macro_rules - Fix range of placeholder value

1 files changed, 1 insertions, 1 deletions

diff --git a/src/macro_rules/parse.cpp b/src/macro_rules/parse.cpp
index 38506a21..f5b0f0e4 100644
--- a/src/macro_rules/parse.cpp
+++ b/src/macro_rules/parse.cpp
@@ -212,7 +212,7 @@ public:
                     // TODO: `error-chain`'s quick_error macro has an arm which refers to an undefined metavar.
                     // - Maybe emit a warning and use a marker index.
                     WARNING(lex.point_span(), W0000, "Macro variable $" << name << " not found");
-                    idx = (1<<30)-1;
+                    idx = (1<<16)-1;    // NOTE: Encoded as a u16
                 }
                 if( var_set_ptr ) {
                     var_set_ptr->insert( ::std::make_pair(idx,true) );