`lia -order` fails with non-canonical `LE` instances

[Rob23oba]

Prerequisites

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Description

lia -order fails to use hypotheses that use non-canonical LE Int instances

Context

Mathlib failures from #11744

Steps to Reproduce

class Preorder (α : Type u) extends LE α

instance instPreorderInt : Preorder Int where

example (c x : Int) (mx : @LE.le Int instPreorderInt.toLE x c) : x ≤ c := by
  lia -order

Expected behavior: lia solves the goal, even without the order module.

Actual behavior: lia only solves the goal if the order module is enabled.

Versions

Lean 4.28.0-nightly-2025-12-20

Impact

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