What compiler does Arduino 1.8.9 use for the ESP32?

Hi All, as the subject line says, I'm trying to figure out what compiler Arduino 1.8.9 uses for the ESP32?

Also, is there a way to make the Arduino IDE display any compiler warnings that may be generated?

I ask because I'm trying to port an Arduino library to mongoose OS and I'm getting many warnings and errors in that environment. I don't know if those warnings appear here as well, and what compiler options may be used here.

Yes, you can set the compiler warning in the preferences. Just go to the File menu.

Don‘t you see which version of gcc is used during compilation in the output window?

Klaus_K: Yes, you can set the compiler warning in the preferences. Just go to the File menu.

Found it, much better.

Don‘t you see which version of gcc is used during compilation in the output window?

No, that information was not shown until I enabled verbose output. Now I can see that and the compiler options.

Thanks very much!

 "/Applications/Arduino-1.8.9 copy.app/Contents/Java/portable/packages/esp8266/tools/xtensa-lx106-elf-gcc/1.20.0-26-gb404fb9-2/bin/xtensa-lx106-elf-g++" --version
xtensa-lx106-elf-g++ (crosstool-NG 1.20.0) 4.8.2
Copyright (C) 2013 Free Software Foundation, Inc.

I'm using a Mac. Unless I enable verbose output, here is all I see after clicking the compile button:

Sketch uses 238712 bytes (18%) of program storage space. Maximum is 1310720 bytes.
Global variables use 12876 bytes (3%) of dynamic memory, leaving 314804 bytes for local variables. Maximum is 327680 bytes.