Hey Guys, long time no see! I've recently started development using a custom (non-Arduino) Atmega32u4 design and custom boards.txt file. 

-- boards.txt snippet
smart7688.build.usb_product="LinkIt Smart 7688 Duo"
smart7688.build.usb_manufacturer="MediaTek Labs"
 

The problem is in the quoting. When I try to build, visual micro adds its own quotes to the gcc line, which double up on the existing quotes:

"C:\Arduino\arduino-1.6.8\hardware\tools\avr/bin/avr-gcc" -c -g -x assembler-with-cpp -mmcu=atmega32u4 -DF_CPU=8000000L -DARDUINO=10608 -DARDUINO_AVR_LINKITSMART7688 -DARDUINO_ARCH_AVR -DUSB_VID=0x0E8D -DUSB_PID=0xAB01 "-DUSB_MANUFACTURER="MediaTek Labs"" "-DUSB_PRODUCT="LinkIt Smart 7688 Duo"" -I"C:\Arduino\arduino-1.6.8\hardware\arduino\avr\cores\arduino" variants\smart7688" "C:\Arduino\arduino-1.6.8\hardware\arduino\avr\cores\arduino\wiring_pulse.S" -o core\wiring_pulse.S.o" 

error*: Labs: No such file or directory

error*: Smart: No such file or directory

error*:7688: No such file or directory

error*: Duo: No such file or directory
Error compiling core
 

If I remove the quotes from the boards.txt, then the define works properly, however when the macro is inserted into USBCore.cpp by the preprocessor, it needs the quotes to be a valid string:

"C:\Arduino\arduino-1.6.8\hardware\tools\avr/bin/avr-g++" -c -g -Os -Wall -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -mmcu=atmega32u4 -DF_CPU=8000000L -DARDUINO=10608 -DARDUINO_AVR_LINKITSMART7688 -DARDUINO_ARCH_AVR -DUSB_VID=0x0E8D -DUSB_PID=0xAB01 "-DUSB_MANUFACTURER=MediaTekLabs" "-DUSB_PRODUCT=LinkItSmart7688Duo" -I"C:\Arduino\arduino-1.6.8\hardware\arduino\avr\cores\arduino" variants\smart7688" "C:\Arduino\arduino-1.6.8\hardware\arduino\avr\cores\arduino\USBCore.cpp" -o core\USBCore.cpp.o"

   LinkItSmart7688Duo was not declared in this scope
USBCore.cpp:49: note  in expansion of macro USB_PRODUCT
   const u8 STRING_PRODUCT[] PROGMEM = USB_PRODUCT

   MediaTekLabs was not declared in this scope
USBCore.cpp:66: note  in expansion of macro USB_MANUFACTURER
   const u8 STRING_MANUFACTURER[] PROGMEM = USB_MANUFACTURER

USBCore.cpp: In function bool SendDescriptor(USBSetup&)

   LinkItSmart7688Duo was not declared in this scope
USBCore.cpp:511: note  in expansion of macro USB_PRODUCT
   return USB_SendStringDescriptor(STRING_PRODUCT, strlen(USB_PRODUCT), TRANSFER_PGM)

   MediaTekLabs was not declared in this scope
USBCore.cpp:514: note  in expansion of macro USB_MANUFACTURER
   return USB_SendStringDescriptor(STRING_MANUFACTURER, strlen(USB_MANUFACTURER), TRANSFER_PGM)
Error compiling core
 

Strangely enough, this works just fine with the Arduino Yun target which gets escaped quotes instead of outer quoting:

-- boards.txt
yun.build.usb_product="Arduino Yun"

"C:\Arduino\arduino-1.6.8\hardware\tools\avr/bin/avr-g++" -c -g -Os -Wall -std=gnu++11 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -mmcu=atmega32u4 -DF_CPU=16000000L -DARDUINO=10608 -DARDUINO_AVR_YUN -DARDUINO_ARCH_AVR -DUSB_VID=0x2341 -DUSB_PID=0x8041 -DUSB_MANUFACTURER="\"Unknown\"" -DUSB_PRODUCT="\"Arduino Yun\"" -I"C:\Users\bmayland\Documents\Arduino\libraries\DigitalWriteFast" -I"C:\Users\bmayland\Documents\Arduino\libraries\rf12_itplus" -I"C:\Users\bmayland\Documents\Arduino\libraries\ShiftRegLCD" -I"C:\Arduino\arduino-1.6.8\libraries" -I"C:\Arduino\arduino-1.6.8\hardware\arduino\avr\libraries" -I"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\Extensions\cg4p4uav.arp\Micro Platforms\default\debuggers" -I"C:\Users\bmayland\Documents\Arduino\libraries" -I"C:\Arduino\arduino-1.6.8\hardware\arduino\avr\cores\arduino" -I"C:\Arduino\arduino-1.6.8\hardware\arduino\avr\variants\yun"  -o o"
 

It seems like the custom boards.txt is being handled differently than the stock Arduino boards.txt? I can work around it by escaping the quotes in the custom boards.txt with \" but it would be nice to have this work out of the box. VMicro 1611.5.1

Well shut my mouth, I didn't even think to check the platform.txt for the expansion. Updated the custom platform.txt, works like a charm both in the Arduino IDE and Visual Micro. Sorry about wasting your time, I will report this upstream to the MediaTek people.

On a side note, I am pleased to see Visual Micro continuing to be improved. Every time there is a new release I say "My my, that is helpful." If I need to switch over the the Arduino IDE, I wonder how people use that thing. It is constantly getting better, but golly it has a long way to go to be as helpful as Visual Studio for working with 10,000 lines of code across 20 files. When I built my new computer this year I bought a new Visual Micro license just to show you how much I care. Keep it up!

Hello, I have similar issue, but do not realize the details yet.
The below code compiled and works fine under Arduino IDE and platformio, so I guess that something wrong is in the visualmicro.

#define BLYNK_PRINT Serial
#define BLYNK_DEBUG

#include <BlynkSimpleYun.h>

char auth[] = "65dc98d70cd2419982e7f47b3cf";
// we need no ssid and password because Linkit connected wifi itself
char a;
int LED = 13 ;

void setup() {
  Serial.begin(115200);
  delay(2000);
  Blynk.begin(auth);
  Serial.println("Blynk.begin");
  pinMode(LED, OUTPUT);
  digitalWrite(LED, LOW);
}

void loop() {

  Blynk.run();

} 

Resulting errors are:

Building core ...
1.43\pic32mx\include\packages\LinkIt\tools\avr-gcc\4.8.1-arduino5/bin/avr-gcc" -c -g -x assembler-with-cpp -mmcu=atmega32u4 -DF_CPU=8000000L -DARDUINO=10805 -DARDUINO_AVR_LINKITSMART7688 -DARDUINO_ARCH_AVR -DUSB_VID=0x0E8D -DUSB_PID=0xAB01 "-DUSB_MANUFACTURER="MediaTek Labs"" "-DUSB_PRODUCT="LinkIt Smart 7688 Duo"" -I"d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino" 2-1.43\pic32mx\include\packages\LinkIt\hardware\avr\0.1.8\variants\smart7688" "d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino\wiring_pulse.S" -o a65e24\core\wiring_pulse.S.o"
1.43\pic32mx\include\packages\LinkIt\tools\avr-gcc\4.8.1-arduino5/bin/avr-gcc" -c -g -Os -Wall -std=gnu11 -ffunction-sections -fdata-sections -MMD -mmcu=atmega32u4 -DF_CPU=8000000L -DARDUINO=10805 -DARDUINO_AVR_LINKITSMART7688 -DARDUINO_ARCH_AVR -DUSB_VID=0x0E8D -DUSB_PID=0xAB01 "-DUSB_MANUFACTURER="MediaTek Labs"" "-DUSB_PRODUCT="LinkIt Smart 7688 Duo"" -I"d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino" 2-1.43\pic32mx\include\packages\LinkIt\hardware\avr\0.1.8\variants\smart7688" "d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino\hooks.c" -o a65e24\core\hooks.c.o"
Error compiling core

error*: Labs: No such file or directory
1.43\pic32mx\include\packages\LinkIt\tools\avr-gcc\4.8.1-arduino5/bin/avr-gcc" -c -g -Os -Wall -std=gnu11 -ffunction-sections -fdata-sections -MMD -mmcu=atmega32u4 -DF_CPU=8000000L -DARDUINO=10805 -DARDUINO_AVR_LINKITSMART7688 -DARDUINO_ARCH_AVR -DUSB_VID=0x0E8D -DUSB_PID=0xAB01 "-DUSB_MANUFACTURER="MediaTek Labs"" "-DUSB_PRODUCT="LinkIt Smart 7688 Duo"" -I"d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino" 2-1.43\pic32mx\include\packages\LinkIt\hardware\avr\0.1.8\variants\smart7688" "d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino\WInterrupts.c" -o a65e24\core\WInterrupts.c.o"
1.43\pic32mx\include\packages\LinkIt\tools\avr-gcc\4.8.1-arduino5/bin/avr-gcc" -c -g -Os -Wall -std=gnu11 -ffunction-sections -fdata-sections -MMD -mmcu=atmega32u4 -DF_CPU=8000000L -DARDUINO=10805 -DARDUINO_AVR_LINKITSMART7688 -DARDUINO_ARCH_AVR -DUSB_VID=0x0E8D -DUSB_PID=0xAB01 "-DUSB_MANUFACTURER="MediaTek Labs"" "-DUSB_PRODUCT="LinkIt Smart 7688 Duo"" -I"d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino" 2-1.43\pic32mx\include\packages\LinkIt\hardware\avr\0.1.8\variants\smart7688" "d:\Arduino-ESP32-IDE\hardware\arduino\avr\cores\arduino\wiring.c" -o a65e24\core\wiring.c.o"

error*: Smart: No such file or directory
Build failed for project 'Blynk'


error*:7688: No such file or directory
error*: Labs: No such file or directory


error*: Duo: No such file or directory
error*: Smart: No such file or directory

error*:7688: No such file or directory 

As could bee seen in first lines, compiler refers to wrong core folder Digilent. I see no resonable explanation to that. 

Also, IDE periodically lost include references, marking red #include <BlynkSimpleYun.h>