
+//~| HELP consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+extern "C" fn rust_no_special_help_for_mut_cstring(s: *mut CString) {}
+extern "C" fn rust_no_special_help_for_mut_cstring_ref(s: &mut CString) {}
diff --git a/tests/ui/lint/lint-ctypes-cstr.stderr b/tests/ui/lint/lint-ctypes-cstr.stderr
new file mode 100644
index 0000000000000..8957758d57732
--- /dev/null
+++ b/tests/ui/lint/lint-ctypes-cstr.stderr
@@ -0,0 +1,84 @@
+error: `extern` block uses type `CStr`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:7:21
+   |
+LL |     fn take_cstr(s: CStr);
+   |                     ^^^^ not FFI-safe
+   |
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
+note: the lint level is defined here
+  --> $DIR/lint-ctypes-cstr.rs:2:9
+   |
+LL | #![deny(improper_ctypes, improper_ctypes_definitions)]
+   |         ^^^^^^^^^^^^^^^
+
+error: `extern` block uses type `CStr`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:10:25
+   |
+LL |     fn take_cstr_ref(s: &CStr);
+   |                         ^^^^^ not FFI-safe
+   |
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
+
+error: `extern` block uses type `CString`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:13:24
+   |
+LL |     fn take_cstring(s: CString);
+   |                        ^^^^^^^ not FFI-safe
+   |
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
+
+error: `extern` block uses type `CString`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:16:28
+   |
+LL |     fn take_cstring_ref(s: &CString);
+   |                            ^^^^^^^^ not FFI-safe
+   |
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
+
+error: `extern` block uses type `CString`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:20:43
+   |
+LL |     fn no_special_help_for_mut_cstring(s: *mut CString);
+   |                                           ^^^^^^^^^^^^ not FFI-safe
+   |
+   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
+   = note: this struct has unspecified layout
+
+error: `extern` block uses type `CString`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:24:47
+   |
+LL |     fn no_special_help_for_mut_cstring_ref(s: &mut CString);
+   |                                               ^^^^^^^^^^^^ not FFI-safe
+   |
+   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
+   = note: this struct has unspecified layout
+
+error: `extern` fn uses type `CStr`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:29:37
+   |
+LL | extern "C" fn rust_take_cstr_ref(s: &CStr) {}
+   |                                     ^^^^^ not FFI-safe
+   |
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
+note: the lint level is defined here
+  --> $DIR/lint-ctypes-cstr.rs:2:26
+   |
+LL | #![deny(improper_ctypes, improper_ctypes_definitions)]
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: `extern` fn uses type `CString`, which is not FFI-safe
+  --> $DIR/lint-ctypes-cstr.rs:32:36
+   |
+LL | extern "C" fn rust_take_cstring(s: CString) {}
+   |                                    ^^^^^^^ not FFI-safe
+   |
+   = help: consider passing a `*const std::ffi::c_char` instead, and use `CStr::as_ptr()`
+   = note: `CStr`/`CString` do not have a guaranteed layout
+
+error: aborting due to 8 previous errors
+
diff --git a/tests/ui/sized/unsized-binding.stderr b/tests/ui/sized/unsized-binding.stderr
index 7c3276032c2b4..8de236cd0b6e0 100644
--- a/tests/ui/sized/unsized-binding.stderr
+++ b/tests/ui/sized/unsized-binding.stderr
@@ -7,6 +7,11 @@ LL |     let x = *"";
    = help: the trait `Sized` is not implemented for `str`
    = note: all local variables must have a statically known size
    = help: unsized locals are gated as an unstable feature
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     let x = *"";
+LL +     let x = "";
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/sized/unsized-str-in-return-expr-arg-and-local.rs b/tests/ui/sized/unsized-str-in-return-expr-arg-and-local.rs
new file mode 100644
index 0000000000000..35abbb80d99e5
--- /dev/null
+++ b/tests/ui/sized/unsized-str-in-return-expr-arg-and-local.rs
@@ -0,0 +1,30 @@
+fn foo() -> impl Sized {
+//~^ ERROR the size for values of type `str` cannot be known at compilation time
+//~| HELP the trait `Sized` is not implemented for `str`
+    *"" //~ HELP consider not dereferencing the expression
+}
+fn bar(_: impl Sized) {}
+struct S;
+
+impl S {
+    fn baz(&self, _: impl Sized) {}
+}
+
+fn main() {
+    let _ = foo();
+    let x = *"";
+    //~^ ERROR the size for values of type `str` cannot be known at compilation time
+    //~| HELP consider not dereferencing the expression
+    //~| HELP the trait `Sized` is not implemented for `str`
+    //~| HELP unsized locals are gated as an unstable feature
+    bar(x);
+    S.baz(x);
+    bar(*"");
+    //~^ ERROR the size for values of type `str` cannot be known at compilation time
+    //~| HELP consider not dereferencing the expression
+    //~| HELP the trait `Sized` is not implemented for `str`
+    S.baz(*"");
+    //~^ ERROR the size for values of type `str` cannot be known at compilation time
+    //~| HELP consider not dereferencing the expression
+    //~| HELP the trait `Sized` is not implemented for `str`
+}
diff --git a/tests/ui/sized/unsized-str-in-return-expr-arg-and-local.stderr b/tests/ui/sized/unsized-str-in-return-expr-arg-and-local.stderr
new file mode 100644
index 0000000000000..9b7258aff1261
--- /dev/null
+++ b/tests/ui/sized/unsized-str-in-return-expr-arg-and-local.stderr
@@ -0,0 +1,74 @@
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/unsized-str-in-return-expr-arg-and-local.rs:1:13
+   |
+LL | fn foo() -> impl Sized {
+   |             ^^^^^^^^^^ doesn't have a size known at compile-time
+...
+LL |     *""
+   |     --- return type was inferred to be `str` here
+   |
+   = help: the trait `Sized` is not implemented for `str`
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     *""
+LL +     ""
+   |
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/unsized-str-in-return-expr-arg-and-local.rs:15:9
+   |
+LL |     let x = *"";
+   |         ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+   = note: all local variables must have a statically known size
+   = help: unsized locals are gated as an unstable feature
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     let x = *"";
+LL +     let x = "";
+   |
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/unsized-str-in-return-expr-arg-and-local.rs:22:9
+   |
+LL |     bar(*"");
+   |     --- ^^^ doesn't have a size known at compile-time
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by a bound in `bar`
+  --> $DIR/unsized-str-in-return-expr-arg-and-local.rs:6:16
+   |
+LL | fn bar(_: impl Sized) {}
+   |                ^^^^^ required by this bound in `bar`
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     bar(*"");
+LL +     bar("");
+   |
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/unsized-str-in-return-expr-arg-and-local.rs:26:11
+   |
+LL |     S.baz(*"");
+   |       --- ^^^ doesn't have a size known at compile-time
+   |       |
+   |       required by a bound introduced by this call
+   |
+   = help: the trait `Sized` is not implemented for `str`
+note: required by a bound in `S::baz`
+  --> $DIR/unsized-str-in-return-expr-arg-and-local.rs:10:27
+   |
+LL |     fn baz(&self, _: impl Sized) {}
+   |                           ^^^^^ required by this bound in `S::baz`
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     S.baz(*"");
+LL +     S.baz("");
+   |
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/suggestions/issue-84973-blacklist.stderr b/tests/ui/suggestions/issue-84973-blacklist.stderr
index 4fd063e46926a..c1ef1cd428e4a 100644
--- a/tests/ui/suggestions/issue-84973-blacklist.stderr
+++ b/tests/ui/suggestions/issue-84973-blacklist.stderr
@@ -66,6 +66,11 @@ note: required by a bound in `f_sized`
    |
 LL | fn f_sized<T: Sized>(t: T) {}
    |               ^^^^^ required by this bound in `f_sized`
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     f_sized(*ref_cl);
+LL +     f_sized(ref_cl);
+   |
 
 error[E0277]: `Rc<{integer}>` cannot be sent between threads safely
   --> $DIR/issue-84973-blacklist.rs:27:12
diff --git a/tests/ui/type-alias-impl-trait/variance.rs b/tests/ui/type-alias-impl-trait/variance.rs
index ba52eaa035971..113f6a4cc4491 100644
--- a/tests/ui/type-alias-impl-trait/variance.rs
+++ b/tests/ui/type-alias-impl-trait/variance.rs
@@ -5,21 +5,21 @@
 trait Captures<'a> {}
 impl<T> Captures<'_> for T {}
 
-type NotCapturedEarly<'a> = impl Sized; //~ [*, o]
+type NotCapturedEarly<'a> = impl Sized; //~ ['a: *, 'a: o]
 //~^ ERROR: unconstrained opaque type
 
-type CapturedEarly<'a> = impl Sized + Captures<'a>; //~ [*, o]
+type CapturedEarly<'a> = impl Sized + Captures<'a>; //~ ['a: *, 'a: o]
 //~^ ERROR: unconstrained opaque type
 
-type NotCapturedLate<'a> = dyn for<'b> Iterator<Item = impl Sized>; //~ [*, o, o]
+type NotCapturedLate<'a> = dyn for<'b> Iterator<Item = impl Sized>; //~ ['a: *, 'b: o, 'a: o]
 //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
 //~| ERROR: unconstrained opaque type
 
-type Captured<'a> = dyn for<'b> Iterator<Item = impl Sized + Captures<'a>>; //~ [*, o, o]
+type Captured<'a> = dyn for<'b> Iterator<Item = impl Sized + Captures<'a>>; //~ ['a: *, 'b: o, 'a: o]
 //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from `dyn` type
 //~| ERROR: unconstrained opaque type
 
-type Bar<'a, 'b: 'b, T> = impl Sized; //~ ERROR [*, *, o, o, o]
+type Bar<'a, 'b: 'b, T> = impl Sized; //~ ERROR ['a: *, 'b: *, T: o, 'a: o, 'b: o]
 //~^ ERROR: unconstrained opaque type
 
 trait Foo<'i> {
@@ -31,24 +31,24 @@ trait Foo<'i> {
 }
 
 impl<'i> Foo<'i> for &'i () {
-    type ImplicitCapture<'a> = impl Sized; //~ [*, *, o, o]
+    type ImplicitCapture<'a> = impl Sized; //~ ['i: *, 'a: *, 'a: o, 'i: o]
     //~^ ERROR: unconstrained opaque type
 
-    type ExplicitCaptureFromHeader<'a> = impl Sized + Captures<'i>; //~ [*, *, o, o]
+    type ExplicitCaptureFromHeader<'a> = impl Sized + Captures<'i>; //~ ['i: *, 'a: *, 'a: o, 'i: o]
     //~^ ERROR: unconstrained opaque type
 
-    type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>; //~ [*, *, o, o]
+    type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>; //~ ['i: *, 'a: *, 'a: o, 'i: o]
     //~^ ERROR: unconstrained opaque type
 }
 
 impl<'i> Foo<'i> for () {
-    type ImplicitCapture<'a> = impl Sized; //~ [*, *, o, o]
+    type ImplicitCapture<'a> = impl Sized; //~ ['i: *, 'a: *, 'a: o, 'i: o]
     //~^ ERROR: unconstrained opaque type
 
-    type ExplicitCaptureFromHeader<'a> = impl Sized + Captures<'i>; //~ [*, *, o, o]
+    type ExplicitCaptureFromHeader<'a> = impl Sized + Captures<'i>; //~ ['i: *, 'a: *, 'a: o, 'i: o]
     //~^ ERROR: unconstrained opaque type
 
-    type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>; //~ [*, *, o, o]
+    type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>; //~ ['i: *, 'a: *, 'a: o, 'i: o]
     //~^ ERROR: unconstrained opaque type
 }
 
@@ -59,15 +59,15 @@ impl<'a> Nesting<'a> for &'a () {
     type Output = &'a ();
 }
 type NestedDeeply<'a> =
-    impl Nesting< //~ [*, o]
+    impl Nesting< //~ ['a: *, 'a: o]
         'a,
-        Output = impl Nesting< //~ [*, o]
+        Output = impl Nesting< //~ ['a: *, 'a: o]
             'a,
-            Output = impl Nesting< //~ [*, o]
+            Output = impl Nesting< //~ ['a: *, 'a: o]
                 'a,
-                Output = impl Nesting< //~ [*, o]
+                Output = impl Nesting< //~ ['a: *, 'a: o]
                     'a,
-                    Output = impl Nesting<'a> //~ [*, o]
+                    Output = impl Nesting<'a> //~ ['a: *, 'a: o]
                 >
             >,
         >,
diff --git a/tests/ui/type-alias-impl-trait/variance.stderr b/tests/ui/type-alias-impl-trait/variance.stderr
index e5ced7a498171..489dfe03d446c 100644
--- a/tests/ui/type-alias-impl-trait/variance.stderr
+++ b/tests/ui/type-alias-impl-trait/variance.stderr
@@ -110,73 +110,73 @@ LL |     type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>;
    |
    = note: `ExplicitCaptureFromGat` must be used in combination with a concrete type within the same impl
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:8:29
    |
 LL | type NotCapturedEarly<'a> = impl Sized;
    |                             ^^^^^^^^^^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:11:26
    |
 LL | type CapturedEarly<'a> = impl Sized + Captures<'a>;
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, o, o]
+error: ['a: *, 'b: o, 'a: o]
   --> $DIR/variance.rs:14:56
    |
 LL | type NotCapturedLate<'a> = dyn for<'b> Iterator<Item = impl Sized>;
    |                                                        ^^^^^^^^^^
 
-error: [*, o, o]
+error: ['a: *, 'b: o, 'a: o]
   --> $DIR/variance.rs:18:49
    |
 LL | type Captured<'a> = dyn for<'b> Iterator<Item = impl Sized + Captures<'a>>;
    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, *, o, o, o]
+error: ['a: *, 'b: *, T: o, 'a: o, 'b: o]
   --> $DIR/variance.rs:22:27
    |
 LL | type Bar<'a, 'b: 'b, T> = impl Sized;
    |                           ^^^^^^^^^^
 
-error: [*, *, o, o]
+error: ['i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:34:32
    |
 LL |     type ImplicitCapture<'a> = impl Sized;
    |                                ^^^^^^^^^^
 
-error: [*, *, o, o]
+error: ['i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:37:42
    |
 LL |     type ExplicitCaptureFromHeader<'a> = impl Sized + Captures<'i>;
    |                                          ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, *, o, o]
+error: ['i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:40:39
    |
 LL |     type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>;
    |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, *, o, o]
+error: ['i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:45:32
    |
 LL |     type ImplicitCapture<'a> = impl Sized;
    |                                ^^^^^^^^^^
 
-error: [*, *, o, o]
+error: ['i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:48:42
    |
 LL |     type ExplicitCaptureFromHeader<'a> = impl Sized + Captures<'i>;
    |                                          ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, *, o, o]
+error: ['i: *, 'a: *, 'a: o, 'i: o]
   --> $DIR/variance.rs:51:39
    |
 LL |     type ExplicitCaptureFromGat<'a> = impl Sized + Captures<'a>;
    |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:62:5
    |
 LL | /     impl Nesting<
@@ -188,7 +188,7 @@ LL | |         >,
 LL | |     >;
    | |_____^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:64:18
    |
 LL |           Output = impl Nesting<
@@ -201,7 +201,7 @@ LL | |             >,
 LL | |         >,
    | |_________^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:66:22
    |
 LL |               Output = impl Nesting<
@@ -214,7 +214,7 @@ LL | |                 >
 LL | |             >,
    | |_____________^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:68:26
    |
 LL |                   Output = impl Nesting<
@@ -224,7 +224,7 @@ LL | |                     Output = impl Nesting<'a>
 LL | |                 >
    | |_________________^
 
-error: [*, o]
+error: ['a: *, 'a: o]
   --> $DIR/variance.rs:70:30
    |
 LL |                     Output = impl Nesting<'a>
diff --git a/tests/ui/unsized/unsized6.stderr b/tests/ui/unsized/unsized6.stderr
index 56e7f60f9ff08..d406120efc532 100644
--- a/tests/ui/unsized/unsized6.stderr
+++ b/tests/ui/unsized/unsized6.stderr
@@ -123,6 +123,11 @@ help: consider removing the `?Sized` bound to make the type parameter `Sized`
 LL - fn f3<X: ?Sized>(x1: Box<X>, x2: Box<X>, x3: Box<X>) {
 LL + fn f3<X>(x1: Box<X>, x2: Box<X>, x3: Box<X>) {
    |
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     let y = *x2;
+LL +     let y = x2;
+   |
 
 error[E0277]: the size for values of type `X` cannot be known at compilation time
   --> $DIR/unsized6.rs:26:10
@@ -177,6 +182,11 @@ help: consider removing the `?Sized` bound to make the type parameter `Sized`
 LL - fn f4<X: ?Sized + T>(x1: Box<X>, x2: Box<X>, x3: Box<X>) {
 LL + fn f4<X: T>(x1: Box<X>, x2: Box<X>, x3: Box<X>) {
    |
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     let y = *x2;
+LL +     let y = x2;
+   |
 
 error[E0277]: the size for values of type `X` cannot be known at compilation time
   --> $DIR/unsized6.rs:34:10
diff --git a/tests/ui/variance/variance-associated-consts.rs b/tests/ui/variance/variance-associated-consts.rs
index 6a44a94df3fdd..97edb7e266ad0 100644
--- a/tests/ui/variance/variance-associated-consts.rs
+++ b/tests/ui/variance/variance-associated-consts.rs
@@ -10,7 +10,7 @@ trait Trait {
 }
 
 #[rustc_variance]
-struct Foo<T: Trait> { //~ ERROR [o]
+struct Foo<T: Trait> { //~ ERROR [T: o]
     field: [u8; <T as Trait>::Const]
     //~^ ERROR: unconstrained generic constant
 }
diff --git a/tests/ui/variance/variance-associated-consts.stderr b/tests/ui/variance/variance-associated-consts.stderr
index b955a7686c2a7..5c3ed93464ac6 100644
--- a/tests/ui/variance/variance-associated-consts.stderr
+++ b/tests/ui/variance/variance-associated-consts.stderr
@@ -9,7 +9,7 @@ help: try adding a `where` bound
 LL | struct Foo<T: Trait> where [(); <T as Trait>::Const]: {
    |                      ++++++++++++++++++++++++++++++++
 
-error: [o]
+error: [T: o]
   --> $DIR/variance-associated-consts.rs:13:1
    |
 LL | struct Foo<T: Trait> {
diff --git a/tests/ui/variance/variance-associated-types.rs b/tests/ui/variance/variance-associated-types.rs
index ecb0821827dc0..07ff41062e881 100644
--- a/tests/ui/variance/variance-associated-types.rs
+++ b/tests/ui/variance/variance-associated-types.rs
@@ -10,12 +10,12 @@ trait Trait<'a> {
 }
 
 #[rustc_variance]
-struct Foo<'a, T : Trait<'a>> { //~ ERROR [+, +]
+struct Foo<'a, T : Trait<'a>> { //~ ERROR ['a: +, T: +]
     field: (T, &'a ())
 }
 
 #[rustc_variance]
-struct Bar<'a, T : Trait<'a>> { //~ ERROR [o, o]
+struct Bar<'a, T : Trait<'a>> { //~ ERROR ['a: o, T: o]
     field: <T as Trait<'a>>::Type
 }
 
diff --git a/tests/ui/variance/variance-associated-types.stderr b/tests/ui/variance/variance-associated-types.stderr
index 70cb246f6e906..ca010b7e7ef40 100644
--- a/tests/ui/variance/variance-associated-types.stderr
+++ b/tests/ui/variance/variance-associated-types.stderr
@@ -1,10 +1,10 @@
-error: [+, +]
+error: ['a: +, T: +]
   --> $DIR/variance-associated-types.rs:13:1
    |
 LL | struct Foo<'a, T : Trait<'a>> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o, o]
+error: ['a: o, T: o]
   --> $DIR/variance-associated-types.rs:18:1
    |
 LL | struct Bar<'a, T : Trait<'a>> {
diff --git a/tests/ui/variance/variance-object-types.rs b/tests/ui/variance/variance-object-types.rs
index 6ded24cd1e9ed..fd03dec982492 100644
--- a/tests/ui/variance/variance-object-types.rs
+++ b/tests/ui/variance/variance-object-types.rs
@@ -4,7 +4,7 @@
 // For better or worse, associated types are invariant, and hence we
 // get an invariant result for `'a`.
 #[rustc_variance]
-struct Foo<'a> { //~ ERROR [o]
+struct Foo<'a> { //~ ERROR ['a: o]
     x: Box<dyn Fn(i32) -> &'a i32 + 'static>
 }
 
diff --git a/tests/ui/variance/variance-object-types.stderr b/tests/ui/variance/variance-object-types.stderr
index 963f3454e1baf..a6fb9b2403a6b 100644
--- a/tests/ui/variance/variance-object-types.stderr
+++ b/tests/ui/variance/variance-object-types.stderr
@@ -1,4 +1,4 @@
-error: [o]
+error: ['a: o]
   --> $DIR/variance-object-types.rs:7:1
    |
 LL | struct Foo<'a> {
diff --git a/tests/ui/variance/variance-regions-direct.rs b/tests/ui/variance/variance-regions-direct.rs
index f1763c403f1a1..2bcacec33ea5a 100644
--- a/tests/ui/variance/variance-regions-direct.rs
+++ b/tests/ui/variance/variance-regions-direct.rs
@@ -6,7 +6,7 @@
 // Regions that just appear in normal spots are contravariant:
 
 #[rustc_variance]
-struct Test2<'a, 'b, 'c> { //~ ERROR [+, +, +]
+struct Test2<'a, 'b, 'c> { //~ ERROR ['a: +, 'b: +, 'c: +]
     x: &'a isize,
     y: &'b [isize],
     c: &'c str
@@ -15,7 +15,7 @@ struct Test2<'a, 'b, 'c> { //~ ERROR [+, +, +]
 // Those same annotations in function arguments become covariant:
 
 #[rustc_variance]
-struct Test3<'a, 'b, 'c> { //~ ERROR [-, -, -]
+struct Test3<'a, 'b, 'c> { //~ ERROR ['a: -, 'b: -, 'c: -]
     x: extern "Rust" fn(&'a isize),
     y: extern "Rust" fn(&'b [isize]),
     c: extern "Rust" fn(&'c str),
@@ -24,7 +24,7 @@ struct Test3<'a, 'b, 'c> { //~ ERROR [-, -, -]
 // Mutability induces invariance:
 
 #[rustc_variance]
-struct Test4<'a, 'b:'a> { //~ ERROR [+, o]
+struct Test4<'a, 'b:'a> { //~ ERROR ['a: +, 'b: o]
     x: &'a mut &'b isize,
 }
 
@@ -32,7 +32,7 @@ struct Test4<'a, 'b:'a> { //~ ERROR [+, o]
 // contravariant context:
 
 #[rustc_variance]
-struct Test5<'a, 'b:'a> { //~ ERROR [-, o]
+struct Test5<'a, 'b:'a> { //~ ERROR ['a: -, 'b: o]
     x: extern "Rust" fn(&'a mut &'b isize),
 }
 
@@ -42,14 +42,14 @@ struct Test5<'a, 'b:'a> { //~ ERROR [-, o]
 // argument list occurs in an invariant context.
 
 #[rustc_variance]
-struct Test6<'a, 'b:'a> { //~ ERROR [+, o]
+struct Test6<'a, 'b:'a> { //~ ERROR ['a: +, 'b: o]
     x: &'a mut extern "Rust" fn(&'b isize),
 }
 
 // No uses at all is bivariant:
 
 #[rustc_variance]
-struct Test7<'a> { //~ ERROR [*]
+struct Test7<'a> { //~ ERROR ['a: *]
     //~^ ERROR: `'a` is never used
     x: isize
 }
@@ -57,7 +57,7 @@ struct Test7<'a> { //~ ERROR [*]
 // Try enums too.
 
 #[rustc_variance]
-enum Test8<'a, 'b, 'c:'b> { //~ ERROR [-, +, o]
+enum Test8<'a, 'b, 'c:'b> { //~ ERROR ['a: -, 'b: +, 'c: o]
     Test8A(extern "Rust" fn(&'a isize)),
     Test8B(&'b [isize]),
     Test8C(&'b mut &'c str),
diff --git a/tests/ui/variance/variance-regions-direct.stderr b/tests/ui/variance/variance-regions-direct.stderr
index edfc888f65667..45ce0303fb251 100644
--- a/tests/ui/variance/variance-regions-direct.stderr
+++ b/tests/ui/variance/variance-regions-direct.stderr
@@ -6,43 +6,43 @@ LL | struct Test7<'a> {
    |
    = help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData`
 
-error: [+, +, +]
+error: ['a: +, 'b: +, 'c: +]
   --> $DIR/variance-regions-direct.rs:9:1
    |
 LL | struct Test2<'a, 'b, 'c> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [-, -, -]
+error: ['a: -, 'b: -, 'c: -]
   --> $DIR/variance-regions-direct.rs:18:1
    |
 LL | struct Test3<'a, 'b, 'c> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [+, o]
+error: ['a: +, 'b: o]
   --> $DIR/variance-regions-direct.rs:27:1
    |
 LL | struct Test4<'a, 'b:'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [-, o]
+error: ['a: -, 'b: o]
   --> $DIR/variance-regions-direct.rs:35:1
    |
 LL | struct Test5<'a, 'b:'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [+, o]
+error: ['a: +, 'b: o]
   --> $DIR/variance-regions-direct.rs:45:1
    |
 LL | struct Test6<'a, 'b:'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*]
+error: ['a: *]
   --> $DIR/variance-regions-direct.rs:52:1
    |
 LL | struct Test7<'a> {
    | ^^^^^^^^^^^^^^^^
 
-error: [-, +, o]
+error: ['a: -, 'b: +, 'c: o]
   --> $DIR/variance-regions-direct.rs:60:1
    |
 LL | enum Test8<'a, 'b, 'c:'b> {
diff --git a/tests/ui/variance/variance-regions-indirect.rs b/tests/ui/variance/variance-regions-indirect.rs
index 31e25641d8c3a..aaa4d3f877995 100644
--- a/tests/ui/variance/variance-regions-indirect.rs
+++ b/tests/ui/variance/variance-regions-indirect.rs
@@ -5,7 +5,7 @@
 #![feature(rustc_attrs)]
 
 #[rustc_variance]
-enum Base<'a, 'b, 'c:'b, 'd> { //~ ERROR [-, +, o, *]
+enum Base<'a, 'b, 'c:'b, 'd> { //~ ERROR ['a: -, 'b: +, 'c: o, 'd: *]
     //~^ ERROR: `'d` is never used
     Test8A(extern "Rust" fn(&'a isize)),
     Test8B(&'b [isize]),
@@ -13,25 +13,25 @@ enum Base<'a, 'b, 'c:'b, 'd> { //~ ERROR [-, +, o, *]
 }
 
 #[rustc_variance]
-struct Derived1<'w, 'x:'y, 'y, 'z> { //~ ERROR [*, o, +, -]
+struct Derived1<'w, 'x:'y, 'y, 'z> { //~ ERROR ['w: *, 'x: o, 'y: +, 'z: -]
     //~^ ERROR: `'w` is never used
     f: Base<'z, 'y, 'x, 'w>
 }
 
 #[rustc_variance] // Combine - and + to yield o
-struct Derived2<'a, 'b:'a, 'c> { //~ ERROR [o, o, *]
+struct Derived2<'a, 'b:'a, 'c> { //~ ERROR ['a: o, 'b: o, 'c: *]
     //~^ ERROR: `'c` is never used
     f: Base<'a, 'a, 'b, 'c>
 }
 
 #[rustc_variance] // Combine + and o to yield o (just pay attention to 'a here)
-struct Derived3<'a:'b, 'b, 'c> { //~ ERROR [o, +, *]
+struct Derived3<'a:'b, 'b, 'c> { //~ ERROR ['a: o, 'b: +, 'c: *]
     //~^ ERROR: `'c` is never used
     f: Base<'a, 'b, 'a, 'c>
 }
 
 #[rustc_variance] // Combine + and * to yield + (just pay attention to 'a here)
-struct Derived4<'a, 'b, 'c:'b> { //~ ERROR [-, +, o]
+struct Derived4<'a, 'b, 'c:'b> { //~ ERROR ['a: -, 'b: +, 'c: o]
     f: Base<'a, 'b, 'c, 'a>
 }
 
diff --git a/tests/ui/variance/variance-regions-indirect.stderr b/tests/ui/variance/variance-regions-indirect.stderr
index 901ec0c6a762b..ed839b3235009 100644
--- a/tests/ui/variance/variance-regions-indirect.stderr
+++ b/tests/ui/variance/variance-regions-indirect.stderr
@@ -30,31 +30,31 @@ LL | struct Derived3<'a:'b, 'b, 'c> {
    |
    = help: consider removing `'c`, referring to it in a field, or using a marker such as `PhantomData`
 
-error: [-, +, o, *]
+error: ['a: -, 'b: +, 'c: o, 'd: *]
   --> $DIR/variance-regions-indirect.rs:8:1
    |
 LL | enum Base<'a, 'b, 'c:'b, 'd> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, o, +, -]
+error: ['w: *, 'x: o, 'y: +, 'z: -]
   --> $DIR/variance-regions-indirect.rs:16:1
    |
 LL | struct Derived1<'w, 'x:'y, 'y, 'z> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o, o, *]
+error: ['a: o, 'b: o, 'c: *]
   --> $DIR/variance-regions-indirect.rs:22:1
    |
 LL | struct Derived2<'a, 'b:'a, 'c> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o, +, *]
+error: ['a: o, 'b: +, 'c: *]
   --> $DIR/variance-regions-indirect.rs:28:1
    |
 LL | struct Derived3<'a:'b, 'b, 'c> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [-, +, o]
+error: ['a: -, 'b: +, 'c: o]
   --> $DIR/variance-regions-indirect.rs:34:1
    |
 LL | struct Derived4<'a, 'b, 'c:'b> {
diff --git a/tests/ui/variance/variance-trait-bounds.rs b/tests/ui/variance/variance-trait-bounds.rs
index 25a01b160ddd1..f86fa2bbef7a0 100644
--- a/tests/ui/variance/variance-trait-bounds.rs
+++ b/tests/ui/variance/variance-trait-bounds.rs
@@ -13,24 +13,24 @@ trait Setter<T> {
 }
 
 #[rustc_variance]
-struct TestStruct<U,T:Setter<U>> { //~ ERROR [+, +]
+struct TestStruct<U,T:Setter<U>> { //~ ERROR [U: +, T: +]
     t: T, u: U
 }
 
 #[rustc_variance]
-enum TestEnum<U,T:Setter<U>> { //~ ERROR [*, +]
+enum TestEnum<U,T:Setter<U>> { //~ ERROR [U: *, T: +]
     //~^ ERROR: `U` is never used
     Foo(T)
 }
 
 #[rustc_variance]
-struct TestContraStruct<U,T:Setter<U>> { //~ ERROR [*, +]
+struct TestContraStruct<U,T:Setter<U>> { //~ ERROR [U: *, T: +]
     //~^ ERROR: `U` is never used
     t: T
 }
 
 #[rustc_variance]
-struct TestBox<U,T:Getter<U>+Setter<U>> { //~ ERROR [*, +]
+struct TestBox<U,T:Getter<U>+Setter<U>> { //~ ERROR [U: *, T: +]
     //~^ ERROR: `U` is never used
     t: T
 }
diff --git a/tests/ui/variance/variance-trait-bounds.stderr b/tests/ui/variance/variance-trait-bounds.stderr
index 95ed18c1ad2bf..49cee3cbeca75 100644
--- a/tests/ui/variance/variance-trait-bounds.stderr
+++ b/tests/ui/variance/variance-trait-bounds.stderr
@@ -25,25 +25,25 @@ LL | struct TestBox<U,T:Getter<U>+Setter<U>> {
    = help: consider removing `U`, referring to it in a field, or using a marker such as `PhantomData`
    = help: if you intended `U` to be a const parameter, use `const U: /* Type */` instead
 
-error: [+, +]
+error: [U: +, T: +]
   --> $DIR/variance-trait-bounds.rs:16:1
    |
 LL | struct TestStruct<U,T:Setter<U>> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, +]
+error: [U: *, T: +]
   --> $DIR/variance-trait-bounds.rs:21:1
    |
 LL | enum TestEnum<U,T:Setter<U>> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, +]
+error: [U: *, T: +]
   --> $DIR/variance-trait-bounds.rs:27:1
    |
 LL | struct TestContraStruct<U,T:Setter<U>> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [*, +]
+error: [U: *, T: +]
   --> $DIR/variance-trait-bounds.rs:33:1
    |
 LL | struct TestBox<U,T:Getter<U>+Setter<U>> {
diff --git a/tests/ui/variance/variance-trait-object-bound.rs b/tests/ui/variance/variance-trait-object-bound.rs
index 11303c4652005..ca80c6b6dce22 100644
--- a/tests/ui/variance/variance-trait-object-bound.rs
+++ b/tests/ui/variance/variance-trait-object-bound.rs
@@ -11,7 +11,7 @@ use std::mem;
 trait T { fn foo(&self); }
 
 #[rustc_variance]
-struct TOption<'a> { //~ ERROR [+]
+struct TOption<'a> { //~ ERROR ['a: +]
     v: Option<Box<dyn T + 'a>>,
 }
 
diff --git a/tests/ui/variance/variance-trait-object-bound.stderr b/tests/ui/variance/variance-trait-object-bound.stderr
index f0471a3461925..0af21ec12cc9b 100644
--- a/tests/ui/variance/variance-trait-object-bound.stderr
+++ b/tests/ui/variance/variance-trait-object-bound.stderr
@@ -1,4 +1,4 @@
-error: [+]
+error: ['a: +]
   --> $DIR/variance-trait-object-bound.rs:14:1
    |
 LL | struct TOption<'a> {
diff --git a/tests/ui/variance/variance-types-bounds.rs b/tests/ui/variance/variance-types-bounds.rs
index d1814dd97a0ad..f4738a2dae1ab 100644
--- a/tests/ui/variance/variance-types-bounds.rs
+++ b/tests/ui/variance/variance-types-bounds.rs
@@ -4,24 +4,24 @@
 #![feature(rustc_attrs)]
 
 #[rustc_variance]
-struct TestImm<A, B> { //~ ERROR [+, +]
+struct TestImm<A, B> { //~ ERROR [A: +, B: +]
     x: A,
     y: B,
 }
 
 #[rustc_variance]
-struct TestMut<A, B:'static> { //~ ERROR [+, o]
+struct TestMut<A, B:'static> { //~ ERROR [A: +, B: o]
     x: A,
     y: &'static mut B,
 }
 
 #[rustc_variance]
-struct TestIndirect<A:'static, B:'static> { //~ ERROR [+, o]
+struct TestIndirect<A:'static, B:'static> { //~ ERROR [A: +, B: o]
     m: TestMut<A, B>
 }
 
 #[rustc_variance]
-struct TestIndirect2<A:'static, B:'static> { //~ ERROR [o, o]
+struct TestIndirect2<A:'static, B:'static> { //~ ERROR [A: o, B: o]
     n: TestMut<A, B>,
     m: TestMut<B, A>
 }
@@ -35,7 +35,7 @@ trait Setter<A> {
 }
 
 #[rustc_variance]
-struct TestObject<A, R> { //~ ERROR [o, o]
+struct TestObject<A, R> { //~ ERROR [A: o, R: o]
     n: Box<dyn Setter<A>+Send>,
     m: Box<dyn Getter<R>+Send>,
 }
diff --git a/tests/ui/variance/variance-types-bounds.stderr b/tests/ui/variance/variance-types-bounds.stderr
index bb81644347693..408c2ae8d3682 100644
--- a/tests/ui/variance/variance-types-bounds.stderr
+++ b/tests/ui/variance/variance-types-bounds.stderr
@@ -1,28 +1,28 @@
-error: [+, +]
+error: [A: +, B: +]
   --> $DIR/variance-types-bounds.rs:7:1
    |
 LL | struct TestImm<A, B> {
    | ^^^^^^^^^^^^^^^^^^^^
 
-error: [+, o]
+error: [A: +, B: o]
   --> $DIR/variance-types-bounds.rs:13:1
    |
 LL | struct TestMut<A, B:'static> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [+, o]
+error: [A: +, B: o]
   --> $DIR/variance-types-bounds.rs:19:1
    |
 LL | struct TestIndirect<A:'static, B:'static> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o, o]
+error: [A: o, B: o]
   --> $DIR/variance-types-bounds.rs:24:1
    |
 LL | struct TestIndirect2<A:'static, B:'static> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o, o]
+error: [A: o, R: o]
   --> $DIR/variance-types-bounds.rs:38:1
    |
 LL | struct TestObject<A, R> {
diff --git a/tests/ui/variance/variance-types.rs b/tests/ui/variance/variance-types.rs
index cfc03b754734d..aa336d1b424c1 100644
--- a/tests/ui/variance/variance-types.rs
+++ b/tests/ui/variance/variance-types.rs
@@ -7,32 +7,32 @@ use std::cell::Cell;
 // not considered bivariant.
 
 #[rustc_variance]
-struct InvariantMut<'a,A:'a,B:'a> { //~ ERROR [+, o, o]
+struct InvariantMut<'a,A:'a,B:'a> { //~ ERROR ['a: +, A: o, B: o]
     t: &'a mut (A,B)
 }
 
 #[rustc_variance]
-struct InvariantCell<A> { //~ ERROR [o]
+struct InvariantCell<A> { //~ ERROR [A: o]
     t: Cell<A>
 }
 
 #[rustc_variance]
-struct InvariantIndirect<A> { //~ ERROR [o]
+struct InvariantIndirect<A> { //~ ERROR [A: o]
     t: InvariantCell<A>
 }
 
 #[rustc_variance]
-struct Covariant<A> { //~ ERROR [+]
+struct Covariant<A> { //~ ERROR [A: +]
     t: A, u: fn() -> A
 }
 
 #[rustc_variance]
-struct Contravariant<A> { //~ ERROR [-]
+struct Contravariant<A> { //~ ERROR [A: -]
     t: fn(A)
 }
 
 #[rustc_variance]
-enum Enum<A,B,C> { //~ ERROR [+, -, o]
+enum Enum<A,B,C> { //~ ERROR [A: +, B: -, C: o]
     Foo(Covariant<A>),
     Bar(Contravariant<B>),
     Zed(Covariant<C>,Contravariant<C>)
diff --git a/tests/ui/variance/variance-types.stderr b/tests/ui/variance/variance-types.stderr
index 0fda4b8036e72..f2a6794942553 100644
--- a/tests/ui/variance/variance-types.stderr
+++ b/tests/ui/variance/variance-types.stderr
@@ -1,34 +1,34 @@
-error: [+, o, o]
+error: ['a: +, A: o, B: o]
   --> $DIR/variance-types.rs:10:1
    |
 LL | struct InvariantMut<'a,A:'a,B:'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o]
+error: [A: o]
   --> $DIR/variance-types.rs:15:1
    |
 LL | struct InvariantCell<A> {
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [o]
+error: [A: o]
   --> $DIR/variance-types.rs:20:1
    |
 LL | struct InvariantIndirect<A> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [+]
+error: [A: +]
   --> $DIR/variance-types.rs:25:1
    |
 LL | struct Covariant<A> {
    | ^^^^^^^^^^^^^^^^^^^
 
-error: [-]
+error: [A: -]
   --> $DIR/variance-types.rs:30:1
    |
 LL | struct Contravariant<A> {
    | ^^^^^^^^^^^^^^^^^^^^^^^
 
-error: [+, -, o]
+error: [A: +, B: -, C: o]
   --> $DIR/variance-types.rs:35:1
    |
 LL | enum Enum<A,B,C> {
diff --git a/triagebot.toml b/triagebot.toml
index 9bb1befb69983..d7bc60e6c6f09 100644
--- a/triagebot.toml
+++ b/triagebot.toml
@@ -951,6 +951,7 @@ libs = [
     "@joboet",
     "@jhpratt",
     "@tgross35",
+    "@thomcc",
 ]
 bootstrap = [
     "@Mark-Simulacrum",