xtensa-lx106-elf-gcc.exe: error: C:/Users/thunder/Downloads/CygwinPortable/App/Runtime/cygwin/home/cygwin/Esp8266-Arduino-Makefile/esp8266/cores/esp8266/cont.S: No such file or directory
xtensa-lx106-elf-gcc.exe: warning: '-x assembler-with-cpp' after last input file has no effect
xtensa-lx106-elf-gcc.exe: fatal error: no input files
xtensa-lx106-elf-gcc.exe: error: C:/Users/thunder/Downloads/CygwinPortable/App/Runtime/cygwin/home/cygwin/Esp8266-Arduino-Makefile/esp8266/cores/esp8266/cont.S: No such file or directory xtensa-lx106-elf-gcc.exe: warning: '-x assembler-with-cpp' after last input file has no effect xtensa-lx106-elf-gcc.exe: fatal error: no input files
Fix by renaming esp8266-2.3.0 to esp8266