Add spacing information to delimiters.

This is an extension of the previous commit. It means the output of
something like this:
```
stringify!(let a: Vec<u32> = vec![];)
```
goes from this:
```
let a: Vec<u32> = vec![] ;
```
With this PR, it now produces this string:
```
let a: Vec<u32> = vec![];
```

10 files changed, 78 insertions, 50 deletions

diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index 3106fad0432..b4693f5a71a 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -6,8 +6,7 @@ use crate::errors::{
 };
 use rustc_ast::ptr::P;
 use rustc_ast::token::{Delimiter, Token, TokenKind};
-use rustc_ast::tokenstream::{AttrTokenStream, AttrTokenTree};
-use rustc_ast::tokenstream::{DelimSpan, Spacing};
+use rustc_ast::tokenstream::{AttrTokenStream, AttrTokenTree, DelimSpacing, DelimSpan, Spacing};
 use rustc_ast::tokenstream::{LazyAttrTokenStream, TokenTree};
 use rustc_ast::NodeId;
 use rustc_ast::{self as ast, AttrStyle, Attribute, HasAttrs, HasTokens, MetaItem};
@@ -242,7 +241,7 @@ impl<'a> StripUnconfigured<'a> {
             stream.0.iter().all(|tree| match tree {
                 AttrTokenTree::Attributes(_) => false,
                 AttrTokenTree::Token(..) => true,
-                AttrTokenTree::Delimited(_, _, inner) => can_skip(inner),
+                AttrTokenTree::Delimited(.., inner) => can_skip(inner),
             })
         }
 
@@ -266,9 +265,9 @@ impl<'a> StripUnconfigured<'a> {
                         None.into_iter()
                     }
                 }
-                AttrTokenTree::Delimited(sp, delim, mut inner) => {
+                AttrTokenTree::Delimited(sp, spacing, delim, mut inner) => {
                     inner = self.configure_tokens(&inner);
-                    Some(AttrTokenTree::Delimited(sp, delim, inner)).into_iter()
+                    Some(AttrTokenTree::Delimited(sp, spacing, delim, inner)).into_iter()
                 }
                 AttrTokenTree::Token(ref token, _)
                     if let TokenKind::Interpolated(nt) = &token.kind =>
@@ -376,6 +375,7 @@ impl<'a> StripUnconfigured<'a> {
         // in `#[attr]`, so just use the span of the `#` token.
         let bracket_group = AttrTokenTree::Delimited(
             DelimSpan::from_single(pound_span),
+            DelimSpacing::new(Spacing::JointHidden, Spacing::Alone),
             Delimiter::Bracket,
             item.tokens
                 .as_ref()
diff --git a/compiler/rustc_expand/src/mbe.rs b/compiler/rustc_expand/src/mbe.rs
index a43b2a00188..ca4a1f327ad 100644
--- a/compiler/rustc_expand/src/mbe.rs
+++ b/compiler/rustc_expand/src/mbe.rs
@@ -13,7 +13,7 @@ pub(crate) mod transcribe;
 
 use metavar_expr::MetaVarExpr;
 use rustc_ast::token::{Delimiter, NonterminalKind, Token, TokenKind};
-use rustc_ast::tokenstream::DelimSpan;
+use rustc_ast::tokenstream::{DelimSpacing, DelimSpan};
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 
@@ -68,7 +68,7 @@ pub(crate) enum KleeneOp {
 enum TokenTree {
     Token(Token),
     /// A delimited sequence, e.g. `($e:expr)` (RHS) or `{ $e }` (LHS).
-    Delimited(DelimSpan, Delimited),
+    Delimited(DelimSpan, DelimSpacing, Delimited),
     /// A kleene-style repetition sequence, e.g. `$($e:expr)*` (RHS) or `$($e),*` (LHS).
     Sequence(DelimSpan, SequenceRepetition),
     /// e.g., `$var`.
@@ -99,7 +99,7 @@ impl TokenTree {
             TokenTree::Token(Token { span, .. })
             | TokenTree::MetaVar(span, _)
             | TokenTree::MetaVarDecl(span, _, _) => span,
-            TokenTree::Delimited(span, _)
+            TokenTree::Delimited(span, ..)
             | TokenTree::MetaVarExpr(span, _)
             | TokenTree::Sequence(span, _) => span.entire(),
         }
diff --git a/compiler/rustc_expand/src/mbe/macro_check.rs b/compiler/rustc_expand/src/mbe/macro_check.rs
index 42c91824baf..0b1f25b67c8 100644
--- a/compiler/rustc_expand/src/mbe/macro_check.rs
+++ b/compiler/rustc_expand/src/mbe/macro_check.rs
@@ -290,7 +290,7 @@ fn check_binders(
         }
         // `MetaVarExpr` can not appear in the LHS of a macro arm
         TokenTree::MetaVarExpr(..) => {}
-        TokenTree::Delimited(_, ref del) => {
+        TokenTree::Delimited(.., ref del) => {
             for tt in &del.tts {
                 check_binders(sess, node_id, tt, macros, binders, ops, valid);
             }
@@ -353,7 +353,7 @@ fn check_occurrences(
             };
             check_ops_is_prefix(sess, node_id, macros, binders, ops, dl.entire(), name);
         }
-        TokenTree::Delimited(_, ref del) => {
+        TokenTree::Delimited(.., ref del) => {
             check_nested_occurrences(sess, node_id, &del.tts, macros, binders, ops, valid);
         }
         TokenTree::Sequence(_, ref seq) => {
@@ -435,8 +435,8 @@ fn check_nested_occurrences(
                 // We check that the meta-variable is correctly used.
                 check_occurrences(sess, node_id, tt, macros, binders, ops, valid);
             }
-            (NestedMacroState::MacroRulesNotName, TokenTree::Delimited(_, del))
-            | (NestedMacroState::MacroName, TokenTree::Delimited(_, del))
+            (NestedMacroState::MacroRulesNotName, TokenTree::Delimited(.., del))
+            | (NestedMacroState::MacroName, TokenTree::Delimited(.., del))
                 if del.delim == Delimiter::Brace =>
             {
                 let macro_rules = state == NestedMacroState::MacroRulesNotName;
@@ -466,7 +466,7 @@ fn check_nested_occurrences(
                 // We check that the meta-variable is correctly used.
                 check_occurrences(sess, node_id, tt, macros, binders, ops, valid);
             }
-            (NestedMacroState::MacroName, TokenTree::Delimited(_, del))
+            (NestedMacroState::MacroName, TokenTree::Delimited(.., del))
                 if del.delim == Delimiter::Parenthesis =>
             {
                 state = NestedMacroState::MacroNameParen;
@@ -481,7 +481,7 @@ fn check_nested_occurrences(
                     valid,
                 );
             }
-            (NestedMacroState::MacroNameParen, TokenTree::Delimited(_, del))
+            (NestedMacroState::MacroNameParen, TokenTree::Delimited(.., del))
                 if del.delim == Delimiter::Brace =>
             {
                 state = NestedMacroState::Empty;
diff --git a/compiler/rustc_expand/src/mbe/macro_parser.rs b/compiler/rustc_expand/src/mbe/macro_parser.rs
index 965beb9bf84..b248a1fe349 100644
--- a/compiler/rustc_expand/src/mbe/macro_parser.rs
+++ b/compiler/rustc_expand/src/mbe/macro_parser.rs
@@ -184,7 +184,7 @@ pub(super) fn compute_locs(matcher: &[TokenTree]) -> Vec<MatcherLoc> {
                 TokenTree::Token(token) => {
                     locs.push(MatcherLoc::Token { token: token.clone() });
                 }
-                TokenTree::Delimited(span, delimited) => {
+                TokenTree::Delimited(span, _, delimited) => {
                     let open_token = Token::new(token::OpenDelim(delimited.delim), span.open);
                     let close_token = Token::new(token::CloseDelim(delimited.delim), span.close);
 
@@ -335,7 +335,7 @@ pub(super) fn count_metavar_decls(matcher: &[TokenTree]) -> usize {
         .map(|tt| match tt {
             TokenTree::MetaVarDecl(..) => 1,
             TokenTree::Sequence(_, seq) => seq.num_captures,
-            TokenTree::Delimited(_, delim) => count_metavar_decls(&delim.tts),
+            TokenTree::Delimited(.., delim) => count_metavar_decls(&delim.tts),
             TokenTree::Token(..) => 0,
             TokenTree::MetaVar(..) | TokenTree::MetaVarExpr(..) => unreachable!(),
         })
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 19734394382..393eec3997b 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -207,7 +207,7 @@ fn expand_macro<'cx>(
     match try_success_result {
         Ok((i, named_matches)) => {
             let (rhs, rhs_span): (&mbe::Delimited, DelimSpan) = match &rhses[i] {
-                mbe::TokenTree::Delimited(span, delimited) => (&delimited, *span),
+                mbe::TokenTree::Delimited(span, _, delimited) => (&delimited, *span),
                 _ => cx.span_bug(sp, "malformed macro rhs"),
             };
             let arm_span = rhses[i].span();
@@ -589,7 +589,7 @@ pub fn compile_declarative_macro(
             .map(|lhs| {
                 // Ignore the delimiters around the matcher.
                 match lhs {
-                    mbe::TokenTree::Delimited(_, delimited) => {
+                    mbe::TokenTree::Delimited(.., delimited) => {
                         mbe::macro_parser::compute_locs(&delimited.tts)
                     }
                     _ => sess.diagnostic().span_bug(def.span, "malformed macro lhs"),
@@ -615,7 +615,7 @@ pub fn compile_declarative_macro(
 fn check_lhs_nt_follows(sess: &ParseSess, def: &ast::Item, lhs: &mbe::TokenTree) -> bool {
     // lhs is going to be like TokenTree::Delimited(...), where the
     // entire lhs is those tts. Or, it can be a "bare sequence", not wrapped in parens.
-    if let mbe::TokenTree::Delimited(_, delimited) = lhs {
+    if let mbe::TokenTree::Delimited(.., delimited) = lhs {
         check_matcher(sess, def, &delimited.tts)
     } else {
         let msg = "invalid macro matcher; matchers must be contained in balanced delimiters";
@@ -668,7 +668,7 @@ fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[mbe::TokenTree]) -> bool {
             | TokenTree::MetaVar(..)
             | TokenTree::MetaVarDecl(..)
             | TokenTree::MetaVarExpr(..) => (),
-            TokenTree::Delimited(_, del) => {
+            TokenTree::Delimited(.., del) => {
                 if !check_lhs_no_empty_seq(sess, &del.tts) {
                     return false;
                 }
@@ -709,14 +709,14 @@ fn check_matcher(sess: &ParseSess, def: &ast::Item, matcher: &[mbe::TokenTree])
 
 fn has_compile_error_macro(rhs: &mbe::TokenTree) -> bool {
     match rhs {
-        mbe::TokenTree::Delimited(_sp, d) => {
+        mbe::TokenTree::Delimited(.., d) => {
             let has_compile_error = d.tts.array_windows::<3>().any(|[ident, bang, args]| {
                 if let mbe::TokenTree::Token(ident) = ident
                     && let TokenKind::Ident(ident, _) = ident.kind
                     && ident == sym::compile_error
                     && let mbe::TokenTree::Token(bang) = bang
                     && let TokenKind::Not = bang.kind
-                    && let mbe::TokenTree::Delimited(_, del) = args
+                    && let mbe::TokenTree::Delimited(.., del) = args
                     && del.delim != Delimiter::Invisible
                 {
                     true
@@ -773,7 +773,7 @@ impl<'tt> FirstSets<'tt> {
                     | TokenTree::MetaVarExpr(..) => {
                         first.replace_with(TtHandle::TtRef(tt));
                     }
-                    TokenTree::Delimited(span, delimited) => {
+                    TokenTree::Delimited(span, _, delimited) => {
                         build_recur(sets, &delimited.tts);
                         first.replace_with(TtHandle::from_token_kind(
                             token::OpenDelim(delimited.delim),
@@ -842,7 +842,7 @@ impl<'tt> FirstSets<'tt> {
                     first.add_one(TtHandle::TtRef(tt));
                     return first;
                 }
-                TokenTree::Delimited(span, delimited) => {
+                TokenTree::Delimited(span, _, delimited) => {
                     first.add_one(TtHandle::from_token_kind(
                         token::OpenDelim(delimited.delim),
                         span.open,
@@ -1087,7 +1087,7 @@ fn check_matcher_core<'tt>(
                     suffix_first = build_suffix_first();
                 }
             }
-            TokenTree::Delimited(span, d) => {
+            TokenTree::Delimited(span, _, d) => {
                 let my_suffix = TokenSet::singleton(TtHandle::from_token_kind(
                     token::CloseDelim(d.delim),
                     span.close,
diff --git a/compiler/rustc_expand/src/mbe/metavar_expr.rs b/compiler/rustc_expand/src/mbe/metavar_expr.rs
index 7cb279a9812..c29edc3dc9f 100644
--- a/compiler/rustc_expand/src/mbe/metavar_expr.rs
+++ b/compiler/rustc_expand/src/mbe/metavar_expr.rs
@@ -35,7 +35,7 @@ impl MetaVarExpr {
     ) -> PResult<'sess, MetaVarExpr> {
         let mut tts = input.trees();
         let ident = parse_ident(&mut tts, sess, outer_span)?;
-        let Some(TokenTree::Delimited(_, Delimiter::Parenthesis, args)) = tts.next() else {
+        let Some(TokenTree::Delimited(.., Delimiter::Parenthesis, args)) = tts.next() else {
             let msg = "meta-variable expression parameter must be wrapped in parentheses";
             return Err(sess.span_diagnostic.struct_span_err(ident.span, msg));
         };
diff --git a/compiler/rustc_expand/src/mbe/quoted.rs b/compiler/rustc_expand/src/mbe/quoted.rs
index 6a99412fc5b..ab9fb20b364 100644
--- a/compiler/rustc_expand/src/mbe/quoted.rs
+++ b/compiler/rustc_expand/src/mbe/quoted.rs
@@ -151,7 +151,7 @@ fn parse_tree<'a>(
             // during parsing.
             let mut next = outer_trees.next();
             let mut trees: Box<dyn Iterator<Item = &tokenstream::TokenTree>>;
-            if let Some(tokenstream::TokenTree::Delimited(_, Delimiter::Invisible, tts)) = next {
+            if let Some(tokenstream::TokenTree::Delimited(.., Delimiter::Invisible, tts)) = next {
                 trees = Box::new(tts.trees());
                 next = trees.next();
             } else {
@@ -160,7 +160,7 @@ fn parse_tree<'a>(
 
             match next {
                 // `tree` is followed by a delimited set of token trees.
-                Some(&tokenstream::TokenTree::Delimited(delim_span, delim, ref tts)) => {
+                Some(&tokenstream::TokenTree::Delimited(delim_span, _, delim, ref tts)) => {
                     if parsing_patterns {
                         if delim != Delimiter::Parenthesis {
                             span_dollar_dollar_or_metavar_in_the_lhs_err(
@@ -258,8 +258,9 @@ fn parse_tree<'a>(
 
         // `tree` is the beginning of a delimited set of tokens (e.g., `(` or `{`). We need to
         // descend into the delimited set and further parse it.
-        &tokenstream::TokenTree::Delimited(span, delim, ref tts) => TokenTree::Delimited(
+        &tokenstream::TokenTree::Delimited(span, spacing, delim, ref tts) => TokenTree::Delimited(
             span,
+            spacing,
             Delimited {
                 delim,
                 tts: parse(tts, parsing_patterns, sess, node_id, features, edition),
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs
index 854f551ea1b..18707cebcd5 100644
--- a/compiler/rustc_expand/src/mbe/transcribe.rs
+++ b/compiler/rustc_expand/src/mbe/transcribe.rs
@@ -7,7 +7,7 @@ use crate::mbe::macro_parser::{MatchedNonterminal, MatchedSeq, MatchedTokenTree,
 use crate::mbe::{self, MetaVarExpr};
 use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::token::{self, Delimiter, Token, TokenKind};
-use rustc_ast::tokenstream::{DelimSpan, Spacing, TokenStream, TokenTree};
+use rustc_ast::tokenstream::{DelimSpacing, DelimSpan, Spacing, TokenStream, TokenTree};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{pluralize, PResult};
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
@@ -31,14 +31,24 @@ impl MutVisitor for Marker {
 
 /// An iterator over the token trees in a delimited token tree (`{ ... }`) or a sequence (`$(...)`).
 enum Frame<'a> {
-    Delimited { tts: &'a [mbe::TokenTree], idx: usize, delim: Delimiter, span: DelimSpan },
-    Sequence { tts: &'a [mbe::TokenTree], idx: usize, sep: Option<Token> },
+    Delimited {
+        tts: &'a [mbe::TokenTree],
+        idx: usize,
+        delim: Delimiter,
+        span: DelimSpan,
+        spacing: DelimSpacing,
+    },
+    Sequence {
+        tts: &'a [mbe::TokenTree],
+        idx: usize,
+        sep: Option<Token>,
+    },
 }
 
 impl<'a> Frame<'a> {
     /// Construct a new frame around the delimited set of tokens.
-    fn new(src: &'a mbe::Delimited, span: DelimSpan) -> Frame<'a> {
-        Frame::Delimited { tts: &src.tts, idx: 0, delim: src.delim, span }
+    fn new(src: &'a mbe::Delimited, span: DelimSpan, spacing: DelimSpacing) -> Frame<'a> {
+        Frame::Delimited { tts: &src.tts, idx: 0, delim: src.delim, span, spacing }
     }
 }
 
@@ -89,8 +99,10 @@ pub(super) fn transcribe<'a>(
     }
 
     // We descend into the RHS (`src`), expanding things as we go. This stack contains the things
-    // we have yet to expand/are still expanding. We start the stack off with the whole RHS.
-    let mut stack: SmallVec<[Frame<'_>; 1]> = smallvec![Frame::new(src, src_span)];
+    // we have yet to expand/are still expanding. We start the stack off with the whole RHS. The
+    // choice of spacing values doesn't matter.
+    let mut stack: SmallVec<[Frame<'_>; 1]> =
+        smallvec![Frame::new(src, src_span, DelimSpacing::new(Spacing::Alone, Spacing::Alone))];
 
     // As we descend in the RHS, we will need to be able to match nested sequences of matchers.
     // `repeats` keeps track of where we are in matching at each level, with the last element being
@@ -144,14 +156,19 @@ pub(super) fn transcribe<'a>(
                 // We are done processing a Delimited. If this is the top-level delimited, we are
                 // done. Otherwise, we unwind the result_stack to append what we have produced to
                 // any previous results.
-                Frame::Delimited { delim, span, .. } => {
+                Frame::Delimited { delim, span, mut spacing, .. } => {
+                    // Hack to force-insert a space after `]` in certain case.
+                    // See discussion of the `hex-literal` crate in #114571.
+                    if delim == Delimiter::Bracket {
+                        spacing.close = Spacing::Alone;
+                    }
                     if result_stack.is_empty() {
                         // No results left to compute! We are back at the top-level.
                         return Ok(TokenStream::new(result));
                     }
 
                     // Step back into the parent Delimited.
-                    let tree = TokenTree::Delimited(span, delim, TokenStream::new(result));
+                    let tree = TokenTree::Delimited(span, spacing, delim, TokenStream::new(result));
                     result = result_stack.pop().unwrap();
                     result.push(tree);
                 }
@@ -258,13 +275,14 @@ pub(super) fn transcribe<'a>(
             // We will produce all of the results of the inside of the `Delimited` and then we will
             // jump back out of the Delimited, pop the result_stack and add the new results back to
             // the previous results (from outside the Delimited).
-            mbe::TokenTree::Delimited(mut span, delimited) => {
+            mbe::TokenTree::Delimited(mut span, spacing, delimited) => {
                 mut_visit::visit_delim_span(&mut span, &mut marker);
                 stack.push(Frame::Delimited {
                     tts: &delimited.tts,
                     delim: delimited.delim,
                     idx: 0,
                     span,
+                    spacing: *spacing,
                 });
                 result_stack.push(mem::take(&mut result));
             }
@@ -374,7 +392,7 @@ fn lockstep_iter_size(
 ) -> LockstepIterSize {
     use mbe::TokenTree;
     match tree {
-        TokenTree::Delimited(_, delimited) => {
+        TokenTree::Delimited(.., delimited) => {
             delimited.tts.iter().fold(LockstepIterSize::Unconstrained, |size, tt| {
                 size.with(lockstep_iter_size(tt, interpolations, repeats))
             })
diff --git a/compiler/rustc_expand/src/parse/tests.rs b/compiler/rustc_expand/src/parse/tests.rs
index a6c6d82b575..7a888250ca1 100644
--- a/compiler/rustc_expand/src/parse/tests.rs
+++ b/compiler/rustc_expand/src/parse/tests.rs
@@ -4,7 +4,7 @@ use crate::tests::{
 
 use rustc_ast::ptr::P;
 use rustc_ast::token::{self, Delimiter, Token};
-use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
+use rustc_ast::tokenstream::{DelimSpacing, DelimSpan, Spacing, TokenStream, TokenTree};
 use rustc_ast::visit;
 use rustc_ast::{self as ast, PatKind};
 use rustc_ast_pretty::pprust::item_to_string;
@@ -77,14 +77,14 @@ fn string_to_tts_macro() {
                 TokenTree::Token(Token { kind: token::Ident(name_macro_rules, false), .. }, _),
                 TokenTree::Token(Token { kind: token::Not, .. }, _),
                 TokenTree::Token(Token { kind: token::Ident(name_zip, false), .. }, _),
-                TokenTree::Delimited(_, macro_delim, macro_tts),
+                TokenTree::Delimited(.., macro_delim, macro_tts),
             ] if name_macro_rules == &kw::MacroRules && name_zip.as_str() == "zip" => {
                 let tts = &macro_tts.trees().collect::<Vec<_>>();
                 match &tts[..] {
                     [
-                        TokenTree::Delimited(_, first_delim, first_tts),
+                        TokenTree::Delimited(.., first_delim, first_tts),
                         TokenTree::Token(Token { kind: token::FatArrow, .. }, _),
-                        TokenTree::Delimited(_, second_delim, second_tts),
+                        TokenTree::Delimited(.., second_delim, second_tts),
                     ] if macro_delim == &Delimiter::Parenthesis => {
                         let tts = &first_tts.trees().collect::<Vec<_>>();
                         match &tts[..] {
@@ -123,6 +123,9 @@ fn string_to_tts_1() {
             TokenTree::token_joint_hidden(token::Ident(Symbol::intern("a"), false), sp(3, 4)),
             TokenTree::Delimited(
                 DelimSpan::from_pair(sp(4, 5), sp(11, 12)),
+                // `JointHidden` because the `(` is followed immediately by
+                // `b`, `Alone` because the `)` is followed by whitespace.
+                DelimSpacing::new(Spacing::JointHidden, Spacing::Alone),
                 Delimiter::Parenthesis,
                 TokenStream::new(vec![
                     TokenTree::token_joint(token::Ident(Symbol::intern("b"), false), sp(5, 6)),
@@ -134,6 +137,10 @@ fn string_to_tts_1() {
             ),
             TokenTree::Delimited(
                 DelimSpan::from_pair(sp(13, 14), sp(18, 19)),
+                // First `Alone` because the `{` is followed by whitespace,
+                // second `Alone` because the `}` is followed immediately by
+                // EOF.
+                DelimSpacing::new(Spacing::Alone, Spacing::Alone),
                 Delimiter::Brace,
                 TokenStream::new(vec![
                     TokenTree::token_joint(token::Ident(Symbol::intern("b"), false), sp(15, 16)),
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index b3b78330801..5308e338d7f 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -5,7 +5,7 @@ use pm::bridge::{
 use pm::{Delimiter, Level};
 use rustc_ast as ast;
 use rustc_ast::token;
-use rustc_ast::tokenstream::{self, Spacing, TokenStream};
+use rustc_ast::tokenstream::{self, DelimSpacing, Spacing, TokenStream};
 use rustc_ast::util::literal::escape_byte_str_symbol;
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
@@ -98,7 +98,7 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
 
         while let Some(tree) = cursor.next() {
             let (Token { kind, span }, joint) = match tree.clone() {
-                tokenstream::TokenTree::Delimited(span, delim, tts) => {
+                tokenstream::TokenTree::Delimited(span, _, delim, tts) => {
                     let delimiter = pm::Delimiter::from_internal(delim);
                     trees.push(TokenTree::Group(Group {
                         delimiter,
@@ -284,10 +284,11 @@ impl ToInternal<SmallVec<[tokenstream::TokenTree; 2]>>
     fn to_internal(self) -> SmallVec<[tokenstream::TokenTree; 2]> {
         use rustc_ast::token::*;
 
-        // The code below is conservative and uses `token_alone` in most
-        // places. When the resulting code is pretty-printed by `print_tts` it
-        // ends up with spaces between most tokens, which is safe but ugly.
-        // It's hard in general to do better when working at the token level.
+        // The code below is conservative, using `token_alone`/`Spacing::Alone`
+        // in most places. When the resulting code is pretty-printed by
+        // `print_tts` it ends up with spaces between most tokens, which is
+        // safe but ugly. It's hard in general to do better when working at the
+        // token level.
         let (tree, rustc) = self;
         match tree {
             TokenTree::Punct(Punct { ch, joint, span }) => {
@@ -330,6 +331,7 @@ impl ToInternal<SmallVec<[tokenstream::TokenTree; 2]>>
             TokenTree::Group(Group { delimiter, stream, span: DelimSpan { open, close, .. } }) => {
                 smallvec![tokenstream::TokenTree::Delimited(
                     tokenstream::DelimSpan { open, close },
+                    DelimSpacing::new(Spacing::Alone, Spacing::Alone),
                     delimiter.to_internal(),
                     stream.unwrap_or_default(),
                 )]