fix an ICE in macro's diagnostic message

1 files changed, 13 insertions, 2 deletions

diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
index 3e21436d313..1f386b8bbbf 100644
--- a/src/librustc_parse/parser/item.rs
+++ b/src/librustc_parse/parser/item.rs
@@ -1742,14 +1742,25 @@ impl<'a> Parser<'a> {
     }
 
     fn report_invalid_macro_expansion_item(&self) {
+        let has_close_delim = self.sess.source_map()
+            .span_to_snippet(self.prev_span)
+            .map(|s| s.ends_with(")") || s.ends_with("]"))
+            .unwrap_or(false);
+        let right_brace_span = if has_close_delim {
+            // it's safe to peel off one character only when it has the close delim
+            self.prev_span.with_lo(self.prev_span.hi() - BytePos(1))
+        } else {
+            self.sess.source_map().next_point(self.prev_span)
+        };
+
         self.struct_span_err(
             self.prev_span,
             "macros that expand to items must be delimited with braces or followed by a semicolon",
         ).multipart_suggestion(
             "change the delimiters to curly braces",
             vec![
-                (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), String::from(" {")),
-                (self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
+                (self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), "{".to_string()),
+                (right_brace_span, '}'.to_string()),
             ],
             Applicability::MaybeIncorrect,
         ).span_suggestion(