14e600801e
This is an experimental feature intended at the moment for ESP-IDF developers only. If IDF_TOOLCHAIN=clang environment variable or CMake variable is set, use toolchain-clang-esp32xx.cmake instead of toolchain-esp32xx.cmake. These changes aren't sufficient to actually build any IDF project with clang; subsequent commits add a few workarounds required to do this. Toolchain files are added for esp32 and esp32s2, which are the targets supported in our llvm-project fork at the moment.