Insert NoDelim groups around nonterminals when lowering macro_rules

Author: Aaron1011

src/librustc_ast/attr/mod.rs

@@ -560,6 +560,9 @@ impl MetaItemKind {
         tokens: &mut impl Iterator<Item = TokenTree>,
     ) -> Option<MetaItemKind> {
         match tokens.next() {
+            Some(TokenTree::Delimited(_, token::NoDelim, inner_tokens)) => {
+                MetaItemKind::name_value_from_tokens(&mut inner_tokens.trees())
+            }
             Some(TokenTree::Token(token)) => {
                 Lit::from_token(&token).ok().map(MetaItemKind::NameValue)
             }
@@ -619,13 +622,20 @@ impl NestedMetaItem {
     where
         I: Iterator<Item = TokenTree>,
     {
-        if let Some(TokenTree::Token(token)) = tokens.peek() {
-            if let Ok(lit) = Lit::from_token(token) {
+        match tokens.peek() {
+            Some(TokenTree::Token(token)) => {
+                if let Ok(lit) = Lit::from_token(token) {
+                    tokens.next();
+                    return Some(NestedMetaItem::Literal(lit));
+                }
+            }
+            Some(TokenTree::Delimited(_, token::NoDelim, inner_tokens)) => {
+                let inner_tokens = inner_tokens.clone();
                 tokens.next();
-                return Some(NestedMetaItem::Literal(lit));
+                return NestedMetaItem::from_tokens(&mut inner_tokens.into_trees().peekable());
             }
+            _ => {}
         }
-
         MetaItem::from_tokens(tokens).map(NestedMetaItem::MetaItem)
     }
 }

src/librustc_ast_lowering/lib.rs

@@ -39,8 +39,8 @@ use rustc_ast::ast;
 use rustc_ast::ast::*;
 use rustc_ast::attr;
 use rustc_ast::node_id::NodeMap;
-use rustc_ast::token::{self, Nonterminal, Token};
-use rustc_ast::tokenstream::{TokenStream, TokenTree};
+use rustc_ast::token::{self, DelimToken, Nonterminal, Token};
+use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
 use rustc_ast::visit::{self, AssocCtxt, Visitor};
 use rustc_ast::walk_list;
 use rustc_ast_pretty::pprust;
@@ -1029,7 +1029,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         match token.kind {
             token::Interpolated(nt, _) => {
                 let tts = (self.nt_to_tokenstream)(&nt, &self.sess.parse_sess, token.span);
-                self.lower_token_stream(tts)
+                TokenTree::Delimited(
+                    DelimSpan::from_single(token.span),
+                    DelimToken::NoDelim,
+                    self.lower_token_stream(tts),
+                )
+                .into()
             }
             _ => TokenTree::Token(token).into(),
         }

src/librustc_expand/mbe/macro_rules.rs

@@ -387,6 +387,7 @@ pub fn compile_declarative_macro(
     def: &ast::Item,
     edition: Edition,
 ) -> SyntaxExtension {
+    debug!("compile_declarative_macro: {:?}", def);
     let mk_syn_ext = |expander| {
         SyntaxExtension::new(
             sess,

src/librustc_middle/ty/context.rs

@@ -1049,6 +1049,7 @@ impl<'tcx> TyCtxt<'tcx> {
                 Some(attr) => attr,
                 None => return Bound::Unbounded,
             };
+            debug!("layout_scalar_valid_range: attr={:?}", attr);
             for meta in attr.meta_item_list().expect("rustc_layout_scalar_valid_range takes args") {
                 match meta.literal().expect("attribute takes lit").kind {
                     ast::LitKind::Int(a, _) => return Bound::Included(a),

src/test/ui/macros/doc-comment.rs

@@ -0,0 +1,25 @@
+// check-pass
+// Tests that we properly handle a nested macro expansion
+// involving a `#[doc]` attribute
+#![deny(missing_docs)]
+//! Crate docs
+
+macro_rules! doc_comment {
+    ($x:expr, $($tt:tt)*) => {
+        #[doc = $x]
+        $($tt)*
+    }
+}
+
+macro_rules! make_comment {
+    () => {
+        doc_comment!("Function docs",
+            pub fn bar() {}
+        );
+    }
+}
+
+
+make_comment!();
+
+fn main() {}

src/test/ui/proc-macro/auxiliary/nested-macro-rules.rs

@@ -0,0 +1,15 @@
+pub struct FirstStruct;
+
+#[macro_export]
+macro_rules! outer_macro {
+    ($name:ident) => {
+        #[macro_export]
+        macro_rules! inner_macro {
+            ($wrapper:ident) => {
+                $wrapper!($name)
+            }
+        }
+    }
+}
+
+outer_macro!(FirstStruct);

src/test/ui/proc-macro/auxiliary/test-macros.rs

@@ -101,6 +101,12 @@ pub fn print_bang(input: TokenStream) -> TokenStream {
     print_helper(input, "BANG")
 }
 
+#[proc_macro]
+pub fn print_bang_consume(input: TokenStream) -> TokenStream {
+    print_helper(input, "BANG");
+    TokenStream::new()
+}
+
 #[proc_macro_attribute]
 pub fn print_attr(_: TokenStream, input: TokenStream) -> TokenStream {
     print_helper(input, "ATTR")

src/test/ui/proc-macro/nested-macro-rules.rs

@@ -0,0 +1,20 @@
+// run-pass
+// aux-build:nested-macro-rules.rs
+// aux-build:test-macros.rs
+// compile-flags: -Z span-debug
+// edition:2018
+
+extern crate nested_macro_rules;
+extern crate test_macros;
+
+use test_macros::print_bang;
+
+use nested_macro_rules::FirstStruct;
+struct SecondStruct;
+
+fn main() {
+    nested_macro_rules::inner_macro!(print_bang);
+
+    nested_macro_rules::outer_macro!(SecondStruct);
+    inner_macro!(print_bang);
+}

src/test/ui/proc-macro/nested-macro-rules.stdout

@@ -0,0 +1,27 @@
+PRINT-BANG INPUT (DISPLAY):  FirstStruct 
+PRINT-BANG INPUT (DEBUG): TokenStream [
+    Group {
+        delimiter: None,
+        stream: TokenStream [
+            Ident {
+                ident: "FirstStruct",
+                span: $DIR/auxiliary/nested-macro-rules.rs:15:14: 15:25 (#3),
+            },
+        ],
+        span: $DIR/auxiliary/nested-macro-rules.rs:9:27: 9:32 (#3),
+    },
+]
+PRINT-BANG INPUT (DISPLAY): SecondStruct
+PRINT-BANG RE-COLLECTED (DISPLAY):  SecondStruct 
+PRINT-BANG INPUT (DEBUG): TokenStream [
+    Group {
+        delimiter: None,
+        stream: TokenStream [
+            Ident {
+                ident: "SecondStruct",
+                span: $DIR/nested-macro-rules.rs:18:38: 18:50 (#9),
+            },
+        ],
+        span: $DIR/auxiliary/nested-macro-rules.rs:9:27: 9:32 (#8),
+    },
+]

src/test/ui/proc-macro/nodelim-groups.rs

@@ -0,0 +1,19 @@
+// run-pass
+// aux-build:test-macros.rs
+// compile-flags: -Z span-debug
+// edition:2018
+//
+// Tests the pretty-printing behavior of inserting `NoDelim` groups
+
+extern crate test_macros;
+use test_macros::print_bang_consume;
+
+macro_rules! expand_it {
+    (($val1:expr) ($val2:expr)) => { expand_it!($val1 + $val2) };
+    ($val:expr) => { print_bang_consume!("hi" $val (1 + 1)) };
+}
+
+fn main() {
+    expand_it!(1 + (25) + 1);
+    expand_it!(("hello".len()) ("world".len()));
+}