This is just how CMake works: each of its "rules" is concrete; you cannot create a "template rule". The reason for that is platform independence: not every build systems supports "templates" for rules.
No idea if Stackoverflow Guy is correct here, but if so ... eh what? Make exists, and make supports pattern rules, and both these things have been true for several decades longer than CMake has existed, so why do we give a stuff about "platform independence"
@dan ugh; ok so I recently found this out but "make supports pattern rules" is arguably false; posix defines make in a completely useless and anemic way that just ... omits patterns?, so really you can only say "gnu make supports pattern rules" and maybe there's some equivalent in BSD land, but bad design in cmake might be a workaround for the fact that posix make is fundamentally flawed.
@dan of course this conveniently ignores the fact that gnu make *is* portable, so the whole idea of being portable across makes is pretty useless but I mean, expecting cmake developers to make reasonable decisions is maybe a bit much.
@technomancy@icosahedron.website it's all just unpleasantly reminiscent of trying to configure sendmail using m4 macros
@dan I guess I'm lucky that when I encountered this problem all I had to do was to specify that the dependency was GNU make, not just "make" but it sounds like you're in much deeper.