Thanks for the post

This means that you are using atmel studio with non-atmel hardware which is not something atmel want you to do. I recommend VS2017.

The issue might be that you did not install support for  32 bit boards when you installed atmel studio

STM is supported but there are a lot of packages, options and combinations. We need know the board support json url you used to get the package and also the information in the yellow box above shows us what you have selected.

Thanks

The first build for the Nucleo or when clicking Rebuild failed. Clicking Build again then worked correctly. The STm32 core supports an options header that you can add to your own code to set #defines and other properties that are documented for use with the core. If an options header has not been added to the local project then the core attempts to create a default header using a pre-build event (hook). Visual micro was running the event to late, after the deep search library discover, so the default header was missing when deep search attempted to run the toolchain.

Whilst you have not said that the Build worked subsequent times or not but this issue would have caused confusion. 

The issue is resolved in the LATEST - 1908.4.0 release here.

https://www.visualmicro.com/forums/YaBB.pl?board=VS_ARDUINO_EXT_RELEASES

Please post another build output if it fails after applying the update.

Thanks

Yes it doesn't make sense. This is the command that is failing. You can run it from cmd.exe, its external compile command.

Does this happen in a new empty project?
Does this happen in Release mode?

[code \8.2.1-1.7/bin/arm-none-eabi-gcc" -mcpu=cortex-m0 -mthumb .h" -c -Os -w -std=gnu11 -ffunction-sections -fdata-sections -nostdlib --param max-inline-insns-single=500 -MMD "-IC:\Users\Joe\Documents\Arduino\STM32_Blink\Blink" s\arduino/avr" s\arduino/stm32" s\arduino/stm32/LL" s\arduino/stm32/usb" s\arduino/stm32/usb/hid" s\arduino/stm32/usb/cdc" em/Drivers/STM32F0xx_HAL_Driver/Inc/" em/Drivers/STM32F0xx_HAL_Driver/Src/" em/STM32F0xx/" em/Middlewares/ST/STM32_USB_Device_Library/Core/Inc" em/Middlewares/ST/STM32_USB_Device_Library/Core/Src" -DSTM32F0xx -DARDUINO=10809 -DARDUINO_NUCLEO_F030R8 -DARDUINO_ARCH_STM32 -DBOARD_NAME=\"NUCLEO_F030R8\" -DSTM32F030x8 -DHAL_UART_MODULE_ENABLED ore/Include/" em/Drivers/CMSIS/Device/ST/STM32F0xx/Include/" em/Drivers/CMSIS/Device/ST/STM32F0xx/Source/Templates/gcc/" s\arduino" ants\NUCLEO_F030R8" ts\NUCLEO_F030R8\PeripheralPins.c" -o 1898\core\..\variant\PeripheralPins.c.o" [/code]

Great. 

I guess there was a file such as board.txt or something causing confusion in the other project. It is possible to zip the project folder of the broken project and email or post so I can see what the problem was? Email address in the yellow box above.

Thanks, since creating the new project you added the stm32 special opt.h with -D compiler defines. This is obviously invalid code used in a special way by the stm core. 

Visual Micro writes original source line numbers to files in the pre-build temp folder such as #line 1. This then caused the stm tool to pass an invalid compiler define. 

The "work in progress 1908.5.4" build no longer adds line numbers to header files so your project will build correctly.

https://www.visualmicro.com/forums/YaBB.pl?board=VS_ARDUINO_EXT_RELEASES