Attach `TokenStream` to `ast::Block`

A `Block` does not have outer attributes, so we only capture tokens when
parsing a `macro_rules!` matcher

compiler/rustc_ast/src/ast.rs

@@ -540,6 +540,7 @@ pub struct Block {
     /// Distinguishes between `unsafe { ... }` and `{ ... }`.
     pub rules: BlockCheckMode,
     pub span: Span,
+    pub tokens: Option<TokenStream>,
 }
 
 /// A match pattern.

compiler/rustc_ast/src/mut_visit.rs

@@ -871,7 +871,7 @@ pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mu
 }
 
 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
-    let Block { id, stmts, rules: _, span } = block.deref_mut();
+    let Block { id, stmts, rules: _, span, tokens: _ } = block.deref_mut();
     vis.visit_id(id);
     stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
     vis.visit_span(span);

compiler/rustc_builtin_macros/src/deriving/mod.rs

@@ -75,6 +75,7 @@ fn call_intrinsic(
         id: ast::DUMMY_NODE_ID,
         rules: ast::BlockCheckMode::Unsafe(ast::CompilerGenerated),
         span,
+        tokens: None,
     }))
 }
 

compiler/rustc_expand/src/build.rs

@@ -207,7 +207,13 @@ pub fn block_expr(&self, expr: P<ast::Expr>) -> P<ast::Block> {
         )
     }
     pub fn block(&self, span: Span, stmts: Vec<ast::Stmt>) -> P<ast::Block> {
-        P(ast::Block { stmts, id: ast::DUMMY_NODE_ID, rules: BlockCheckMode::Default, span })
+        P(ast::Block {
+            stmts,
+            id: ast::DUMMY_NODE_ID,
+            rules: BlockCheckMode::Default,
+            span,
+            tokens: None,
+        })
     }
 
     pub fn expr(&self, span: Span, kind: ast::ExprKind) -> P<ast::Expr> {

compiler/rustc_interface/src/util.rs

@@ -693,6 +693,7 @@ fn stmt_to_block(
                 rules,
                 id: resolver.next_node_id(),
                 span: rustc_span::DUMMY_SP,
+                tokens: None,
             }
         }
 

compiler/rustc_parse/src/lib.rs

@@ -268,6 +268,7 @@ pub fn nt_to_tokenstream(nt: &Nonterminal, sess: &ParseSess, span: Span) -> Toke
         Nonterminal::NtItem(ref item) => {
             prepend_attrs(sess, &item.attrs, item.tokens.as_ref(), span)
         }
+        Nonterminal::NtBlock(ref block) => block.tokens.clone(),
         Nonterminal::NtPat(ref pat) => pat.tokens.clone(),
         Nonterminal::NtIdent(ident, is_raw) => {
             Some(tokenstream::TokenTree::token(token::Ident(ident.name, is_raw), ident.span).into())

compiler/rustc_parse/src/parser/nonterminal.rs

@@ -111,7 +111,14 @@ pub fn parse_nonterminal(&mut self, kind: NonterminalKind) -> PResult<'a, Nonter
                     return Err(self.struct_span_err(self.token.span, "expected an item keyword"));
                 }
             },
-            NonterminalKind::Block => token::NtBlock(self.parse_block()?),
+            NonterminalKind::Block => {
+                let (mut block, tokens) = self.collect_tokens(|this| this.parse_block())?;
+                // We have have eaten an NtBlock, which could already have tokens
+                if block.tokens.is_none() {
+                    block.tokens = Some(tokens);
+                }
+                token::NtBlock(block)
+            }
             NonterminalKind::Stmt => match self.parse_stmt()? {
                 Some(s) => token::NtStmt(s),
                 None => return Err(self.struct_span_err(self.token.span, "expected a statement")),

compiler/rustc_parse/src/parser/stmt.rs

@@ -411,7 +411,7 @@ pub fn parse_full_stmt(&mut self) -> PResult<'a, Option<Stmt>> {
     }
 
     pub(super) fn mk_block(&self, stmts: Vec<Stmt>, rules: BlockCheckMode, span: Span) -> P<Block> {
-        P(Block { stmts, id: DUMMY_NODE_ID, rules, span })
+        P(Block { stmts, id: DUMMY_NODE_ID, rules, span, tokens: None })
     }
 
     pub(super) fn mk_stmt(&self, span: Span, kind: StmtKind) -> Stmt {