Remove `NtBlock`, `Nonterminal`, and `TokenKind::Interpolated`.

`NtBlock` is the last remaining variant of `Nonterminal`, so once it is
gone then `Nonterminal` can be removed as well.

18 files changed, 108 insertions, 388 deletions

diff --git a/compiler/rustc_ast/src/ast_traits.rs b/compiler/rustc_ast/src/ast_traits.rs
index c9e2e9911ef..7f98e7ba8a6 100644
--- a/compiler/rustc_ast/src/ast_traits.rs
+++ b/compiler/rustc_ast/src/ast_traits.rs
@@ -6,7 +6,6 @@ use std::fmt;
 use std::marker::PhantomData;
 
 use crate::ptr::P;
-use crate::token::Nonterminal;
 use crate::tokenstream::LazyAttrTokenStream;
 use crate::{
     Arm, AssocItem, AttrItem, AttrKind, AttrVec, Attribute, Block, Crate, Expr, ExprField,
@@ -206,19 +205,6 @@ impl HasTokens for Attribute {
     }
 }
 
-impl HasTokens for Nonterminal {
-    fn tokens(&self) -> Option<&LazyAttrTokenStream> {
-        match self {
-            Nonterminal::NtBlock(block) => block.tokens(),
-        }
-    }
-    fn tokens_mut(&mut self) -> Option<&mut Option<LazyAttrTokenStream>> {
-        match self {
-            Nonterminal::NtBlock(block) => block.tokens_mut(),
-        }
-    }
-}
-
 /// A trait for AST nodes having (or not having) attributes.
 pub trait HasAttrs {
     /// This is `true` if this `HasAttrs` might support 'custom' (proc-macro) inner
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index f7d13acdfc4..3d4fa546984 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -843,9 +843,9 @@ fn visit_lazy_tts<T: MutVisitor>(vis: &mut T, lazy_tts: &mut Option<LazyAttrToke
     visit_lazy_tts_opt_mut(vis, lazy_tts.as_mut());
 }
 
-/// Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
-/// In practice the ident part is not actually used by specific visitors right now,
-/// but there's a test below checking that it works.
+/// Applies ident visitor if it's an ident. In practice this is not actually
+/// used by specific visitors right now, but there's a test below checking that
+/// it works.
 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
 pub fn visit_token<T: MutVisitor>(vis: &mut T, t: &mut Token) {
     let Token { kind, span } = t;
@@ -863,46 +863,12 @@ pub fn visit_token<T: MutVisitor>(vis: &mut T, t: &mut Token) {
         token::NtLifetime(ident, _is_raw) => {
             vis.visit_ident(ident);
         }
-        token::Interpolated(nt) => {
-            let nt = Arc::make_mut(nt);
-            visit_nonterminal(vis, nt);
-        }
         _ => {}
     }
     vis.visit_span(span);
 }
 
 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
-/// Applies the visitor to elements of interpolated nodes.
-//
-// N.B., this can occur only when applying a visitor to partially expanded
-// code, where parsed pieces have gotten implanted ito *other* macro
-// invocations. This is relevant for macro hygiene, but possibly not elsewhere.
-//
-// One problem here occurs because the types for flat_map_item, flat_map_stmt,
-// etc., allow the visitor to return *multiple* items; this is a problem for the
-// nodes here, because they insist on having exactly one piece. One solution
-// would be to mangle the MutVisitor trait to include one-to-many and
-// one-to-one versions of these entry points, but that would probably confuse a
-// lot of people and help very few. Instead, I'm just going to put in dynamic
-// checks. I think the performance impact of this will be pretty much
-// nonexistent. The danger is that someone will apply a `MutVisitor` to a
-// partially expanded node, and will be confused by the fact that their
-// `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
-// nodes. Hopefully they'll wind up reading this comment, and doing something
-// appropriate.
-//
-// BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
-// contain multiple items, but decided against it when I looked at
-// `parse_item_or_view_item` and tried to figure out what I would do with
-// multiple items there....
-fn visit_nonterminal<T: MutVisitor>(vis: &mut T, nt: &mut token::Nonterminal) {
-    match nt {
-        token::NtBlock(block) => vis.visit_block(block),
-    }
-}
-
-// No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
 fn visit_defaultness<T: MutVisitor>(vis: &mut T, defaultness: &mut Defaultness) {
     match defaultness {
         Defaultness::Default(span) => vis.visit_span(span),
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index d57a369eebf..de80bb47aff 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -1,13 +1,10 @@
 use std::borrow::Cow;
 use std::fmt;
-use std::sync::Arc;
 
 pub use LitKind::*;
-pub use Nonterminal::*;
 pub use NtExprKind::*;
 pub use NtPatKind::*;
 pub use TokenKind::*;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::edition::Edition;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, kw, sym};
@@ -16,7 +13,6 @@ use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, kw, sym};
 use rustc_span::{Ident, Symbol};
 
 use crate::ast;
-use crate::ptr::P;
 use crate::util::case::Case;
 
 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
@@ -35,8 +31,8 @@ pub enum InvisibleOrigin {
     // `proc_macro::Delimiter::to_internal`, i.e. returned by a proc macro.
     ProcMacro,
 
-    // Converted from `TokenKind::Interpolated` in
-    // `TokenStream::flatten_token`. Treated similarly to `ProcMacro`.
+    // Converted from `TokenKind::NtLifetime` in `TokenStream::flatten_token`.
+    // Treated similarly to `ProcMacro`.
     FlattenToken,
 }
 
@@ -337,9 +333,7 @@ impl From<IdentIsRaw> for bool {
     }
 }
 
-// SAFETY: due to the `Clone` impl below, all fields of all variants other than
-// `Interpolated` must impl `Copy`.
-#[derive(PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
+#[derive(Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum TokenKind {
     /* Expression-operator symbols. */
     /// `=`
@@ -468,21 +462,6 @@ pub enum TokenKind {
     /// the `lifetime` metavariable in the macro's RHS.
     NtLifetime(Ident, IdentIsRaw),
 
-    /// An embedded AST node, as produced by a macro. This only exists for
-    /// historical reasons. We'd like to get rid of it, for multiple reasons.
-    /// - It's conceptually very strange. Saying a token can contain an AST
-    ///   node is like saying, in natural language, that a word can contain a
-    ///   sentence.
-    /// - It requires special handling in a bunch of places in the parser.
-    /// - It prevents `Token` from implementing `Copy`.
-    /// It adds complexity and likely slows things down. Please don't add new
-    /// occurrences of this token kind!
-    ///
-    /// The span in the surrounding `Token` is that of the metavariable in the
-    /// macro's RHS. The span within the Nonterminal is that of the fragment
-    /// passed to the macro at the call site.
-    Interpolated(Arc<Nonterminal>),
-
     /// A doc comment token.
     /// `Symbol` is the doc comment's data excluding its "quotes" (`///`, `/**`, etc)
     /// similarly to symbols in string literal tokens.
@@ -492,19 +471,6 @@ pub enum TokenKind {
     Eof,
 }
 
-impl Clone for TokenKind {
-    fn clone(&self) -> Self {
-        // `TokenKind` would impl `Copy` if it weren't for `Interpolated`. So
-        // for all other variants, this implementation of `clone` is just like
-        // a copy. This is faster than the `derive(Clone)` version which has a
-        // separate path for every variant.
-        match self {
-            Interpolated(nt) => Interpolated(Arc::clone(nt)),
-            _ => unsafe { std::ptr::read(self) },
-        }
-    }
-}
-
 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct Token {
     pub kind: TokenKind,
@@ -600,7 +566,7 @@ impl Token {
             | FatArrow | Pound | Dollar | Question | SingleQuote => true,
 
             OpenDelim(..) | CloseDelim(..) | Literal(..) | DocComment(..) | Ident(..)
-            | NtIdent(..) | Lifetime(..) | NtLifetime(..) | Interpolated(..) | Eof => false,
+            | NtIdent(..) | Lifetime(..) | NtLifetime(..) | Eof => false,
         }
     }
 
@@ -631,7 +597,6 @@ impl Token {
             PathSep                           | // global path
             Lifetime(..)                      | // labeled loop
             Pound                             => true, // expression attributes
-            Interpolated(ref nt) => matches!(&**nt, NtBlock(..)),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Block |
                 MetaVarKind::Expr { .. } |
@@ -703,7 +668,6 @@ impl Token {
         match self.kind {
             OpenDelim(Delimiter::Brace) | Literal(..) | Minus => true,
             Ident(name, IdentIsRaw::No) if name.is_bool_lit() => true,
-            Interpolated(ref nt) => matches!(&**nt, NtBlock(..)),
             OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
                 MetaVarKind::Expr { .. } | MetaVarKind::Block | MetaVarKind::Literal,
             ))) => true,
@@ -831,31 +795,20 @@ impl Token {
     /// Is this a pre-parsed expression dropped into the token stream
     /// (which happens while parsing the result of macro expansion)?
     pub fn is_metavar_expr(&self) -> bool {
-        #[allow(irrefutable_let_patterns)] // FIXME: temporary
-        if let Interpolated(nt) = &self.kind
-            && let NtBlock(_) = &**nt
-        {
-            true
-        } else if matches!(
+        matches!(
             self.is_metavar_seq(),
-            Some(MetaVarKind::Expr { .. } | MetaVarKind::Literal | MetaVarKind::Path)
-        ) {
-            true
-        } else {
-            matches!(self.is_metavar_seq(), Some(MetaVarKind::Path))
-        }
+            Some(
+                MetaVarKind::Expr { .. }
+                    | MetaVarKind::Literal
+                    | MetaVarKind::Path
+                    | MetaVarKind::Block
+            )
+        )
     }
 
-    /// Is the token an interpolated block (`$b:block`)?
-    pub fn is_whole_block(&self) -> bool {
-        #[allow(irrefutable_let_patterns)] // FIXME: temporary
-        if let Interpolated(nt) = &self.kind
-            && let NtBlock(..) = &**nt
-        {
-            return true;
-        }
-
-        false
+    /// Are we at a block from a metavar (`$b:block`)?
+    pub fn is_metavar_block(&self) -> bool {
+        matches!(self.is_metavar_seq(), Some(MetaVarKind::Block))
     }
 
     /// Returns `true` if the token is either the `mut` or `const` keyword.
@@ -1024,7 +977,7 @@ impl Token {
                 | PercentEq | CaretEq | AndEq | OrEq | ShlEq | ShrEq | At | DotDotDot | DotDotEq
                 | Comma | Semi | PathSep | RArrow | LArrow | FatArrow | Pound | Dollar | Question
                 | OpenDelim(..) | CloseDelim(..) | Literal(..) | Ident(..) | NtIdent(..)
-                | Lifetime(..) | NtLifetime(..) | Interpolated(..) | DocComment(..) | Eof,
+                | Lifetime(..) | NtLifetime(..) | DocComment(..) | Eof,
                 _,
             ) => {
                 return None;
@@ -1063,12 +1016,6 @@ pub enum NtExprKind {
     Expr2021 { inferred: bool },
 }
 
-#[derive(Clone, Encodable, Decodable)]
-/// For interpolation during macro expansion.
-pub enum Nonterminal {
-    NtBlock(P<ast::Block>),
-}
-
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, HashStable_Generic)]
 pub enum NonterminalKind {
     Item,
@@ -1152,47 +1099,6 @@ impl fmt::Display for NonterminalKind {
     }
 }
 
-impl Nonterminal {
-    pub fn use_span(&self) -> Span {
-        match self {
-            NtBlock(block) => block.span,
-        }
-    }
-
-    pub fn descr(&self) -> &'static str {
-        match self {
-            NtBlock(..) => "block",
-        }
-    }
-}
-
-impl PartialEq for Nonterminal {
-    fn eq(&self, _rhs: &Self) -> bool {
-        // FIXME: Assume that all nonterminals are not equal, we can't compare them
-        // correctly based on data from AST. This will prevent them from matching each other
-        // in macros. The comparison will become possible only when each nonterminal has an
-        // attached token stream from which it was parsed.
-        false
-    }
-}
-
-impl fmt::Debug for Nonterminal {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match *self {
-            NtBlock(..) => f.pad("NtBlock(..)"),
-        }
-    }
-}
-
-impl<CTX> HashStable<CTX> for Nonterminal
-where
-    CTX: crate::HashStableContext,
-{
-    fn hash_stable(&self, _hcx: &mut CTX, _hasher: &mut StableHasher) {
-        panic!("interpolated tokens should not be present in the HIR")
-    }
-}
-
 // Some types are used a lot. Make sure they don't unintentionally get bigger.
 #[cfg(target_pointer_width = "64")]
 mod size_asserts {
@@ -1202,7 +1108,6 @@ mod size_asserts {
     // tidy-alphabetical-start
     static_assert_size!(Lit, 12);
     static_assert_size!(LitKind, 2);
-    static_assert_size!(Nonterminal, 8);
     static_assert_size!(Token, 24);
     static_assert_size!(TokenKind, 16);
     // tidy-alphabetical-end
diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index fb331e74aeb..3b457303cac 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -25,7 +25,7 @@ use rustc_span::{DUMMY_SP, Span, SpanDecoder, SpanEncoder, Symbol, sym};
 
 use crate::ast::AttrStyle;
 use crate::ast_traits::{HasAttrs, HasTokens};
-use crate::token::{self, Delimiter, InvisibleOrigin, Nonterminal, Token, TokenKind};
+use crate::token::{self, Delimiter, InvisibleOrigin, Token, TokenKind};
 use crate::{AttrVec, Attribute};
 
 /// Part of a `TokenStream`.
@@ -305,11 +305,6 @@ pub struct AttrsTarget {
 }
 
 /// A `TokenStream` is an abstract sequence of tokens, organized into [`TokenTree`]s.
-///
-/// The goal is for procedural macros to work with `TokenStream`s and `TokenTree`s
-/// instead of a representation of the abstract syntax tree.
-/// Today's `TokenTree`s can still contain AST via `token::Interpolated` for
-/// backwards compatibility.
 #[derive(Clone, Debug, Default, Encodable, Decodable)]
 pub struct TokenStream(pub(crate) Arc<Vec<TokenTree>>);
 
@@ -476,12 +471,6 @@ impl TokenStream {
         TokenStream::new(tts)
     }
 
-    pub fn from_nonterminal_ast(nt: &Nonterminal) -> TokenStream {
-        match nt {
-            Nonterminal::NtBlock(block) => TokenStream::from_ast(block),
-        }
-    }
-
     fn flatten_token(token: &Token, spacing: Spacing) -> TokenTree {
         match token.kind {
             token::NtIdent(ident, is_raw) => {
@@ -493,12 +482,6 @@ impl TokenStream {
                 Delimiter::Invisible(InvisibleOrigin::FlattenToken),
                 TokenStream::token_alone(token::Lifetime(ident.name, is_raw), ident.span),
             ),
-            token::Interpolated(ref nt) => TokenTree::Delimited(
-                DelimSpan::from_single(token.span),
-                DelimSpacing::new(Spacing::JointHidden, spacing),
-                Delimiter::Invisible(InvisibleOrigin::FlattenToken),
-                TokenStream::from_nonterminal_ast(&nt).flattened(),
-            ),
             _ => TokenTree::Token(token.clone(), spacing),
         }
     }
@@ -516,10 +499,9 @@ impl TokenStream {
     pub fn flattened(&self) -> TokenStream {
         fn can_skip(stream: &TokenStream) -> bool {
             stream.iter().all(|tree| match tree {
-                TokenTree::Token(token, _) => !matches!(
-                    token.kind,
-                    token::NtIdent(..) | token::NtLifetime(..) | token::Interpolated(..)
-                ),
+                TokenTree::Token(token, _) => {
+                    !matches!(token.kind, token::NtIdent(..) | token::NtLifetime(..))
+                }
                 TokenTree::Delimited(.., inner) => can_skip(inner),
             })
         }
diff --git a/compiler/rustc_ast_pretty/src/pprust/mod.rs b/compiler/rustc_ast_pretty/src/pprust/mod.rs
index 97cb6e52d56..551506f2aef 100644
--- a/compiler/rustc_ast_pretty/src/pprust/mod.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/mod.rs
@@ -5,14 +5,10 @@ pub mod state;
 use std::borrow::Cow;
 
 use rustc_ast as ast;
-use rustc_ast::token::{Nonterminal, Token, TokenKind};
+use rustc_ast::token::{Token, TokenKind};
 use rustc_ast::tokenstream::{TokenStream, TokenTree};
 pub use state::{AnnNode, Comments, PpAnn, PrintState, State, print_crate};
 
-pub fn nonterminal_to_string(nt: &Nonterminal) -> String {
-    State::new().nonterminal_to_string(nt)
-}
-
 /// Print the token kind precisely, without converting `$crate` into its respective crate name.
 pub fn token_kind_to_string(tok: &TokenKind) -> Cow<'static, str> {
     State::new().token_kind_to_string(tok)
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index 3dbfc191f8f..64a0a2ed97d 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -11,7 +11,7 @@ use std::sync::Arc;
 
 use rustc_ast::attr::AttrIdGenerator;
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, CommentKind, Delimiter, IdentIsRaw, Nonterminal, Token, TokenKind};
+use rustc_ast::token::{self, CommentKind, Delimiter, IdentIsRaw, Token, TokenKind};
 use rustc_ast::tokenstream::{Spacing, TokenStream, TokenTree};
 use rustc_ast::util::classify;
 use rustc_ast::util::comments::{Comment, CommentStyle};
@@ -876,14 +876,6 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         }
     }
 
-    fn nonterminal_to_string(&self, nt: &Nonterminal) -> String {
-        // We extract the token stream from the AST fragment and pretty print
-        // it, rather than using AST pretty printing, because `Nonterminal` is
-        // slated for removal in #124141. (This method will also then be
-        // removed.)
-        self.tts_to_string(&TokenStream::from_nonterminal_ast(nt))
-    }
-
     /// Print the token kind precisely, without converting `$crate` into its respective crate name.
     fn token_kind_to_string(&self, tok: &TokenKind) -> Cow<'static, str> {
         self.token_kind_to_string_ext(tok, None)
@@ -976,8 +968,6 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                 doc_comment_to_string(comment_kind, attr_style, data).into()
             }
             token::Eof => "<eof>".into(),
-
-            token::Interpolated(ref nt) => self.nonterminal_to_string(&nt).into(),
         }
     }
 
diff --git a/compiler/rustc_attr_parsing/src/parser.rs b/compiler/rustc_attr_parsing/src/parser.rs
index a8a1460591c..384fae59873 100644
--- a/compiler/rustc_attr_parsing/src/parser.rs
+++ b/compiler/rustc_attr_parsing/src/parser.rs
@@ -485,25 +485,7 @@ impl<'a> MetaItemListParserContext<'a> {
         }
 
         // or a path.
-        let path =
-            if let Some(TokenTree::Token(Token { kind: token::Interpolated(_), span, .. }, _)) =
-                self.inside_delimiters.peek()
-            {
-                self.inside_delimiters.next();
-                // We go into this path if an expr ended up in an attribute that
-                // expansion did not turn into a literal. Say, `#[repr(align(macro!()))]`
-                // where the macro didn't expand to a literal. An error is already given
-                // for this at this point, and then we do continue. This makes this path
-                // reachable...
-                let e = self.dcx.span_delayed_bug(
-                    *span,
-                    "expr in place where literal is expected (builtin attr parsing)",
-                );
-
-                return Some(MetaItemOrLitParser::Err(*span, e));
-            } else {
-                self.next_path()?
-            };
+        let path = self.next_path()?;
 
         // Paths can be followed by:
         // - `(more meta items)` (another list)
diff --git a/compiler/rustc_builtin_macros/src/cfg_eval.rs b/compiler/rustc_builtin_macros/src/cfg_eval.rs
index b3ba9073118..ea0bbd0e31a 100644
--- a/compiler/rustc_builtin_macros/src/cfg_eval.rs
+++ b/compiler/rustc_builtin_macros/src/cfg_eval.rs
@@ -92,11 +92,11 @@ impl CfgEval<'_> {
         // the location of `#[cfg]` and `#[cfg_attr]` in the token stream. The tokenization
         // process is lossless, so this process is invisible to proc-macros.
 
-        // 'Flatten' all nonterminals (i.e. `TokenKind::Interpolated`)
+        // 'Flatten' all nonterminals (i.e. `TokenKind::Nt{Ident,Lifetime}`)
         // to `None`-delimited groups containing the corresponding tokens. This
         // is normally delayed until the proc-macro server actually needs to
-        // provide a `TokenKind::Interpolated` to a proc-macro. We do this earlier,
-        // so that we can handle cases like:
+        // provide tokens to a proc-macro. We do this earlier, so that we can
+        // handle cases like:
         //
         // ```rust
         // #[cfg_eval] #[cfg] $item
diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index bcc2703c39b..27924544de5 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -238,13 +238,7 @@ impl<'a> StripUnconfigured<'a> {
                     Some(AttrTokenTree::Delimited(sp, spacing, delim, inner))
                 }
                 AttrTokenTree::Token(
-                    Token {
-                        kind:
-                            TokenKind::NtIdent(..)
-                            | TokenKind::NtLifetime(..)
-                            | TokenKind::Interpolated(..),
-                        ..
-                    },
+                    Token { kind: TokenKind::NtIdent(..) | TokenKind::NtLifetime(..), .. },
                     _,
                 ) => {
                     panic!("Nonterminal should have been flattened: {:?}", tree);
diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
index e60a9e83184..30961a2b404 100644
--- a/compiler/rustc_expand/src/mbe/diagnostics.rs
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -66,9 +66,7 @@ pub(super) fn failed_to_match_macro(
     }
 
     if let MatcherLoc::Token { token: expected_token } = &remaining_matcher
-        && (matches!(expected_token.kind, TokenKind::Interpolated(_))
-            || matches!(token.kind, TokenKind::Interpolated(_))
-            || matches!(expected_token.kind, TokenKind::OpenDelim(Delimiter::Invisible(_)))
+        && (matches!(expected_token.kind, TokenKind::OpenDelim(Delimiter::Invisible(_)))
             || matches!(token.kind, TokenKind::OpenDelim(Delimiter::Invisible(_))))
     {
         err.note("captured metavariables except for `:tt`, `:ident` and `:lifetime` cannot be compared to other tokens");
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index 6e47ed6eb67..79a5c7ea31b 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -1,5 +1,4 @@
 use std::mem;
-use std::sync::Arc;
 
 use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::token::{
@@ -307,7 +306,9 @@ pub(super) fn transcribe<'a>(
                     let tt = match cur_matched {
                         MatchedSingle(ParseNtResult::Tt(tt)) => {
                             // `tt`s are emitted into the output stream directly as "raw tokens",
-                            // without wrapping them into groups.
+                            // without wrapping them into groups. Other variables are emitted into
+                            // the output stream as groups with `Delimiter::Invisible` to maintain
+                            // parsing priorities.
                             maybe_use_metavar_location(psess, &stack, sp, tt, &mut marker)
                         }
                         MatchedSingle(ParseNtResult::Ident(ident, is_raw)) => {
@@ -325,6 +326,11 @@ pub(super) fn transcribe<'a>(
                         MatchedSingle(ParseNtResult::Item(item)) => {
                             mk_delimited(item.span, MetaVarKind::Item, TokenStream::from_ast(item))
                         }
+                        MatchedSingle(ParseNtResult::Block(block)) => mk_delimited(
+                            block.span,
+                            MetaVarKind::Block,
+                            TokenStream::from_ast(block),
+                        ),
                         MatchedSingle(ParseNtResult::Stmt(stmt)) => {
                             let stream = if let StmtKind::Empty = stmt.kind {
                                 // FIXME: Properly collect tokens for empty statements.
@@ -385,15 +391,6 @@ pub(super) fn transcribe<'a>(
                         MatchedSingle(ParseNtResult::Vis(vis)) => {
                             mk_delimited(vis.span, MetaVarKind::Vis, TokenStream::from_ast(vis))
                         }
-                        MatchedSingle(ParseNtResult::Nt(nt)) => {
-                            // Other variables are emitted into the output stream as groups with
-                            // `Delimiter::Invisible` to maintain parsing priorities.
-                            // `Interpolated` is currently used for such groups in rustc parser.
-                            marker.visit_span(&mut sp);
-                            let use_span = nt.use_span();
-                            with_metavar_spans(|mspans| mspans.insert(use_span, sp));
-                            TokenTree::token_alone(token::Interpolated(Arc::clone(nt)), sp)
-                        }
                         MatchedSeq(..) => {
                             // We were unable to descend far enough. This is an error.
                             return Err(dcx.create_err(VarStillRepeating { span: sp, ident }));
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index ee6306e3961..2706a5eb3d7 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -309,15 +309,6 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                     }));
                 }
 
-                Interpolated(nt) => {
-                    let stream = TokenStream::from_nonterminal_ast(&nt);
-                    trees.push(TokenTree::Group(Group {
-                        delimiter: pm::Delimiter::None,
-                        stream: Some(stream),
-                        span: DelimSpan::from_single(span),
-                    }))
-                }
-
                 OpenDelim(..) | CloseDelim(..) => unreachable!(),
                 Eof => unreachable!(),
             }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index e1e6b93abf3..83df18ae286 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -637,9 +637,7 @@ 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::NtIdent(..) | TokenKind::NtLifetime(..) | TokenKind::Interpolated(..) => {
-                self.prev_token.span
-            }
+            TokenKind::NtIdent(..) | TokenKind::NtLifetime(..) => self.prev_token.span,
             TokenKind::CloseDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
                 // `expr.span` is the interpolated span, because invisible open
                 // and close delims both get marked with the same span, one
@@ -1386,15 +1384,7 @@ impl<'a> Parser<'a> {
         maybe_recover_from_interpolated_ty_qpath!(self, true);
 
         let span = self.token.span;
-        if let token::Interpolated(nt) = &self.token.kind {
-            match &**nt {
-                token::NtBlock(block) => {
-                    let block = block.clone();
-                    self.bump();
-                    return Ok(self.mk_expr(self.prev_token.span, ExprKind::Block(block, None)));
-                }
-            };
-        } else if let Some(expr) = self.eat_metavar_seq_with_matcher(
+        if let Some(expr) = self.eat_metavar_seq_with_matcher(
             |mv_kind| matches!(mv_kind, MetaVarKind::Expr { .. }),
             |this| {
                 // Force collection (as opposed to just `parse_expr`) is required to avoid the
@@ -1415,9 +1405,13 @@ impl<'a> Parser<'a> {
             self.eat_metavar_seq(MetaVarKind::Literal, |this| this.parse_literal_maybe_minus())
         {
             return Ok(lit);
-        } else if let Some(path) = self.eat_metavar_seq(MetaVarKind::Path, |this| {
-            this.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))
-        }) {
+        } else if let Some(block) =
+            self.eat_metavar_seq(MetaVarKind::Block, |this| this.parse_block())
+        {
+            return Ok(self.mk_expr(span, ExprKind::Block(block, None)));
+        } else if let Some(path) =
+            self.eat_metavar_seq(MetaVarKind::Path, |this| this.parse_path(PathStyle::Type))
+        {
             return Ok(self.mk_expr(span, ExprKind::Path(None, path)));
         }
 
@@ -1671,7 +1665,7 @@ impl<'a> Parser<'a> {
         } else if self.eat_keyword(exp!(Loop)) {
             self.parse_expr_loop(label, lo)
         } else if self.check_noexpect(&token::OpenDelim(Delimiter::Brace))
-            || self.token.is_whole_block()
+            || self.token.is_metavar_block()
         {
             self.parse_expr_block(label, lo, BlockCheckMode::Default)
         } else if !ate_colon
@@ -2349,7 +2343,7 @@ impl<'a> Parser<'a> {
             }
         }
 
-        if self.token.is_whole_block() {
+        if self.token.is_metavar_block() {
             self.dcx().emit_err(errors::InvalidBlockMacroSegment {
                 span: self.token.span,
                 context: lo.to(self.token.span),
@@ -2472,7 +2466,7 @@ impl<'a> Parser<'a> {
         if self.may_recover()
             && self.token.can_begin_expr()
             && !matches!(self.token.kind, TokenKind::OpenDelim(Delimiter::Brace))
-            && !self.token.is_whole_block()
+            && !self.token.is_metavar_block()
         {
             let snapshot = self.create_snapshot_for_diagnostic();
             let restrictions =
@@ -3519,7 +3513,7 @@ impl<'a> Parser<'a> {
         self.token.is_keyword(kw::Do)
             && self.is_keyword_ahead(1, &[kw::Catch])
             && self
-                .look_ahead(2, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block())
+                .look_ahead(2, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_metavar_block())
             && !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
     }
 
@@ -3530,7 +3524,7 @@ impl<'a> Parser<'a> {
     fn is_try_block(&self) -> bool {
         self.token.is_keyword(kw::Try)
             && self
-                .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block())
+                .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_metavar_block())
             && self.token_uninterpolated_span().at_least_rust_2018()
     }
 
@@ -3564,12 +3558,12 @@ impl<'a> Parser<'a> {
                 // `async move {`
                 self.is_keyword_ahead(lookahead + 1, &[kw::Move, kw::Use])
                     && self.look_ahead(lookahead + 2, |t| {
-                        *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block()
+                        *t == token::OpenDelim(Delimiter::Brace) || t.is_metavar_block()
                     })
             ) || (
                 // `async {`
                 self.look_ahead(lookahead + 1, |t| {
-                    *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block()
+                    *t == token::OpenDelim(Delimiter::Brace) || t.is_metavar_block()
                 })
             ))
     }
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index a8208e4717b..83c0bceb20a 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -2543,7 +2543,7 @@ impl<'a> Parser<'a> {
             self.expect_semi()?;
             *sig_hi = self.prev_token.span;
             (AttrVec::new(), None)
-        } else if self.check(exp!(OpenBrace)) || self.token.is_whole_block() {
+        } else if self.check(exp!(OpenBrace)) || self.token.is_metavar_block() {
             self.parse_block_common(self.token.span, BlockCheckMode::Default, None)
                 .map(|(attrs, body)| (attrs, Some(body)))?
         } else if self.token == token::Eq {
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 392a1c1057a..bb9393b8918 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -13,7 +13,6 @@ mod ty;
 
 use std::assert_matches::debug_assert_matches;
 use std::ops::Range;
-use std::sync::Arc;
 use std::{fmt, mem, slice};
 
 use attr_wrapper::{AttrWrapper, UsePreAttrPos};
@@ -24,8 +23,8 @@ pub use pat::{CommaRecoveryMode, RecoverColon, RecoverComma};
 use path::PathStyle;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{
-    self, Delimiter, IdentIsRaw, InvisibleOrigin, MetaVarKind, Nonterminal, NtExprKind, NtPatKind,
-    Token, TokenKind,
+    self, Delimiter, IdentIsRaw, InvisibleOrigin, MetaVarKind, NtExprKind, NtPatKind, Token,
+    TokenKind,
 };
 use rustc_ast::tokenstream::{AttrsTarget, Spacing, TokenStream, TokenTree};
 use rustc_ast::util::case::Case;
@@ -98,21 +97,6 @@ pub enum ForceCollect {
     No,
 }
 
-#[macro_export]
-macro_rules! maybe_whole {
-    ($p:expr, $constructor:ident, |$x:ident| $e:expr) => {
-        #[allow(irrefutable_let_patterns)] // FIXME: temporary
-        if let token::Interpolated(nt) = &$p.token.kind
-            && let token::$constructor(x) = &**nt
-        {
-            #[allow(unused_mut)]
-            let mut $x = x.clone();
-            $p.bump();
-            return Ok($e);
-        }
-    };
-}
-
 /// If the next tokens are ill-formed `$ty::` recover them as `<$ty>::`.
 #[macro_export]
 macro_rules! maybe_recover_from_interpolated_ty_qpath {
@@ -459,7 +443,6 @@ pub fn token_descr(token: &Token) -> String {
         (Some(TokenDescription::MetaVar(kind)), _) => format!("`{kind}` metavariable"),
         (None, TokenKind::NtIdent(..)) => format!("identifier `{s}`"),
         (None, TokenKind::NtLifetime(..)) => format!("lifetime `{s}`"),
-        (None, TokenKind::Interpolated(node)) => format!("{} `{s}`", node.descr()),
         (None, _) => format!("`{s}`"),
     }
 }
@@ -828,8 +811,10 @@ 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, token::NtBlock(..)),
                 token::OpenDelim(Delimiter::Brace) => true,
+                token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(
+                    MetaVarKind::Block,
+                ))) => true,
                 _ => false,
             })
     }
@@ -1375,7 +1360,7 @@ impl<'a> Parser<'a> {
         // Avoid const blocks and const closures to be parsed as const items
         if (self.check_const_closure() == is_closure)
             && !self
-                .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_whole_block())
+                .look_ahead(1, |t| *t == token::OpenDelim(Delimiter::Brace) || t.is_metavar_block())
             && self.eat_keyword_case(exp!(Const), case)
         {
             Const::Yes(self.prev_token_uninterpolated_span())
@@ -1732,7 +1717,6 @@ impl<'a> Parser<'a> {
     pub fn token_uninterpolated_span(&self) -> Span {
         match &self.token.kind {
             token::NtIdent(ident, _) | token::NtLifetime(ident, _) => ident.span,
-            token::Interpolated(nt) => nt.use_span(),
             token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
                 self.look_ahead(1, |t| t.span)
             }
@@ -1744,7 +1728,6 @@ impl<'a> Parser<'a> {
     pub fn prev_token_uninterpolated_span(&self) -> Span {
         match &self.prev_token.kind {
             token::NtIdent(ident, _) | token::NtLifetime(ident, _) => ident.span,
-            token::Interpolated(nt) => nt.use_span(),
             token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => {
                 self.look_ahead(0, |t| t.span)
             }
@@ -1801,6 +1784,7 @@ pub enum ParseNtResult {
     Ident(Ident, IdentIsRaw),
     Lifetime(Ident, IdentIsRaw),
     Item(P<ast::Item>),
+    Block(P<ast::Block>),
     Stmt(P<ast::Stmt>),
     Pat(P<ast::Pat>, NtPatKind),
     Expr(P<ast::Expr>, NtExprKind),
@@ -1809,7 +1793,4 @@ pub enum ParseNtResult {
     Meta(P<ast::AttrItem>),
     Path(P<ast::Path>),
     Vis(P<ast::Visibility>),
-
-    /// This variant will eventually be removed, along with `Token::Interpolate`.
-    Nt(Arc<Nonterminal>),
 }
diff --git a/compiler/rustc_parse/src/parser/nonterminal.rs b/compiler/rustc_parse/src/parser/nonterminal.rs
index b4e540d670d..576de776684 100644
--- a/compiler/rustc_parse/src/parser/nonterminal.rs
+++ b/compiler/rustc_parse/src/parser/nonterminal.rs
@@ -1,14 +1,7 @@
-use std::sync::Arc;
-
-use rustc_ast::HasTokens;
 use rustc_ast::ptr::P;
-use rustc_ast::token::Nonterminal::*;
 use rustc_ast::token::NtExprKind::*;
 use rustc_ast::token::NtPatKind::*;
-use rustc_ast::token::{
-    self, Delimiter, InvisibleOrigin, MetaVarKind, Nonterminal, NonterminalKind, Token,
-};
-use rustc_ast_pretty::pprust;
+use rustc_ast::token::{self, Delimiter, InvisibleOrigin, MetaVarKind, NonterminalKind, Token};
 use rustc_errors::PResult;
 use rustc_span::{Ident, kw};
 
@@ -45,13 +38,6 @@ impl<'a> Parser<'a> {
             }
         }
 
-        /// Old variant of `may_be_ident`. Being phased out.
-        fn nt_may_be_ident(nt: &Nonterminal) -> bool {
-            match nt {
-                NtBlock(_) => false,
-            }
-        }
-
         match kind {
             // `expr_2021` and earlier
             NonterminalKind::Expr(Expr2021 { .. }) => {
@@ -83,16 +69,12 @@ impl<'a> Parser<'a> {
                 | token::Ident(..)
                 | token::NtIdent(..)
                 | token::NtLifetime(..)
-                | token::Interpolated(_)
                 | token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(_))) => true,
                 _ => token.can_begin_type(),
             },
             NonterminalKind::Block => match &token.kind {
                 token::OpenDelim(Delimiter::Brace) => true,
                 token::NtLifetime(..) => true,
-                token::Interpolated(nt) => match &**nt {
-                    NtBlock(_) => true,
-                },
                 token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(k))) => match k {
                     MetaVarKind::Block
                     | MetaVarKind::Stmt
@@ -112,7 +94,6 @@ impl<'a> Parser<'a> {
             },
             NonterminalKind::Path | NonterminalKind::Meta => match &token.kind {
                 token::PathSep | token::Ident(..) | token::NtIdent(..) => true,
-                token::Interpolated(nt) => nt_may_be_ident(nt),
                 token::OpenDelim(Delimiter::Invisible(InvisibleOrigin::MetaVar(kind))) => {
                     may_be_ident(*kind)
                 }
@@ -136,62 +117,52 @@ impl<'a> Parser<'a> {
         // 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,
-        // we always capture tokens for any `Nonterminal` which needs them.
-        let mut nt = match kind {
+        // we always capture tokens for any nonterminal that needs them.
+        match kind {
             // Note that TT is treated differently to all the others.
-            NonterminalKind::TT => return Ok(ParseNtResult::Tt(self.parse_token_tree())),
+            NonterminalKind::TT => Ok(ParseNtResult::Tt(self.parse_token_tree())),
             NonterminalKind::Item => match self.parse_item(ForceCollect::Yes)? {
-                Some(item) => return Ok(ParseNtResult::Item(item)),
-                None => {
-                    return Err(self
-                        .dcx()
-                        .create_err(UnexpectedNonterminal::Item(self.token.span)));
-                }
+                Some(item) => Ok(ParseNtResult::Item(item)),
+                None => Err(self.dcx().create_err(UnexpectedNonterminal::Item(self.token.span))),
             },
             NonterminalKind::Block => {
                 // While a block *expression* may have attributes (e.g. `#[my_attr] { ... }`),
                 // the ':block' matcher does not support them
-                NtBlock(self.collect_tokens_no_attrs(|this| this.parse_block())?)
+                Ok(ParseNtResult::Block(self.collect_tokens_no_attrs(|this| this.parse_block())?))
             }
             NonterminalKind::Stmt => match self.parse_stmt(ForceCollect::Yes)? {
-                Some(stmt) => return Ok(ParseNtResult::Stmt(P(stmt))),
+                Some(stmt) => Ok(ParseNtResult::Stmt(P(stmt))),
                 None => {
-                    return Err(self
-                        .dcx()
-                        .create_err(UnexpectedNonterminal::Statement(self.token.span)));
+                    Err(self.dcx().create_err(UnexpectedNonterminal::Statement(self.token.span)))
                 }
             },
-            NonterminalKind::Pat(pat_kind) => {
-                return Ok(ParseNtResult::Pat(
-                    self.collect_tokens_no_attrs(|this| match pat_kind {
-                        PatParam { .. } => this.parse_pat_no_top_alt(None, None),
-                        PatWithOr => this.parse_pat_no_top_guard(
-                            None,
-                            RecoverComma::No,
-                            RecoverColon::No,
-                            CommaRecoveryMode::EitherTupleOrPipe,
-                        ),
-                    })?,
-                    pat_kind,
-                ));
-            }
+            NonterminalKind::Pat(pat_kind) => Ok(ParseNtResult::Pat(
+                self.collect_tokens_no_attrs(|this| match pat_kind {
+                    PatParam { .. } => this.parse_pat_no_top_alt(None, None),
+                    PatWithOr => this.parse_pat_no_top_guard(
+                        None,
+                        RecoverComma::No,
+                        RecoverColon::No,
+                        CommaRecoveryMode::EitherTupleOrPipe,
+                    ),
+                })?,
+                pat_kind,
+            )),
             NonterminalKind::Expr(expr_kind) => {
-                return Ok(ParseNtResult::Expr(self.parse_expr_force_collect()?, expr_kind));
+                Ok(ParseNtResult::Expr(self.parse_expr_force_collect()?, expr_kind))
             }
             NonterminalKind::Literal => {
                 // The `:literal` matcher does not support attributes.
-                return Ok(ParseNtResult::Literal(
+                Ok(ParseNtResult::Literal(
                     self.collect_tokens_no_attrs(|this| this.parse_literal_maybe_minus())?,
-                ));
-            }
-            NonterminalKind::Ty => {
-                return Ok(ParseNtResult::Ty(
-                    self.collect_tokens_no_attrs(|this| this.parse_ty_no_question_mark_recover())?,
-                ));
+                ))
             }
-            // this could be handled like a token, since it is one
+            NonterminalKind::Ty => Ok(ParseNtResult::Ty(
+                self.collect_tokens_no_attrs(|this| this.parse_ty_no_question_mark_recover())?,
+            )),
+            // This could be handled like a token, since it is one.
             NonterminalKind::Ident => {
-                return if let Some((ident, is_raw)) = get_macro_ident(&self.token) {
+                if let Some((ident, is_raw)) = get_macro_ident(&self.token) {
                     self.bump();
                     Ok(ParseNtResult::Ident(ident, is_raw))
                 } else {
@@ -199,25 +170,22 @@ impl<'a> Parser<'a> {
                         span: self.token.span,
                         token: self.token.clone(),
                     }))
-                };
-            }
-            NonterminalKind::Path => {
-                return Ok(ParseNtResult::Path(P(
-                    self.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))?
-                )));
+                }
             }
+            NonterminalKind::Path => Ok(ParseNtResult::Path(P(
+                self.collect_tokens_no_attrs(|this| this.parse_path(PathStyle::Type))?
+            ))),
             NonterminalKind::Meta => {
-                return Ok(ParseNtResult::Meta(P(self.parse_attr_item(ForceCollect::Yes)?)));
+                Ok(ParseNtResult::Meta(P(self.parse_attr_item(ForceCollect::Yes)?)))
             }
             NonterminalKind::Vis => {
-                return Ok(ParseNtResult::Vis(P(self.collect_tokens_no_attrs(|this| {
-                    this.parse_visibility(FollowedByType::Yes)
-                })?)));
+                Ok(ParseNtResult::Vis(P(self
+                    .collect_tokens_no_attrs(|this| this.parse_visibility(FollowedByType::Yes))?)))
             }
             NonterminalKind::Lifetime => {
                 // We want to keep `'keyword` parsing, just like `keyword` is still
                 // an ident for nonterminal purposes.
-                return if let Some((ident, is_raw)) = self.token.lifetime() {
+                if let Some((ident, is_raw)) = self.token.lifetime() {
                     self.bump();
                     Ok(ParseNtResult::Lifetime(ident, is_raw))
                 } else {
@@ -225,21 +193,9 @@ impl<'a> Parser<'a> {
                         span: self.token.span,
                         token: self.token.clone(),
                     }))
-                };
+                }
             }
-        };
-
-        // If tokens are supported at all, they should be collected.
-        if matches!(nt.tokens_mut(), Some(None)) {
-            panic!(
-                "Missing tokens for nt {:?} at {:?}: {:?}",
-                nt,
-                nt.use_span(),
-                pprust::nonterminal_to_string(&nt)
-            );
         }
-
-        Ok(ParseNtResult::Nt(Arc::new(nt)))
     }
 }
 
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index 97cd4d2117f..953bc303012 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -23,8 +23,8 @@ use super::{
     AttrWrapper, BlockMode, FnParseMode, ForceCollect, Parser, Restrictions, SemiColonMode,
     Trailing, UsePreAttrPos,
 };
-use crate::errors::MalformedLoopLabel;
-use crate::{errors, exp, maybe_whole};
+use crate::errors::{self, MalformedLoopLabel};
+use crate::exp;
 
 impl<'a> Parser<'a> {
     /// Parses a statement. This stops just before trailing semicolons on everything but items.
@@ -681,7 +681,9 @@ impl<'a> Parser<'a> {
         blk_mode: BlockCheckMode,
         loop_header: Option<Span>,
     ) -> PResult<'a, (AttrVec, P<Block>)> {
-        maybe_whole!(self, NtBlock, |block| (AttrVec::new(), block));
+        if let Some(block) = self.eat_metavar_seq(MetaVarKind::Block, |this| this.parse_block()) {
+            return Ok((AttrVec::new(), block));
+        }
 
         let maybe_ident = self.prev_token.clone();
         self.maybe_recover_unexpected_block_label(loop_header);
@@ -896,7 +898,7 @@ impl<'a> Parser<'a> {
                                 {
                                     if self.token == token::Colon
                                         && self.look_ahead(1, |token| {
-                                            token.is_whole_block()
+                                            token.is_metavar_block()
                                                 || matches!(
                                                     token.kind,
                                                     token::Ident(
diff --git a/tests/ui/macros/macro-as-fn-body.rs b/tests/ui/macros/macro-as-fn-body.rs
index e0542edc2a5..188c7f7f728 100644
--- a/tests/ui/macros/macro-as-fn-body.rs
+++ b/tests/ui/macros/macro-as-fn-body.rs
@@ -1,7 +1,7 @@
 //
 //@ run-pass
 //
-// Description - ensure Interpolated blocks can act as valid function bodies
+// Description - ensure block metavariables can act as valid function bodies
 // Covered cases: free functions, struct methods, and default trait functions
 
 macro_rules! def_fn {