Arduino for STM32

From: https://arduino.stackexchange.com/questions/33104/how-do-i-order-the-gcc-compiler-to-generate-s-flag-in-arduino-ide

Compiler flags are defined in the platform.txt of the board you have selected in the Tools > Board menu. You can also add compiler flags via a build.extra_flags property in ...

I was trying to build some already existing C code with stm32duino.
It ran into issue because the C code uses C99 struct initializers, which arent in the C++ specification.
The situation is described https://stackoverflow.com/questions/18731707/why-does-c11-not-support-designated-initializer-lists ...

is preprocessor directive defined for board selected from arduino-IDE?
I have code for multiple boards, it needs to know which board is built for so correct source is built and stuff like pin definitions. Because the nucleo boards typically have arduino-uno form-factor, but others arent and need ...