silly question maybe, but what is the c++ (standard) version of the compiler? Or where can I find out?
somewhere in the tools directory is the toolchain. the compiler takes the command line parameter --version and will happily report its version if asked nicely.
../../Arduino-ESP8266/tools/xtensa-lx106-elf/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.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
More specific: https://gcc.gnu.org/gcc-4.8/cxx0x_status.html