bug#65518: 30.0.50; [FR Eglot] Completions over all workspace symbols

[Gerd Möllmann]

I'm in a C buffer with Eglot running, and I want to go to the definition
of something whose name I know, but point is not on an identifier naming
that thing.  For instance, I want to go the definition of Lisp_Package
(in an obsure branch having a struct Lisp_Package), while point is
somewhere.

C-u M-. offers some completions, but Lisp_Package is not among them.
Not using a completion and entering Lisp_Package works.

Feature request: Could the completions be made to contain all workspace
symbols. maybe as a n optional feature?  Lsp-mode has something doing
that, and I found it quite useful with Helm.

In GNU Emacs 30.0.50 (build 2, aarch64-apple-darwin22.6.0, NS
 appkit-2299.70 Version 13.5 (Build 22G74)) of 2023-08-24 built on
 Mini.fritz.box
Repository revision: 53c07bd04bf59f63e49af2c626714bf3fdd03ad6
Repository branch: scratch/pkg
Windowing system distributor 'Apple', version 10.3.2299
System Description:  macOS 13.5