Compilation failures after updating to v3.x ESP32 Arduino Core

[Roger-random]

Symptom:

After updating to v3.x ESP32 Arduino Core, the first compilation error will be:

ESP_8_BIT_composite.cpp:45:55: error: invalid conversion from 'const volatile void*' to 'volatile void*' [-fpermissive]

HOWEVER, this is not the core issue, it's just the first breaking change to cause a error. (Default compiler flags changed in v2.x to v3.x.)

Downstream are deeper problems with this library's dependency on deprecated ESP32 legacy DAC driver, which has been (or will soon be) removed. Replacement DAC driver does not expose the same functionality.

Reference:

Espressif's documentation on breaking changes: https://docs.espressif.com/projects/arduino-esp32/en/latest/migration_guides/2.x_to_3.0.html

Workaround:

The current workaround is to downgrade ESP32 Arduino Core to an earlier version in the v2.x lineage. I understand this is not a satisfactory long-term solution.

Why did Espressif do this?

The following is my observation/hypothesis/guess and not from Espressif.

Espressif seized upon the fame of the successful "ESP32" name and has released many variants. Some are VERY different from the original chip, but they are all supported by ESP-IDF which ESP32 Arduino Core is built upon. ESP-IDF has the job of keeping things in sync across the entire ESP32 library, so software developers won't have to worry about details of hardware differences between variants.

Unfortunately, this means ESP-IDF is restricted to the subset supported by all ESP variations on a peripheral. Creative hacks like the ESP_8_BIT composite video code (which this library is built from) depended on features outside of that lowest-common-denominator subset. So while the original ESP32 (no suffix) DAC can do this, but newer ESP32-[???] variation DAC could not, so it was removed from ESP-IDF.