Yes it is. If the programmer can only say, “For this machine/year/build/combination of software with specific versions it behaves like this” then it is undefined. If there are no guarantees that a function will behave like that in the next release then it is undefined. That might be fine for home use, but you don’t really want to ship it to customers like that. If you do they better understand that they are buying a niche product and paying extra for it, that support might cost extra and they may need that extra support at some unknown time in the future when everything explodes at 3am in the morning.
Yes it is. If the programmer can only say, “For this machine/year/build/combination of software with specific versions it behaves like this” then it is undefined. If there are no guarantees that a function will behave like that in the next release then it is undefined. That might be fine for home use, but you don’t really want to ship it to customers like that. If you do they better understand that they are buying a niche product and paying extra for it, that support might cost extra and they may need that extra support at some unknown time in the future when everything explodes at 3am in the morning.