--- a/src/Pure/Syntax/syntax_ext.ML Thu Mar 12 23:05:11 2020 +0100
+++ b/src/Pure/Syntax/syntax_ext.ML Fri Mar 13 16:04:27 2020 +0100
@@ -243,7 +243,7 @@
val read_block_indent =
Bg o block_indent o #1 o Library.read_int o map Symbol_Pos.symbol;
-val is_meta = member (op =) ["(", ")", "/", "_", "\<index>", Symbol.open_, Symbol.close];
+val is_meta = member (op =) ["'", "(", ")", "/", "_", "\<index>", Symbol.open_, Symbol.close];
val scan_delim =
scan_one Symbol.is_control ::: Symbol_Pos.scan_cartouche "Mixfix error: " ||