`handleDocumentSymbol` returns an incomplete list of declarations

[lua-vr]

Prerequisites

Please put an X between the brackets as you perform the following steps:

• [x] Check that your issue is not already filed: https://github.com/leanprover/lean4/issues
• [x] Reduce the issue to a minimal, self-contained, reproducible test case. Avoid dependencies to Mathlib or Batteries.
• [x] Test your test case against the latest nightly release, for example on https://live.lean-lang.org/#project=lean-nightly (You can also use the settings there to switch to “Lean nightly”)

Description

The current handleDocumentSymbol implementation only considers top-level syntax before any elaboration or macro expansion. As a result, declarations like Mathlib's lemmas or even declarations inside open ... in blocks are not reported by the server (in response to textDocument/documentSymbol).

Context

I first discussed it in Zulip. I noticed the server did not include lemma declarations in the document symbols (which I use frequently to navigate in files through Emacs' consult-imenu).

Steps to Reproduce

1. Write, in a file,

   open Lean in
   theorem foo : 1 = 1 := rfl
   
   macro "stupid" dec:command : command => pure dec
   
   stupid def bar := 1
   

2. In some editor with LSP support, check document symbols. For instance, in VSCode, this can be seen by clicking the three dots in the header line.

Expected behavior: foo and bar are reported as document symbols Actual behavior: foo and bar are missing from document symbols

Versions

4.24.0-nightly-2025-08-30

Additional Information

I wrote a fix (my purpose when writing it was to learn more about Lean internals):

https://github.com/estradilua/lean4/commit/9c48fd4c3ad6de81b2dd590c4f8893e743be8b16

If you think it's acceptable, I can create a PR.

Impact

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