bv_decide throws an unknown free variable error if there is an hypothesis b.toNat > 0 in the context

[alexkeizer]

Prerequisites

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• Reduce the issue to a minimal, self-contained, reproducible test case.
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Description

In the following MWE, bv_decide complains about an unknown free variable.
If we remove the hypothesis h, bv_decide will correctly come up with a counterexample,
or if we rephrase h in term of bitvector le, (i.e., b > 0), bv_decide correctly comes up with a proof, so it seems the presence of toNat is problematic.

import Std.Tactic.BVDecide

example
    (b : BitVec 64)
    (h : b.toNat > 0) :
    b > 0 := by
  bv_decide -- unknown free variable '_fvar.394'

Context

Minimized from LNSym

Steps to Reproduce

1. Load the MWE

Expected behavior: I expect bv_decide to either come up with a proof, a counterexample, or a meaningful error to explain why it couldn't do either.

Actual behavior: I get "unknown fvar"

Versions

nightly-2024-10-09 on MacOS

Impact

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