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-rw-r--r--compiler/rustc_ast_pretty/src/pprust/state.rs6
-rw-r--r--compiler/rustc_feature/src/builtin_attrs.rs5
-rw-r--r--compiler/rustc_hir_pretty/src/lib.rs6
-rw-r--r--compiler/rustc_index/src/lib.rs4
-rw-r--r--compiler/rustc_infer/src/infer/outlives/obligations.rs4
-rw-r--r--compiler/rustc_infer/src/traits/util.rs17
-rw-r--r--compiler/rustc_lint/src/internal.rs33
-rw-r--r--compiler/rustc_lint/src/lib.rs6
-rw-r--r--compiler/rustc_lint/src/pass_by_value.rs94
-rw-r--r--compiler/rustc_middle/src/ty/context.rs1
-rw-r--r--compiler/rustc_middle/src/ty/mod.rs1
-rw-r--r--compiler/rustc_parse/src/parser/diagnostics.rs30
-rw-r--r--compiler/rustc_parse/src/parser/expr.rs4
-rw-r--r--compiler/rustc_parse/src/parser/ty.rs26
-rw-r--r--compiler/rustc_passes/src/check_attr.rs19
-rw-r--r--compiler/rustc_span/src/symbol.rs32
-rw-r--r--compiler/rustc_target/src/spec/armv6k_nintendo_3ds.rs1
-rw-r--r--compiler/rustc_trait_selection/src/traits/select/confirmation.rs4
18 files changed, 241 insertions, 52 deletions
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index fa9a20f2e03..32a4a0751d8 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -1357,9 +1357,7 @@ impl<'a> State<'a> {
                 self.bclose(item.span, empty);
             }
             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
-                self.head("");
-                self.print_visibility(&item.vis);
-                self.word_nbsp("trait");
+                self.head(visibility_qualified(&item.vis, "trait"));
                 self.print_ident(item.ident);
                 self.print_generic_params(&generics.params);
                 let mut real_bounds = Vec::with_capacity(bounds.len());
@@ -1377,6 +1375,8 @@ impl<'a> State<'a> {
                 self.print_type_bounds("=", &real_bounds);
                 self.print_where_clause(&generics.where_clause);
                 self.word(";");
+                self.end(); // end inner head-block
+                self.end(); // end outer head-block
             }
             ast::ItemKind::MacCall(ref mac) => {
                 self.print_mac(mac);
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index f25b2d8f566..46817bc9c3f 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -623,6 +623,11 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         lang, Normal, template!(NameValueStr: "name"), DuplicatesOk, lang_items,
         "language items are subject to change",
     ),
+    rustc_attr!(
+        rustc_pass_by_value, Normal,
+        template!(Word), WarnFollowing,
+        "#[rustc_pass_by_value] is used to mark types that must be passed by value instead of reference."
+    ),
     BuiltinAttribute {
         name: sym::rustc_diagnostic_item,
         type_: Normal,
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 4c9e2d7fe42..1fd226291d1 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -705,9 +705,7 @@ impl<'a> State<'a> {
                 self.bclose(item.span);
             }
             hir::ItemKind::TraitAlias(ref generics, ref bounds) => {
-                self.head("");
-                self.print_visibility(&item.vis);
-                self.word_nbsp("trait");
+                self.head(visibility_qualified(&item.vis, "trait"));
                 self.print_ident(item.ident);
                 self.print_generic_params(&generics.params);
                 let mut real_bounds = Vec::with_capacity(bounds.len());
@@ -725,6 +723,8 @@ impl<'a> State<'a> {
                 self.print_bounds("=", real_bounds);
                 self.print_where_clause(&generics.where_clause);
                 self.word(";");
+                self.end(); // end inner head-block
+                self.end(); // end outer head-block
             }
         }
         self.ann.post(self, AnnNode::Item(item))
diff --git a/compiler/rustc_index/src/lib.rs b/compiler/rustc_index/src/lib.rs
index 359b1859c68..7919e409253 100644
--- a/compiler/rustc_index/src/lib.rs
+++ b/compiler/rustc_index/src/lib.rs
@@ -9,7 +9,3 @@
 pub mod bit_set;
 pub mod interval;
 pub mod vec;
-
-// FIXME(#56935): Work around ICEs during cross-compilation.
-#[allow(unused)]
-extern crate rustc_macros;
diff --git a/compiler/rustc_infer/src/infer/outlives/obligations.rs b/compiler/rustc_infer/src/infer/outlives/obligations.rs
index 74eb263a633..a5276afc5bf 100644
--- a/compiler/rustc_infer/src/infer/outlives/obligations.rs
+++ b/compiler/rustc_infer/src/infer/outlives/obligations.rs
@@ -164,7 +164,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
             "cannot process registered region obligations in a snapshot"
         );
 
-        debug!("process_registered_region_obligations()");
+        debug!(?param_env, "process_registered_region_obligations()");
 
         let my_region_obligations = self.take_registered_region_obligations();
 
@@ -356,6 +356,8 @@ where
         let trait_bounds: Vec<_> =
             self.verify_bound.projection_declared_bounds_from_trait(projection_ty).collect();
 
+        debug!(?trait_bounds);
+
         // Compute the bounds we can derive from the environment. This
         // is an "approximate" match -- in some cases, these bounds
         // may not apply.
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs
index 65443fd88d7..674c75fdee5 100644
--- a/compiler/rustc_infer/src/traits/util.rs
+++ b/compiler/rustc_infer/src/traits/util.rs
@@ -241,10 +241,19 @@ impl<'tcx> Elaborator<'tcx> {
 
                             Component::UnresolvedInferenceVariable(_) => None,
 
-                            Component::Projection(_) | Component::EscapingProjection(_) => {
-                                // We can probably do more here. This
-                                // corresponds to a case like `<T as
-                                // Foo<'a>>::U: 'b`.
+                            Component::Projection(projection) => {
+                                // We might end up here if we have `Foo<<Bar as Baz>::Assoc>: 'a`.
+                                // With this, we can deduce that `<Bar as Baz>::Assoc: 'a`.
+                                let ty =
+                                    tcx.mk_projection(projection.item_def_id, projection.substs);
+                                Some(ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(
+                                    ty, r_min,
+                                )))
+                            }
+
+                            Component::EscapingProjection(_) => {
+                                // We might be able to do more here, but we don't
+                                // want to deal with escaping vars right now.
                                 None
                             }
                         })
diff --git a/compiler/rustc_lint/src/internal.rs b/compiler/rustc_lint/src/internal.rs
index c64a67b6b9f..7353cd6b876 100644
--- a/compiler/rustc_lint/src/internal.rs
+++ b/compiler/rustc_lint/src/internal.rs
@@ -5,10 +5,7 @@ use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext}
 use rustc_ast as ast;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
-use rustc_hir::{
-    GenericArg, HirId, Item, ItemKind, MutTy, Mutability, Node, Path, PathSegment, QPath, Ty,
-    TyKind,
-};
+use rustc_hir::{GenericArg, HirId, Item, ItemKind, Node, Path, PathSegment, QPath, Ty, TyKind};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -59,13 +56,6 @@ declare_tool_lint! {
 }
 
 declare_tool_lint! {
-    pub rustc::TY_PASS_BY_REFERENCE,
-    Allow,
-    "passing `Ty` or `TyCtxt` by reference",
-    report_in_external_macro: true
-}
-
-declare_tool_lint! {
     pub rustc::USAGE_OF_QUALIFIED_TY,
     Allow,
     "using `ty::{Ty,TyCtxt}` instead of importing it",
@@ -74,7 +64,6 @@ declare_tool_lint! {
 
 declare_lint_pass!(TyTyKind => [
     USAGE_OF_TY_TYKIND,
-    TY_PASS_BY_REFERENCE,
     USAGE_OF_QUALIFIED_TY,
 ]);
 
@@ -131,26 +120,6 @@ impl<'tcx> LateLintPass<'tcx> for TyTyKind {
                     }
                 }
             }
-            TyKind::Rptr(_, MutTy { ty: inner_ty, mutbl: Mutability::Not }) => {
-                if let Some(impl_did) = cx.tcx.impl_of_method(ty.hir_id.owner.to_def_id()) {
-                    if cx.tcx.impl_trait_ref(impl_did).is_some() {
-                        return;
-                    }
-                }
-                if let Some(t) = is_ty_or_ty_ctxt(cx, &inner_ty) {
-                    cx.struct_span_lint(TY_PASS_BY_REFERENCE, ty.span, |lint| {
-                        lint.build(&format!("passing `{}` by reference", t))
-                            .span_suggestion(
-                                ty.span,
-                                "try passing by value",
-                                t,
-                                // Changing type of function argument
-                                Applicability::MaybeIncorrect,
-                            )
-                            .emit();
-                    })
-                }
-            }
             _ => {}
         }
     }
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index c6145ae0d51..4aa8505c940 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -56,6 +56,7 @@ mod non_ascii_idents;
 mod non_fmt_panic;
 mod nonstandard_style;
 mod noop_method_call;
+mod pass_by_value;
 mod passes;
 mod redundant_semicolon;
 mod traits;
@@ -85,6 +86,7 @@ use non_ascii_idents::*;
 use non_fmt_panic::NonPanicFmt;
 use nonstandard_style::*;
 use noop_method_call::*;
+use pass_by_value::*;
 use redundant_semicolon::*;
 use traits::*;
 use types::*;
@@ -490,6 +492,8 @@ fn register_internals(store: &mut LintStore) {
     store.register_late_pass(|| Box::new(ExistingDocKeyword));
     store.register_lints(&TyTyKind::get_lints());
     store.register_late_pass(|| Box::new(TyTyKind));
+    store.register_lints(&PassByValue::get_lints());
+    store.register_late_pass(|| Box::new(PassByValue));
     store.register_group(
         false,
         "rustc::internal",
@@ -497,8 +501,8 @@ fn register_internals(store: &mut LintStore) {
         vec![
             LintId::of(DEFAULT_HASH_TYPES),
             LintId::of(USAGE_OF_TY_TYKIND),
+            LintId::of(PASS_BY_VALUE),
             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
-            LintId::of(TY_PASS_BY_REFERENCE),
             LintId::of(USAGE_OF_QUALIFIED_TY),
             LintId::of(EXISTING_DOC_KEYWORD),
         ],
diff --git a/compiler/rustc_lint/src/pass_by_value.rs b/compiler/rustc_lint/src/pass_by_value.rs
new file mode 100644
index 00000000000..26d0560bf89
--- /dev/null
+++ b/compiler/rustc_lint/src/pass_by_value.rs
@@ -0,0 +1,94 @@
+use crate::{LateContext, LateLintPass, LintContext};
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_hir::def::Res;
+use rustc_hir::{GenericArg, PathSegment, QPath, TyKind};
+use rustc_middle::ty;
+use rustc_span::symbol::sym;
+
+declare_tool_lint! {
+    /// The `rustc_pass_by_value` lint marks a type with `#[rustc_pass_by_value]` requiring it to always be passed by value.
+    /// This is usually used for types that are thin wrappers around references, so there is no benefit to an extra
+    /// layer of indirection. (Example: `Ty` which is a reference to a `TyS`)
+    pub rustc::PASS_BY_VALUE,
+    Warn,
+    "pass by reference of a type flagged as `#[rustc_pass_by_value]`",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(PassByValue => [PASS_BY_VALUE]);
+
+impl<'tcx> LateLintPass<'tcx> for PassByValue {
+    fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx hir::Ty<'tcx>) {
+        match &ty.kind {
+            TyKind::Rptr(_, hir::MutTy { ty: inner_ty, mutbl: hir::Mutability::Not }) => {
+                if let Some(impl_did) = cx.tcx.impl_of_method(ty.hir_id.owner.to_def_id()) {
+                    if cx.tcx.impl_trait_ref(impl_did).is_some() {
+                        return;
+                    }
+                }
+                if let Some(t) = path_for_pass_by_value(cx, &inner_ty) {
+                    cx.struct_span_lint(PASS_BY_VALUE, ty.span, |lint| {
+                        lint.build(&format!("passing `{}` by reference", t))
+                            .span_suggestion(
+                                ty.span,
+                                "try passing by value",
+                                t,
+                                // Changing type of function argument
+                                Applicability::MaybeIncorrect,
+                            )
+                            .emit();
+                    })
+                }
+            }
+            _ => {}
+        }
+    }
+}
+
+fn path_for_pass_by_value(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> Option<String> {
+    if let TyKind::Path(QPath::Resolved(_, path)) = &ty.kind {
+        match path.res {
+            Res::Def(_, def_id) if cx.tcx.has_attr(def_id, sym::rustc_pass_by_value) => {
+                let name = cx.tcx.item_name(def_id).to_ident_string();
+                let path_segment = path.segments.last().unwrap();
+                return Some(format!("{}{}", name, gen_args(cx, path_segment)));
+            }
+            Res::SelfTy(None, Some((did, _))) => {
+                if let ty::Adt(adt, substs) = cx.tcx.type_of(did).kind() {
+                    if cx.tcx.has_attr(adt.did, sym::rustc_pass_by_value) {
+                        return Some(cx.tcx.def_path_str_with_substs(adt.did, substs));
+                    }
+                }
+            }
+            _ => (),
+        }
+    }
+
+    None
+}
+
+fn gen_args(cx: &LateContext<'_>, segment: &PathSegment<'_>) -> String {
+    if let Some(args) = &segment.args {
+        let params = args
+            .args
+            .iter()
+            .map(|arg| match arg {
+                GenericArg::Lifetime(lt) => lt.name.ident().to_string(),
+                GenericArg::Type(ty) => {
+                    cx.tcx.sess.source_map().span_to_snippet(ty.span).unwrap_or_default()
+                }
+                GenericArg::Const(c) => {
+                    cx.tcx.sess.source_map().span_to_snippet(c.span).unwrap_or_default()
+                }
+                GenericArg::Infer(_) => String::from("_"),
+            })
+            .collect::<Vec<_>>();
+
+        if !params.is_empty() {
+            return format!("<{}>", params.join(", "));
+        }
+    }
+
+    String::new()
+}
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 9f38421294d..e7b99995ca4 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -961,6 +961,7 @@ pub struct FreeRegionInfo {
 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/ty.html
 #[derive(Copy, Clone)]
 #[rustc_diagnostic_item = "TyCtxt"]
+#[cfg_attr(not(bootstrap), rustc_pass_by_value)]
 pub struct TyCtxt<'tcx> {
     gcx: &'tcx GlobalCtxt<'tcx>,
 }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index ceb8795a1a8..d6e89e52b95 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -464,6 +464,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
 }
 
 #[rustc_diagnostic_item = "Ty"]
+#[cfg_attr(not(bootstrap), rustc_pass_by_value)]
 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
 
 impl ty::EarlyBoundRegion {
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 4121a759c37..612d4508565 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -1,5 +1,5 @@
 use super::pat::Expected;
-use super::ty::AllowPlus;
+use super::ty::{AllowPlus, IsAsCast};
 use super::{
     BlockMode, Parser, PathStyle, RecoverColon, RecoverComma, Restrictions, SemiColonMode, SeqSep,
     TokenExpectType, TokenType,
@@ -1032,6 +1032,34 @@ impl<'a> Parser<'a> {
         }
     }
 
+    /// Swift lets users write `Ty?` to mean `Option<Ty>`. Parse the construct and recover from it.
+    pub(super) fn maybe_recover_from_question_mark(
+        &mut self,
+        ty: P<Ty>,
+        is_as_cast: IsAsCast,
+    ) -> P<Ty> {
+        if let IsAsCast::Yes = is_as_cast {
+            return ty;
+        }
+        if self.token == token::Question {
+            self.bump();
+            self.struct_span_err(self.prev_token.span, "invalid `?` in type")
+                .span_label(self.prev_token.span, "`?` is only allowed on expressions, not types")
+                .multipart_suggestion(
+                    "if you meant to express that the type might not contain a value, use the `Option` wrapper type",
+                    vec![
+                        (ty.span.shrink_to_lo(), "Option<".to_string()),
+                        (self.prev_token.span, ">".to_string()),
+                    ],
+                    Applicability::MachineApplicable,
+                )
+                .emit();
+            self.mk_ty(ty.span.to(self.prev_token.span), TyKind::Err)
+        } else {
+            ty
+        }
+    }
+
     pub(super) fn maybe_recover_from_bad_type_plus(
         &mut self,
         allow_plus: AllowPlus,
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index f706a98a4fc..cd3846d5a22 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -682,7 +682,7 @@ impl<'a> Parser<'a> {
         // Save the state of the parser before parsing type normally, in case there is a
         // LessThan comparison after this cast.
         let parser_snapshot_before_type = self.clone();
-        let cast_expr = match self.parse_ty_no_plus() {
+        let cast_expr = match self.parse_as_cast_ty() {
             Ok(rhs) => mk_expr(self, lhs, rhs),
             Err(mut type_err) => {
                 // Rewind to before attempting to parse the type with generics, to recover
@@ -808,7 +808,7 @@ impl<'a> Parser<'a> {
                 "casts cannot be followed by {}",
                 match with_postfix.kind {
                     ExprKind::Index(_, _) => "indexing",
-                    ExprKind::Try(_) => "?",
+                    ExprKind::Try(_) => "`?`",
                     ExprKind::Field(_, _) => "a field access",
                     ExprKind::MethodCall(_, _, _) => "a method call",
                     ExprKind::Call(_, _) => "a function call",
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index 02a774ba129..566b77a5e9e 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -44,6 +44,11 @@ pub(super) enum RecoverQPath {
     No,
 }
 
+pub(super) enum IsAsCast {
+    Yes,
+    No,
+}
+
 /// Signals whether parsing a type should recover `->`.
 ///
 /// More specifically, when parsing a function like:
@@ -100,6 +105,7 @@ impl<'a> Parser<'a> {
             RecoverQPath::Yes,
             RecoverReturnSign::Yes,
             None,
+            IsAsCast::No,
         )
     }
 
@@ -113,6 +119,7 @@ impl<'a> Parser<'a> {
             RecoverQPath::Yes,
             RecoverReturnSign::Yes,
             Some(ty_params),
+            IsAsCast::No,
         )
     }
 
@@ -126,6 +133,7 @@ impl<'a> Parser<'a> {
             RecoverQPath::Yes,
             RecoverReturnSign::Yes,
             None,
+            IsAsCast::No,
         )
     }
 
@@ -142,9 +150,22 @@ impl<'a> Parser<'a> {
             RecoverQPath::Yes,
             RecoverReturnSign::Yes,
             None,
+            IsAsCast::No,
         )
     }
 
+    /// Parses a type following an `as` cast. Similar to `parse_ty_no_plus`, but signaling origin
+    /// for better diagnostics involving `?`.
+    pub(super) fn parse_as_cast_ty(&mut self) -> PResult<'a, P<Ty>> {
+        self.parse_ty_common(
+            AllowPlus::No,
+            AllowCVariadic::No,
+            RecoverQPath::Yes,
+            RecoverReturnSign::Yes,
+            None,
+            IsAsCast::Yes,
+        )
+    }
     /// Parse a type without recovering `:` as `->` to avoid breaking code such as `where fn() : for<'a>`
     pub(super) fn parse_ty_for_where_clause(&mut self) -> PResult<'a, P<Ty>> {
         self.parse_ty_common(
@@ -153,6 +174,7 @@ impl<'a> Parser<'a> {
             RecoverQPath::Yes,
             RecoverReturnSign::OnlyFatArrow,
             None,
+            IsAsCast::No,
         )
     }
 
@@ -171,6 +193,7 @@ impl<'a> Parser<'a> {
                 recover_qpath,
                 recover_return_sign,
                 None,
+                IsAsCast::No,
             )?;
             FnRetTy::Ty(ty)
         } else if recover_return_sign.can_recover(&self.token.kind) {
@@ -191,6 +214,7 @@ impl<'a> Parser<'a> {
                 recover_qpath,
                 recover_return_sign,
                 None,
+                IsAsCast::No,
             )?;
             FnRetTy::Ty(ty)
         } else {
@@ -205,6 +229,7 @@ impl<'a> Parser<'a> {
         recover_qpath: RecoverQPath,
         recover_return_sign: RecoverReturnSign,
         ty_generics: Option<&Generics>,
+        is_as_cast: IsAsCast,
     ) -> PResult<'a, P<Ty>> {
         let allow_qpath_recovery = recover_qpath == RecoverQPath::Yes;
         maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery);
@@ -280,6 +305,7 @@ impl<'a> Parser<'a> {
         // Try to recover from use of `+` with incorrect priority.
         self.maybe_report_ambiguous_plus(allow_plus, impl_dyn_multi, &ty);
         self.maybe_recover_from_bad_type_plus(allow_plus, &ty)?;
+        let ty = self.maybe_recover_from_question_mark(ty, is_as_cast);
         self.maybe_recover_from_bad_qpath(ty, allow_qpath_recovery)
     }
 
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index eca7d84e95d..41d4d5115a4 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -114,6 +114,7 @@ impl CheckAttrVisitor<'_> {
                 }
                 sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target),
                 sym::must_use => self.check_must_use(hir_id, &attr, span, target),
+                sym::rustc_pass_by_value => self.check_pass_by_value(&attr, span, target),
                 sym::rustc_const_unstable
                 | sym::rustc_const_stable
                 | sym::unstable
@@ -1066,6 +1067,24 @@ impl CheckAttrVisitor<'_> {
         is_valid
     }
 
+    /// Warns against some misuses of `#[pass_by_value]`
+    fn check_pass_by_value(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+        match target {
+            Target::Struct | Target::Enum | Target::TyAlias => true,
+            _ => {
+                self.tcx
+                    .sess
+                    .struct_span_err(
+                        attr.span,
+                        "`pass_by_value` attribute should be applied to a struct, enum or type alias.",
+                    )
+                    .span_label(*span, "is not a struct, enum or type alias")
+                    .emit();
+                false
+            }
+        }
+    }
+
     /// Warns against some misuses of `#[must_use]`
     fn check_must_use(
         &self,
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index f99d5cfad0a..14ac286476c 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -336,8 +336,10 @@ symbols! {
         asm_sym,
         asm_unwind,
         assert,
+        assert_eq_macro,
         assert_inhabited,
         assert_macro,
+        assert_ne_macro,
         assert_receiver_is_total_eq,
         assert_uninit_valid,
         assert_zero_valid,
@@ -407,6 +409,7 @@ symbols! {
         cfg_doctest,
         cfg_eval,
         cfg_hide,
+        cfg_macro,
         cfg_panic,
         cfg_sanitize,
         cfg_target_abi,
@@ -434,15 +437,18 @@ symbols! {
         coerce_unsized,
         cold,
         column,
+        column_macro,
         compare_and_swap,
         compare_exchange,
         compare_exchange_weak,
         compile_error,
+        compile_error_macro,
         compiler_builtins,
         compiler_fence,
         concat,
         concat_bytes,
         concat_idents,
+        concat_macro,
         conservative_impl_trait,
         console,
         const_allocate,
@@ -522,10 +528,13 @@ symbols! {
         custom_inner_attributes,
         custom_test_frameworks,
         d,
+        dbg_macro,
         dead_code,
         dealloc,
         debug,
+        debug_assert_eq_macro,
         debug_assert_macro,
+        debug_assert_ne_macro,
         debug_assertions,
         debug_struct,
         debug_trait_builder,
@@ -597,6 +606,9 @@ symbols! {
         encode,
         end,
         env,
+        env_macro,
+        eprint_macro,
+        eprintln_macro,
         eq,
         ermsb_target_feature,
         exact_div,
@@ -644,6 +656,7 @@ symbols! {
         field,
         field_init_shorthand,
         file,
+        file_macro,
         fill,
         finish,
         flags,
@@ -666,6 +679,7 @@ symbols! {
         format,
         format_args,
         format_args_capture,
+        format_args_macro,
         format_args_nl,
         format_macro,
         freeze,
@@ -732,7 +746,10 @@ symbols! {
         in_band_lifetimes,
         include,
         include_bytes,
+        include_bytes_macro,
+        include_macro,
         include_str,
+        include_str_macro,
         inclusive_range_syntax,
         index,
         index_mut,
@@ -780,6 +797,7 @@ symbols! {
         lifetime,
         likely,
         line,
+        line_macro,
         link,
         link_args,
         link_cfg,
@@ -823,6 +841,7 @@ symbols! {
         masked,
         match_beginning_vert,
         match_default_bindings,
+        matches_macro,
         maxnumf32,
         maxnumf64,
         may_dangle,
@@ -859,6 +878,7 @@ symbols! {
         modifiers,
         module,
         module_path,
+        module_path_macro,
         more_qualified_paths,
         more_struct_aliases,
         movbe_target_feature,
@@ -942,6 +962,7 @@ symbols! {
         optin_builtin_traits,
         option,
         option_env,
+        option_env_macro,
         options,
         or,
         or_patterns,
@@ -1005,6 +1026,8 @@ symbols! {
         prelude_import,
         preserves_flags,
         primitive,
+        print_macro,
+        println_macro,
         proc_dash_macro: "proc-macro",
         proc_macro,
         proc_macro_attribute,
@@ -1147,6 +1170,7 @@ symbols! {
         rustc_paren_sugar,
         rustc_partition_codegened,
         rustc_partition_reused,
+        rustc_pass_by_value,
         rustc_peek,
         rustc_peek_definite_init,
         rustc_peek_liveness,
@@ -1292,6 +1316,7 @@ symbols! {
         str,
         str_alloc,
         stringify,
+        stringify_macro,
         struct_field_attributes,
         struct_inherit,
         struct_variant,
@@ -1335,6 +1360,8 @@ symbols! {
         then_with,
         thread,
         thread_local,
+        thread_local_macro,
+        todo_macro,
         tool_attributes,
         tool_lints,
         trace_macros,
@@ -1385,6 +1412,7 @@ symbols! {
         underscore_imports,
         underscore_lifetimes,
         uniform_paths,
+        unimplemented_macro,
         unit,
         universal_impl_trait,
         unix,
@@ -1393,6 +1421,7 @@ symbols! {
         unpin,
         unreachable,
         unreachable_code,
+        unreachable_macro,
         unrestricted_attribute_tokens,
         unsafe_block_in_unsafe_fn,
         unsafe_cell,
@@ -1423,6 +1452,7 @@ symbols! {
         var,
         variant_count,
         vec,
+        vec_macro,
         version,
         vis,
         visible_private_types,
@@ -1447,7 +1477,9 @@ symbols! {
         wrapping_sub,
         wreg,
         write_bytes,
+        write_macro,
         write_str,
+        writeln_macro,
         x87_reg,
         xer,
         xmm_reg,
diff --git a/compiler/rustc_target/src/spec/armv6k_nintendo_3ds.rs b/compiler/rustc_target/src/spec/armv6k_nintendo_3ds.rs
index afe8bbb3528..3e3a6ac82a4 100644
--- a/compiler/rustc_target/src/spec/armv6k_nintendo_3ds.rs
+++ b/compiler/rustc_target/src/spec/armv6k_nintendo_3ds.rs
@@ -36,6 +36,7 @@ pub fn target() -> Target {
             features: "+vfp2".to_string(),
             pre_link_args,
             exe_suffix: ".elf".to_string(),
+            no_default_libraries: false,
             ..Default::default()
         },
     }
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 36af78b66ed..669b6023397 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -206,7 +206,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             })?);
 
             if let ty::Projection(..) = placeholder_self_ty.kind() {
-                for predicate in tcx.predicates_of(def_id).instantiate_own(tcx, substs).predicates {
+                let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs).predicates;
+                debug!(?predicates, "projection predicates");
+                for predicate in predicates {
                     let normalized = normalize_with_depth_to(
                         self,
                         obligation.param_env,
generated by cgit-pink 1.4.1-3-g733a5 (git 2.37.1) at 2025-11-06 05:06:22 +0000