Usage of realizable constant `foo.eq_1` in privately imported module makes it private

Prerequisites

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Description

I have a situation where a module contains a public, exposed declaration x. Its equation x.eq_1 is public, but if a module imports another module privately that uses x.eq_1, then x.eq_1 is suddenly only available in the private context.

This suggests to me a problem with the handling of realizable constants.

Context

The problem occurred when I simped away instMonadLiftTOfMonadLift in some iterator module that was only privately imported into Std.Do.Triple.SpecLemmas but tried to assign the spec attribute to instMonadLiftTOfMonadLift.eq_1, which then failed because the constant was not in the public environment.

See https://github.com/leanprover/lean4/pull/10653; this PR uses the workaround of publicly importing the offending module into Std.Do.Triple.SpecLemmas.

Steps to Reproduce

1. Check out the Lake project in this branch: https://github.com/datokrat/lean-bug-reproductions/tree/bugs4
2. Open Reproductions/Basic.lean and observe that Lean complains that instX.eq_1 is not available in the public scope. (In fact, it even panics.)

Reproductions/A.lean:

module

public class X

@[expose]
public def x : X where

Reproductions/B.lean:

module

public import Reproductions.A

public theorem t : x = x := by
  simp only [x]

Reproductions/Basic.lean:

module

public import Reproductions.A
import Reproductions.B

-- `x` has an exposed body:
/--
info: @[expose] def x : X :=
{ }
-/
#guard_msgs in
#print x

@[expose]
public def aa := x.eq_1

Either removing import Reproductions.B or making it a public import eliminates the error.

Expected behavior:

The additional import should have no effect on the visibility of x.eq_1. It should always be publicly available.

Actual behavior:

x.eq_1 is considered private in Basic.lean and using it in the public scope causes a panic.

Versions

Lean 4.25.0-nightly-2025-10-01
Target: arm64-apple-darwin23.6.0 macOS

Impact

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Run the reproducer in Reproductions/Basic.lean with Reproductions/A.lean and Reproductions/B.lean, comparing private and public imports. Trace how the exposed declaration x.eq_1 is made available across imports. Done means the extra private import neither changes public visibility nor causes the reported error or panic.