Contrast with FPC's compiler mode pragmas for different dialects. [0] FPC shows the effects of this story in the long term: there are several major divergences in behavior supported by the modes, and some individual features can be toggled per-unit or sometimes with a finer grain. [1] Since you're allowed to mix and match different units, the fragmentation poses little threat to any individual programmer, and it's possible to dial in assertions, optimizations, and calling conventions in a targeted fashion.

[0] https://www.freepascal.org/docs-html/user/userse33.html

[1] https://www.freepascal.org/docs-html/prog/progch1.html#progs...