Rollup merge of #39730 - jseyfried:fix_empty_seq_rep_ice, r=nrc

macros: fix ICE on certain sequence repetitions

Fixes #39709.
r? @nrc

1 files changed, 14 insertions, 5 deletions

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b051928ff9d..2c4fa8e15ed 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -302,11 +302,20 @@ impl<'a> Parser<'a> {
                 if i + 1 < tts.len() {
                     self.tts.push((tts, i + 1));
                 }
-                if let TokenTree::Token(sp, tok) = tt {
-                    TokenAndSpan { tok: tok, sp: sp }
-                } else {
-                    self.tts.push((tt, 0));
-                    continue
+                // FIXME(jseyfried): remove after fixing #39390 in #39419.
+                if self.quote_depth > 0 {
+                    if let TokenTree::Sequence(sp, _) = tt {
+                        self.span_err(sp, "attempted to repeat an expression containing no \
+                                           syntax variables matched as repeating at this depth");
+                    }
+                }
+                match tt {
+                    TokenTree::Token(sp, tok) => TokenAndSpan { tok: tok, sp: sp },
+                    _ if tt.len() > 0 => {
+                        self.tts.push((tt, 0));
+                        continue
+                    }
+                    _ => continue,
                 }
             } else {
                 TokenAndSpan { tok: token::Eof, sp: self.span }