diff --git a/compiler/rustc_builtin_macros/src/alloc_error_handler.rs b/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
index 09d892768b464..1df2812e0c887 100644
--- a/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
+++ b/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
@@ -80,7 +80,7 @@ fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span
     let params = thin_vec![cx.param(span, size, ty_usize.clone()), cx.param(span, align, ty_usize)];
     let decl = cx.fn_decl(params, never);
     let header = FnHeader { safety: Safety::Unsafe(span), ..FnHeader::default() };
-    let sig = FnSig { decl, header, span: span };
+    let sig = FnSig { decl, header, span };
 
     let body = Some(cx.block_expr(call));
     let kind = ItemKind::Fn(Box::new(Fn {
diff --git a/compiler/rustc_builtin_macros/src/cfg_eval.rs b/compiler/rustc_builtin_macros/src/cfg_eval.rs
index dc1874bfecbda..4b05c144d37d7 100644
--- a/compiler/rustc_builtin_macros/src/cfg_eval.rs
+++ b/compiler/rustc_builtin_macros/src/cfg_eval.rs
@@ -202,7 +202,7 @@ impl CfgEval<'_> {
         }
 
         // Now that we have our re-parsed `AttrTokenStream`, recursively configuring
-        // our attribute target will correctly the tokens as well.
+        // our attribute target will correctly configure the tokens as well.
         flat_map_annotatable(self, annotatable)
     }
 }
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index 77da4e4caea0f..b52e6259944d7 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -78,6 +78,7 @@ pub fn from_target_feature(
                 Some(sym::loongarch_target_feature) => rust_features.loongarch_target_feature,
                 Some(sym::lahfsahf_target_feature) => rust_features.lahfsahf_target_feature,
                 Some(sym::prfchw_target_feature) => rust_features.prfchw_target_feature,
+                Some(sym::sha512_sm_x86) => rust_features.sha512_sm_x86,
                 Some(sym::x86_amx_intrinsics) => rust_features.x86_amx_intrinsics,
                 Some(sym::xop_target_feature) => rust_features.xop_target_feature,
                 Some(sym::s390x_target_feature) => rust_features.s390x_target_feature,
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 03210085a12c9..86102bbecd04e 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -591,6 +591,8 @@ declare_features! (
     (incomplete, return_type_notation, "1.70.0", Some(109417)),
     /// Allows `extern "rust-cold"`.
     (unstable, rust_cold_cc, "1.63.0", Some(97544)),
+    /// Allows use of x86 SHA512, SM3 and SM4 target-features and intrinsics
+    (unstable, sha512_sm_x86, "CURRENT_RUSTC_VERSION", Some(126624)),
     /// Shortern the tail expression lifetime
     (unstable, shorter_tail_lifetimes, "1.79.0", Some(123739)),
     /// Allows the use of SIMD types in functions declared in `extern` blocks.
diff --git a/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs b/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs
index c39c86f6fe8f1..e3b1967da09c7 100644
--- a/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs
+++ b/compiler/rustc_lint/src/macro_expr_fragment_specifier_2024_migration.rs
@@ -1,5 +1,5 @@
-//! Migration code for the `expr_fragment_specifier_2024`
-//! rule.
+//! Migration code for the `expr_fragment_specifier_2024` rule.
+
 use rustc_ast::token::{Token, TokenKind};
 use rustc_ast::tokenstream::{TokenStream, TokenTree};
 use rustc_session::lint::FutureIncompatibilityReason;
diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index f34ef071e21ec..8fdfbcee38546 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -8,7 +8,7 @@ use rustc_span::{sym, BytePos, Span};
 use thin_vec::ThinVec;
 use tracing::debug;
 
-use super::{AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle};
+use super::{AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, ParserRange, PathStyle};
 use crate::{errors, fluent_generated as fluent, maybe_whole};
 
 // Public for rustfmt usage
@@ -313,8 +313,8 @@ impl<'a> Parser<'a> {
                 // inner attribute, for possible later processing in a `LazyAttrTokenStream`.
                 if let Capturing::Yes = self.capture_state.capturing {
                     let end_pos = self.num_bump_calls;
-                    let range = start_pos..end_pos;
-                    self.capture_state.inner_attr_ranges.insert(attr.id, range);
+                    let parser_range = ParserRange(start_pos..end_pos);
+                    self.capture_state.inner_attr_parser_ranges.insert(attr.id, parser_range);
                 }
                 attrs.push(attr);
             } else {
diff --git a/compiler/rustc_parse/src/parser/attr_wrapper.rs b/compiler/rustc_parse/src/parser/attr_wrapper.rs
index 611dbc0535c61..abf61036c2deb 100644
--- a/compiler/rustc_parse/src/parser/attr_wrapper.rs
+++ b/compiler/rustc_parse/src/parser/attr_wrapper.rs
@@ -10,7 +10,10 @@ use rustc_errors::PResult;
 use rustc_session::parse::ParseSess;
 use rustc_span::{sym, Span, DUMMY_SP};
 
-use super::{Capturing, FlatToken, ForceCollect, Parser, ReplaceRange, TokenCursor};
+use super::{
+    Capturing, FlatToken, ForceCollect, NodeRange, NodeReplacement, Parser, ParserRange,
+    TokenCursor,
+};
 
 /// A wrapper type to ensure that the parser handles outer attributes correctly.
 /// When we parse outer attributes, we need to ensure that we capture tokens
@@ -28,8 +31,8 @@ use super::{Capturing, FlatToken, ForceCollect, Parser, ReplaceRange, TokenCurso
 #[derive(Debug, Clone)]
 pub struct AttrWrapper {
     attrs: AttrVec,
-    // The start of the outer attributes in the token cursor.
-    // This allows us to create a `ReplaceRange` for the entire attribute
+    // The start of the outer attributes in the parser's token stream.
+    // This lets us create a `NodeReplacement` for the entire attribute
     // target, including outer attributes.
     start_pos: u32,
 }
@@ -53,10 +56,9 @@ impl AttrWrapper {
 
     /// Prepend `self.attrs` to `attrs`.
     // FIXME: require passing an NT to prevent misuse of this method
-    pub(crate) fn prepend_to_nt_inner(self, attrs: &mut AttrVec) {
-        let mut self_attrs = self.attrs;
-        mem::swap(attrs, &mut self_attrs);
-        attrs.extend(self_attrs);
+    pub(crate) fn prepend_to_nt_inner(mut self, attrs: &mut AttrVec) {
+        mem::swap(attrs, &mut self.attrs);
+        attrs.extend(self.attrs);
     }
 
     pub fn is_empty(&self) -> bool {
@@ -89,7 +91,7 @@ struct LazyAttrTokenStreamImpl {
     cursor_snapshot: TokenCursor,
     num_calls: u32,
     break_last_token: bool,
-    replace_ranges: Box<[ReplaceRange]>,
+    node_replacements: Box<[NodeReplacement]>,
 }
 
 impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
@@ -104,21 +106,24 @@ impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
             .chain(iter::repeat_with(|| FlatToken::Token(cursor_snapshot.next())))
             .take(self.num_calls as usize);
 
-        if self.replace_ranges.is_empty() {
+        if self.node_replacements.is_empty() {
             make_attr_token_stream(tokens, self.break_last_token)
         } else {
             let mut tokens: Vec<_> = tokens.collect();
-            let mut replace_ranges = self.replace_ranges.to_vec();
-            replace_ranges.sort_by_key(|(range, _)| range.start);
+            let mut node_replacements = self.node_replacements.to_vec();
+            node_replacements.sort_by_key(|(range, _)| range.0.start);
 
             #[cfg(debug_assertions)]
-            for [(range, tokens), (next_range, next_tokens)] in replace_ranges.array_windows() {
+            for [(node_range, tokens), (next_node_range, next_tokens)] in
+                node_replacements.array_windows()
+            {
                 assert!(
-                    range.end <= next_range.start || range.end >= next_range.end,
-                    "Replace ranges should either be disjoint or nested: ({:?}, {:?}) ({:?}, {:?})",
-                    range,
+                    node_range.0.end <= next_node_range.0.start
+                        || node_range.0.end >= next_node_range.0.end,
+                    "Node ranges should be disjoint or nested: ({:?}, {:?}) ({:?}, {:?})",
+                    node_range,
                     tokens,
-                    next_range,
+                    next_node_range,
                     next_tokens,
                 );
             }
@@ -136,20 +141,23 @@ impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
             // start position, we ensure that any (outer) replace range which
             // encloses another (inner) replace range will fully overwrite the
             // inner range's replacement.
-            for (range, target) in replace_ranges.into_iter().rev() {
-                assert!(!range.is_empty(), "Cannot replace an empty range: {range:?}");
+            for (node_range, target) in node_replacements.into_iter().rev() {
+                assert!(
+                    !node_range.0.is_empty(),
+                    "Cannot replace an empty node range: {:?}",
+                    node_range.0
+                );
 
                 // Replace the tokens in range with zero or one `FlatToken::AttrsTarget`s, plus
                 // enough `FlatToken::Empty`s to fill up the rest of the range. This keeps the
                 // total length of `tokens` constant throughout the replacement process, allowing
-                // us to use all of the `ReplaceRanges` entries without adjusting indices.
+                // us to do all replacements without adjusting indices.
                 let target_len = target.is_some() as usize;
                 tokens.splice(
-                    (range.start as usize)..(range.end as usize),
-                    target
-                        .into_iter()
-                        .map(|target| FlatToken::AttrsTarget(target))
-                        .chain(iter::repeat(FlatToken::Empty).take(range.len() - target_len)),
+                    (node_range.0.start as usize)..(node_range.0.end as usize),
+                    target.into_iter().map(|target| FlatToken::AttrsTarget(target)).chain(
+                        iter::repeat(FlatToken::Empty).take(node_range.0.len() - target_len),
+                    ),
                 );
             }
             make_attr_token_stream(tokens.into_iter(), self.break_last_token)
@@ -216,7 +224,7 @@ impl<'a> Parser<'a> {
         let cursor_snapshot = self.token_cursor.clone();
         let start_pos = self.num_bump_calls;
         let has_outer_attrs = !attrs.attrs.is_empty();
-        let replace_ranges_start = self.capture_state.replace_ranges.len();
+        let parser_replacements_start = self.capture_state.parser_replacements.len();
 
         // We set and restore `Capturing::Yes` on either side of the call to
         // `f`, so we can distinguish the outermost call to
@@ -271,7 +279,7 @@ impl<'a> Parser<'a> {
             return Ok(ret);
         }
 
-        let replace_ranges_end = self.capture_state.replace_ranges.len();
+        let parser_replacements_end = self.capture_state.parser_replacements.len();
 
         assert!(
             !(self.break_last_token && capture_trailing),
@@ -288,15 +296,16 @@ impl<'a> Parser<'a> {
 
         let num_calls = end_pos - start_pos;
 
-        // Take the captured ranges for any inner attributes that we parsed in
-        // `Parser::parse_inner_attributes`, and pair them in a `ReplaceRange`
-        // with `None`, which means the relevant tokens will be removed. (More
-        // details below.)
-        let mut inner_attr_replace_ranges = Vec::new();
+        // Take the captured `ParserRange`s for any inner attributes that we parsed in
+        // `Parser::parse_inner_attributes`, and pair them in a `ParserReplacement` with `None`,
+        // which means the relevant tokens will be removed. (More details below.)
+        let mut inner_attr_parser_replacements = Vec::new();
         for attr in ret.attrs() {
             if attr.style == ast::AttrStyle::Inner {
-                if let Some(attr_range) = self.capture_state.inner_attr_ranges.remove(&attr.id) {
-                    inner_attr_replace_ranges.push((attr_range, None));
+                if let Some(inner_attr_parser_range) =
+                    self.capture_state.inner_attr_parser_ranges.remove(&attr.id)
+                {
+                    inner_attr_parser_replacements.push((inner_attr_parser_range, None));
                 } else {
                     self.dcx().span_delayed_bug(attr.span, "Missing token range for attribute");
                 }
@@ -305,37 +314,41 @@ impl<'a> Parser<'a> {
 
         // This is hot enough for `deep-vector` that checking the conditions for an empty iterator
         // is measurably faster than actually executing the iterator.
-        let replace_ranges: Box<[ReplaceRange]> =
-            if replace_ranges_start == replace_ranges_end && inner_attr_replace_ranges.is_empty() {
-                Box::new([])
-            } else {
-                // Grab any replace ranges that occur *inside* the current AST node. We will
-                // perform the actual replacement only when we convert the `LazyAttrTokenStream` to
-                // an `AttrTokenStream`.
-                self.capture_state.replace_ranges[replace_ranges_start..replace_ranges_end]
-                    .iter()
-                    .cloned()
-                    .chain(inner_attr_replace_ranges.iter().cloned())
-                    .map(|(range, data)| ((range.start - start_pos)..(range.end - start_pos), data))
-                    .collect()
-            };
+        let node_replacements: Box<[_]> = if parser_replacements_start == parser_replacements_end
+            && inner_attr_parser_replacements.is_empty()
+        {
+            Box::new([])
+        } else {
+            // Grab any replace ranges that occur *inside* the current AST node. Convert them
+            // from `ParserRange` form to `NodeRange` form. We will perform the actual
+            // replacement only when we convert the `LazyAttrTokenStream` to an
+            // `AttrTokenStream`.
+            self.capture_state.parser_replacements
+                [parser_replacements_start..parser_replacements_end]
+                .iter()
+                .cloned()
+                .chain(inner_attr_parser_replacements.iter().cloned())
+                .map(|(parser_range, data)| (NodeRange::new(parser_range, start_pos), data))
+                .collect()
+        };
 
         // What is the status here when parsing the example code at the top of this method?
         //
         // When parsing `g`:
         // - `start_pos..end_pos` is `12..33` (`fn g { ... }`, excluding the outer attr).
-        // - `inner_attr_replace_ranges` has one entry (`5..15`, when counting from `fn`), to
+        // - `inner_attr_parser_replacements` has one entry (`ParserRange(17..27)`), to
         //   delete the inner attr's tokens.
-        //   - This entry is put into the lazy tokens for `g`, i.e. deleting the inner attr from
-        //     those tokens (if they get evaluated).
+        //   - This entry is converted to `NodeRange(5..15)` (relative to the `fn`) and put into
+        //     the lazy tokens for `g`, i.e. deleting the inner attr from those tokens (if they get
+        //     evaluated).
         //   - Those lazy tokens are also put into an `AttrsTarget` that is appended to `self`'s
         //     replace ranges at the bottom of this function, for processing when parsing `m`.
-        // - `replace_ranges_start..replace_ranges_end` is empty.
+        // - `parser_replacements_start..parser_replacements_end` is empty.
         //
         // When parsing `m`:
         // - `start_pos..end_pos` is `0..34` (`mod m`, excluding the `#[cfg_eval]` attribute).
-        // - `inner_attr_replace_ranges` is empty.
-        // - `replace_range_start..replace_ranges_end` has one entry.
+        // - `inner_attr_parser_replacements` is empty.
+        // - `parser_replacements_start..parser_replacements_end` has one entry.
         //   - One `AttrsTarget` (added below when parsing `g`) to replace all of `g` (`3..33`,
         //     including its outer attribute), with:
         //     - `attrs`: includes the outer and the inner attr.
@@ -346,7 +359,7 @@ impl<'a> Parser<'a> {
             num_calls,
             cursor_snapshot,
             break_last_token: self.break_last_token,
-            replace_ranges,
+            node_replacements,
         });
 
         // If we support tokens and don't already have them, store the newly captured tokens.
@@ -367,7 +380,7 @@ impl<'a> Parser<'a> {
             // What is the status here when parsing the example code at the top of this method?
             //
             // When parsing `g`, we add one entry:
-            // - The `start_pos..end_pos` (`3..33`) entry has a new `AttrsTarget` with:
+            // - The pushed entry (`ParserRange(3..33)`) has a new `AttrsTarget` with:
             //   - `attrs`: includes the outer and the inner attr.
             //   - `tokens`: lazy tokens for `g` (with its inner attr deleted).
             //
@@ -378,12 +391,14 @@ impl<'a> Parser<'a> {
             // cfg-expand this AST node.
             let start_pos = if has_outer_attrs { attrs.start_pos } else { start_pos };
             let target = AttrsTarget { attrs: ret.attrs().iter().cloned().collect(), tokens };
-            self.capture_state.replace_ranges.push((start_pos..end_pos, Some(target)));
+            self.capture_state
+                .parser_replacements
+                .push((ParserRange(start_pos..end_pos), Some(target)));
         } else if matches!(self.capture_state.capturing, Capturing::No) {
             // Only clear the ranges once we've finished capturing entirely, i.e. we've finished
             // the outermost call to this method.
-            self.capture_state.replace_ranges.clear();
-            self.capture_state.inner_attr_ranges.clear();
+            self.capture_state.parser_replacements.clear();
+            self.capture_state.inner_attr_parser_ranges.clear();
         }
         Ok(ret)
     }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 1b053c39e64b4..ccf8dcdf0b6f2 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -40,14 +40,6 @@ use super::{
 };
 use crate::{errors, maybe_recover_from_interpolated_ty_qpath};
 
-#[derive(Debug)]
-pub(super) enum LhsExpr {
-    // Already parsed just the outer attributes.
-    Unparsed { attrs: AttrWrapper },
-    // Already parsed the expression.
-    Parsed { expr: P<Expr>, starts_statement: bool },
-}
-
 #[derive(Debug)]
 enum DestructuredFloat {
     /// 1e2
@@ -113,30 +105,31 @@ impl<'a> Parser<'a> {
         r: Restrictions,
         attrs: AttrWrapper,
     ) -> PResult<'a, P<Expr>> {
-        self.with_res(r, |this| this.parse_expr_assoc_with(0, LhsExpr::Unparsed { attrs }))
+        self.with_res(r, |this| this.parse_expr_assoc_with(0, attrs))
     }
 
     /// Parses an associative expression with operators of at least `min_prec` precedence.
     pub(super) fn parse_expr_assoc_with(
         &mut self,
         min_prec: usize,
-        lhs: LhsExpr,
+        attrs: AttrWrapper,
     ) -> PResult<'a, P<Expr>> {
-        let mut starts_stmt = false;
-        let mut lhs = match lhs {
-            LhsExpr::Parsed { expr, starts_statement } => {
-                starts_stmt = starts_statement;
-                expr
-            }
-            LhsExpr::Unparsed { attrs } => {
-                if self.token.is_range_separator() {
-                    return self.parse_expr_prefix_range(attrs);
-                } else {
-                    self.parse_expr_prefix(attrs)?
-                }
-            }
+        let lhs = if self.token.is_range_separator() {
+            return self.parse_expr_prefix_range(attrs);
+        } else {
+            self.parse_expr_prefix(attrs)?
         };
+        self.parse_expr_assoc_rest_with(min_prec, false, lhs)
+    }
 
+    /// Parses the rest of an associative expression (i.e. the part after the lhs) with operators
+    /// of at least `min_prec` precedence.
+    pub(super) fn parse_expr_assoc_rest_with(
+        &mut self,
+        min_prec: usize,
+        starts_stmt: bool,
+        mut lhs: P<Expr>,
+    ) -> PResult<'a, P<Expr>> {
         if !self.should_continue_as_assoc_expr(&lhs) {
             return Ok(lhs);
         }
@@ -272,7 +265,7 @@ impl<'a> Parser<'a> {
             };
             let rhs = self.with_res(restrictions - Restrictions::STMT_EXPR, |this| {
                 let attrs = this.parse_outer_attributes()?;
-                this.parse_expr_assoc_with(prec + prec_adjustment, LhsExpr::Unparsed { attrs })
+                this.parse_expr_assoc_with(prec + prec_adjustment, attrs)
             })?;
 
             let span = self.mk_expr_sp(&lhs, lhs_span, rhs.span);
@@ -447,7 +440,7 @@ impl<'a> Parser<'a> {
             let maybe_lt = self.token.clone();
             let attrs = self.parse_outer_attributes()?;
             Some(
-                self.parse_expr_assoc_with(prec + 1, LhsExpr::Unparsed { attrs })
+                self.parse_expr_assoc_with(prec + 1, attrs)
                     .map_err(|err| self.maybe_err_dotdotlt_syntax(maybe_lt, err))?,
             )
         } else {
@@ -504,12 +497,9 @@ impl<'a> Parser<'a> {
             let (span, opt_end) = if this.is_at_start_of_range_notation_rhs() {
                 // RHS must be parsed with more associativity than the dots.
                 let attrs = this.parse_outer_attributes()?;
-                this.parse_expr_assoc_with(
-                    op.unwrap().precedence() + 1,
-                    LhsExpr::Unparsed { attrs },
-                )
-                .map(|x| (lo.to(x.span), Some(x)))
-                .map_err(|err| this.maybe_err_dotdotlt_syntax(maybe_lt, err))?
+                this.parse_expr_assoc_with(op.unwrap().precedence() + 1, attrs)
+                    .map(|x| (lo.to(x.span), Some(x)))
+                    .map_err(|err| this.maybe_err_dotdotlt_syntax(maybe_lt, err))?
             } else {
                 (lo, None)
             };
@@ -889,7 +879,7 @@ impl<'a> Parser<'a> {
         mut e: P<Expr>,
         lo: Span,
     ) -> PResult<'a, P<Expr>> {
-        let res = ensure_sufficient_stack(|| {
+        let mut res = ensure_sufficient_stack(|| {
             loop {
                 let has_question =
                     if self.prev_token.kind == TokenKind::Ident(kw::Return, IdentIsRaw::No) {
@@ -936,17 +926,13 @@ impl<'a> Parser<'a> {
 
         // Stitch the list of outer attributes onto the return value. A little
         // bit ugly, but the best way given the current code structure.
-        if attrs.is_empty() {
-            res
-        } else {
-            res.map(|expr| {
-                expr.map(|mut expr| {
-                    attrs.extend(expr.attrs);
-                    expr.attrs = attrs;
-                    expr
-                })
-            })
+        if !attrs.is_empty()
+            && let Ok(expr) = &mut res
+        {
+            mem::swap(&mut expr.attrs, &mut attrs);
+            expr.attrs.extend(attrs)
         }
+        res
     }
 
     pub(super) fn parse_dot_suffix_expr(
@@ -2647,10 +2633,7 @@ impl<'a> Parser<'a> {
             self.expect(&token::Eq)?;
         }
         let attrs = self.parse_outer_attributes()?;
-        let expr = self.parse_expr_assoc_with(
-            1 + prec_let_scrutinee_needs_par(),
-            LhsExpr::Unparsed { attrs },
-        )?;
+        let expr = self.parse_expr_assoc_with(1 + prec_let_scrutinee_needs_par(), attrs)?;
         let span = lo.to(expr.span);
         Ok(self.mk_expr(span, ExprKind::Let(pat, expr, span, recovered)))
     }
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index e01f605722b72..0fbf8c0fbcbbc 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -192,24 +192,54 @@ struct ClosureSpans {
     body: Span,
 }
 
-/// Indicates a range of tokens that should be replaced by
-/// the tokens in the provided `AttrsTarget`. This is used in two
-/// places during token collection:
+/// A token range within a `Parser`'s full token stream.
+#[derive(Clone, Debug)]
+struct ParserRange(Range<u32>);
+
+/// A token range within an individual AST node's (lazy) token stream, i.e.
+/// relative to that node's first token. Distinct from `ParserRange` so the two
+/// kinds of range can't be mixed up.
+#[derive(Clone, Debug)]
+struct NodeRange(Range<u32>);
+
+/// Indicates a range of tokens that should be replaced by an `AttrsTarget`
+/// (replacement) or be replaced by nothing (deletion). This is used in two
+/// places during token collection.
+///
+/// 1. Replacement. During the parsing of an AST node that may have a
+///    `#[derive]` attribute, when we parse a nested AST node that has `#[cfg]`
+///    or `#[cfg_attr]`, we replace the entire inner AST node with
+///    `FlatToken::AttrsTarget`. This lets us perform eager cfg-expansion on an
+///    `AttrTokenStream`.
 ///
-/// 1. During the parsing of an AST node that may have a `#[derive]`
-/// attribute, we parse a nested AST node that has `#[cfg]` or `#[cfg_attr]`
-/// In this case, we use a `ReplaceRange` to replace the entire inner AST node
-/// with `FlatToken::AttrsTarget`, allowing us to perform eager cfg-expansion
-/// on an `AttrTokenStream`.
+/// 2. Deletion. We delete inner attributes from all collected token streams,
+///    and instead track them through the `attrs` field on the AST node. This
+///    lets us manipulate them similarly to outer attributes. When we create a
+///    `TokenStream`, the inner attributes are inserted into the proper place
+///    in the token stream.
 ///
-/// 2. When we parse an inner attribute while collecting tokens. We
-/// remove inner attributes from the token stream entirely, and
-/// instead track them through the `attrs` field on the AST node.
-/// This allows us to easily manipulate them (for example, removing
-/// the first macro inner attribute to invoke a proc-macro).
-/// When create a `TokenStream`, the inner attributes get inserted
-/// into the proper place in the token stream.
-type ReplaceRange = (Range<u32>, Option<AttrsTarget>);
+/// Each replacement starts off in `ParserReplacement` form but is converted to
+/// `NodeReplacement` form when it is attached to a single AST node, via
+/// `LazyAttrTokenStreamImpl`.
+type ParserReplacement = (ParserRange, Option<AttrsTarget>);
+
+/// See the comment on `ParserReplacement`.
+type NodeReplacement = (NodeRange, Option<AttrsTarget>);
+
+impl NodeRange {
+    // Converts a range within a parser's tokens to a range within a
+    // node's tokens beginning at `start_pos`.
+    //
+    // For example, imagine a parser with 50 tokens in its token stream, a
+    // function that spans `ParserRange(20..40)` and an inner attribute within
+    // that function that spans `ParserRange(30..35)`. We would find the inner
+    // attribute's range within the function's tokens by subtracting 20, which
+    // is the position of the function's start token. This gives
+    // `NodeRange(10..15)`.
+    fn new(ParserRange(parser_range): ParserRange, start_pos: u32) -> NodeRange {
+        NodeRange((parser_range.start - start_pos)..(parser_range.end - start_pos))
+    }
+}
 
 /// Controls how we capture tokens. Capturing can be expensive,
 /// so we try to avoid performing capturing in cases where
@@ -226,8 +256,8 @@ enum Capturing {
 #[derive(Clone, Debug)]
 struct CaptureState {
     capturing: Capturing,
-    replace_ranges: Vec<ReplaceRange>,
-    inner_attr_ranges: FxHashMap<AttrId, Range<u32>>,
+    parser_replacements: Vec<ParserReplacement>,
+    inner_attr_parser_ranges: FxHashMap<AttrId, ParserRange>,
 }
 
 /// Iterator over a `TokenStream` that produces `Token`s. It's a bit odd that
@@ -417,8 +447,8 @@ impl<'a> Parser<'a> {
             subparser_name,
             capture_state: CaptureState {
                 capturing: Capturing::No,
-                replace_ranges: Vec::new(),
-                inner_attr_ranges: Default::default(),
+                parser_replacements: Vec::new(),
+                inner_attr_parser_ranges: Default::default(),
             },
             current_closure: None,
             recovery: Recovery::Allowed,
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index b6f85cc90324c..5bfb8bdf776a0 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -25,7 +25,7 @@ use crate::errors::{
     UnexpectedParenInRangePat, UnexpectedParenInRangePatSugg,
     UnexpectedVertVertBeforeFunctionParam, UnexpectedVertVertInPattern, WrapInParens,
 };
-use crate::parser::expr::{could_be_unclosed_char_literal, LhsExpr};
+use crate::parser::expr::could_be_unclosed_char_literal;
 use crate::{maybe_recover_from_interpolated_ty_qpath, maybe_whole};
 
 #[derive(PartialEq, Copy, Clone)]
@@ -403,8 +403,9 @@ impl<'a> Parser<'a> {
 
             // Parse an associative expression such as `+ expr`, `% expr`, ...
             // Assignements, ranges and `|` are disabled by [`Restrictions::IS_PAT`].
-            let lhs = LhsExpr::Parsed { expr, starts_statement: false };
-            if let Ok(expr) = snapshot.parse_expr_assoc_with(0, lhs).map_err(|err| err.cancel()) {
+            if let Ok(expr) =
+                snapshot.parse_expr_assoc_rest_with(0, false, expr).map_err(|err| err.cancel())
+            {
                 // We got a valid expression.
                 self.restore_snapshot(snapshot);
                 self.restrictions.remove(Restrictions::IS_PAT);
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index 7b0daaa14335f..b3efb87a4a26a 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -17,7 +17,6 @@ use thin_vec::{thin_vec, ThinVec};
 
 use super::attr::InnerAttrForbiddenReason;
 use super::diagnostics::AttemptLocalParseRecovery;
-use super::expr::LhsExpr;
 use super::pat::{PatternLocation, RecoverComma};
 use super::path::PathStyle;
 use super::{
@@ -66,7 +65,12 @@ impl<'a> Parser<'a> {
         }
 
         Ok(Some(if self.token.is_keyword(kw::Let) {
-            self.parse_local_mk(lo, attrs, capture_semi, force_collect)?
+            self.collect_tokens_trailing_token(attrs, force_collect, |this, attrs| {
+                this.expect_keyword(kw::Let)?;
+                let local = this.parse_local(attrs)?;
+                let trailing = capture_semi && this.token.kind == token::Semi;
+                Ok((this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Let(local)), trailing))
+            })?
         } else if self.is_kw_followed_by_ident(kw::Mut) && self.may_recover() {
             self.recover_stmt_local_after_let(
                 lo,
@@ -112,13 +116,12 @@ impl<'a> Parser<'a> {
                 }
             }
         } else if let Some(item) = self.parse_item_common(
-            attrs.clone(),
+            attrs.clone(), // FIXME: unwanted clone of attrs
             false,
             true,
             FnParseMode { req_name: |_| true, req_body: true },
             force_collect,
         )? {
-            // FIXME: Bad copy of attrs
             self.mk_stmt(lo.to(item.span), StmtKind::Item(P(item)))
         } else if self.eat(&token::Semi) {
             // Do not attempt to parse an expression if we're done here.
@@ -173,7 +176,7 @@ impl<'a> Parser<'a> {
             // Perform this outside of the `collect_tokens_trailing_token` closure,
             // since our outer attributes do not apply to this part of the expression
             let expr = self.with_res(Restrictions::STMT_EXPR, |this| {
-                this.parse_expr_assoc_with(0, LhsExpr::Parsed { expr, starts_statement: true })
+                this.parse_expr_assoc_rest_with(0, true, expr)
             })?;
             Ok(self.mk_stmt(lo.to(self.prev_token.span), StmtKind::Expr(expr)))
         } else {
@@ -206,8 +209,7 @@ impl<'a> Parser<'a> {
             let e = self.mk_expr(lo.to(hi), ExprKind::MacCall(mac));
             let e = self.maybe_recover_from_bad_qpath(e)?;
             let e = self.parse_expr_dot_or_call_with(attrs, e, lo)?;
-            let e = self
-                .parse_expr_assoc_with(0, LhsExpr::Parsed { expr: e, starts_statement: false })?;
+            let e = self.parse_expr_assoc_rest_with(0, false, e)?;
             StmtKind::Expr(e)
         };
         Ok(self.mk_stmt(lo.to(hi), kind))
@@ -247,21 +249,6 @@ impl<'a> Parser<'a> {
         Ok(stmt)
     }
 
-    fn parse_local_mk(
-        &mut self,
-        lo: Span,
-        attrs: AttrWrapper,
-        capture_semi: bool,
-        force_collect: ForceCollect,
-    ) -> PResult<'a, Stmt> {
-        self.collect_tokens_trailing_token(attrs, force_collect, |this, attrs| {
-            this.expect_keyword(kw::Let)?;
-            let local = this.parse_local(attrs)?;
-            let trailing = capture_semi && this.token.kind == token::Semi;
-            Ok((this.mk_stmt(lo.to(this.prev_token.span), StmtKind::Let(local)), trailing))
-        })
-    }
-
     /// Parses a local variable declaration.
     fn parse_local(&mut self, attrs: AttrVec) -> PResult<'a, P<Local>> {
         let lo = self.prev_token.span;
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index 761d6acdbaeb9..ca3efc11201e1 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -588,7 +588,7 @@ pub fn report_cycle<'a>(
         cycle_stack,
         stack_bottom: stack[0].query.description.to_owned(),
         alias,
-        cycle_usage: cycle_usage,
+        cycle_usage,
         stack_count,
         note_span: (),
     };
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index e8563f50158a5..9977fa7425a3e 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1705,6 +1705,7 @@ symbols! {
         self_in_typedefs,
         self_struct_ctor,
         semitransparent,
+        sha512_sm_x86,
         shadow_call_stack,
         shl,
         shl_assign,
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 532507cb18244..e52f2fc06df06 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -238,6 +238,9 @@ const X86_ALLOWED_FEATURES: &[(&str, Stability)] = &[
     ("rdseed", Stable),
     ("rtm", Unstable(sym::rtm_target_feature)),
     ("sha", Stable),
+    ("sha512", Unstable(sym::sha512_sm_x86)),
+    ("sm3", Unstable(sym::sha512_sm_x86)),
+    ("sm4", Unstable(sym::sha512_sm_x86)),
     ("sse", Stable),
     ("sse2", Stable),
     ("sse3", Stable),
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index ef40d3b203f48..38f50955b122e 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -1173,6 +1173,7 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
     /// ```
     ///
     /// [memory layout]: self#memory-layout
+    #[must_use = "losing the pointer will leak memory"]
     #[stable(feature = "box_raw", since = "1.4.0")]
     #[inline]
     pub fn into_raw(b: Self) -> *mut T {
@@ -1226,6 +1227,7 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
     /// ```
     ///
     /// [memory layout]: self#memory-layout
+    #[must_use = "losing the pointer will leak memory"]
     #[unstable(feature = "allocator_api", issue = "32838")]
     #[inline]
     pub fn into_raw_with_allocator(b: Self) -> (*mut T, A) {
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index bc0874fc13f46..13d218e43a7af 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -1372,6 +1372,7 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
     /// let x = unsafe { Rc::from_raw_in(ptr, alloc) };
     /// assert_eq!(&*x, "hello");
     /// ```
+    #[must_use = "losing the pointer will leak memory"]
     #[unstable(feature = "allocator_api", issue = "32838")]
     pub fn into_raw_with_allocator(this: Self) -> (*const T, A) {
         let this = mem::ManuallyDrop::new(this);
@@ -3107,6 +3108,7 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> {
     ///
     /// [`from_raw_in`]: Weak::from_raw_in
     /// [`as_ptr`]: Weak::as_ptr
+    #[must_use = "losing the pointer will leak memory"]
     #[inline]
     #[unstable(feature = "allocator_api", issue = "32838")]
     pub fn into_raw_with_allocator(self) -> (*const T, A) {
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 01fe950cf3fdd..124230812df56 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -900,7 +900,7 @@ impl String {
     /// let rebuilt = unsafe { String::from_raw_parts(ptr, len, cap) };
     /// assert_eq!(rebuilt, "hello");
     /// ```
-    #[must_use = "`self` will be dropped if the result is not used"]
+    #[must_use = "losing the pointer will leak memory"]
     #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
     pub fn into_raw_parts(self) -> (*mut u8, usize, usize) {
         self.vec.into_raw_parts()
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index dfd22204c81fa..b4e0bc5fcbe41 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -878,6 +878,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// };
     /// assert_eq!(rebuilt, [4294967295, 0, 1]);
     /// ```
+    #[must_use = "losing the pointer will leak memory"]
     #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
     pub fn into_raw_parts(self) -> (*mut T, usize, usize) {
         let mut me = ManuallyDrop::new(self);
@@ -921,6 +922,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// };
     /// assert_eq!(rebuilt, [4294967295, 0, 1]);
     /// ```
+    #[must_use = "losing the pointer will leak memory"]
     #[unstable(feature = "allocator_api", issue = "32838")]
     // #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
     pub fn into_raw_parts_with_alloc(self) -> (*mut T, usize, usize, A) {
diff --git a/library/core/src/arch.rs b/library/core/src/arch.rs
index 31d6bc36fc8b9..d681bd124fe13 100644
--- a/library/core/src/arch.rs
+++ b/library/core/src/arch.rs
@@ -4,6 +4,15 @@
 #[stable(feature = "simd_arch", since = "1.27.0")]
 pub use crate::core_arch::arch::*;
 
+#[cfg(bootstrap)]
+#[allow(dead_code)]
+#[unstable(feature = "sha512_sm_x86", issue = "126624")]
+fn dummy() {
+    // AArch64 also has a target feature named `sm4`, so we need `#![feature(sha512_sm_x86)]` in lib.rs
+    // But as the bootstrap compiler doesn't know about this feature yet, we need to convert it to a
+    // library feature until bootstrap gets bumped
+}
+
 /// Inline assembly.
 ///
 /// Refer to [Rust By Example] for a usage guide and the [reference] for
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 0917631e04500..9306581dca93d 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -260,6 +260,7 @@
 #![feature(powerpc_target_feature)]
 #![feature(riscv_target_feature)]
 #![feature(rtm_target_feature)]
+#![feature(sha512_sm_x86)]
 #![feature(sse4a_target_feature)]
 #![feature(tbm_target_feature)]
 #![feature(wasm_target_feature)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 37417f38b5448..05e33d47bac39 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -667,7 +667,6 @@ mod panicking;
 #[allow(dead_code, unused_attributes, fuzzy_provenance_casts, unsafe_op_in_unsafe_fn)]
 mod backtrace_rs;
 
-// Re-export macros defined in core.
 #[unstable(feature = "cfg_match", issue = "115585")]
 pub use core::cfg_match;
 #[unstable(
@@ -686,6 +685,7 @@ pub use core::{
     env, file, format_args, format_args_nl, include, include_bytes, include_str, line, log_syntax,
     module_path, option_env, stringify, trace_macros,
 };
+// Re-export macros defined in core.
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow(deprecated, deprecated_in_future)]
 pub use core::{
diff --git a/library/std/src/os/fd/raw.rs b/library/std/src/os/fd/raw.rs
index 1e6ecd7d7a67a..0d99d5492a268 100644
--- a/library/std/src/os/fd/raw.rs
+++ b/library/std/src/os/fd/raw.rs
@@ -138,6 +138,7 @@ pub trait IntoRawFd {
     /// let raw_fd: RawFd = f.into_raw_fd();
     /// # Ok::<(), io::Error>(())
     /// ```
+    #[must_use = "losing the raw file descriptor may leak resources"]
     #[stable(feature = "into_raw_os", since = "1.4.0")]
     fn into_raw_fd(self) -> RawFd;
 }
diff --git a/library/std/src/os/solid/io.rs b/library/std/src/os/solid/io.rs
index 9e89d9fbc1b81..2d18f33961506 100644
--- a/library/std/src/os/solid/io.rs
+++ b/library/std/src/os/solid/io.rs
@@ -342,6 +342,7 @@ pub trait IntoRawFd {
     /// This function **transfers ownership** of the underlying file descriptor
     /// to the caller. Callers are then the unique owners of the file descriptor
     /// and must close the descriptor once it's no longer needed.
+    #[must_use = "losing the raw file descriptor may leak resources"]
     fn into_raw_fd(self) -> RawFd;
 }
 
diff --git a/library/std/src/os/windows/io/raw.rs b/library/std/src/os/windows/io/raw.rs
index 4ba07e3d2afa5..6658248d574c9 100644
--- a/library/std/src/os/windows/io/raw.rs
+++ b/library/std/src/os/windows/io/raw.rs
@@ -85,6 +85,7 @@ pub trait IntoRawHandle {
     /// However, transferring ownership is not strictly required. Use a
     /// `Into<OwnedHandle>::into` implementation for an API which strictly
     /// transfers ownership.
+    #[must_use = "losing the raw handle may leak resources"]
     #[stable(feature = "into_raw_os", since = "1.4.0")]
     fn into_raw_handle(self) -> RawHandle;
 }
@@ -228,6 +229,7 @@ pub trait IntoRawSocket {
     /// However, transferring ownership is not strictly required. Use a
     /// `Into<OwnedSocket>::into` implementation for an API which strictly
     /// transfers ownership.
+    #[must_use = "losing the raw socket may leak resources"]
     #[stable(feature = "into_raw_os", since = "1.4.0")]
     fn into_raw_socket(self) -> RawSocket;
 }
diff --git a/library/std/src/sys/pal/sgx/thread.rs b/library/std/src/sys/pal/sgx/thread.rs
index df65d1cc8fc48..cecd53c352c5a 100644
--- a/library/std/src/sys/pal/sgx/thread.rs
+++ b/library/std/src/sys/pal/sgx/thread.rs
@@ -1,4 +1,5 @@
 #![cfg_attr(test, allow(dead_code))] // why is this necessary?
+
 use super::abi::usercalls;
 use super::unsupported;
 use crate::ffi::CStr;
diff --git a/library/std/src/sys/pal/unix/kernel_copy.rs b/library/std/src/sys/pal/unix/kernel_copy.rs
index 652b2e1feb7ad..a671383cb7957 100644
--- a/library/std/src/sys/pal/unix/kernel_copy.rs
+++ b/library/std/src/sys/pal/unix/kernel_copy.rs
@@ -60,6 +60,7 @@ use crate::net::TcpStream;
 use crate::os::unix::fs::FileTypeExt;
 use crate::os::unix::io::{AsRawFd, FromRawFd, RawFd};
 use crate::os::unix::net::UnixStream;
+use crate::pipe::{PipeReader, PipeWriter};
 use crate::process::{ChildStderr, ChildStdin, ChildStdout};
 use crate::ptr;
 use crate::sync::atomic::{AtomicBool, AtomicU8, Ordering};
@@ -405,6 +406,30 @@ impl CopyWrite for &UnixStream {
     }
 }
 
+impl CopyRead for PipeReader {
+    fn properties(&self) -> CopyParams {
+        CopyParams(FdMeta::Pipe, Some(self.as_raw_fd()))
+    }
+}
+
+impl CopyRead for &PipeReader {
+    fn properties(&self) -> CopyParams {
+        CopyParams(FdMeta::Pipe, Some(self.as_raw_fd()))
+    }
+}
+
+impl CopyWrite for PipeWriter {
+    fn properties(&self) -> CopyParams {
+        CopyParams(FdMeta::Pipe, Some(self.as_raw_fd()))
+    }
+}
+
+impl CopyWrite for &PipeWriter {
+    fn properties(&self) -> CopyParams {
+        CopyParams(FdMeta::Pipe, Some(self.as_raw_fd()))
+    }
+}
+
 impl CopyWrite for ChildStdin {
     fn properties(&self) -> CopyParams {
         CopyParams(FdMeta::Pipe, Some(self.as_raw_fd()))
diff --git a/library/std/src/sys/pal/windows/net.rs b/library/std/src/sys/pal/windows/net.rs
index e27fdb72256f4..ce995f5ed5af7 100644
--- a/library/std/src/sys/pal/windows/net.rs
+++ b/library/std/src/sys/pal/windows/net.rs
@@ -21,6 +21,7 @@ pub mod netc {
     //!
     //! Some Windows API types are not quite what's expected by our cross-platform
     //! net code. E.g. naming differences or different pointer types.
+
     use core::ffi::{c_char, c_int, c_uint, c_ulong, c_ushort, c_void};
 
     use crate::sys::c::{self, ADDRESS_FAMILY, ADDRINFOA, SOCKADDR, SOCKET};
diff --git a/library/std/src/sys/pal/windows/process.rs b/library/std/src/sys/pal/windows/process.rs
index c285e1530a521..06eae5a07b068 100644
--- a/library/std/src/sys/pal/windows/process.rs
+++ b/library/std/src/sys/pal/windows/process.rs
@@ -564,7 +564,7 @@ impl Stdio {
             Ok(io) => unsafe {
                 let io = Handle::from_raw_handle(io);
                 let ret = io.duplicate(0, true, c::DUPLICATE_SAME_ACCESS);
-                io.into_raw_handle();
+                let _ = io.into_raw_handle(); // Don't close the handle
                 ret
             },
             // If no stdio handle is available, then propagate the null value.
diff --git a/library/std/src/sys/pal/windows/stdio.rs b/library/std/src/sys/pal/windows/stdio.rs
index dc63a2219c315..575f2250eb91c 100644
--- a/library/std/src/sys/pal/windows/stdio.rs
+++ b/library/std/src/sys/pal/windows/stdio.rs
@@ -94,7 +94,7 @@ fn write(handle_id: u32, data: &[u8], incomplete_utf8: &mut IncompleteUtf8) -> i
         unsafe {
             let handle = Handle::from_raw_handle(handle);
             let ret = handle.write(data);
-            handle.into_raw_handle(); // Don't close the handle
+            let _ = handle.into_raw_handle(); // Don't close the handle
             return ret;
         }
     }
@@ -243,7 +243,7 @@ impl io::Read for Stdin {
             unsafe {
                 let handle = Handle::from_raw_handle(handle);
                 let ret = handle.read(buf);
-                handle.into_raw_handle(); // Don't close the handle
+                let _ = handle.into_raw_handle(); // Don't close the handle
                 return ret;
             }
         }
diff --git a/src/tools/compiletest/src/command-list.rs b/src/tools/compiletest/src/command-list.rs
index 288f90ea12399..0706f3bee05c1 100644
--- a/src/tools/compiletest/src/command-list.rs
+++ b/src/tools/compiletest/src/command-list.rs
@@ -18,6 +18,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "check-test-line-numbers-match",
     "compare-output-lines-by-subset",
     "compile-flags",
+    "doc-flags",
     "dont-check-compiler-stderr",
     "dont-check-compiler-stdout",
     "dont-check-failure-status",
@@ -226,6 +227,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "should-ice",
     "stderr-per-bitwidth",
     "test-mir-pass",
+    "unique-doc-out-dir",
     "unset-exec-env",
     "unset-rustc-env",
     // Used by the tidy check `unknown_revision`.
diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index cde3e3295c631..1fc24301c85e6 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -95,6 +95,8 @@ pub struct TestProps {
     pub compile_flags: Vec<String>,
     // Extra flags to pass when the compiled code is run (such as --bench)
     pub run_flags: Vec<String>,
+    /// Extra flags to pass to rustdoc but not the compiler.
+    pub doc_flags: Vec<String>,
     // If present, the name of a file that this test should match when
     // pretty-printed
     pub pp_exact: Option<PathBuf>,
@@ -122,6 +124,9 @@ pub struct TestProps {
     pub unset_exec_env: Vec<String>,
     // Build documentation for all specified aux-builds as well
     pub build_aux_docs: bool,
+    /// Build the documentation for each crate in a unique output directory.
+    /// Uses <root output directory>/docs/<test name>/doc
+    pub unique_doc_out_dir: bool,
     // Flag to force a crate to be built with the host architecture
     pub force_host: bool,
     // Check stdout for error-pattern output as well as stderr
@@ -220,8 +225,10 @@ mod directives {
     pub const REGEX_ERROR_PATTERN: &'static str = "regex-error-pattern";
     pub const COMPILE_FLAGS: &'static str = "compile-flags";
     pub const RUN_FLAGS: &'static str = "run-flags";
+    pub const DOC_FLAGS: &'static str = "doc-flags";
     pub const SHOULD_ICE: &'static str = "should-ice";
     pub const BUILD_AUX_DOCS: &'static str = "build-aux-docs";
+    pub const UNIQUE_DOC_OUT_DIR: &'static str = "unique-doc-out-dir";
     pub const FORCE_HOST: &'static str = "force-host";
     pub const CHECK_STDOUT: &'static str = "check-stdout";
     pub const CHECK_RUN_RESULTS: &'static str = "check-run-results";
@@ -267,6 +274,7 @@ impl TestProps {
             regex_error_patterns: vec![],
             compile_flags: vec![],
             run_flags: vec![],
+            doc_flags: vec![],
             pp_exact: None,
             aux_builds: vec![],
             aux_bins: vec![],
@@ -281,6 +289,7 @@ impl TestProps {
             exec_env: vec![],
             unset_exec_env: vec![],
             build_aux_docs: false,
+            unique_doc_out_dir: false,
             force_host: false,
             check_stdout: false,
             check_run_results: false,
@@ -378,6 +387,8 @@ impl TestProps {
                         |r| r,
                     );
 
+                    config.push_name_value_directive(ln, DOC_FLAGS, &mut self.doc_flags, |r| r);
+
                     fn split_flags(flags: &str) -> Vec<String> {
                         // Individual flags can be single-quoted to preserve spaces; see
                         // <https://github.com/rust-lang/rust/pull/115948/commits/957c5db6>.
@@ -415,6 +426,8 @@ impl TestProps {
 
                     config.set_name_directive(ln, SHOULD_ICE, &mut self.should_ice);
                     config.set_name_directive(ln, BUILD_AUX_DOCS, &mut self.build_aux_docs);
+                    config.set_name_directive(ln, UNIQUE_DOC_OUT_DIR, &mut self.unique_doc_out_dir);
+
                     config.set_name_directive(ln, FORCE_HOST, &mut self.force_host);
                     config.set_name_directive(ln, CHECK_STDOUT, &mut self.check_stdout);
                     config.set_name_directive(ln, CHECK_RUN_RESULTS, &mut self.check_run_results);
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 1f15605d8beed..b1b6d6fc8eb18 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -1,5 +1,6 @@
 // ignore-tidy-filelength
 
+use std::borrow::Cow;
 use std::collections::{HashMap, HashSet};
 use std::ffi::{OsStr, OsString};
 use std::fs::{self, create_dir_all, File, OpenOptions};
@@ -723,7 +724,7 @@ impl<'test> TestCx<'test> {
         self.maybe_add_external_args(&mut rustc, &self.config.target_rustcflags);
         rustc.args(&self.props.compile_flags);
 
-        self.compose_and_run_compiler(rustc, Some(src))
+        self.compose_and_run_compiler(rustc, Some(src), self.testpaths)
     }
 
     fn run_debuginfo_test(&self) {
@@ -1579,13 +1580,15 @@ impl<'test> TestCx<'test> {
             passes,
         );
 
-        self.compose_and_run_compiler(rustc, None)
+        self.compose_and_run_compiler(rustc, None, self.testpaths)
     }
 
-    fn document(&self, out_dir: &Path) -> ProcRes {
+    /// `root_out_dir` and `root_testpaths` refer to the parameters of the actual test being run.
+    /// Auxiliaries, no matter how deep, have the same root_out_dir and root_testpaths.
+    fn document(&self, root_out_dir: &Path, root_testpaths: &TestPaths) -> ProcRes {
         if self.props.build_aux_docs {
             for rel_ab in &self.props.aux_builds {
-                let aux_testpaths = self.compute_aux_test_paths(&self.testpaths, rel_ab);
+                let aux_testpaths = self.compute_aux_test_paths(root_testpaths, rel_ab);
                 let aux_props =
                     self.props.from_aux_file(&aux_testpaths.file, self.revision, self.config);
                 let aux_cx = TestCx {
@@ -1596,7 +1599,9 @@ impl<'test> TestCx<'test> {
                 };
                 // Create the directory for the stdout/stderr files.
                 create_dir_all(aux_cx.output_base_dir()).unwrap();
-                let auxres = aux_cx.document(out_dir);
+                // use root_testpaths here, because aux-builds should have the
+                // same --out-dir and auxiliary directory.
+                let auxres = aux_cx.document(&root_out_dir, root_testpaths);
                 if !auxres.status.success() {
                     return auxres;
                 }
@@ -1606,21 +1611,40 @@ impl<'test> TestCx<'test> {
         let aux_dir = self.aux_output_dir_name();
 
         let rustdoc_path = self.config.rustdoc_path.as_ref().expect("--rustdoc-path not passed");
-        let mut rustdoc = Command::new(rustdoc_path);
 
+        // actual --out-dir given to the auxiliary or test, as opposed to the root out dir for the entire
+        // test
+        let out_dir: Cow<'_, Path> = if self.props.unique_doc_out_dir {
+            let file_name = self.testpaths.file.file_stem().expect("file name should not be empty");
+            let out_dir = PathBuf::from_iter([
+                root_out_dir,
+                Path::new("docs"),
+                Path::new(file_name),
+                Path::new("doc"),
+            ]);
+            create_dir_all(&out_dir).unwrap();
+            Cow::Owned(out_dir)
+        } else {
+            Cow::Borrowed(root_out_dir)
+        };
+
+        let mut rustdoc = Command::new(rustdoc_path);
+        let current_dir = output_base_dir(self.config, root_testpaths, self.safe_revision());
+        rustdoc.current_dir(current_dir);
         rustdoc
             .arg("-L")
             .arg(self.config.run_lib_path.to_str().unwrap())
             .arg("-L")
             .arg(aux_dir)
             .arg("-o")
-            .arg(out_dir)
+            .arg(out_dir.as_ref())
             .arg("--deny")
             .arg("warnings")
             .arg(&self.testpaths.file)
             .arg("-A")
             .arg("internal_features")
-            .args(&self.props.compile_flags);
+            .args(&self.props.compile_flags)
+            .args(&self.props.doc_flags);
 
         if self.config.mode == RustdocJson {
             rustdoc.arg("--output-format").arg("json").arg("-Zunstable-options");
@@ -1630,7 +1654,7 @@ impl<'test> TestCx<'test> {
             rustdoc.arg(format!("-Clinker={}", linker));
         }
 
-        self.compose_and_run_compiler(rustdoc, None)
+        self.compose_and_run_compiler(rustdoc, None, root_testpaths)
     }
 
     fn exec_compiled_test(&self) -> ProcRes {
@@ -1828,9 +1852,16 @@ impl<'test> TestCx<'test> {
         }
     }
 
-    fn compose_and_run_compiler(&self, mut rustc: Command, input: Option<String>) -> ProcRes {
+    /// `root_testpaths` refers to the path of the original test.
+    /// the auxiliary and the test with an aux-build have the same `root_testpaths`.
+    fn compose_and_run_compiler(
+        &self,
+        mut rustc: Command,
+        input: Option<String>,
+        root_testpaths: &TestPaths,
+    ) -> ProcRes {
         let aux_dir = self.aux_output_dir();
-        self.build_all_auxiliary(&self.testpaths, &aux_dir, &mut rustc);
+        self.build_all_auxiliary(root_testpaths, &aux_dir, &mut rustc);
 
         rustc.envs(self.props.rustc_env.clone());
         self.props.unset_rustc_env.iter().fold(&mut rustc, Command::env_remove);
@@ -2545,7 +2576,7 @@ impl<'test> TestCx<'test> {
             Vec::new(),
         );
 
-        let proc_res = self.compose_and_run_compiler(rustc, None);
+        let proc_res = self.compose_and_run_compiler(rustc, None, self.testpaths);
         let output_path = self.get_filecheck_file("ll");
         (proc_res, output_path)
     }
@@ -2581,7 +2612,7 @@ impl<'test> TestCx<'test> {
             Vec::new(),
         );
 
-        let proc_res = self.compose_and_run_compiler(rustc, None);
+        let proc_res = self.compose_and_run_compiler(rustc, None, self.testpaths);
         let output_path = self.get_filecheck_file("s");
         (proc_res, output_path)
     }
@@ -2664,7 +2695,7 @@ impl<'test> TestCx<'test> {
         let out_dir = self.output_base_dir();
         remove_and_create_dir_all(&out_dir);
 
-        let proc_res = self.document(&out_dir);
+        let proc_res = self.document(&out_dir, &self.testpaths);
         if !proc_res.status.success() {
             self.fatal_proc_rec("rustdoc failed!", &proc_res);
         }
@@ -2723,7 +2754,7 @@ impl<'test> TestCx<'test> {
         let aux_dir = new_rustdoc.aux_output_dir();
         new_rustdoc.build_all_auxiliary(&new_rustdoc.testpaths, &aux_dir, &mut rustc);
 
-        let proc_res = new_rustdoc.document(&compare_dir);
+        let proc_res = new_rustdoc.document(&compare_dir, &new_rustdoc.testpaths);
         if !proc_res.status.success() {
             eprintln!("failed to run nightly rustdoc");
             return;
@@ -2847,7 +2878,7 @@ impl<'test> TestCx<'test> {
         let out_dir = self.output_base_dir();
         remove_and_create_dir_all(&out_dir);
 
-        let proc_res = self.document(&out_dir);
+        let proc_res = self.document(&out_dir, &self.testpaths);
         if !proc_res.status.success() {
             self.fatal_proc_rec("rustdoc failed!", &proc_res);
         }
@@ -2923,31 +2954,24 @@ impl<'test> TestCx<'test> {
     fn check_rustdoc_test_option(&self, res: ProcRes) {
         let mut other_files = Vec::new();
         let mut files: HashMap<String, Vec<usize>> = HashMap::new();
-        let cwd = env::current_dir().unwrap();
-        files.insert(
-            self.testpaths
-                .file
-                .strip_prefix(&cwd)
-                .unwrap_or(&self.testpaths.file)
-                .to_str()
-                .unwrap()
-                .replace('\\', "/"),
-            self.get_lines(&self.testpaths.file, Some(&mut other_files)),
-        );
+        let normalized = fs::canonicalize(&self.testpaths.file).expect("failed to canonicalize");
+        let normalized = normalized.to_str().unwrap().replace('\\', "/");
+        files.insert(normalized, self.get_lines(&self.testpaths.file, Some(&mut other_files)));
         for other_file in other_files {
             let mut path = self.testpaths.file.clone();
             path.set_file_name(&format!("{}.rs", other_file));
-            files.insert(
-                path.strip_prefix(&cwd).unwrap_or(&path).to_str().unwrap().replace('\\', "/"),
-                self.get_lines(&path, None),
-            );
+            let path = fs::canonicalize(path).expect("failed to canonicalize");
+            let normalized = path.to_str().unwrap().replace('\\', "/");
+            files.insert(normalized, self.get_lines(&path, None));
         }
 
         let mut tested = 0;
         for _ in res.stdout.split('\n').filter(|s| s.starts_with("test ")).inspect(|s| {
             if let Some((left, right)) = s.split_once(" - ") {
                 let path = left.rsplit("test ").next().unwrap();
-                if let Some(ref mut v) = files.get_mut(&path.replace('\\', "/")) {
+                let path = fs::canonicalize(&path).expect("failed to canonicalize");
+                let path = path.to_str().unwrap().replace('\\', "/");
+                if let Some(ref mut v) = files.get_mut(&path) {
                     tested += 1;
                     let mut iter = right.split("(line ");
                     iter.next();
@@ -3779,7 +3803,7 @@ impl<'test> TestCx<'test> {
         if let Some(nodejs) = &self.config.nodejs {
             let out_dir = self.output_base_dir();
 
-            self.document(&out_dir);
+            self.document(&out_dir, &self.testpaths);
 
             let root = self.config.find_rust_src_root().unwrap();
             let file_stem =
@@ -4095,7 +4119,7 @@ impl<'test> TestCx<'test> {
                 rustc.arg(crate_name);
             }
 
-            let res = self.compose_and_run_compiler(rustc, None);
+            let res = self.compose_and_run_compiler(rustc, None, self.testpaths);
             if !res.status.success() {
                 self.fatal_proc_rec("failed to compile fixed code", &res);
             }
diff --git a/src/tools/compiletest/src/runtest/coverage.rs b/src/tools/compiletest/src/runtest/coverage.rs
index 6ee147da5a965..05191a159801c 100644
--- a/src/tools/compiletest/src/runtest/coverage.rs
+++ b/src/tools/compiletest/src/runtest/coverage.rs
@@ -191,7 +191,7 @@ impl<'test> TestCx<'test> {
 
         rustdoc_cmd.arg(&self.testpaths.file);
 
-        let proc_res = self.compose_and_run_compiler(rustdoc_cmd, None);
+        let proc_res = self.compose_and_run_compiler(rustdoc_cmd, None, self.testpaths);
         if !proc_res.status.success() {
             self.fatal_proc_rec("rustdoc --test failed!", &proc_res)
         }
diff --git a/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/auxiliary/q.rs b/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/auxiliary/q.rs
new file mode 100644
index 0000000000000..5d0881029cb2f
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/auxiliary/q.rs
@@ -0,0 +1,2 @@
+//@ build-aux-docs
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/auxiliary/t.rs b/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/auxiliary/t.rs
new file mode 100644
index 0000000000000..fab9ec4a92b96
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/auxiliary/t.rs
@@ -0,0 +1,4 @@
+//@ aux-build:q.rs
+//@ build-aux-docs
+extern crate q;
+pub trait Tango {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/s.rs b/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/s.rs
new file mode 100644
index 0000000000000..85c460ace642f
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-transitive-no-index/s.rs
@@ -0,0 +1,16 @@
+//@ aux-build:t.rs
+//@ build-aux-docs
+//@ has q/struct.Quebec.html
+//@ has s/struct.Sierra.html
+//@ has t/trait.Tango.html
+//@ hasraw s/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/t/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Quebec'
+
+// We document multiple crates into the same output directory, which
+// merges the cross-crate information. Everything is available.
+extern crate t;
+pub struct Sierra;
+impl t::Tango for Sierra {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-transitive/auxiliary/q.rs b/tests/rustdoc/cross-crate-info/cargo-transitive/auxiliary/q.rs
new file mode 100644
index 0000000000000..932a0b17206d6
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-transitive/auxiliary/q.rs
@@ -0,0 +1,5 @@
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/cargo-transitive/auxiliary/t.rs b/tests/rustdoc/cross-crate-info/cargo-transitive/auxiliary/t.rs
new file mode 100644
index 0000000000000..c21a59c65188f
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-transitive/auxiliary/t.rs
@@ -0,0 +1,7 @@
+//@ aux-build:q.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate q;
+pub trait Tango {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-transitive/s.rs b/tests/rustdoc/cross-crate-info/cargo-transitive/s.rs
new file mode 100644
index 0000000000000..68bfc34883bd8
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-transitive/s.rs
@@ -0,0 +1,24 @@
+//@ aux-build:t.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="q/index.html"]' 'q'
+//@ has index.html '//ul[@class="all-items"]//a[@href="s/index.html"]' 's'
+//@ has index.html '//ul[@class="all-items"]//a[@href="t/index.html"]' 't'
+//@ has q/struct.Quebec.html
+//@ has s/struct.Sierra.html
+//@ has t/trait.Tango.html
+//@ hasraw s/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/t/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Tango'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Quebec'
+
+// We document multiple crates into the same output directory, which
+// merges the cross-crate information. Everything is available.
+extern crate t;
+pub struct Sierra;
+impl t::Tango for Sierra {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-two-no-index/auxiliary/f.rs b/tests/rustdoc/cross-crate-info/cargo-two-no-index/auxiliary/f.rs
new file mode 100644
index 0000000000000..abc580a388cd2
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-two-no-index/auxiliary/f.rs
@@ -0,0 +1,2 @@
+//@ build-aux-docs
+pub trait Foxtrot {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-two-no-index/e.rs b/tests/rustdoc/cross-crate-info/cargo-two-no-index/e.rs
new file mode 100644
index 0000000000000..c93298f969eab
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-two-no-index/e.rs
@@ -0,0 +1,14 @@
+//@ aux-build:f.rs
+//@ build-aux-docs
+//@ has e/enum.Echo.html
+//@ has f/trait.Foxtrot.html
+//@ hasraw e/enum.Echo.html 'Foxtrot'
+//@ hasraw trait.impl/f/trait.Foxtrot.js 'enum.Echo.html'
+//@ hasraw search-index.js 'Foxtrot'
+//@ hasraw search-index.js 'Echo'
+
+// document two crates in the same way that cargo does. do not provide
+// --enable-index-page
+extern crate f;
+pub enum Echo {}
+impl f::Foxtrot for Echo {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-two/auxiliary/f.rs b/tests/rustdoc/cross-crate-info/cargo-two/auxiliary/f.rs
new file mode 100644
index 0000000000000..a2a7033b13112
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-two/auxiliary/f.rs
@@ -0,0 +1,5 @@
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub trait Foxtrot {}
diff --git a/tests/rustdoc/cross-crate-info/cargo-two/e.rs b/tests/rustdoc/cross-crate-info/cargo-two/e.rs
new file mode 100644
index 0000000000000..00f86cbc34889
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/cargo-two/e.rs
@@ -0,0 +1,21 @@
+//@ aux-build:f.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="f/index.html"]' 'f'
+//@ has index.html '//ul[@class="all-items"]//a[@href="e/index.html"]' 'e'
+//@ has e/enum.Echo.html
+//@ has f/trait.Foxtrot.html
+//@ hasraw e/enum.Echo.html 'Foxtrot'
+//@ hasraw trait.impl/f/trait.Foxtrot.js 'enum.Echo.html'
+//@ hasraw search-index.js 'Foxtrot'
+//@ hasraw search-index.js 'Echo'
+
+// document two crates in the same way that cargo does, writing them both
+// into the same output directory
+extern crate f;
+pub enum Echo {}
+impl f::Foxtrot for Echo {}
diff --git a/tests/rustdoc/cross-crate-info/index-on-last/auxiliary/f.rs b/tests/rustdoc/cross-crate-info/index-on-last/auxiliary/f.rs
new file mode 100644
index 0000000000000..abc580a388cd2
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/index-on-last/auxiliary/f.rs
@@ -0,0 +1,2 @@
+//@ build-aux-docs
+pub trait Foxtrot {}
diff --git a/tests/rustdoc/cross-crate-info/index-on-last/e.rs b/tests/rustdoc/cross-crate-info/index-on-last/e.rs
new file mode 100644
index 0000000000000..ffee898cd966d
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/index-on-last/e.rs
@@ -0,0 +1,20 @@
+//@ aux-build:f.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="f/index.html"]' 'f'
+//@ has index.html '//ul[@class="all-items"]//a[@href="e/index.html"]' 'e'
+//@ has e/enum.Echo.html
+//@ has f/trait.Foxtrot.html
+//@ hasraw e/enum.Echo.html 'Foxtrot'
+//@ hasraw trait.impl/f/trait.Foxtrot.js 'enum.Echo.html'
+//@ hasraw search-index.js 'Foxtrot'
+//@ hasraw search-index.js 'Echo'
+
+// only declare --enable-index-page to the last rustdoc invocation
+extern crate f;
+pub enum Echo {}
+impl f::Foxtrot for Echo {}
diff --git a/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/q.rs b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/q.rs
new file mode 100644
index 0000000000000..932a0b17206d6
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/q.rs
@@ -0,0 +1,5 @@
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/r.rs b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/r.rs
new file mode 100644
index 0000000000000..2c0db2abc53d9
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/r.rs
@@ -0,0 +1,7 @@
+//@ aux-build:s.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate s;
+pub type Romeo = s::Sierra;
diff --git a/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/s.rs b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/s.rs
new file mode 100644
index 0000000000000..355d3f1aaa883
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/s.rs
@@ -0,0 +1,8 @@
+//@ aux-build:t.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate t;
+pub struct Sierra;
+impl t::Tango for Sierra {}
diff --git a/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/t.rs b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/t.rs
new file mode 100644
index 0000000000000..c21a59c65188f
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/kitchen-sink/auxiliary/t.rs
@@ -0,0 +1,7 @@
+//@ aux-build:q.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+extern crate q;
+pub trait Tango {}
diff --git a/tests/rustdoc/cross-crate-info/kitchen-sink/i.rs b/tests/rustdoc/cross-crate-info/kitchen-sink/i.rs
new file mode 100644
index 0000000000000..bcb9464795af2
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/kitchen-sink/i.rs
@@ -0,0 +1,30 @@
+//@ aux-build:r.rs
+//@ aux-build:q.rs
+//@ aux-build:t.rs
+//@ aux-build:s.rs
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html
+//@ has index.html '//ul[@class="all-items"]//a[@href="i/index.html"]' 'i'
+//@ has index.html '//ul[@class="all-items"]//a[@href="q/index.html"]' 'q'
+//@ has index.html '//ul[@class="all-items"]//a[@href="r/index.html"]' 'r'
+//@ has index.html '//ul[@class="all-items"]//a[@href="s/index.html"]' 's'
+//@ has index.html '//ul[@class="all-items"]//a[@href="t/index.html"]' 't'
+//@ has q/struct.Quebec.html
+//@ has r/type.Romeo.html
+//@ has s/struct.Sierra.html
+//@ has t/trait.Tango.html
+//@ hasraw s/struct.Sierra.html 'Tango'
+//@ hasraw trait.impl/t/trait.Tango.js 'struct.Sierra.html'
+//@ hasraw search-index.js 'Quebec'
+//@ hasraw search-index.js 'Romeo'
+//@ hasraw search-index.js 'Sierra'
+//@ hasraw search-index.js 'Tango'
+//@ has type.impl/s/struct.Sierra.js
+//@ hasraw type.impl/s/struct.Sierra.js 'Tango'
+//@ hasraw type.impl/s/struct.Sierra.js 'Romeo'
+
+// document everything in the default mode
diff --git a/tests/rustdoc/cross-crate-info/single-crate-baseline/q.rs b/tests/rustdoc/cross-crate-info/single-crate-baseline/q.rs
new file mode 100644
index 0000000000000..c5e3dc0a0f4e5
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/single-crate-baseline/q.rs
@@ -0,0 +1,12 @@
+//@ build-aux-docs
+//@ doc-flags:--enable-index-page
+//@ doc-flags:-Zunstable-options
+
+//@ has index.html
+//@ has index.html '//h1' 'List of all crates'
+//@ has index.html '//ul[@class="all-items"]//a[@href="q/index.html"]' 'q'
+//@ has q/struct.Quebec.html
+//@ hasraw search-index.js 'Quebec'
+
+// there's nothing cross-crate going on here
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/single-crate-no-index/q.rs b/tests/rustdoc/cross-crate-info/single-crate-no-index/q.rs
new file mode 100644
index 0000000000000..d3e71fa0ce35f
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/single-crate-no-index/q.rs
@@ -0,0 +1,6 @@
+//@ build-aux-docs
+//@ has q/struct.Quebec.html
+//@ hasraw search-index.js 'Quebec'
+
+// there's nothing cross-crate going on here
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/transitive/auxiliary/q.rs b/tests/rustdoc/cross-crate-info/transitive/auxiliary/q.rs
new file mode 100644
index 0000000000000..5d0881029cb2f
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/transitive/auxiliary/q.rs
@@ -0,0 +1,2 @@
+//@ build-aux-docs
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/transitive/auxiliary/t.rs b/tests/rustdoc/cross-crate-info/transitive/auxiliary/t.rs
new file mode 100644
index 0000000000000..fab9ec4a92b96
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/transitive/auxiliary/t.rs
@@ -0,0 +1,4 @@
+//@ aux-build:q.rs
+//@ build-aux-docs
+extern crate q;
+pub trait Tango {}
diff --git a/tests/rustdoc/cross-crate-info/transitive/s.rs b/tests/rustdoc/cross-crate-info/transitive/s.rs
new file mode 100644
index 0000000000000..0a4e5f646ddaa
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/transitive/s.rs
@@ -0,0 +1,6 @@
+//@ aux-build:t.rs
+//@ build-aux-docs
+// simple test to see if we support building transitive crates
+extern crate t;
+pub struct Sierra;
+impl t::Tango for Sierra {}
diff --git a/tests/rustdoc/cross-crate-info/two/auxiliary/f.rs b/tests/rustdoc/cross-crate-info/two/auxiliary/f.rs
new file mode 100644
index 0000000000000..abc580a388cd2
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/two/auxiliary/f.rs
@@ -0,0 +1,2 @@
+//@ build-aux-docs
+pub trait Foxtrot {}
diff --git a/tests/rustdoc/cross-crate-info/two/e.rs b/tests/rustdoc/cross-crate-info/two/e.rs
new file mode 100644
index 0000000000000..9665af62706d1
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/two/e.rs
@@ -0,0 +1,6 @@
+//@ aux-build:f.rs
+//@ build-aux-docs
+// simple test to assert that we can do a two-level aux-build
+extern crate f;
+pub enum Echo {}
+impl f::Foxtrot for Echo {}
diff --git a/tests/rustdoc/cross-crate-info/working-dir-examples/q.rs b/tests/rustdoc/cross-crate-info/working-dir-examples/q.rs
new file mode 100644
index 0000000000000..a7ab062fd9e28
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/working-dir-examples/q.rs
@@ -0,0 +1,10 @@
+//@ build-aux-docs
+//@ doc-flags:--scrape-examples-output-path=examples
+//@ doc-flags:--scrape-examples-target-crate=q
+//@ doc-flags:-Zunstable-options
+
+//@ has examples
+
+// where will --scrape-examples-output-path resolve the path to be?
+// should be the root output directory
+pub struct Quebec;
diff --git a/tests/rustdoc/cross-crate-info/write-docs-somewhere-else/auxiliary/f.rs b/tests/rustdoc/cross-crate-info/write-docs-somewhere-else/auxiliary/f.rs
new file mode 100644
index 0000000000000..f8c9adcaf9cad
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/write-docs-somewhere-else/auxiliary/f.rs
@@ -0,0 +1,3 @@
+//@ build-aux-docs
+//@ unique-doc-out-dir
+pub trait Foxtrot {}
diff --git a/tests/rustdoc/cross-crate-info/write-docs-somewhere-else/e.rs b/tests/rustdoc/cross-crate-info/write-docs-somewhere-else/e.rs
new file mode 100644
index 0000000000000..9dcec211e1787
--- /dev/null
+++ b/tests/rustdoc/cross-crate-info/write-docs-somewhere-else/e.rs
@@ -0,0 +1,14 @@
+//@ aux-build:f.rs
+//@ build-aux-docs
+//@ has e/enum.Echo.html
+//@ !has f/trait.Foxtrot.html
+//@ hasraw e/enum.Echo.html 'Foxtrot'
+//@ hasraw trait.impl/f/trait.Foxtrot.js 'enum.Echo.html'
+//@ !hasraw search-index.js 'Foxtrot'
+//@ hasraw search-index.js 'Echo'
+
+// test the fact that our test runner will document this crate somewhere
+// else
+extern crate f;
+pub enum Echo {}
+impl f::Foxtrot for Echo {}
diff --git a/tests/ui/check-cfg/mix.stderr b/tests/ui/check-cfg/mix.stderr
index 57cbe173c7896..520cffc4b0268 100644
--- a/tests/ui/check-cfg/mix.stderr
+++ b/tests/ui/check-cfg/mix.stderr
@@ -251,7 +251,7 @@ warning: unexpected `cfg` condition value: `zebra`
 LL |     cfg!(target_feature = "zebra");
    |          ^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 199 more
+   = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, and `avx512vpopcntdq` and 201 more
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
 
 warning: 27 warnings emitted
diff --git a/tests/ui/check-cfg/well-known-values.stderr b/tests/ui/check-cfg/well-known-values.stderr
index 00abb5f5e5ca0..d780e04e729a2 100644
--- a/tests/ui/check-cfg/well-known-values.stderr
+++ b/tests/ui/check-cfg/well-known-values.stderr
@@ -165,7 +165,7 @@ warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
 LL |     target_feature = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, `avx512vpopcntdq`, `avxifma`, `avxneconvert`, `avxvnni`, `avxvnniint16`, `avxvnniint8`, `backchain`, `bf16`, `bmi1`, `bmi2`, `bti`, `bulk-memory`, `c`, `cache`, `cmpxchg16b`, `crc`, `crt-static`, `d`, `d32`, `dit`, `doloop`, `dotprod`, `dpb`, `dpb2`, `dsp`, `dsp1e2`, `dspe60`, `e`, `e1`, `e2`, `edsp`, `elrw`, `ermsb`, `exception-handling`, `extended-const`, `f`, `f16c`, `f32mm`, `f64mm`, `fcma`, `fdivdu`, `fhm`, `flagm`, `float1e2`, `float1e3`, `float3e4`, `float7e60`, `floate1`, `fma`, `fp-armv8`, `fp16`, `fp64`, `fpuv2_df`, `fpuv2_sf`, `fpuv3_df`, `fpuv3_hf`, `fpuv3_hi`, `fpuv3_sf`, `frecipe`, `frintts`, `fxsr`, `gfni`, `hard-float`, `hard-float-abi`, `hard-tp`, `high-registers`, `hvx`, `hvx-length128b`, `hwdiv`, `i8mm`, `jsconv`, `lahfsahf`, `lasx`, `lbt`, `lor`, `lse`, `lsx`, `lvz`, `lzcnt`, `m`, `mclass`, `movbe`, `mp`, `mp1e2`, `msa`, `mte`, `multivalue`, `mutable-globals`, `neon`, `nontrapping-fptoint`, `nvic`, `paca`, `pacg`, `pan`, `pclmulqdq`, `pmuv3`, `popcnt`, `power10-vector`, `power8-altivec`, `power8-vector`, `power9-altivec`, `power9-vector`, `prfchw`, `rand`, `ras`, `rclass`, `rcpc`, `rcpc2`, `rdm`, `rdrand`, `rdseed`, `reference-types`, `relax`, `relaxed-simd`, `rtm`, `sb`, `sha`, `sha2`, `sha3`, `sign-ext`, `simd128`, `sm4`, `spe`, `ssbs`, `sse`, `sse2`, `sse3`, `sse4.1`, `sse4.2`, `sse4a`, `ssse3`, `sve`, `sve2`, `sve2-aes`, `sve2-bitperm`, `sve2-sha3`, `sve2-sm4`, `tbm`, `thumb-mode`, `thumb2`, `tme`, `trust`, `trustzone`, `ual`, `unaligned-scalar-mem`, `v`, `v5te`, `v6`, `v6k`, `v6t2`, `v7`, `v8`, `v8.1a`, `v8.2a`, `v8.3a`, `v8.4a`, `v8.5a`, `v8.6a`, `v8.7a`, `vaes`, `vdsp2e60f`, `vdspv1`, `vdspv2`, `vector`, `vfp2`, `vfp3`, `vfp4`, `vh`, `virt`, `virtualization`, `vpclmulqdq`, `vsx`, `xop`, `xsave`, `xsavec`, `xsaveopt`, `xsaves`, `zba`, `zbb`, `zbc`, `zbkb`, `zbkc`, `zbkx`, `zbs`, `zdinx`, `zfh`, `zfhmin`, `zfinx`, `zhinx`, `zhinxmin`, `zk`, `zkn`, `zknd`, `zkne`, `zknh`, `zkr`, `zks`, `zksed`, `zksh`, and `zkt`
+   = note: expected values for `target_feature` are: `10e60`, `2e3`, `3e3r1`, `3e3r2`, `3e3r3`, `3e7`, `7e10`, `a`, `aclass`, `adx`, `aes`, `altivec`, `alu32`, `amx-bf16`, `amx-complex`, `amx-fp16`, `amx-int8`, `amx-tile`, `atomics`, `avx`, `avx2`, `avx512bf16`, `avx512bitalg`, `avx512bw`, `avx512cd`, `avx512dq`, `avx512f`, `avx512fp16`, `avx512ifma`, `avx512vbmi`, `avx512vbmi2`, `avx512vl`, `avx512vnni`, `avx512vp2intersect`, `avx512vpopcntdq`, `avxifma`, `avxneconvert`, `avxvnni`, `avxvnniint16`, `avxvnniint8`, `backchain`, `bf16`, `bmi1`, `bmi2`, `bti`, `bulk-memory`, `c`, `cache`, `cmpxchg16b`, `crc`, `crt-static`, `d`, `d32`, `dit`, `doloop`, `dotprod`, `dpb`, `dpb2`, `dsp`, `dsp1e2`, `dspe60`, `e`, `e1`, `e2`, `edsp`, `elrw`, `ermsb`, `exception-handling`, `extended-const`, `f`, `f16c`, `f32mm`, `f64mm`, `fcma`, `fdivdu`, `fhm`, `flagm`, `float1e2`, `float1e3`, `float3e4`, `float7e60`, `floate1`, `fma`, `fp-armv8`, `fp16`, `fp64`, `fpuv2_df`, `fpuv2_sf`, `fpuv3_df`, `fpuv3_hf`, `fpuv3_hi`, `fpuv3_sf`, `frecipe`, `frintts`, `fxsr`, `gfni`, `hard-float`, `hard-float-abi`, `hard-tp`, `high-registers`, `hvx`, `hvx-length128b`, `hwdiv`, `i8mm`, `jsconv`, `lahfsahf`, `lasx`, `lbt`, `lor`, `lse`, `lsx`, `lvz`, `lzcnt`, `m`, `mclass`, `movbe`, `mp`, `mp1e2`, `msa`, `mte`, `multivalue`, `mutable-globals`, `neon`, `nontrapping-fptoint`, `nvic`, `paca`, `pacg`, `pan`, `pclmulqdq`, `pmuv3`, `popcnt`, `power10-vector`, `power8-altivec`, `power8-vector`, `power9-altivec`, `power9-vector`, `prfchw`, `rand`, `ras`, `rclass`, `rcpc`, `rcpc2`, `rdm`, `rdrand`, `rdseed`, `reference-types`, `relax`, `relaxed-simd`, `rtm`, `sb`, `sha`, `sha2`, `sha3`, `sha512`, `sign-ext`, `simd128`, `sm3`, `sm4`, `spe`, `ssbs`, `sse`, `sse2`, `sse3`, `sse4.1`, `sse4.2`, `sse4a`, `ssse3`, `sve`, `sve2`, `sve2-aes`, `sve2-bitperm`, `sve2-sha3`, `sve2-sm4`, `tbm`, `thumb-mode`, `thumb2`, `tme`, `trust`, `trustzone`, `ual`, `unaligned-scalar-mem`, `v`, `v5te`, `v6`, `v6k`, `v6t2`, `v7`, `v8`, `v8.1a`, `v8.2a`, `v8.3a`, `v8.4a`, `v8.5a`, `v8.6a`, `v8.7a`, `vaes`, `vdsp2e60f`, `vdspv1`, `vdspv2`, `vector`, `vfp2`, `vfp3`, `vfp4`, `vh`, `virt`, `virtualization`, `vpclmulqdq`, `vsx`, `xop`, `xsave`, `xsavec`, `xsaveopt`, `xsaves`, `zba`, `zbb`, `zbc`, `zbkb`, `zbkc`, `zbkx`, `zbs`, `zdinx`, `zfh`, `zfhmin`, `zfinx`, `zhinx`, `zhinxmin`, `zk`, `zkn`, `zknd`, `zkne`, `zknh`, `zkr`, `zks`, `zksed`, `zksh`, and `zkt`
    = 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`
diff --git a/tests/ui/feature-gates/feature-gate-sha512_sm_x86.rs b/tests/ui/feature-gates/feature-gate-sha512_sm_x86.rs
new file mode 100644
index 0000000000000..176a40ecf5370
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-sha512_sm_x86.rs
@@ -0,0 +1,6 @@
+//@ only-x86_64
+#[target_feature(enable = "sha512")]
+//~^ ERROR: currently unstable
+unsafe fn foo() {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-sha512_sm_x86.stderr b/tests/ui/feature-gates/feature-gate-sha512_sm_x86.stderr
new file mode 100644
index 0000000000000..da9eea095a332
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-sha512_sm_x86.stderr
@@ -0,0 +1,13 @@
+error[E0658]: the target feature `sha512` is currently unstable
+  --> $DIR/feature-gate-sha512_sm_x86.rs:2:18
+   |
+LL | #[target_feature(enable = "sha512")]
+   |                  ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #126624 <https://github.com/rust-lang/rust/issues/126624> for more information
+   = help: add `#![feature(sha512_sm_x86)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.