fix(library/init/function): make injective semireducible (#604)
fix(library/init/function): make injective semireducible (#604)

https://leanprover.zulipchat.com/#narrow/stream/287929-mathlib4/topic/bad.20simp.20lemmas/near/249899277



leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean,leanprover-community/lean