What do you expect the -E flags to do?

You can use the flags as you have done or you can override any build command using a local project board.txt file.

You need to understand what you are trying to achieve with the -E request. In fact the deep search compiler uses -E to find all libraries.

I can't see why using the same defs.h file would make sense for every file that is compiled and also if the output of the compiler is changed by the -E so that an object file is no longer outputted.

I suggest you switch on "vMicro>Compiler>Show build properties" and also "Verbose" so that you can see how the build works and what variables can be overridden in a board.txt. You will also see the way unique names are created during the build process using the current file or folder name {variable}

I hope this helps, it is a GCC question and little outside of the support this forum provides.


ps: The "Deep Search" gcc -E results are cached below the temp build folder that you will discover using the above suggestions.