> I guess linking against an "as old as you need to support" libc dynamically isn't the end of the world, but it does constrain the build environment somewhat.

> I guess linking against an "as old as you need to support" libc dynamically isn't the end of the world, but it does constrain the build environment somewhat. I can't speak for Windows, but on macOS, you build for older targets by passing `-(mmacos|ios)-version-min=` to the compiler to specify your deployment target version; this is used to determine symbol visibility, API visibility, toggled #ifdefs, etc. The provided version is also stored in the Mach-O load commands of your executable, and will used to select compatible symbols (and enable compatibility shims) when loading your binary's image at runtime. No need for static linking — or jumping through hoops to build against an "as old as you need to support" set of installed libraries.