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-rw-r--r--compiler/rustc_parse/src/errors.rs2
-rw-r--r--compiler/rustc_parse/src/lexer/tokentrees.rs2
-rw-r--r--compiler/rustc_parse/src/parser/attr.rs2
-rw-r--r--compiler/rustc_parse/src/parser/diagnostics.rs99
-rw-r--r--compiler/rustc_parse/src/parser/expr.rs42
-rw-r--r--compiler/rustc_parse/src/parser/item.rs58
-rw-r--r--compiler/rustc_parse/src/parser/mod.rs32
-rw-r--r--compiler/rustc_parse/src/parser/nonterminal.rs69
-rw-r--r--compiler/rustc_parse/src/parser/pat.rs2
-rw-r--r--compiler/rustc_parse/src/parser/path.rs2
-rw-r--r--compiler/rustc_parse/src/parser/stmt.rs4
-rw-r--r--compiler/rustc_parse/src/parser/ty.rs58
12 files changed, 196 insertions, 176 deletions
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index 2f68a299f26..3f08a830b0c 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -83,7 +83,7 @@ pub(crate) struct IncorrectSemicolon<'a> {
     #[suggestion(style = "short", code = "", applicability = "machine-applicable")]
     pub span: Span,
     #[help]
-    pub opt_help: Option<()>,
+    pub show_help: bool,
     pub name: &'a str,
 }
 
diff --git a/compiler/rustc_parse/src/lexer/tokentrees.rs b/compiler/rustc_parse/src/lexer/tokentrees.rs
index b5a5a2a90ee..eabe0226b2f 100644
--- a/compiler/rustc_parse/src/lexer/tokentrees.rs
+++ b/compiler/rustc_parse/src/lexer/tokentrees.rs
@@ -241,7 +241,7 @@ impl<'psess, 'src> TokenTreesReader<'psess, 'src> {
         // we have no way of tracking this in the lexer itself, so we piggyback on the parser
         let mut in_cond = false;
         while parser.token != token::Eof {
-            if let Err(diff_err) = parser.err_diff_marker() {
+            if let Err(diff_err) = parser.err_vcs_conflict_marker() {
                 diff_errs.push(diff_err);
             } else if parser.is_keyword_ahead(0, &[kw::If, kw::While]) {
                 in_cond = true;
diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index d5d8060d909..a57eb70c705 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -363,7 +363,7 @@ impl<'a> Parser<'a> {
         // We can't use `maybe_whole` here because it would bump in the `None`
         // case, which we don't want.
         if let token::Interpolated(nt) = &self.token.kind
-            && let token::NtMeta(attr_item) = &nt.0
+            && let token::NtMeta(attr_item) = &**nt
         {
             match attr_item.meta(attr_item.path.span) {
                 Some(meta) => {
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 50698dbf9c1..ac12787f2ef 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -1817,34 +1817,31 @@ impl<'a> Parser<'a> {
         Ok(P(T::recovered(Some(P(QSelf { ty, path_span, position: 0 })), path)))
     }
 
-    pub fn maybe_consume_incorrect_semicolon(&mut self, items: &[P<Item>]) -> bool {
-        if self.token.kind == TokenKind::Semi {
-            self.bump();
-
-            let mut err =
-                IncorrectSemicolon { span: self.prev_token.span, opt_help: None, name: "" };
+    /// This function gets called in places where a semicolon is NOT expected and if there's a
+    /// semicolon it emits the appropriate error and returns true.
+    pub fn maybe_consume_incorrect_semicolon(&mut self, previous_item: Option<&Item>) -> bool {
+        if self.token.kind != TokenKind::Semi {
+            return false;
+        }
 
-            if !items.is_empty() {
-                let previous_item = &items[items.len() - 1];
-                let previous_item_kind_name = match previous_item.kind {
+        // Check previous item to add it to the diagnostic, for example to say
+        // `enum declarations are not followed by a semicolon`
+        let err = match previous_item {
+            Some(previous_item) => {
+                let name = match previous_item.kind {
                     // Say "braced struct" because tuple-structs and
                     // braceless-empty-struct declarations do take a semicolon.
-                    ItemKind::Struct(..) => Some("braced struct"),
-                    ItemKind::Enum(..) => Some("enum"),
-                    ItemKind::Trait(..) => Some("trait"),
-                    ItemKind::Union(..) => Some("union"),
-                    _ => None,
+                    ItemKind::Struct(..) => "braced struct",
+                    _ => previous_item.kind.descr(),
                 };
-                if let Some(name) = previous_item_kind_name {
-                    err.opt_help = Some(());
-                    err.name = name;
-                }
+                IncorrectSemicolon { span: self.token.span, name, show_help: true }
             }
-            self.dcx().emit_err(err);
-            true
-        } else {
-            false
-        }
+            None => IncorrectSemicolon { span: self.token.span, name: "", show_help: false },
+        };
+        self.dcx().emit_err(err);
+
+        self.bump();
+        true
     }
 
     /// Creates a `Diag` for an unexpected token `t` and tries to recover if it is a
@@ -2372,9 +2369,9 @@ impl<'a> Parser<'a> {
         // in a subsequent macro invocation (#71039).
         let mut tok = self.token.clone();
         let mut labels = vec![];
-        while let TokenKind::Interpolated(node) = &tok.kind {
-            let tokens = node.0.tokens();
-            labels.push(node.clone());
+        while let TokenKind::Interpolated(nt) = &tok.kind {
+            let tokens = nt.tokens();
+            labels.push(nt.clone());
             if let Some(tokens) = tokens
                 && let tokens = tokens.to_attr_token_stream()
                 && let tokens = tokens.0.deref()
@@ -2387,27 +2384,20 @@ impl<'a> Parser<'a> {
         }
         let mut iter = labels.into_iter().peekable();
         let mut show_link = false;
-        while let Some(node) = iter.next() {
-            let descr = node.0.descr();
+        while let Some(nt) = iter.next() {
+            let descr = nt.descr();
             if let Some(next) = iter.peek() {
-                let next_descr = next.0.descr();
+                let next_descr = next.descr();
                 if next_descr != descr {
-                    err.span_label(next.1, format!("this macro fragment matcher is {next_descr}"));
-                    err.span_label(node.1, format!("this macro fragment matcher is {descr}"));
-                    err.span_label(
-                        next.0.use_span(),
-                        format!("this is expected to be {next_descr}"),
-                    );
+                    err.span_label(next.use_span(), format!("this is expected to be {next_descr}"));
                     err.span_label(
-                        node.0.use_span(),
+                        nt.use_span(),
                         format!(
                             "this is interpreted as {}, but it is expected to be {}",
                             next_descr, descr,
                         ),
                     );
                     show_link = true;
-                } else {
-                    err.span_label(node.1, "");
                 }
             }
         }
@@ -2964,13 +2954,23 @@ impl<'a> Parser<'a> {
         err
     }
 
-    pub fn is_diff_marker(&mut self, long_kind: &TokenKind, short_kind: &TokenKind) -> bool {
+    /// This checks if this is a conflict marker, depending of the parameter passed.
+    ///
+    /// * `>>>>>`
+    /// * `=====`
+    /// * `<<<<<`
+    ///
+    pub fn is_vcs_conflict_marker(
+        &mut self,
+        long_kind: &TokenKind,
+        short_kind: &TokenKind,
+    ) -> bool {
         (0..3).all(|i| self.look_ahead(i, |tok| tok == long_kind))
             && self.look_ahead(3, |tok| tok == short_kind)
     }
 
-    fn diff_marker(&mut self, long_kind: &TokenKind, short_kind: &TokenKind) -> Option<Span> {
-        if self.is_diff_marker(long_kind, short_kind) {
+    fn conflict_marker(&mut self, long_kind: &TokenKind, short_kind: &TokenKind) -> Option<Span> {
+        if self.is_vcs_conflict_marker(long_kind, short_kind) {
             let lo = self.token.span;
             for _ in 0..4 {
                 self.bump();
@@ -2980,15 +2980,16 @@ impl<'a> Parser<'a> {
         None
     }
 
-    pub fn recover_diff_marker(&mut self) {
-        if let Err(err) = self.err_diff_marker() {
+    pub fn recover_vcs_conflict_marker(&mut self) {
+        if let Err(err) = self.err_vcs_conflict_marker() {
             err.emit();
             FatalError.raise();
         }
     }
 
-    pub fn err_diff_marker(&mut self) -> PResult<'a, ()> {
-        let Some(start) = self.diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) else {
+    pub fn err_vcs_conflict_marker(&mut self) -> PResult<'a, ()> {
+        let Some(start) = self.conflict_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt)
+        else {
             return Ok(());
         };
         let mut spans = Vec::with_capacity(3);
@@ -3000,13 +3001,15 @@ impl<'a> Parser<'a> {
             if self.token.kind == TokenKind::Eof {
                 break;
             }
-            if let Some(span) = self.diff_marker(&TokenKind::OrOr, &TokenKind::BinOp(token::Or)) {
+            if let Some(span) = self.conflict_marker(&TokenKind::OrOr, &TokenKind::BinOp(token::Or))
+            {
                 middlediff3 = Some(span);
             }
-            if let Some(span) = self.diff_marker(&TokenKind::EqEq, &TokenKind::Eq) {
+            if let Some(span) = self.conflict_marker(&TokenKind::EqEq, &TokenKind::Eq) {
                 middle = Some(span);
             }
-            if let Some(span) = self.diff_marker(&TokenKind::BinOp(token::Shr), &TokenKind::Gt) {
+            if let Some(span) = self.conflict_marker(&TokenKind::BinOp(token::Shr), &TokenKind::Gt)
+            {
                 spans.push(span);
                 end = Some(span);
                 break;
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 577003e94fb..d2d21624150 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -45,7 +45,7 @@ use thin_vec::{thin_vec, ThinVec};
 macro_rules! maybe_whole_expr {
     ($p:expr) => {
         if let token::Interpolated(nt) = &$p.token.kind {
-            match &nt.0 {
+            match &**nt {
                 token::NtExpr(e) | token::NtLiteral(e) => {
                     let e = e.clone();
                     $p.bump();
@@ -497,8 +497,7 @@ impl<'a> Parser<'a> {
 
     /// Checks if this expression is a successfully parsed statement.
     fn expr_is_complete(&self, e: &Expr) -> bool {
-        self.restrictions.contains(Restrictions::STMT_EXPR)
-            && !classify::expr_requires_semi_to_be_stmt(e)
+        self.restrictions.contains(Restrictions::STMT_EXPR) && classify::expr_is_complete(e)
     }
 
     /// Parses `x..y`, `x..=y`, and `x..`/`x..=`.
@@ -725,7 +724,9 @@ impl<'a> Parser<'a> {
     /// Returns the span of expr if it was not interpolated, or the span of the interpolated token.
     fn interpolated_or_expr_span(&self, expr: &Expr) -> Span {
         match self.prev_token.kind {
-            TokenKind::Interpolated(..) => self.prev_token.span,
+            TokenKind::NtIdent(..) | TokenKind::NtLifetime(..) | TokenKind::Interpolated(..) => {
+                self.prev_token.span
+            }
             _ => expr.span,
         }
     }
@@ -2691,8 +2692,33 @@ impl<'a> Parser<'a> {
             let first_tok_span = self.token.span;
             match self.parse_expr() {
                 Ok(cond)
-                // If it's not a free-standing expression, and is followed by a block,
-                // then it's very likely the condition to an `else if`.
+                // Try to guess the difference between a "condition-like" vs
+                // "statement-like" expression.
+                //
+                // We are seeing the following code, in which $cond is neither
+                // ExprKind::Block nor ExprKind::If (the 2 cases wherein this
+                // would be valid syntax).
+                //
+                //     if ... {
+                //     } else $cond
+                //
+                // If $cond is "condition-like" such as ExprKind::Binary, we
+                // want to suggest inserting `if`.
+                //
+                //     if ... {
+                //     } else if a == b {
+                //            ^^
+                //     }
+                //
+                // If $cond is "statement-like" such as ExprKind::While then we
+                // want to suggest wrapping in braces.
+                //
+                //     if ... {
+                //     } else {
+                //            ^
+                //         while true {}
+                //     }
+                //     ^
                     if self.check(&TokenKind::OpenDelim(Delimiter::Brace))
                         && classify::expr_requires_semi_to_be_stmt(&cond) =>
                 {
@@ -3136,7 +3162,7 @@ impl<'a> Parser<'a> {
                         err
                     })?;
 
-                let require_comma = classify::expr_requires_semi_to_be_stmt(&expr)
+                let require_comma = !classify::expr_is_complete(&expr)
                     && this.token != token::CloseDelim(Delimiter::Brace);
 
                 if !require_comma {
@@ -3708,7 +3734,7 @@ impl<'a> Parser<'a> {
     /// Parses `ident (COLON expr)?`.
     fn parse_expr_field(&mut self) -> PResult<'a, ExprField> {
         let attrs = self.parse_outer_attributes()?;
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
             let lo = this.token.span;
 
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index df6996dbc45..34cdf8a9b5f 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -49,6 +49,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Parses the contents of a module (inner attributes followed by module items).
+    /// We exit once we hit `term`
     pub fn parse_mod(
         &mut self,
         term: &TokenKind,
@@ -59,13 +60,13 @@ impl<'a> Parser<'a> {
         let post_attr_lo = self.token.span;
         let mut items = ThinVec::new();
         while let Some(item) = self.parse_item(ForceCollect::No)? {
+            self.maybe_consume_incorrect_semicolon(Some(&item));
             items.push(item);
-            self.maybe_consume_incorrect_semicolon(&items);
         }
 
         if !self.eat(term) {
             let token_str = super::token_descr(&self.token);
-            if !self.maybe_consume_incorrect_semicolon(&items) {
+            if !self.maybe_consume_incorrect_semicolon(items.last().map(|x| &**x)) {
                 let msg = format!("expected item, found {token_str}");
                 let mut err = self.dcx().struct_span_err(self.token.span, msg);
                 let span = self.token.span;
@@ -101,9 +102,9 @@ impl<'a> Parser<'a> {
         fn_parse_mode: FnParseMode,
         force_collect: ForceCollect,
     ) -> PResult<'a, Option<Item>> {
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         let attrs = self.parse_outer_attributes()?;
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         self.parse_item_common(attrs, true, false, fn_parse_mode, force_collect)
     }
 
@@ -194,12 +195,12 @@ impl<'a> Parser<'a> {
         fn_parse_mode: FnParseMode,
         case: Case,
     ) -> PResult<'a, Option<ItemInfo>> {
-        let def_final = def == &Defaultness::Final;
+        let check_pub = def == &Defaultness::Final;
         let mut def_ = || mem::replace(def, Defaultness::Final);
 
         let info = if self.eat_keyword_case(kw::Use, case) {
             self.parse_use_item()?
-        } else if self.check_fn_front_matter(def_final, case) {
+        } else if self.check_fn_front_matter(check_pub, case) {
             // FUNCTION ITEM
             let (ident, sig, generics, body) =
                 self.parse_fn(attrs, fn_parse_mode, lo, vis, case)?;
@@ -310,7 +311,7 @@ impl<'a> Parser<'a> {
         Ok(Some(info))
     }
 
-    fn recover_import_as_use(&mut self) -> PResult<'a, Option<(Ident, ItemKind)>> {
+    fn recover_import_as_use(&mut self) -> PResult<'a, Option<ItemInfo>> {
         let span = self.token.span;
         let token_name = super::token_descr(&self.token);
         let snapshot = self.create_snapshot_for_diagnostic();
@@ -328,7 +329,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn parse_use_item(&mut self) -> PResult<'a, (Ident, ItemKind)> {
+    fn parse_use_item(&mut self) -> PResult<'a, ItemInfo> {
         let tree = self.parse_use_tree()?;
         if let Err(mut e) = self.expect_semi() {
             match tree.kind {
@@ -723,7 +724,7 @@ impl<'a> Parser<'a> {
             if self.recover_doc_comment_before_brace() {
                 continue;
             }
-            self.recover_diff_marker();
+            self.recover_vcs_conflict_marker();
             match parse_item(self) {
                 Ok(None) => {
                     let mut is_unnecessary_semicolon = !items.is_empty()
@@ -1070,7 +1071,7 @@ impl<'a> Parser<'a> {
     /// ```
     fn parse_use_tree_list(&mut self) -> PResult<'a, ThinVec<(UseTree, ast::NodeId)>> {
         self.parse_delim_comma_seq(Delimiter::Brace, |p| {
-            p.recover_diff_marker();
+            p.recover_vcs_conflict_marker();
             Ok((p.parse_use_tree()?, DUMMY_NODE_ID))
         })
         .map(|(r, _)| r)
@@ -1497,9 +1498,9 @@ impl<'a> Parser<'a> {
     }
 
     fn parse_enum_variant(&mut self, span: Span) -> PResult<'a, Option<Variant>> {
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         let variant_attrs = self.parse_outer_attributes()?;
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         let help = "enum variants can be `Variant`, `Variant = <integer>`, \
                     `Variant(Type, ..., TypeN)` or `Variant { fields: Types }`";
         self.collect_tokens_trailing_token(
@@ -1688,6 +1689,10 @@ impl<'a> Parser<'a> {
         Ok((class_name, ItemKind::Union(vdata, generics)))
     }
 
+    /// This function parses the fields of record structs:
+    ///
+    ///   - `struct S { ... }`
+    ///   - `enum E { Variant { ... } }`
     pub(crate) fn parse_record_struct_body(
         &mut self,
         adt_ty: &str,
@@ -1714,19 +1719,10 @@ impl<'a> Parser<'a> {
             self.eat(&token::CloseDelim(Delimiter::Brace));
         } else {
             let token_str = super::token_descr(&self.token);
-            let msg = format!(
-                "expected {}`{{` after struct name, found {}",
-                if parsed_where { "" } else { "`where`, or " },
-                token_str
-            );
+            let where_str = if parsed_where { "" } else { "`where`, or " };
+            let msg = format!("expected {where_str}`{{` after struct name, found {token_str}");
             let mut err = self.dcx().struct_span_err(self.token.span, msg);
-            err.span_label(
-                self.token.span,
-                format!(
-                    "expected {}`{{` after struct name",
-                    if parsed_where { "" } else { "`where`, or " }
-                ),
-            );
+            err.span_label(self.token.span, format!("expected {where_str}`{{` after struct name",));
             return Err(err);
         }
 
@@ -1740,7 +1736,7 @@ impl<'a> Parser<'a> {
             let attrs = p.parse_outer_attributes()?;
             p.collect_tokens_trailing_token(attrs, ForceCollect::No, |p, attrs| {
                 let mut snapshot = None;
-                if p.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
+                if p.is_vcs_conflict_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
                     // Account for `<<<<<<<` diff markers. We can't proactively error here because
                     // that can be a valid type start, so we snapshot and reparse only we've
                     // encountered another parse error.
@@ -1751,7 +1747,7 @@ impl<'a> Parser<'a> {
                     Ok(vis) => vis,
                     Err(err) => {
                         if let Some(ref mut snapshot) = snapshot {
-                            snapshot.recover_diff_marker();
+                            snapshot.recover_vcs_conflict_marker();
                         }
                         return Err(err);
                     }
@@ -1760,7 +1756,7 @@ impl<'a> Parser<'a> {
                     Ok(ty) => ty,
                     Err(err) => {
                         if let Some(ref mut snapshot) = snapshot {
-                            snapshot.recover_diff_marker();
+                            snapshot.recover_vcs_conflict_marker();
                         }
                         return Err(err);
                     }
@@ -1785,9 +1781,9 @@ impl<'a> Parser<'a> {
 
     /// Parses an element of a struct declaration.
     fn parse_field_def(&mut self, adt_ty: &str) -> PResult<'a, FieldDef> {
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         let attrs = self.parse_outer_attributes()?;
-        self.recover_diff_marker();
+        self.recover_vcs_conflict_marker();
         self.collect_tokens_trailing_token(attrs, ForceCollect::No, |this, attrs| {
             let lo = this.token.span;
             let vis = this.parse_visibility(FollowedByType::No)?;
@@ -2647,7 +2643,7 @@ impl<'a> Parser<'a> {
         }
 
         let (mut params, _) = self.parse_paren_comma_seq(|p| {
-            p.recover_diff_marker();
+            p.recover_vcs_conflict_marker();
             let snapshot = p.create_snapshot_for_diagnostic();
             let param = p.parse_param_general(req_name, first_param).or_else(|e| {
                 let guar = e.emit();
@@ -2841,7 +2837,7 @@ impl<'a> Parser<'a> {
 
     fn is_named_param(&self) -> bool {
         let offset = match &self.token.kind {
-            token::Interpolated(nt) => match &nt.0 {
+            token::Interpolated(nt) => match &**nt {
                 token::NtPat(..) => return self.look_ahead(1, |t| t == &token::Colon),
                 _ => 0,
             },
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index bfb6c4a3885..3e0a98a55ae 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -11,7 +11,6 @@ mod stmt;
 mod ty;
 
 use crate::lexer::UnmatchedDelim;
-use ast::token::IdentIsRaw;
 pub use attr_wrapper::AttrWrapper;
 pub use diagnostics::AttemptLocalParseRecovery;
 pub(crate) use expr::ForbiddenLetReason;
@@ -21,7 +20,7 @@ pub use path::PathStyle;
 
 use core::fmt;
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, Delimiter, Token, TokenKind};
+use rustc_ast::token::{self, Delimiter, IdentIsRaw, Nonterminal, Token, TokenKind};
 use rustc_ast::tokenstream::{AttributesData, DelimSpacing, DelimSpan, Spacing};
 use rustc_ast::tokenstream::{TokenStream, TokenTree, TokenTreeCursor};
 use rustc_ast::util::case::Case;
@@ -32,6 +31,7 @@ use rustc_ast::{
 };
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::sync::Lrc;
 use rustc_errors::{Applicability, Diag, FatalError, MultiSpan, PResult};
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -107,7 +107,7 @@ pub enum TrailingToken {
 macro_rules! maybe_whole {
     ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
         if let token::Interpolated(nt) = &$p.token.kind
-            && let token::$constructor(x) = &nt.0
+            && let token::$constructor(x) = &**nt
         {
             #[allow(unused_mut)]
             let mut $x = x.clone();
@@ -125,7 +125,7 @@ macro_rules! maybe_recover_from_interpolated_ty_qpath {
             && $self.may_recover()
             && $self.look_ahead(1, |t| t == &token::PathSep)
             && let token::Interpolated(nt) = &$self.token.kind
-            && let token::NtTy(ty) = &nt.0
+            && let token::NtTy(ty) = &**nt
         {
             let ty = ty.clone();
             $self.bump();
@@ -407,7 +407,9 @@ pub(super) fn token_descr(token: &Token) -> String {
         (Some(TokenDescription::Keyword), _) => Some("keyword"),
         (Some(TokenDescription::ReservedKeyword), _) => Some("reserved keyword"),
         (Some(TokenDescription::DocComment), _) => Some("doc comment"),
-        (None, TokenKind::Interpolated(node)) => Some(node.0.descr()),
+        (None, TokenKind::NtIdent(..)) => Some("identifier"),
+        (None, TokenKind::NtLifetime(..)) => Some("lifetime"),
+        (None, TokenKind::Interpolated(node)) => Some(node.descr()),
         (None, _) => None,
     };
 
@@ -708,7 +710,7 @@ impl<'a> Parser<'a> {
     fn check_inline_const(&self, dist: usize) -> bool {
         self.is_keyword_ahead(dist, &[kw::Const])
             && self.look_ahead(dist + 1, |t| match &t.kind {
-                token::Interpolated(nt) => matches!(&nt.0, token::NtBlock(..)),
+                token::Interpolated(nt) => matches!(&**nt, token::NtBlock(..)),
                 token::OpenDelim(Delimiter::Brace) => true,
                 _ => false,
             })
@@ -1631,19 +1633,11 @@ pub enum FlatToken {
 
 // Metavar captures of various kinds.
 #[derive(Clone, Debug)]
-pub enum ParseNtResult<NtType> {
+pub enum ParseNtResult {
     Tt(TokenTree),
-    Nt(NtType),
-}
+    Ident(Ident, IdentIsRaw),
+    Lifetime(Ident),
 
-impl<T> ParseNtResult<T> {
-    pub fn map_nt<F, U>(self, mut f: F) -> ParseNtResult<U>
-    where
-        F: FnMut(T) -> U,
-    {
-        match self {
-            ParseNtResult::Tt(tt) => ParseNtResult::Tt(tt),
-            ParseNtResult::Nt(nt) => ParseNtResult::Nt(f(nt)),
-        }
-    }
+    /// This case will eventually be removed, along with `Token::Interpolate`.
+    Nt(Lrc<Nonterminal>),
 }
diff --git a/compiler/rustc_parse/src/parser/nonterminal.rs b/compiler/rustc_parse/src/parser/nonterminal.rs
index 73b17353ac9..a6f0ab78b5c 100644
--- a/compiler/rustc_parse/src/parser/nonterminal.rs
+++ b/compiler/rustc_parse/src/parser/nonterminal.rs
@@ -1,7 +1,8 @@
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, Delimiter, Nonterminal, Nonterminal::*, NonterminalKind, Token};
+use rustc_ast::token::{self, Delimiter, Nonterminal::*, NonterminalKind, Token};
 use rustc_ast::HasTokens;
 use rustc_ast_pretty::pprust;
+use rustc_data_structures::sync::Lrc;
 use rustc_errors::PResult;
 use rustc_span::symbol::{kw, Ident};
 
@@ -24,15 +25,13 @@ impl<'a> Parser<'a> {
                 | NtPat(_)
                 | NtExpr(_)
                 | NtTy(_)
-                | NtIdent(..)
                 | NtLiteral(_) // `true`, `false`
                 | NtMeta(_)
                 | NtPath(_) => true,
 
                 NtItem(_)
                 | NtBlock(_)
-                | NtVis(_)
-                | NtLifetime(_) => false,
+                | NtVis(_) => false,
             }
         }
 
@@ -49,25 +48,30 @@ impl<'a> Parser<'a> {
             NonterminalKind::Literal => token.can_begin_literal_maybe_minus(),
             NonterminalKind::Vis => match token.kind {
                 // The follow-set of :vis + "priv" keyword + interpolated
-                token::Comma | token::Ident(..) | token::Interpolated(_) => true,
+                token::Comma
+                | token::Ident(..)
+                | token::NtIdent(..)
+                | token::NtLifetime(..)
+                | token::Interpolated(_) => true,
                 _ => token.can_begin_type(),
             },
             NonterminalKind::Block => match &token.kind {
                 token::OpenDelim(Delimiter::Brace) => true,
-                token::Interpolated(nt) => match &nt.0 {
-                    NtBlock(_) | NtLifetime(_) | NtStmt(_) | NtExpr(_) | NtLiteral(_) => true,
-                    NtItem(_) | NtPat(_) | NtTy(_) | NtIdent(..) | NtMeta(_) | NtPath(_)
-                    | NtVis(_) => false,
+                token::NtLifetime(..) => true,
+                token::Interpolated(nt) => match &**nt {
+                    NtBlock(_) | NtStmt(_) | NtExpr(_) | NtLiteral(_) => true,
+                    NtItem(_) | NtPat(_) | NtTy(_) | NtMeta(_) | NtPath(_) | NtVis(_) => false,
                 },
                 _ => false,
             },
             NonterminalKind::Path | NonterminalKind::Meta => match &token.kind {
-                token::PathSep | token::Ident(..) => true,
-                token::Interpolated(nt) => may_be_ident(&nt.0),
+                token::PathSep | token::Ident(..) | token::NtIdent(..) => true,
+                token::Interpolated(nt) => may_be_ident(nt),
                 _ => false,
             },
             NonterminalKind::PatParam { .. } | NonterminalKind::PatWithOr => match &token.kind {
-                token::Ident(..) |                          // box, ref, mut, and other identifiers (can stricten)
+                // box, ref, mut, and other identifiers (can stricten)
+                token::Ident(..) | token::NtIdent(..) |
                 token::OpenDelim(Delimiter::Parenthesis) |  // tuple pattern
                 token::OpenDelim(Delimiter::Bracket) |      // slice pattern
                 token::BinOp(token::And) |                  // reference
@@ -81,14 +85,11 @@ impl<'a> Parser<'a> {
                 token::BinOp(token::Shl) => true,           // path (double UFCS)
                 // leading vert `|` or-pattern
                 token::BinOp(token::Or) => matches!(kind, NonterminalKind::PatWithOr),
-                token::Interpolated(nt) => may_be_ident(&nt.0),
+                token::Interpolated(nt) => may_be_ident(nt),
                 _ => false,
             },
             NonterminalKind::Lifetime => match &token.kind {
-                token::Lifetime(_) => true,
-                token::Interpolated(nt) => {
-                    matches!(&nt.0, NtLifetime(_))
-                }
+                token::Lifetime(_) | token::NtLifetime(..) => true,
                 _ => false,
             },
             NonterminalKind::TT | NonterminalKind::Item | NonterminalKind::Stmt => {
@@ -100,10 +101,7 @@ impl<'a> Parser<'a> {
     /// Parse a non-terminal (e.g. MBE `:pat` or `:ident`). Inlined because there is only one call
     /// site.
     #[inline]
-    pub fn parse_nonterminal(
-        &mut self,
-        kind: NonterminalKind,
-    ) -> PResult<'a, ParseNtResult<Nonterminal>> {
+    pub fn parse_nonterminal(&mut self, kind: NonterminalKind) -> PResult<'a, ParseNtResult> {
         // A `macro_rules!` invocation may pass a captured item/expr to a proc-macro,
         // which requires having captured tokens available. Since we cannot determine
         // in advance whether or not a proc-macro will be (transitively) invoked,
@@ -156,15 +154,16 @@ impl<'a> Parser<'a> {
             }
 
             // this could be handled like a token, since it is one
-            NonterminalKind::Ident if let Some((ident, is_raw)) = get_macro_ident(&self.token) => {
-                self.bump();
-                NtIdent(ident, is_raw)
-            }
             NonterminalKind::Ident => {
-                return Err(self.dcx().create_err(UnexpectedNonterminal::Ident {
-                    span: self.token.span,
-                    token: self.token.clone(),
-                }));
+                return if let Some((ident, is_raw)) = get_macro_ident(&self.token) {
+                    self.bump();
+                    Ok(ParseNtResult::Ident(ident, is_raw))
+                } else {
+                    Err(self.dcx().create_err(UnexpectedNonterminal::Ident {
+                        span: self.token.span,
+                        token: self.token.clone(),
+                    }))
+                };
             }
             NonterminalKind::Path => {
                 NtPath(P(self.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))?))
@@ -175,14 +174,14 @@ impl<'a> Parser<'a> {
                     .collect_tokens_no_attrs(|this| this.parse_visibility(FollowedByType::Yes))?))
             }
             NonterminalKind::Lifetime => {
-                if self.check_lifetime() {
-                    NtLifetime(self.expect_lifetime().ident)
+                return if self.check_lifetime() {
+                    Ok(ParseNtResult::Lifetime(self.expect_lifetime().ident))
                 } else {
-                    return Err(self.dcx().create_err(UnexpectedNonterminal::Lifetime {
+                    Err(self.dcx().create_err(UnexpectedNonterminal::Lifetime {
                         span: self.token.span,
                         token: self.token.clone(),
-                    }));
-                }
+                    }))
+                };
             }
         };
 
@@ -196,7 +195,7 @@ impl<'a> Parser<'a> {
             );
         }
 
-        Ok(ParseNtResult::Nt(nt))
+        Ok(ParseNtResult::Nt(Lrc::new(nt)))
     }
 }
 
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 78d3d019bf4..8af415f7c9d 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -757,7 +757,7 @@ impl<'a> Parser<'a> {
 
         // Make sure we don't allow e.g. `let mut $p;` where `$p:pat`.
         if let token::Interpolated(nt) = &self.token.kind {
-            if let token::NtPat(..) = &nt.0 {
+            if let token::NtPat(..) = &**nt {
                 self.expected_ident_found_err().emit();
             }
         }
diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index 3636a357978..c37d3f0441d 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -193,7 +193,7 @@ impl<'a> Parser<'a> {
         maybe_whole!(self, NtPath, |path| reject_generics_if_mod_style(self, path.into_inner()));
 
         if let token::Interpolated(nt) = &self.token.kind {
-            if let token::NtTy(ty) = &nt.0 {
+            if let token::NtTy(ty) = &**nt {
                 if let ast::TyKind::Path(None, path) = &ty.kind {
                     let path = path.clone();
                     self.bump();
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index d70afebf1b2..7424fbea9b0 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -567,7 +567,7 @@ impl<'a> Parser<'a> {
             if self.token == token::Eof {
                 break;
             }
-            if self.is_diff_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
+            if self.is_vcs_conflict_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
                 // Account for `<<<<<<<` diff markers. We can't proactively error here because
                 // that can be a valid path start, so we snapshot and reparse only we've
                 // encountered another parse error.
@@ -576,7 +576,7 @@ impl<'a> Parser<'a> {
             let stmt = match self.parse_full_stmt(recover) {
                 Err(mut err) if recover.yes() => {
                     if let Some(ref mut snapshot) = snapshot {
-                        snapshot.recover_diff_marker();
+                        snapshot.recover_vcs_conflict_marker();
                     }
                     if self.token == token::Colon {
                         // if a previous and next token of the current one is
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index 7096b201f84..2f08a48c7bc 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -675,8 +675,8 @@ impl<'a> Parser<'a> {
         let precise_capturing = if self.eat_keyword(kw::Use) {
             let use_span = self.prev_token.span;
             self.psess.gated_spans.gate(sym::precise_capturing, use_span);
-            let args = self.parse_precise_capturing_args()?;
-            Some(P((args, use_span)))
+            let (args, args_span) = self.parse_precise_capturing_args()?;
+            Some(P((args, use_span.to(args_span))))
         } else {
             None
         };
@@ -689,32 +689,34 @@ impl<'a> Parser<'a> {
         Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds, precise_capturing))
     }
 
-    fn parse_precise_capturing_args(&mut self) -> PResult<'a, ThinVec<PreciseCapturingArg>> {
-        Ok(self
-            .parse_unspanned_seq(
-                &TokenKind::Lt,
-                &TokenKind::Gt,
-                SeqSep::trailing_allowed(token::Comma),
-                |self_| {
-                    if self_.check_keyword(kw::SelfUpper) {
-                        self_.bump();
-                        Ok(PreciseCapturingArg::Arg(
-                            ast::Path::from_ident(self_.prev_token.ident().unwrap().0),
-                            DUMMY_NODE_ID,
-                        ))
-                    } else if self_.check_ident() {
-                        Ok(PreciseCapturingArg::Arg(
-                            ast::Path::from_ident(self_.parse_ident()?),
-                            DUMMY_NODE_ID,
-                        ))
-                    } else if self_.check_lifetime() {
-                        Ok(PreciseCapturingArg::Lifetime(self_.expect_lifetime()))
-                    } else {
-                        self_.unexpected_any()
-                    }
-                },
-            )?
-            .0)
+    fn parse_precise_capturing_args(
+        &mut self,
+    ) -> PResult<'a, (ThinVec<PreciseCapturingArg>, Span)> {
+        let lo = self.token.span;
+        let (args, _) = self.parse_unspanned_seq(
+            &TokenKind::Lt,
+            &TokenKind::Gt,
+            SeqSep::trailing_allowed(token::Comma),
+            |self_| {
+                if self_.check_keyword(kw::SelfUpper) {
+                    self_.bump();
+                    Ok(PreciseCapturingArg::Arg(
+                        ast::Path::from_ident(self_.prev_token.ident().unwrap().0),
+                        DUMMY_NODE_ID,
+                    ))
+                } else if self_.check_ident() {
+                    Ok(PreciseCapturingArg::Arg(
+                        ast::Path::from_ident(self_.parse_ident()?),
+                        DUMMY_NODE_ID,
+                    ))
+                } else if self_.check_lifetime() {
+                    Ok(PreciseCapturingArg::Lifetime(self_.expect_lifetime()))
+                } else {
+                    self_.unexpected_any()
+                }
+            },
+        )?;
+        Ok((args, lo.to(self.prev_token.span)))
     }
 
     /// Is a `dyn B0 + ... + Bn` type allowed here?