Hi! I came across this problem as well. I use the __attribute__((section(".data"))) as a kind of hack to get a function in the RAM using the standard linker file and startup provided for ST microcontrollers. Not being able to make a debug build is inaccepable! With older GCC/binutils versions this problem didn't exist. However, I found a workaround, I now use __attribute__((section(".datax"))). In the Linker script they include *(.data*) so this works and it does not generate the errors. Just wanted to share this in case anyone else is stuck at this.
Best regards, Manuel Köppen