C++ has never been officially supported by mspgcc, and this appears to
require a change to the compiler rather than simple header modification:
C++ apparently does something unexpected with attribute merges.
I've confirmed the behavior. Please enter this as a bug at
I'm unable to duplicate that with the following program using msp430-gcc
-Os -mmcu=msp430fr5969 -c x.c and similar variants.
The attributes are documented at
https://sourceforge.net/apps/mediawiki/mspgcc/index.php?title=Gcc47:20-Bit_Designbut
it should not be necessary for you to be aware of them
