Generating (or subscribing to?) the mqtt rx topic crashes the application with a corrupted backtrace if the rx topic contains an variable whose value is not empty. To duplicate: Enable MQTT in the wizard and build the default project. Optionally adjust the device_id default value to be an empty string to observe a successful connection instead. Observed on ESP32.

[cpq]

@robertc2000 I was not able to reproduce it. Please try to reproduce on your side.

"Generating (or subscribing to?) the mqtt rx" - cannot reproduce that. If I just enable MQTT in a default config, works fine (uses non-empty device_id expansion). If I use a non-existent variable, works too. Let me know the way to reproduce, please!

@dvosully please let us know the sequence to reproduce that

[dvosully]

I think the functions doing variable expansion have been changed since I reported that issue, I'll check again later but it may have been fixed already. At the time, running the default project with MQTT enabled would cause it to occur.

[dvosully]

I can confirm this is no longer an issue. expandvar got patched between reporting and now. The fix was:

---      n2 = mg_snprintf(tmp + n1, len - n1, "%M", s_vars[vi].fn);
+++      n2 = mg_snprintf(tmp + n1, len - n1, "%M", glue_pfn, s_vars[vi].fn);

[cpq]

@dvosully thanks David!