6 files changed, 31 insertions, 15 deletions
diff --git a/src/libsyntax/parse/lexer/tokentrees.rs b/src/libsyntax/parse/lexer/tokentrees.rs
index e5ba7e45309..b4dd23c9f9b 100644
--- a/src/libsyntax/parse/lexer/tokentrees.rs
+++ b/src/libsyntax/parse/lexer/tokentrees.rs
@@ -1,3 +1,4 @@
+use rustc_data_structures::fx::FxHashMap;
 use syntax_pos::Span;
 
 use crate::print::pprust::token_to_string;
@@ -16,6 +17,7 @@ impl<'a> StringReader<'a> {
             unmatched_braces: Vec::new(),
             matching_delim_spans: Vec::new(),
             last_unclosed_found_span: None,
+            last_delim_empty_block_spans: FxHashMap::default()
         };
         let res = tt_reader.parse_all_token_trees();
         (res, tt_reader.unmatched_braces)
@@ -34,6 +36,7 @@ struct TokenTreesReader<'a> {
     /// Used only for error recovery when arriving to EOF with mismatched braces.
     matching_delim_spans: Vec<(token::DelimToken, Span, Span)>,
     last_unclosed_found_span: Option<Span>,
+    last_delim_empty_block_spans: FxHashMap<token::DelimToken, Span>
 }
 
 impl<'a> TokenTreesReader<'a> {
@@ -121,13 +124,20 @@ impl<'a> TokenTreesReader<'a> {
                     // Correct delimiter.
                     token::CloseDelim(d) if d == delim => {
                         let (open_brace, open_brace_span) = self.open_braces.pop().unwrap();
+                        let close_brace_span = self.token.span;
+
+                        if tts.is_empty() {
+                            let empty_block_span = open_brace_span.to(close_brace_span);
+                            self.last_delim_empty_block_spans.insert(delim, empty_block_span);
+                        }
+
                         if self.open_braces.len() == 0 {
                             // Clear up these spans to avoid suggesting them as we've found
                             // properly matched delimiters so far for an entire block.
                             self.matching_delim_spans.clear();
                         } else {
                             self.matching_delim_spans.push(
-                                (open_brace, open_brace_span, self.token.span),
+                                (open_brace, open_brace_span, close_brace_span),
                             );
                         }
                         // Parse the close delimiter.
@@ -193,13 +203,20 @@ impl<'a> TokenTreesReader<'a> {
                     tts.into()
                 ).into())
             },
-            token::CloseDelim(_) => {
+            token::CloseDelim(delim) => {
                 // An unexpected closing delimiter (i.e., there is no
                 // matching opening delimiter).
                 let token_str = token_to_string(&self.token);
                 let msg = format!("unexpected close delimiter: `{}`", token_str);
                 let mut err = self.string_reader.sess.span_diagnostic
                     .struct_span_err(self.token.span, &msg);
+
+                if let Some(span) = self.last_delim_empty_block_spans.remove(&delim) {
+                    err.span_label(
+                        span,
+                        "this block is empty, you might have not meant to close it"
+                    );
+                }
                 err.span_label(self.token.span, "unexpected close delimiter");
                 Err(err)
             },
diff --git a/src/libsyntax/parse/literal.rs b/src/libsyntax/parse/literal.rs
index 14e1696610a..7952e293a53 100644
--- a/src/libsyntax/parse/literal.rs
+++ b/src/libsyntax/parse/literal.rs
@@ -3,7 +3,7 @@
 use crate::ast::{self, Lit, LitKind};
 use crate::parse::token::{self, Token};
 use crate::symbol::{kw, sym, Symbol};
-use crate::tokenstream::{TokenStream, TokenTree};
+use crate::tokenstream::TokenTree;
 
 use log::debug;
 use rustc_data_structures::sync::Lrc;
@@ -216,13 +216,13 @@ impl Lit {
         Lit { token: kind.to_lit_token(), kind, span }
     }
 
-    /// Losslessly convert an AST literal into a token stream.
-    crate fn tokens(&self) -> TokenStream {
+    /// Losslessly convert an AST literal into a token tree.
+    crate fn token_tree(&self) -> TokenTree {
         let token = match self.token.kind {
             token::Bool => token::Ident(self.token.symbol, false),
             _ => token::Literal(self.token),
         };
-        TokenTree::token(token, self.span).into()
+        TokenTree::token(token, self.span)
     }
 }
 
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 9cb410a8ae3..6bbd8be0cb9 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -285,10 +285,10 @@ impl TokenCursor {
             token::NoDelim,
             &if doc_comment_style(&name.as_str()) == AttrStyle::Inner {
                 [TokenTree::token(token::Pound, sp), TokenTree::token(token::Not, sp), body]
-                    .iter().cloned().collect::<TokenStream>().into()
+                    .iter().cloned().collect::<TokenStream>()
             } else {
                 [TokenTree::token(token::Pound, sp), body]
-                    .iter().cloned().collect::<TokenStream>().into()
+                    .iter().cloned().collect::<TokenStream>()
             },
         )));
 
diff --git a/src/libsyntax/parse/parser/attr.rs b/src/libsyntax/parse/parser/attr.rs
index 6f7d1ead4c1..188a144cac9 100644
--- a/src/libsyntax/parse/parser/attr.rs
+++ b/src/libsyntax/parse/parser/attr.rs
@@ -6,7 +6,6 @@ use crate::tokenstream::{TokenStream, TokenTree};
 use crate::source_map::Span;
 
 use log::debug;
-use smallvec::smallvec;
 
 #[derive(Debug)]
 enum InnerAttributeParsePolicy<'a> {
@@ -193,15 +192,15 @@ impl<'a> Parser<'a> {
                         is_interpolated_expr = true;
                     }
                 }
-                let tokens = if is_interpolated_expr {
+                let token_tree = if is_interpolated_expr {
                     // We need to accept arbitrary interpolated expressions to continue
                     // supporting things like `doc = $expr` that work on stable.
                     // Non-literal interpolated expressions are rejected after expansion.
-                    self.parse_token_tree().into()
+                    self.parse_token_tree()
                 } else {
-                    self.parse_unsuffixed_lit()?.tokens()
+                    self.parse_unsuffixed_lit()?.token_tree()
                 };
-                TokenStream::from_streams(smallvec![eq.into(), tokens])
+                TokenStream::new(vec![eq.into(), token_tree.into()])
             } else {
                 TokenStream::default()
             };
diff --git a/src/libsyntax/parse/parser/expr.rs b/src/libsyntax/parse/parser/expr.rs
index 273f5a5ffa3..67a530ec683 100644
--- a/src/libsyntax/parse/parser/expr.rs
+++ b/src/libsyntax/parse/parser/expr.rs
@@ -423,7 +423,7 @@ impl<'a> Parser<'a> {
                 self.struct_span_err(span_of_tilde, "`~` cannot be used as a unary operator")
                     .span_suggestion_short(
                         span_of_tilde,
-                        "use `!` to perform bitwise negation",
+                        "use `!` to perform bitwise not",
                         "!".to_owned(),
                         Applicability::MachineApplicable
                     )
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index e527989fb0b..4a8b25c6107 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -33,7 +33,7 @@ pub enum BinOpToken {
 }
 
 /// A delimiter token.
-#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
+#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 pub enum DelimToken {
     /// A round parenthesis (i.e., `(` or `)`).
     Paren,