unable to compile avr-g++: error: missing filename after '-o'

tried compiling bare sketch and receive error

IDE version 1.6.6
boards updated to 1.6.10 (this is the only thing I can think of that changed)

any suggestions.

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}
Arduino: 1.6.6 (Windows 10), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\arduino-builder -dump-prefs -logger=machine -hardware "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware" -hardware "C:\Users\big Munkee\AppData\Local\Arduino15\packages" -tools "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\tools-builder" -tools "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr" -tools "C:\Users\big Munkee\AppData\Local\Arduino15\packages" -built-in-libraries "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\libraries" -libraries "C:\Users\big Munkee\Documents\Arduino\libraries" -fqbn=arduino:avr:mega:cpu=atmega2560 -vid-pid=0X2341_0X0010 -ide-version=10606 -build-path "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp" -warnings=none -prefs=build.warn_data_percentage=75 -verbose "C:\Users\B\AppData\Local\Temp\untitled1998493078.tmp\sketch_mar11a\sketch_mar11a.ino"
C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\arduino-builder -compile -logger=machine -hardware "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware" -hardware "C:\Users\big Munkee\AppData\Local\Arduino15\packages" -tools "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\tools-builder" -tools "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr" -tools "C:\Users\big Munkee\AppData\Local\Arduino15\packages" -built-in-libraries "C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\libraries" -libraries "C:\Users\big Munkee\Documents\Arduino\libraries" -fqbn=arduino:avr:mega:cpu=atmega2560 -vid-pid=0X2341_0X0010 -ide-version=10606 -build-path "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp" -warnings=none -prefs=build.warn_data_percentage=75 -verbose "C:\Users\B\AppData\Local\Temp\untitled1998493078.tmp\sketch_mar11a\sketch_mar11a.ino"
"C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics  -w -x c++ -M -MG -MP -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10606 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR   "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\cores\arduino" "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\variants\mega" "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp\sketch\sketch_mar11a.ino.cpp"
"C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics  -w -x c++ -M -MG -MP -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10606 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR   "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\cores\arduino" "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\variants\mega" "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp\sketch\sketch_mar11a.ino.cpp"
"C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics  -w -x c++ -M -MG -MP -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10606 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR   "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\cores\arduino" "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\variants\mega" "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp\sketch\sketch_mar11a.ino.cpp"
"C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics  -w -x c++ -M -MG -MP -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10606 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR   "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\cores\arduino" "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\variants\mega" "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp\sketch\sketch_mar11a.ino.cpp"
"C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics  -w -x c++ -M -MG -MP -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10606 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR   "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\cores\arduino" "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\variants\mega" "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp\sketch\sketch_mar11a.ino.cpp"
"C:\Program Files\arduino-1.6.6-windows\arduino-1.6.6\hardware\tools\avr/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics  -w -x c++ -E -CC -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=10606 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR   "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\cores\arduino" "-IC:\Users\big Munkee\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.10\variants\mega" "C:\Users\B\AppData\Local\Temp\buildbbab05327e329a203b3a6c69747f8b78.tmp\sketch\sketch_mar11a.ino.cpp" -o ""
avr-g++: error: missing filename after '-o'

exit status 1
Error compiling.

A bunch of people have had IDE 1.6.x problems, including IDE crashes and bizarre compile errors, when they have an old 1.5.x/1.6.x installation. Those problems seem to be caused by out-of-date executables that the new IDE saves outside the IDE installation directory. Perhaps that is what is causing your particular problem. In such cases it appears that the fix is to delete or rename the old "Arduino15" directory and re-install 1.6.x.

On Mac OS X: /Users/(username)/Library/Arduino15

On Windows: C:\Users(username)\AppData\Roaming\Arduino15

On Linux: /home/(username)/.arduino15 (a.k.a. ~/.arduino15)