run-emitter.c:142:61: warning: self-comparison always evaluates to false [-Wtautological-compare]

Source code is

             || (event2->data.scalar.quoted_implicit != event2->data.scalar.quoted_implicit)

Maybe better code

             || (event1->data.scalar.quoted_implicit != event2->data.scalar.quoted_implicit)

Adding flag -Wtautological-compare to your builds will help catch problems like this in future.