Fix default value for hash_collision in EVMState
#17
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`false` is a `Bool`. The intended default value. `False` is the `Prop` representing a contradiction, not the intended default value of `hash_collision`, but since `False` is a decidable proposition, Lean automatically treats this as `decide False` which is a `Bool`. Although we can actually prove `false = False` in Lean, using `false` directly is preferable.
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This fixes the default value for
hash_collisionas defined inEVMState.leanfalseis aBool. The intended default value.Falseis theProprepresenting a contradiction, not the intended default value ofhash_collision, but sinceFalseis a decidable proposition, Lean automatically treats this asdecide Falsewhich is aBool. Although we can actually provefalse = Falsein Lean, usingfalsedirectly is preferable.The way this is handled in Lean leads to the following:
theorem false_eq_false : false = false := by rfl -- succeeds (of course)theorem false_eq_False₁ : false = False := by rfl -- failstheorem false_eq_False₂ : false = False := by simp -- succeedsThis has implications when doing proofs relating to the default value for
hash_collision, such as here:Clear/Generated/erc20shim/ERC20Shim/fun_allowance_user.lean
Line 400 in 4bd6a34
hash_collisionback toFalsethere causeslake build +Generated.erc20shim.ERC20Shim.fun_allowance_userto fail. We could work around this in the proof, but it seems better to fixEVMState.leaninstead.