Versioning matters _a lot_

[TyOverby]

Imagine the following project structure. Assume this is after Cargo is finished.

• My Game
  • piston
  • graphics
  • sdl2_game_window (backend)
    • sdl2
    • piston
    • gl
  • opengl_graphics (backend)
    • gl
    • graphics
    • image

Notice how both sdl2_game_window and opengl_graphics depend on gl. If we screw up and release with both those backends depending on different versions of gl, then we have a massive potential for bugs.

But even if we do everything correctly and our users screw up and depend on sdl2_game_window and opengl_graphics with incompatible versions, then there is the possibility of those same bugs.

It even gets worse when you realize that the user could select a piston version and an incompatible backend for piston.

[TyOverby]

I've opened an issue on Cargo
rust-lang/cargo#73

[bvssvni]

It is nice to start thinking of this now so we can give early feedback to the Cargo project.

[bvssvni]

I'm closing this discussion to clean up the issue tracker.