Substitutibility probably doesn't apply here in the way you're implying and if it did it would likely be hampered by the 9th circuits findings about transformation in sony v connectix. Arguments here likely would look at rust not having a stable ABI, and hence not being inherently substitutable as a libray (grit-lib), less clear as an executable (grit-cli) on that side
basics of copyright law - the fundamental thing being protected is the expression... is a rust program's expression the same expression as a c program? I'd say generally not.
Substitutibility probably doesn't apply here in the way you're implying and if it did it would likely be hampered by the 9th circuits findings about transformation in sony v connectix. Arguments here likely would look at rust not having a stable ABI, and hence not being inherently substitutable as a libray (grit-lib), less clear as an executable (grit-cli) on that side
basics of copyright law - the fundamental thing being protected is the expression... is a rust program's expression the same expression as a c program? I'd say generally not.