lean4-htt/tests/lean/run/exact_private.lean
Kim Morrison c74d24aaaa
fix: allow exact? to suggest local private declarations (#11736)
This PR fixes an issue where `exact?` would not suggest private
declarations defined in the current module.

## Problem

When using `exact?` in a file with private declarations, those private
declarations were not being suggested even though they are valid and
accessible:

```lean
module

axiom P : Prop
private axiom p : P
example : P := by exact? -- error: could not find lemma
```

The problem was that `blacklistInsertion` in `LazyDiscrTree` was
filtering out all declarations whose names matched `isInternalDetail`,
which includes private names due to their `_private.Module.0.name`
structure.

## Solution

The fix adds a helper function `isPrivateNameOf` that checks if a
private declaration belongs to a specific module. The
`blacklistInsertion` function now allows private declarations belonging
to the current module (`env.header.mainModule`) to pass through the
filter.

Private declarations from imported modules are still filtered out, as
they may reference internal declarations that aren't accessible (which
would cause processing errors).

Zulip discussion:
https://leanprover.zulipchat.com/#narrow/channel/270676-lean4/topic/.60exact.3F.60.20and.20private.20declarations/near/564586152

🤖 Prepared with Claude Code

---------

Co-authored-by: Claude <noreply@anthropic.com>
2025-12-19 04:05:54 +00:00

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Text

module
/-!
# Tests for `exact?` with private declarations
This tests that `exact?` can suggest private theorems defined locally in the same module.
-/
-- Test that exact? suggests private declarations
axiom P : Prop
private axiom p : P
/--
info: Try this:
[apply] exact p
-/
#guard_msgs in
example : P := by exact?