Hmm, I don't think we can make this change if it breaks builds for people using older versions. How old a version will the new flags work with? Is it possible the make the flags version dependent?

intel removes flags from compilers with error after only two years? such an unimportant change should basically never be done ...
I don't think its a good idea to break builds on older compilers, especially as its a commercial one where upgrading may be difficult.

I only have 2013 and 2015 installed, so testing is limited, but I have found the new options in ifort documentation dated 2003. (Found it here.) It seems the options have been deprecated for while. But yes, it would have been better if ifort had thrown an error, instead of silently ignoring the options.

I've found other early references, so let's give this a try. Thanks @ahjulstad .