syntax_pos::Symbol should not implement Sync

Fixes #42407

diff --git a/src/libsyntax_pos/symbol.rs b/src/libsyntax_pos/symbol.rs
index 73c0256f2c1f50babdde07d8a7a5c8c6e0e8f196..6b5caff27e8f020b7fdfcd74e199c7ebd29ac2b9 100644 (file)
--- a/src/libsyntax_pos/symbol.rs
+++ b/src/libsyntax_pos/symbol.rs
@@ -81,6 +81,7 @@ fn decode<D: Decoder>(d: &mut D) -> Result<Ident, D::Error> {
 
 // The interner in thread-local, so `Symbol` shouldn't move between threads.
 impl !Send for Symbol { }
+impl !Sync for Symbol { }
 
 impl Symbol {
     /// Maps a string to its interned representation.