> If I add the gcsafe pragma to my callback proc, it now compiles without > errors! Where's my "extended error information"?
There is a phase ordering problem in today's compiler so that in rare cases `.gcsafe` isn't inferred the way it should be. (Known problem.) The good news is that when the code compiles with `.gcsafe`, it really is GC safe and nothing to worry about. There is also [https://github.com/nim-lang/RFCs/issues/142](https://github.com/nim-lang/RFCs/issues/142) for how to evolve the "GC safety" issues.
