I’d hate to make this something only useable by the clojure main repl tgough - would be better to happen always if using some other repl, so would be better to do at construction. I have a better handle on how to do so now, but don’t know if it’s too late for 1.10.

With the recent error message work (great work!) the symbol appears to be available, but it not currently passed to the "explain-out" function: https://github.com/clojure/clojure/blob/b182982007df934394f0bc68b3a238ca9f200dd1/src/clj/clojure/main.clj#L268-L279

Would it be possible to "assoc" this into the "spec" passed to "spec/explain-out"? This would allow custom printers to refer to the name of the spec, which would be very useful.

An alternative approach would be for users to set up custom error handlers in the REPL, but this is much more involved than setting up a third-party implementation of "explain-out"

The issue here is that at the point where the macro spec error is created, we don't have any way to know the proper caller information. The stack at that point is the compiler macroexpansion, not the invoking code. macroexpansion does know that context and that's what it adds when wrapping with a CompilerException (that's the primary purpose of CompilerException).

I think to change that we would need to convey that info out of band into the spec check. Well, maybe that's possible. I'll look at it again.

I'm glad to hear this will be included in the CompilerException, but I think it still is useful to include in the spec explain-data.

When printing a spec error, it would be clearer if macro expansion spec errors and instrumentation errors could be printed in a similar format (if the user chooses a custom spec printer). It may be disruptive to look for the caller information in one place for macro expansion errors and a different place for instrumentation errors.

Furthermore, spec printers may choose to do novel things with this caller information like adding color to output or printing the actual code instead of the line numbers. It'd be nice to do have all this information available for the spec printer to customize.

After CLJ-2373, the caller information for spec macro failures will be conveyed in a wrapper CompilerException (as with other compiler and macroexpansion errors). Should consider whether this issue is effectively resolved as a result.