mixing code c and c++

I write all of my code on STM32s in C++. I'm using IAR. There are no problems calling C APIs such as CubeHAL or the Standard Peripheral Library, or <Whatever>OS. This is not surprising because C is almost always valid C++. I don't use any third party C++ libraries, but can't imagine that being difficult. Basically, just write a C++ project and it'll all work out. I would avoid STL. I don't use exceptions or RTTI either, but suspect these are not as expensive some people claim. 

I typically implement drivers and other application objects (FSMs, protocols, etc.) as Myers singletons to ensure that they are initialised once, in the correct order, and globally available, but this is just preference. I usually give them abstract interfaces to hide the implementation and facilitate unit testing.

Update: This is actually even easier than I thought.

After creating the original C project (and having worked with it for 2 months now) I found out that I can just convert it using the eclipse/truestudio built in converter feature (file - new - other - convert project).

This worked perfectly well with a full blown HAL + FreeRTOS + USB + FATFS project.

All I had to do was copy the symbols and directories from the C compiler over to C++. And I changed the main.c name to main.cpp. Don't know yet whether that makes a difference though.

But the C++ compiler is so much better as it is more tedious about clean&proper coding. I found some places where I've been a bit slack before and the C compiler just didn't bother.

So in short, the workflow:

1. Create CubeMX project

2. Import to TrueStudio (in my case, haven't tested anything else yet)

3. Convert to C++ and copy compiler settings from C. All easily doable in the GUI settings part

4. rename main.c to main.cpp

5. done, start coding/including C++ code

6. Don't forget to add the C++ wrapper to your header files (that got me a couple of times).