Hello, currently I am migrating my project from keil 4 to keil 5 and came along the error : #pragma anon_unions is a arm compiler 5 extension. I've made it as a comment now. Is commenting the right thing to do ?

Well Sal,

in the screenshot you attached it says "which is enabled by default in armclang" it means you do not need to do anything to enable the feature, you can, however, disable the feature meaning compiler will by default complain about it with -pedantic option.

So, by default, you are good to go.

Well Sal,

in the screenshot you attached it says "which is enabled by default in armclang" it means you do not need to do anything to enable the feature, you can, however, disable the feature meaning compiler will by default complain about it with -pedantic option.

So, by default, you are good to go.