22 files changed, 597 insertions, 259 deletions

diff --git a/Cargo.lock b/Cargo.lock
index b8ec667fda2..95e1787980a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -789,9 +789,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.82"
+version = "0.1.84"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18cd7635fea7bb481ea543b392789844c1ad581299da70184c7175ce3af76603"
+checksum = "989b2c1ca6e90ad06fdc69d1d1862fa28d27a977be6d92ae2fa762cf61fe0b10"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index 15dcc584738..c2b1b96cd64 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -1,7 +1,7 @@
 use crate::base::*;
 use crate::config::StripUnconfigured;
 use crate::hygiene::SyntaxContext;
-use crate::mbe::macro_rules::annotate_err_with_kind;
+use crate::mbe::diagnostics::annotate_err_with_kind;
 use crate::module::{mod_dir_path, parse_external_mod, DirOwnership, ParsedExternalMod};
 use crate::placeholders::{placeholder, PlaceholderExpander};
 
diff --git a/compiler/rustc_expand/src/mbe.rs b/compiler/rustc_expand/src/mbe.rs
index 63bafd7b046..a43b2a00188 100644
--- a/compiler/rustc_expand/src/mbe.rs
+++ b/compiler/rustc_expand/src/mbe.rs
@@ -3,6 +3,7 @@
 //! why we call this module `mbe`. For external documentation, prefer the
 //! official terminology: "declarative macros".
 
+pub(crate) mod diagnostics;
 pub(crate) mod macro_check;
 pub(crate) mod macro_parser;
 pub(crate) mod macro_rules;
diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
new file mode 100644
index 00000000000..197f056917f
--- /dev/null
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -0,0 +1,257 @@
+use std::borrow::Cow;
+
+use crate::base::{DummyResult, ExtCtxt, MacResult};
+use crate::expand::{parse_ast_fragment, AstFragmentKind};
+use crate::mbe::{
+    macro_parser::{MatcherLoc, NamedParseResult, ParseResult::*, TtParser},
+    macro_rules::{try_match_macro, Tracker},
+};
+use rustc_ast::token::{self, Token};
+use rustc_ast::tokenstream::TokenStream;
+use rustc_ast_pretty::pprust;
+use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, DiagnosticMessage};
+use rustc_parse::parser::{Parser, Recovery};
+use rustc_span::source_map::SourceMap;
+use rustc_span::symbol::Ident;
+use rustc_span::Span;
+
+use super::macro_rules::{parser_from_cx, NoopTracker};
+
+pub(super) fn failed_to_match_macro<'cx>(
+    cx: &'cx mut ExtCtxt<'_>,
+    sp: Span,
+    def_span: Span,
+    name: Ident,
+    arg: TokenStream,
+    lhses: &[Vec<MatcherLoc>],
+) -> Box<dyn MacResult + 'cx> {
+    let sess = &cx.sess.parse_sess;
+
+    // An error occurred, try the expansion again, tracking the expansion closely for better diagnostics.
+    let mut tracker = CollectTrackerAndEmitter::new(cx, sp);
+
+    let try_success_result = try_match_macro(sess, name, &arg, lhses, &mut tracker);
+
+    if try_success_result.is_ok() {
+        // Nonterminal parser recovery might turn failed matches into successful ones,
+        // but for that it must have emitted an error already
+        tracker.cx.sess.delay_span_bug(sp, "Macro matching returned a success on the second try");
+    }
+
+    if let Some(result) = tracker.result {
+        // An irrecoverable error occurred and has been emitted.
+        return result;
+    }
+
+    let Some((token, label, remaining_matcher)) = tracker.best_failure else {
+        return DummyResult::any(sp);
+    };
+
+    let span = token.span.substitute_dummy(sp);
+
+    let mut err = cx.struct_span_err(span, &parse_failure_msg(&token));
+    err.span_label(span, label);
+    if !def_span.is_dummy() && !cx.source_map().is_imported(def_span) {
+        err.span_label(cx.source_map().guess_head_span(def_span), "when calling this macro");
+    }
+
+    annotate_doc_comment(&mut err, sess.source_map(), span);
+
+    if let Some(span) = remaining_matcher.span() {
+        err.span_note(span, format!("while trying to match {remaining_matcher}"));
+    } else {
+        err.note(format!("while trying to match {remaining_matcher}"));
+    }
+
+    // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
+    if let Some((arg, comma_span)) = arg.add_comma() {
+        for lhs in lhses {
+            let parser = parser_from_cx(sess, arg.clone(), Recovery::Allowed);
+            let mut tt_parser = TtParser::new(name);
+
+            if let Success(_) =
+                tt_parser.parse_tt(&mut Cow::Borrowed(&parser), lhs, &mut NoopTracker)
+            {
+                if comma_span.is_dummy() {
+                    err.note("you might be missing a comma");
+                } else {
+                    err.span_suggestion_short(
+                        comma_span,
+                        "missing comma here",
+                        ", ",
+                        Applicability::MachineApplicable,
+                    );
+                }
+            }
+        }
+    }
+    err.emit();
+    cx.trace_macros_diag();
+    DummyResult::any(sp)
+}
+
+/// The tracker used for the slow error path that collects useful info for diagnostics.
+struct CollectTrackerAndEmitter<'a, 'cx, 'matcher> {
+    cx: &'a mut ExtCtxt<'cx>,
+    remaining_matcher: Option<&'matcher MatcherLoc>,
+    /// Which arm's failure should we report? (the one furthest along)
+    best_failure: Option<(Token, &'static str, MatcherLoc)>,
+    root_span: Span,
+    result: Option<Box<dyn MacResult + 'cx>>,
+}
+
+impl<'a, 'cx, 'matcher> Tracker<'matcher> for CollectTrackerAndEmitter<'a, 'cx, 'matcher> {
+    fn before_match_loc(&mut self, parser: &TtParser, matcher: &'matcher MatcherLoc) {
+        if self.remaining_matcher.is_none()
+            || (parser.has_no_remaining_items_for_step() && *matcher != MatcherLoc::Eof)
+        {
+            self.remaining_matcher = Some(matcher);
+        }
+    }
+
+    fn after_arm(&mut self, result: &NamedParseResult) {
+        match result {
+            Success(_) => {
+                // Nonterminal parser recovery might turn failed matches into successful ones,
+                // but for that it must have emitted an error already
+                self.cx.sess.delay_span_bug(
+                    self.root_span,
+                    "should not collect detailed info for successful macro match",
+                );
+            }
+            Failure(token, msg) => match self.best_failure {
+                Some((ref best_token, _, _)) if best_token.span.lo() >= token.span.lo() => {}
+                _ => {
+                    self.best_failure = Some((
+                        token.clone(),
+                        msg,
+                        self.remaining_matcher
+                            .expect("must have collected matcher already")
+                            .clone(),
+                    ))
+                }
+            },
+            Error(err_sp, msg) => {
+                let span = err_sp.substitute_dummy(self.root_span);
+                self.cx.struct_span_err(span, msg).emit();
+                self.result = Some(DummyResult::any(span));
+            }
+            ErrorReported(_) => self.result = Some(DummyResult::any(self.root_span)),
+        }
+    }
+
+    fn description() -> &'static str {
+        "detailed"
+    }
+
+    fn recovery() -> Recovery {
+        Recovery::Allowed
+    }
+}
+
+impl<'a, 'cx> CollectTrackerAndEmitter<'a, 'cx, '_> {
+    fn new(cx: &'a mut ExtCtxt<'cx>, root_span: Span) -> Self {
+        Self { cx, remaining_matcher: None, best_failure: None, root_span, result: None }
+    }
+}
+
+pub(super) fn emit_frag_parse_err(
+    mut e: DiagnosticBuilder<'_, rustc_errors::ErrorGuaranteed>,
+    parser: &Parser<'_>,
+    orig_parser: &mut Parser<'_>,
+    site_span: Span,
+    arm_span: Span,
+    kind: AstFragmentKind,
+) {
+    // FIXME(davidtwco): avoid depending on the error message text
+    if parser.token == token::Eof
+        && let DiagnosticMessage::Str(message) = &e.message[0].0
+        && message.ends_with(", found `<eof>`")
+    {
+        let msg = &e.message[0];
+        e.message[0] = (
+            DiagnosticMessage::Str(format!(
+                "macro expansion ends with an incomplete expression: {}",
+                message.replace(", found `<eof>`", ""),
+            )),
+            msg.1,
+        );
+        if !e.span.is_dummy() {
+            // early end of macro arm (#52866)
+            e.replace_span_with(parser.token.span.shrink_to_hi());
+        }
+    }
+    if e.span.is_dummy() {
+        // Get around lack of span in error (#30128)
+        e.replace_span_with(site_span);
+        if !parser.sess.source_map().is_imported(arm_span) {
+            e.span_label(arm_span, "in this macro arm");
+        }
+    } else if parser.sess.source_map().is_imported(parser.token.span) {
+        e.span_label(site_span, "in this macro invocation");
+    }
+    match kind {
+        // Try a statement if an expression is wanted but failed and suggest adding `;` to call.
+        AstFragmentKind::Expr => match parse_ast_fragment(orig_parser, AstFragmentKind::Stmts) {
+            Err(err) => err.cancel(),
+            Ok(_) => {
+                e.note(
+                    "the macro call doesn't expand to an expression, but it can expand to a statement",
+                );
+                e.span_suggestion_verbose(
+                    site_span.shrink_to_hi(),
+                    "add `;` to interpret the expansion as a statement",
+                    ";",
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        },
+        _ => annotate_err_with_kind(&mut e, kind, site_span),
+    };
+    e.emit();
+}
+
+pub(crate) fn annotate_err_with_kind(err: &mut Diagnostic, kind: AstFragmentKind, span: Span) {
+    match kind {
+        AstFragmentKind::Ty => {
+            err.span_label(span, "this macro call doesn't expand to a type");
+        }
+        AstFragmentKind::Pat => {
+            err.span_label(span, "this macro call doesn't expand to a pattern");
+        }
+        _ => {}
+    };
+}
+
+#[derive(Subdiagnostic)]
+enum ExplainDocComment {
+    #[label(expand_explain_doc_comment_inner)]
+    Inner {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(expand_explain_doc_comment_outer)]
+    Outer {
+        #[primary_span]
+        span: Span,
+    },
+}
+
+pub(super) fn annotate_doc_comment(err: &mut Diagnostic, sm: &SourceMap, span: Span) {
+    if let Ok(src) = sm.span_to_snippet(span) {
+        if src.starts_with("///") || src.starts_with("/**") {
+            err.subdiagnostic(ExplainDocComment::Outer { span });
+        } else if src.starts_with("//!") || src.starts_with("/*!") {
+            err.subdiagnostic(ExplainDocComment::Inner { span });
+        }
+    }
+}
+
+/// Generates an appropriate parsing failure message. For EOF, this is "unexpected end...". For
+/// other tokens, this is "unexpected token...".
+pub(super) fn parse_failure_msg(tok: &Token) -> String {
+    match tok.kind {
+        token::Eof => "unexpected end of macro invocation".to_string(),
+        _ => format!("no rules expected the token `{}`", pprust::token_to_string(tok),),
+    }
+}
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 5da410e41a7..2dbb90e2190 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -2,6 +2,7 @@ use crate::base::{DummyResult, ExtCtxt, MacResult, TTMacroExpander};
 use crate::base::{SyntaxExtension, SyntaxExtensionKind};
 use crate::expand::{ensure_complete_parse, parse_ast_fragment, AstFragment, AstFragmentKind};
 use crate::mbe;
+use crate::mbe::diagnostics::{annotate_doc_comment, parse_failure_msg};
 use crate::mbe::macro_check;
 use crate::mbe::macro_parser::{Error, ErrorReported, Failure, Success, TtParser};
 use crate::mbe::macro_parser::{MatchedSeq, MatchedTokenTree, MatcherLoc};
@@ -14,9 +15,7 @@ use rustc_ast::{NodeId, DUMMY_NODE_ID};
 use rustc_ast_pretty::pprust;
 use rustc_attr::{self as attr, TransparencyError};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
-use rustc_errors::{
-    Applicability, Diagnostic, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed,
-};
+use rustc_errors::{Applicability, ErrorGuaranteed};
 use rustc_feature::Features;
 use rustc_lint_defs::builtin::{
     RUST_2021_INCOMPATIBLE_OR_PATTERNS, SEMICOLON_IN_EXPRESSIONS_FROM_MACROS,
@@ -27,7 +26,6 @@ use rustc_session::parse::ParseSess;
 use rustc_session::Session;
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::Transparency;
-use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, sym, Ident, MacroRulesNormalizedIdent};
 use rustc_span::Span;
 
@@ -35,6 +33,7 @@ use std::borrow::Cow;
 use std::collections::hash_map::Entry;
 use std::{mem, slice};
 
+use super::diagnostics;
 use super::macro_parser::{NamedMatches, NamedParseResult};
 
 pub(crate) struct ParserAnyMacro<'a> {
@@ -51,74 +50,6 @@ pub(crate) struct ParserAnyMacro<'a> {
     is_local: bool,
 }
 
-pub(crate) fn annotate_err_with_kind(err: &mut Diagnostic, kind: AstFragmentKind, span: Span) {
-    match kind {
-        AstFragmentKind::Ty => {
-            err.span_label(span, "this macro call doesn't expand to a type");
-        }
-        AstFragmentKind::Pat => {
-            err.span_label(span, "this macro call doesn't expand to a pattern");
-        }
-        _ => {}
-    };
-}
-
-fn emit_frag_parse_err(
-    mut e: DiagnosticBuilder<'_, rustc_errors::ErrorGuaranteed>,
-    parser: &Parser<'_>,
-    orig_parser: &mut Parser<'_>,
-    site_span: Span,
-    arm_span: Span,
-    kind: AstFragmentKind,
-) {
-    // FIXME(davidtwco): avoid depending on the error message text
-    if parser.token == token::Eof
-        && let DiagnosticMessage::Str(message) = &e.message[0].0
-        && message.ends_with(", found `<eof>`")
-    {
-        let msg = &e.message[0];
-        e.message[0] = (
-            DiagnosticMessage::Str(format!(
-                "macro expansion ends with an incomplete expression: {}",
-                message.replace(", found `<eof>`", ""),
-            )),
-            msg.1,
-        );
-        if !e.span.is_dummy() {
-            // early end of macro arm (#52866)
-            e.replace_span_with(parser.token.span.shrink_to_hi());
-        }
-    }
-    if e.span.is_dummy() {
-        // Get around lack of span in error (#30128)
-        e.replace_span_with(site_span);
-        if !parser.sess.source_map().is_imported(arm_span) {
-            e.span_label(arm_span, "in this macro arm");
-        }
-    } else if parser.sess.source_map().is_imported(parser.token.span) {
-        e.span_label(site_span, "in this macro invocation");
-    }
-    match kind {
-        // Try a statement if an expression is wanted but failed and suggest adding `;` to call.
-        AstFragmentKind::Expr => match parse_ast_fragment(orig_parser, AstFragmentKind::Stmts) {
-            Err(err) => err.cancel(),
-            Ok(_) => {
-                e.note(
-                    "the macro call doesn't expand to an expression, but it can expand to a statement",
-                );
-                e.span_suggestion_verbose(
-                    site_span.shrink_to_hi(),
-                    "add `;` to interpret the expansion as a statement",
-                    ";",
-                    Applicability::MaybeIncorrect,
-                );
-            }
-        },
-        _ => annotate_err_with_kind(&mut e, kind, site_span),
-    };
-    e.emit();
-}
-
 impl<'a> ParserAnyMacro<'a> {
     pub(crate) fn make(mut self: Box<ParserAnyMacro<'a>>, kind: AstFragmentKind) -> AstFragment {
         let ParserAnyMacro {
@@ -134,7 +65,7 @@ impl<'a> ParserAnyMacro<'a> {
         let fragment = match parse_ast_fragment(parser, kind) {
             Ok(f) => f,
             Err(err) => {
-                emit_frag_parse_err(err, parser, snapshot, site_span, arm_span, kind);
+                diagnostics::emit_frag_parse_err(err, parser, snapshot, site_span, arm_span, kind);
                 return kind.dummy(site_span);
             }
         };
@@ -224,7 +155,7 @@ pub(super) trait Tracker<'matcher> {
 }
 
 /// A noop tracker that is used in the hot path of the expansion, has zero overhead thanks to monomorphization.
-struct NoopTracker;
+pub(super) struct NoopTracker;
 
 impl<'matcher> Tracker<'matcher> for NoopTracker {
     fn before_match_loc(&mut self, _: &TtParser, _: &'matcher MatcherLoc) {}
@@ -331,135 +262,10 @@ fn expand_macro<'cx>(
         }
     }
 
-    // An error occurred, try the expansion again, tracking the expansion closely for better diagnostics.
-    let mut tracker = CollectTrackerAndEmitter::new(cx, sp);
-
-    let try_success_result = try_match_macro(sess, name, &arg, lhses, &mut tracker);
-
-    if try_success_result.is_ok() {
-        // Nonterminal parser recovery might turn failed matches into successful ones,
-        // but for that it must have emitted an error already
-        tracker.cx.sess.delay_span_bug(sp, "Macro matching returned a success on the second try");
-    }
-
-    if let Some(result) = tracker.result {
-        // An irrecoverable error occurred and has been emitted.
-        return result;
-    }
-
-    let Some((token, label, remaining_matcher)) = tracker.best_failure else {
-        return DummyResult::any(sp);
-    };
-
-    let span = token.span.substitute_dummy(sp);
-
-    let mut err = cx.struct_span_err(span, &parse_failure_msg(&token));
-    err.span_label(span, label);
-    if !def_span.is_dummy() && !cx.source_map().is_imported(def_span) {
-        err.span_label(cx.source_map().guess_head_span(def_span), "when calling this macro");
-    }
-
-    annotate_doc_comment(&mut err, sess.source_map(), span);
-
-    if let Some(span) = remaining_matcher.span() {
-        err.span_note(span, format!("while trying to match {remaining_matcher}"));
-    } else {
-        err.note(format!("while trying to match {remaining_matcher}"));
-    }
-
-    // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
-    if let Some((arg, comma_span)) = arg.add_comma() {
-        for lhs in lhses {
-            let parser = parser_from_cx(sess, arg.clone(), Recovery::Allowed);
-            let mut tt_parser = TtParser::new(name);
-
-            if let Success(_) =
-                tt_parser.parse_tt(&mut Cow::Borrowed(&parser), lhs, &mut NoopTracker)
-            {
-                if comma_span.is_dummy() {
-                    err.note("you might be missing a comma");
-                } else {
-                    err.span_suggestion_short(
-                        comma_span,
-                        "missing comma here",
-                        ", ",
-                        Applicability::MachineApplicable,
-                    );
-                }
-            }
-        }
-    }
-    err.emit();
-    cx.trace_macros_diag();
-    DummyResult::any(sp)
+    diagnostics::failed_to_match_macro(cx, sp, def_span, name, arg, lhses)
 }
 
-/// The tracker used for the slow error path that collects useful info for diagnostics.
-struct CollectTrackerAndEmitter<'a, 'cx, 'matcher> {
-    cx: &'a mut ExtCtxt<'cx>,
-    remaining_matcher: Option<&'matcher MatcherLoc>,
-    /// Which arm's failure should we report? (the one furthest along)
-    best_failure: Option<(Token, &'static str, MatcherLoc)>,
-    root_span: Span,
-    result: Option<Box<dyn MacResult + 'cx>>,
-}
-
-impl<'a, 'cx, 'matcher> Tracker<'matcher> for CollectTrackerAndEmitter<'a, 'cx, 'matcher> {
-    fn before_match_loc(&mut self, parser: &TtParser, matcher: &'matcher MatcherLoc) {
-        if self.remaining_matcher.is_none()
-            || (parser.has_no_remaining_items_for_step() && *matcher != MatcherLoc::Eof)
-        {
-            self.remaining_matcher = Some(matcher);
-        }
-    }
-
-    fn after_arm(&mut self, result: &NamedParseResult) {
-        match result {
-            Success(_) => {
-                // Nonterminal parser recovery might turn failed matches into successful ones,
-                // but for that it must have emitted an error already
-                self.cx.sess.delay_span_bug(
-                    self.root_span,
-                    "should not collect detailed info for successful macro match",
-                );
-            }
-            Failure(token, msg) => match self.best_failure {
-                Some((ref best_token, _, _)) if best_token.span.lo() >= token.span.lo() => {}
-                _ => {
-                    self.best_failure = Some((
-                        token.clone(),
-                        msg,
-                        self.remaining_matcher
-                            .expect("must have collected matcher already")
-                            .clone(),
-                    ))
-                }
-            },
-            Error(err_sp, msg) => {
-                let span = err_sp.substitute_dummy(self.root_span);
-                self.cx.struct_span_err(span, msg).emit();
-                self.result = Some(DummyResult::any(span));
-            }
-            ErrorReported(_) => self.result = Some(DummyResult::any(self.root_span)),
-        }
-    }
-
-    fn description() -> &'static str {
-        "detailed"
-    }
-
-    fn recovery() -> Recovery {
-        Recovery::Allowed
-    }
-}
-
-impl<'a, 'cx> CollectTrackerAndEmitter<'a, 'cx, '_> {
-    fn new(cx: &'a mut ExtCtxt<'cx>, root_span: Span) -> Self {
-        Self { cx, remaining_matcher: None, best_failure: None, root_span, result: None }
-    }
-}
-
-enum CanRetry {
+pub(super) enum CanRetry {
     Yes,
     /// We are not allowed to retry macro expansion as a fatal error has been emitted already.
     No(ErrorGuaranteed),
@@ -469,7 +275,7 @@ enum CanRetry {
 /// and nothing if it failed. On failure, it's the callers job to use `track` accordingly to record all errors
 /// correctly.
 #[instrument(level = "debug", skip(sess, arg, lhses, track), fields(tracking = %T::description()))]
-fn try_match_macro<'matcher, T: Tracker<'matcher>>(
+pub(super) fn try_match_macro<'matcher, T: Tracker<'matcher>>(
     sess: &ParseSess,
     name: Ident,
     arg: &TokenStream,
@@ -769,30 +575,6 @@ pub fn compile_declarative_macro(
     (mk_syn_ext(expander), rule_spans)
 }
 
-#[derive(Subdiagnostic)]
-enum ExplainDocComment {
-    #[label(expand_explain_doc_comment_inner)]
-    Inner {
-        #[primary_span]
-        span: Span,
-    },
-    #[label(expand_explain_doc_comment_outer)]
-    Outer {
-        #[primary_span]
-        span: Span,
-    },
-}
-
-fn annotate_doc_comment(err: &mut Diagnostic, sm: &SourceMap, span: Span) {
-    if let Ok(src) = sm.span_to_snippet(span) {
-        if src.starts_with("///") || src.starts_with("/**") {
-            err.subdiagnostic(ExplainDocComment::Outer { span });
-        } else if src.starts_with("//!") || src.starts_with("/*!") {
-            err.subdiagnostic(ExplainDocComment::Inner { span });
-        }
-    }
-}
-
 fn check_lhs_nt_follows(sess: &ParseSess, def: &ast::Item, lhs: &mbe::TokenTree) -> bool {
     // lhs is going to be like TokenTree::Delimited(...), where the
     // entire lhs is those tts. Or, it can be a "bare sequence", not wrapped in parens.
@@ -1577,15 +1359,6 @@ fn quoted_tt_to_string(tt: &mbe::TokenTree) -> String {
     }
 }
 
-fn parser_from_cx(sess: &ParseSess, tts: TokenStream, recovery: Recovery) -> Parser<'_> {
+pub(super) fn parser_from_cx(sess: &ParseSess, tts: TokenStream, recovery: Recovery) -> Parser<'_> {
     Parser::new(sess, tts, true, rustc_parse::MACRO_ARGUMENTS).recovery(recovery)
 }
-
-/// Generates an appropriate parsing failure message. For EOF, this is "unexpected end...". For
-/// other tokens, this is "unexpected token...".
-fn parse_failure_msg(tok: &Token) -> String {
-    match tok.kind {
-        token::Eof => "unexpected end of macro invocation".to_string(),
-        _ => format!("no rules expected the token `{}`", pprust::token_to_string(tok),),
-    }
-}
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 97186589a4f..e5f6b0c0c65 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -187,7 +187,7 @@ pub use thin::ThinBox;
 
 mod thin;
 
-/// A pointer type for heap allocation.
+/// A pointer type that uniquely owns a heap allocation of type `T`.
 ///
 /// See the [module-level documentation](../../std/boxed/index.html) for more.
 #[lang = "owned_box"]
diff --git a/library/core/src/alloc/layout.rs b/library/core/src/alloc/layout.rs
index f50d9a8e1bd..ac3d84718d5 100644
--- a/library/core/src/alloc/layout.rs
+++ b/library/core/src/alloc/layout.rs
@@ -157,9 +157,10 @@ impl Layout {
     /// allocate backing structure for `T` (which could be a trait
     /// or other unsized type like a slice).
     #[stable(feature = "alloc_layout", since = "1.28.0")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[must_use]
     #[inline]
-    pub fn for_value<T: ?Sized>(t: &T) -> Self {
+    pub const fn for_value<T: ?Sized>(t: &T) -> Self {
         let (size, align) = (mem::size_of_val(t), mem::align_of_val(t));
         // SAFETY: see rationale in `new` for why this is using the unsafe variant
         unsafe { Layout::from_size_align_unchecked(size, align) }
@@ -191,8 +192,9 @@ impl Layout {
     /// [trait object]: ../../book/ch17-02-trait-objects.html
     /// [extern type]: ../../unstable-book/language-features/extern-types.html
     #[unstable(feature = "layout_for_ptr", issue = "69835")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[must_use]
-    pub unsafe fn for_value_raw<T: ?Sized>(t: *const T) -> Self {
+    pub const unsafe fn for_value_raw<T: ?Sized>(t: *const T) -> Self {
         // SAFETY: we pass along the prerequisites of these functions to the caller
         let (size, align) = unsafe { (mem::size_of_val_raw(t), mem::align_of_val_raw(t)) };
         // SAFETY: see rationale in `new` for why this is using the unsafe variant
@@ -229,8 +231,9 @@ impl Layout {
     /// Returns an error if the combination of `self.size()` and the given
     /// `align` violates the conditions listed in [`Layout::from_size_align`].
     #[stable(feature = "alloc_layout_manipulation", since = "1.44.0")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
-    pub fn align_to(&self, align: usize) -> Result<Self, LayoutError> {
+    pub const fn align_to(&self, align: usize) -> Result<Self, LayoutError> {
         Layout::from_size_align(self.size(), cmp::max(self.align(), align))
     }
 
@@ -287,10 +290,11 @@ impl Layout {
     /// This is equivalent to adding the result of `padding_needed_for`
     /// to the layout's current size.
     #[stable(feature = "alloc_layout_manipulation", since = "1.44.0")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[must_use = "this returns a new `Layout`, \
                   without modifying the original"]
     #[inline]
-    pub fn pad_to_align(&self) -> Layout {
+    pub const fn pad_to_align(&self) -> Layout {
         let pad = self.padding_needed_for(self.align());
         // This cannot overflow. Quoting from the invariant of Layout:
         // > `size`, when rounded up to the nearest multiple of `align`,
@@ -311,8 +315,9 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `LayoutError`.
     #[unstable(feature = "alloc_layout_extra", issue = "55724")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
-    pub fn repeat(&self, n: usize) -> Result<(Self, usize), LayoutError> {
+    pub const fn repeat(&self, n: usize) -> Result<(Self, usize), LayoutError> {
         // This cannot overflow. Quoting from the invariant of Layout:
         // > `size`, when rounded up to the nearest multiple of `align`,
         // > must not overflow isize (i.e., the rounded value must be
@@ -321,7 +326,8 @@ impl Layout {
         let alloc_size = padded_size.checked_mul(n).ok_or(LayoutError)?;
 
         // The safe constructor is called here to enforce the isize size limit.
-        Layout::from_size_alignment(alloc_size, self.align).map(|layout| (layout, padded_size))
+        let layout = Layout::from_size_alignment(alloc_size, self.align)?;
+        Ok((layout, padded_size))
     }
 
     /// Creates a layout describing the record for `self` followed by
@@ -370,8 +376,9 @@ impl Layout {
     /// # assert_eq!(repr_c(&[u64, u32, u16, u32]), Ok((s, vec![0, 8, 12, 16])));
     /// ```
     #[stable(feature = "alloc_layout_manipulation", since = "1.44.0")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
-    pub fn extend(&self, next: Self) -> Result<(Self, usize), LayoutError> {
+    pub const fn extend(&self, next: Self) -> Result<(Self, usize), LayoutError> {
         let new_align = cmp::max(self.align, next.align);
         let pad = self.padding_needed_for(next.align());
 
@@ -396,8 +403,9 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `LayoutError`.
     #[unstable(feature = "alloc_layout_extra", issue = "55724")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
-    pub fn repeat_packed(&self, n: usize) -> Result<Self, LayoutError> {
+    pub const fn repeat_packed(&self, n: usize) -> Result<Self, LayoutError> {
         let size = self.size().checked_mul(n).ok_or(LayoutError)?;
         // The safe constructor is called here to enforce the isize size limit.
         Layout::from_size_alignment(size, self.align)
@@ -410,8 +418,9 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `LayoutError`.
     #[unstable(feature = "alloc_layout_extra", issue = "55724")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
-    pub fn extend_packed(&self, next: Self) -> Result<Self, LayoutError> {
+    pub const fn extend_packed(&self, next: Self) -> Result<Self, LayoutError> {
         let new_size = self.size().checked_add(next.size()).ok_or(LayoutError)?;
         // The safe constructor is called here to enforce the isize size limit.
         Layout::from_size_alignment(new_size, self.align)
@@ -422,13 +431,18 @@ impl Layout {
     /// On arithmetic overflow or when the total size would exceed
     /// `isize::MAX`, returns `LayoutError`.
     #[stable(feature = "alloc_layout_manipulation", since = "1.44.0")]
+    #[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
     #[inline]
-    pub fn array<T>(n: usize) -> Result<Self, LayoutError> {
+    pub const fn array<T>(n: usize) -> Result<Self, LayoutError> {
         // Reduce the amount of code we need to monomorphize per `T`.
         return inner(mem::size_of::<T>(), Alignment::of::<T>(), n);
 
         #[inline]
-        fn inner(element_size: usize, align: Alignment, n: usize) -> Result<Layout, LayoutError> {
+        const fn inner(
+            element_size: usize,
+            align: Alignment,
+            n: usize,
+        ) -> Result<Layout, LayoutError> {
             // We need to check two things about the size:
             //  - That the total size won't overflow a `usize`, and
             //  - That the total size still fits in an `isize`.
diff --git a/library/core/src/error.rs b/library/core/src/error.rs
index c9c7cdf4def..7152300abcb 100644
--- a/library/core/src/error.rs
+++ b/library/core/src/error.rs
@@ -506,3 +506,6 @@ impl Error for crate::ffi::FromBytesWithNulError {
 
 #[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
 impl Error for crate::ffi::FromBytesUntilNulError {}
+
+#[unstable(feature = "get_many_mut", issue = "104642")]
+impl<const N: usize> Error for crate::slice::GetManyMutError<N> {}
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index e7ea558a955..1823fd30062 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -99,6 +99,8 @@
 // Library features:
 #![feature(const_align_offset)]
 #![feature(const_align_of_val)]
+#![feature(const_align_of_val_raw)]
+#![feature(const_alloc_layout)]
 #![feature(const_arguments_as_str)]
 #![feature(const_array_into_iter_constructors)]
 #![feature(const_bigint_helper_methods)]
@@ -141,6 +143,7 @@
 #![feature(const_ptr_write)]
 #![feature(const_raw_ptr_comparison)]
 #![feature(const_size_of_val)]
+#![feature(const_size_of_val_raw)]
 #![feature(const_slice_from_raw_parts_mut)]
 #![feature(const_slice_ptr_len)]
 #![feature(const_slice_split_at_mut)]
diff --git a/library/core/src/ptr/alignment.rs b/library/core/src/ptr/alignment.rs
index 1390e09dd96..64a5290c3a2 100644
--- a/library/core/src/ptr/alignment.rs
+++ b/library/core/src/ptr/alignment.rs
@@ -9,7 +9,9 @@ use crate::{cmp, fmt, hash, mem, num};
 /// Note that particularly large alignments, while representable in this type,
 /// are likely not to be supported by actual allocators and linkers.
 #[unstable(feature = "ptr_alignment_type", issue = "102070")]
-#[derive(Copy, Clone, Eq, PartialEq)]
+#[derive(Copy, Clone, Eq)]
+#[cfg_attr(bootstrap, derive(PartialEq))]
+#[cfg_attr(not(bootstrap), derive_const(PartialEq))]
 #[repr(transparent)]
 pub struct Alignment(AlignmentEnum);
 
@@ -167,16 +169,18 @@ impl From<Alignment> for usize {
     }
 }
 
+#[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
 #[unstable(feature = "ptr_alignment_type", issue = "102070")]
-impl cmp::Ord for Alignment {
+impl const cmp::Ord for Alignment {
     #[inline]
     fn cmp(&self, other: &Self) -> cmp::Ordering {
-        self.as_nonzero().cmp(&other.as_nonzero())
+        self.as_nonzero().get().cmp(&other.as_nonzero().get())
     }
 }
 
+#[rustc_const_unstable(feature = "const_alloc_layout", issue = "67521")]
 #[unstable(feature = "ptr_alignment_type", issue = "102070")]
-impl cmp::PartialOrd for Alignment {
+impl const cmp::PartialOrd for Alignment {
     #[inline]
     fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
         Some(self.cmp(other))
@@ -198,7 +202,9 @@ type AlignmentEnum = AlignmentEnum32;
 #[cfg(target_pointer_width = "64")]
 type AlignmentEnum = AlignmentEnum64;
 
-#[derive(Copy, Clone, Eq, PartialEq)]
+#[derive(Copy, Clone, Eq)]
+#[cfg_attr(bootstrap, derive(PartialEq))]
+#[cfg_attr(not(bootstrap), derive_const(PartialEq))]
 #[repr(u16)]
 enum AlignmentEnum16 {
     _Align1Shl0 = 1 << 0,
@@ -219,7 +225,9 @@ enum AlignmentEnum16 {
     _Align1Shl15 = 1 << 15,
 }
 
-#[derive(Copy, Clone, Eq, PartialEq)]
+#[derive(Copy, Clone, Eq)]
+#[cfg_attr(bootstrap, derive(PartialEq))]
+#[cfg_attr(not(bootstrap), derive_const(PartialEq))]
 #[repr(u32)]
 enum AlignmentEnum32 {
     _Align1Shl0 = 1 << 0,
@@ -256,7 +264,9 @@ enum AlignmentEnum32 {
     _Align1Shl31 = 1 << 31,
 }
 
-#[derive(Copy, Clone, Eq, PartialEq)]
+#[derive(Copy, Clone, Eq)]
+#[cfg_attr(bootstrap, derive(PartialEq))]
+#[cfg_attr(not(bootstrap), derive_const(PartialEq))]
 #[repr(u64)]
 enum AlignmentEnum64 {
     _Align1Shl0 = 1 << 0,
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index af64fbc8e9e..969029e262e 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -119,6 +119,11 @@ impl<T: ?Sized> *const T {
     /// assert_eq!(p1.to_bits() - p0.to_bits(), 4);
     /// ```
     #[unstable(feature = "ptr_to_from_bits", issue = "91126")]
+    #[deprecated(
+        since = "1.67",
+        note = "replaced by the `exposed_addr` method, or update your code \
+            to follow the strict provenance rules using its APIs"
+    )]
     pub fn to_bits(self) -> usize
     where
         T: Sized,
@@ -140,6 +145,11 @@ impl<T: ?Sized> *const T {
     /// assert_eq!(<*const u8>::from_bits(1), dangling);
     /// ```
     #[unstable(feature = "ptr_to_from_bits", issue = "91126")]
+    #[deprecated(
+        since = "1.67",
+        note = "replaced by the `ptr::from_exposed_addr` function, or update \
+            your code to follow the strict provenance rules using its APIs"
+    )]
     #[allow(fuzzy_provenance_casts)] // this is an unstable and semi-deprecated cast function
     pub fn from_bits(bits: usize) -> Self
     where
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index d6872ba1c20..d1b3a634433 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -125,6 +125,11 @@ impl<T: ?Sized> *mut T {
     /// assert_eq!(p1.to_bits() - p0.to_bits(), 4);
     /// ```
     #[unstable(feature = "ptr_to_from_bits", issue = "91126")]
+    #[deprecated(
+        since = "1.67",
+        note = "replaced by the `exposed_addr` method, or update your code \
+            to follow the strict provenance rules using its APIs"
+    )]
     pub fn to_bits(self) -> usize
     where
         T: Sized,
@@ -146,6 +151,11 @@ impl<T: ?Sized> *mut T {
     /// assert_eq!(<*mut u8>::from_bits(1), dangling);
     /// ```
     #[unstable(feature = "ptr_to_from_bits", issue = "91126")]
+    #[deprecated(
+        since = "1.67",
+        note = "replaced by the `ptr::from_exposed_addr_mut` function, or \
+            update your code to follow the strict provenance rules using its APIs"
+    )]
     #[allow(fuzzy_provenance_casts)] // this is an unstable and semi-deprecated cast function
     pub fn from_bits(bits: usize) -> Self
     where
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index ad90e00b8a0..04486ed2d14 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -7,6 +7,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::cmp::Ordering::{self, Greater, Less};
+use crate::fmt;
 use crate::intrinsics::{assert_unsafe_precondition, exact_div};
 use crate::marker::Copy;
 use crate::mem::{self, SizedTypeProperties};
@@ -4082,6 +4083,88 @@ impl<T> [T] {
         *self = rem;
         Some(last)
     }
+
+    /// Returns mutable references to many indices at once, without doing any checks.
+    ///
+    /// For a safe alternative see [`get_many_mut`].
+    ///
+    /// # Safety
+    ///
+    /// Calling this method with overlapping or out-of-bounds indices is *[undefined behavior]*
+    /// even if the resulting references are not used.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(get_many_mut)]
+    ///
+    /// let x = &mut [1, 2, 4];
+    ///
+    /// unsafe {
+    ///     let [a, b] = x.get_many_unchecked_mut([0, 2]);
+    ///     *a *= 10;
+    ///     *b *= 100;
+    /// }
+    /// assert_eq!(x, &[10, 2, 400]);
+    /// ```
+    ///
+    /// [`get_many_mut`]: slice::get_many_mut
+    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
+    #[unstable(feature = "get_many_mut", issue = "104642")]
+    #[inline]
+    pub unsafe fn get_many_unchecked_mut<const N: usize>(
+        &mut self,
+        indices: [usize; N],
+    ) -> [&mut T; N] {
+        // NB: This implementation is written as it is because any variation of
+        // `indices.map(|i| self.get_unchecked_mut(i))` would make miri unhappy,
+        // or generate worse code otherwise. This is also why we need to go
+        // through a raw pointer here.
+        let slice: *mut [T] = self;
+        let mut arr: mem::MaybeUninit<[&mut T; N]> = mem::MaybeUninit::uninit();
+        let arr_ptr = arr.as_mut_ptr();
+
+        // SAFETY: We expect `indices` to contain disjunct values that are
+        // in bounds of `self`.
+        unsafe {
+            for i in 0..N {
+                let idx = *indices.get_unchecked(i);
+                *(*arr_ptr).get_unchecked_mut(i) = &mut *slice.get_unchecked_mut(idx);
+            }
+            arr.assume_init()
+        }
+    }
+
+    /// Returns mutable references to many indices at once.
+    ///
+    /// Returns an error if any index is out-of-bounds, or if the same index was
+    /// passed more than once.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(get_many_mut)]
+    ///
+    /// let v = &mut [1, 2, 3];
+    /// if let Ok([a, b]) = v.get_many_mut([0, 2]) {
+    ///     *a = 413;
+    ///     *b = 612;
+    /// }
+    /// assert_eq!(v, &[413, 2, 612]);
+    /// ```
+    #[unstable(feature = "get_many_mut", issue = "104642")]
+    #[inline]
+    pub fn get_many_mut<const N: usize>(
+        &mut self,
+        indices: [usize; N],
+    ) -> Result<[&mut T; N], GetManyMutError<N>> {
+        if !get_many_check_valid(&indices, self.len()) {
+            return Err(GetManyMutError { _private: () });
+        }
+        // SAFETY: The `get_many_check_valid()` call checked that all indices
+        // are disjunct and in bounds.
+        unsafe { Ok(self.get_many_unchecked_mut(indices)) }
+    }
 }
 
 impl<T, const N: usize> [[T; N]] {
@@ -4304,3 +4387,56 @@ impl<T, const N: usize> SlicePattern for [T; N] {
         self
     }
 }
+
+/// This checks every index against each other, and against `len`.
+///
+/// This will do `binomial(N + 1, 2) = N * (N + 1) / 2 = 0, 1, 3, 6, 10, ..`
+/// comparison operations.
+fn get_many_check_valid<const N: usize>(indices: &[usize; N], len: usize) -> bool {
+    // NB: The optimzer should inline the loops into a sequence
+    // of instructions without additional branching.
+    let mut valid = true;
+    for (i, &idx) in indices.iter().enumerate() {
+        valid &= idx < len;
+        for &idx2 in &indices[..i] {
+            valid &= idx != idx2;
+        }
+    }
+    valid
+}
+
+/// The error type returned by [`get_many_mut<N>`][`slice::get_many_mut`].
+///
+/// It indicates one of two possible errors:
+/// - An index is out-of-bounds.
+/// - The same index appeared multiple times in the array.
+///
+/// # Examples
+///
+/// ```
+/// #![feature(get_many_mut)]
+///
+/// let v = &mut [1, 2, 3];
+/// assert!(v.get_many_mut([0, 999]).is_err());
+/// assert!(v.get_many_mut([1, 1]).is_err());
+/// ```
+#[unstable(feature = "get_many_mut", issue = "104642")]
+// NB: The N here is there to be forward-compatible with adding more details
+// to the error type at a later point
+pub struct GetManyMutError<const N: usize> {
+    _private: (),
+}
+
+#[unstable(feature = "get_many_mut", issue = "104642")]
+impl<const N: usize> fmt::Debug for GetManyMutError<N> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("GetManyMutError").finish_non_exhaustive()
+    }
+}
+
+#[unstable(feature = "get_many_mut", issue = "104642")]
+impl<const N: usize> fmt::Display for GetManyMutError<N> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt("an index is out of bounds or appeared multiple times in the array", f)
+    }
+}
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 68f7dcdd5d6..99d4a40c4c9 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -108,6 +108,7 @@
 #![feature(provide_any)]
 #![feature(utf8_chunks)]
 #![feature(is_ascii_octdigit)]
+#![feature(get_many_mut)]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![deny(fuzzy_provenance_casts)]
 
diff --git a/library/core/tests/slice.rs b/library/core/tests/slice.rs
index 9e1fbea7914..4e06e0f4398 100644
--- a/library/core/tests/slice.rs
+++ b/library/core/tests/slice.rs
@@ -2595,3 +2595,63 @@ fn test_flatten_mut_size_overflow() {
     let x = &mut [[(); usize::MAX]; 2][..];
     let _ = x.flatten_mut();
 }
+
+#[test]
+fn test_get_many_mut_normal_2() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    let [a, b] = v.get_many_mut([3, 0]).unwrap();
+    *a += 10;
+    *b += 100;
+    assert_eq!(v, vec![101, 2, 3, 14, 5]);
+}
+
+#[test]
+fn test_get_many_mut_normal_3() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    let [a, b, c] = v.get_many_mut([0, 4, 2]).unwrap();
+    *a += 10;
+    *b += 100;
+    *c += 1000;
+    assert_eq!(v, vec![11, 2, 1003, 4, 105]);
+}
+
+#[test]
+fn test_get_many_mut_empty() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    let [] = v.get_many_mut([]).unwrap();
+    assert_eq!(v, vec![1, 2, 3, 4, 5]);
+}
+
+#[test]
+fn test_get_many_mut_single_first() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    let [a] = v.get_many_mut([0]).unwrap();
+    *a += 10;
+    assert_eq!(v, vec![11, 2, 3, 4, 5]);
+}
+
+#[test]
+fn test_get_many_mut_single_last() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    let [a] = v.get_many_mut([4]).unwrap();
+    *a += 10;
+    assert_eq!(v, vec![1, 2, 3, 4, 15]);
+}
+
+#[test]
+fn test_get_many_mut_oob_nonempty() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    assert!(v.get_many_mut([5]).is_err());
+}
+
+#[test]
+fn test_get_many_mut_oob_empty() {
+    let mut v: Vec<i32> = vec![];
+    assert!(v.get_many_mut([0]).is_err());
+}
+
+#[test]
+fn test_get_many_mut_duplicate() {
+    let mut v = vec![1, 2, 3, 4, 5];
+    assert!(v.get_many_mut([1, 3, 3, 4]).is_err());
+}
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 9334c833bb6..63ee6c521d7 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -347,6 +347,7 @@
 #![feature(stdsimd)]
 #![feature(test)]
 #![feature(trace_macros)]
+#![feature(get_many_mut)]
 //
 // Only used in tests/benchmarks:
 //
diff --git a/library/std/src/sys_common/once/generic.rs b/library/std/src/sys_common/once/generic.rs
index acf5f247164..d953a674592 100644
--- a/library/std/src/sys_common/once/generic.rs
+++ b/library/std/src/sys_common/once/generic.rs
@@ -107,6 +107,7 @@ struct WaiterQueue<'a> {
 
 impl Once {
     #[inline]
+    #[rustc_const_stable(feature = "const_once_new", since = "1.32.0")]
     pub const fn new() -> Once {
         Once { state_and_queue: AtomicPtr::new(ptr::invalid_mut(INCOMPLETE)) }
     }
diff --git a/src/bootstrap/Cargo.lock b/src/bootstrap/Cargo.lock
index a59dc4f87a6..0cd778a0cbb 100644
--- a/src/bootstrap/Cargo.lock
+++ b/src/bootstrap/Cargo.lock
@@ -53,6 +53,7 @@ dependencies = [
  "hex",
  "ignore",
  "libc",
+ "object",
  "once_cell",
  "opener",
  "pretty_assertions",
@@ -401,6 +402,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "object"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21158b2c33aa6d4561f1c0a6ea283ca92bc54802a93b263e910746d679a7eb53"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
 name = "once_cell"
 version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/src/bootstrap/Cargo.toml b/src/bootstrap/Cargo.toml
index 813c8075605..4c24c214d2c 100644
--- a/src/bootstrap/Cargo.toml
+++ b/src/bootstrap/Cargo.toml
@@ -42,6 +42,7 @@ getopts = "0.2.19"
 cc = "1.0.69"
 libc = "0.2"
 hex = "0.4"
+object = { version = "0.29.0", default-features = false, features = ["archive", "coff", "read_core", "unaligned"] }
 serde = { version = "1.0.8", features = ["derive"] }
 serde_json = "1.0.2"
 sha2 = "0.10"
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index aacd2c7eab9..2fef7f65827 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -10,10 +10,14 @@
 
 use std::collections::HashSet;
 use std::env;
+use std::ffi::OsStr;
 use std::fs;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
+use object::read::archive::ArchiveFile;
+use object::BinaryFormat;
+
 use crate::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
 use crate::cache::{Interned, INTERNER};
 use crate::channel;
@@ -555,6 +559,39 @@ fn skip_host_target_lib(builder: &Builder<'_>, compiler: Compiler) -> bool {
     }
 }
 
+/// Check that all objects in rlibs for UEFI targets are COFF. This
+/// ensures that the C compiler isn't producing ELF objects, which would
+/// not link correctly with the COFF objects.
+fn verify_uefi_rlib_format(builder: &Builder<'_>, target: TargetSelection, stamp: &Path) {
+    if !target.ends_with("-uefi") {
+        return;
+    }
+
+    for (path, _) in builder.read_stamp_file(stamp) {
+        if path.extension() != Some(OsStr::new("rlib")) {
+            continue;
+        }
+
+        let data = t!(fs::read(&path));
+        let data = data.as_slice();
+        let archive = t!(ArchiveFile::parse(data));
+        for member in archive.members() {
+            let member = t!(member);
+            let member_data = t!(member.data(data));
+
+            let is_coff = match object::File::parse(member_data) {
+                Ok(member_file) => member_file.format() == BinaryFormat::Coff,
+                Err(_) => false,
+            };
+
+            if !is_coff {
+                let member_name = String::from_utf8_lossy(member.name());
+                panic!("member {} in {} is not COFF", member_name, path.display());
+            }
+        }
+    }
+}
+
 /// Copy stamped files into an image's `target/lib` directory.
 fn copy_target_libs(builder: &Builder<'_>, target: TargetSelection, image: &Path, stamp: &Path) {
     let dst = image.join("lib/rustlib").join(target.triple).join("lib");
@@ -610,6 +647,7 @@ impl Step for Std {
 
         let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
         let stamp = compile::libstd_stamp(builder, compiler_to_use, target);
+        verify_uefi_rlib_format(builder, target, &stamp);
         copy_target_libs(builder, target, &tarball.image_dir(), &stamp);
 
         Some(tarball.generate())
diff --git a/src/ci/docker/host-x86_64/dist-various-2/Dockerfile b/src/ci/docker/host-x86_64/dist-various-2/Dockerfile
index e1adabaac9b..93ef7dfcbf5 100644
--- a/src/ci/docker/host-x86_64/dist-various-2/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-various-2/Dockerfile
@@ -61,6 +61,12 @@ ENV \
     AR_i686_unknown_freebsd=i686-unknown-freebsd12-ar \
     CC_i686_unknown_freebsd=i686-unknown-freebsd12-clang \
     CXX_i686_unknown_freebsd=i686-unknown-freebsd12-clang++ \
+    CC_aarch64_unknown_uefi=clang-11 \
+    CXX_aarch64_unknown_uefi=clang++-11 \
+    CC_i686_unknown_uefi=clang-11 \
+    CXX_i686_unknown_uefi=clang++-11 \
+    CC_x86_64_unknown_uefi=clang-11 \
+    CXX_x86_64_unknown_uefi=clang++-11 \
     CC=gcc-8 \
     CXX=g++-8
 
diff --git a/src/ci/docker/host-x86_64/test-various/Dockerfile b/src/ci/docker/host-x86_64/test-various/Dockerfile
index b0f35bcb9cc..0bddffa3436 100644
--- a/src/ci/docker/host-x86_64/test-various/Dockerfile
+++ b/src/ci/docker/host-x86_64/test-various/Dockerfile
@@ -1,6 +1,7 @@
 FROM ubuntu:20.04
 
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+  clang-11 \
   g++ \
   make \
   ninja-build \
@@ -67,7 +68,9 @@ ENV MUSL_TARGETS=x86_64-unknown-linux-musl \
 ENV MUSL_SCRIPT python3 /checkout/x.py --stage 2 test --host='' --target $MUSL_TARGETS
 
 COPY host-x86_64/test-various/uefi_qemu_test /uefi_qemu_test
-ENV UEFI_TARGETS=x86_64-unknown-uefi
+ENV UEFI_TARGETS=x86_64-unknown-uefi \
+    CC_x86_64_unknown_uefi=clang-11 \
+    CXX_x86_64_unknown_uefi=clang++-11
 ENV UEFI_SCRIPT python3 /checkout/x.py --stage 2 build --host='' --target $UEFI_TARGETS && \
   python3 -u /uefi_qemu_test/run.py