And since I mentioned it before and now have Arduino AVR Boards 1.6.206 installed again, here's the error message I get when compiling a specific program that uses a stupid number of templates and macros:
E:\electronics\arduino\libraries\EtherEvent/EtherEvent.h: In function 'bool EtherEventClass::send<IPAddress, IPAddress, __FlashStringHelper const*>(EthernetClient&, unsigned char const*, unsigned int, IPAddress, IPAddress, __FlashStringHelper const*) [clone .isra.15] [clone .constprop]':
E:\electronics\arduino\libraries\EtherEvent/EtherEvent.h:474:5: internal compiler error: Segmentation fault
}
^
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
lto-wrapper.exe: fatal error: C:\Users\per\AppData\Local\Arduino15\packages\arduino\tools\avr-gcc\5.4.0-atmel3.6.1-arduino2/bin/avr-gcc returned 1 exit status
compilation terminated.
c:/users/per/appdata/local/arduino15/packages/arduino/tools/avr-gcc/5.4.0-atmel3.6.1-arduino2/bin/../lib/gcc/avr/5.4.0/../../../../avr/bin/ld.exe: error: lto-wrapper failed
collect2.exe: error: ld returned 1 exit status
Every time I started to simplify it to produce a reasonable bug report the error would go away but if anyone wants to have a look I'm happy to provide everything you need to reproduce it. The program compiles fine with Arduino AVR Boards 1.6.21 and earlier.
The new toolchain has been in the pipeline for a long time now so I suspect it's planned to hit the next release. I definitely would like to see any serious issues resolved before it's unleashed on the masses. It shows how important it is for the community to get involved in the beta testing process. It takes some effort and inconvenience but so does providing support on the forum for all the people affected by a bug that goes out in a production release. I know there have been at least two threads here already regarding the Arduino as ISP problem.