Hi Jonathan,
Glad things are (mostly) working!
TL;DR: I think textDocument/definition tries to do what you want, but needs some form of index to work well.
The one thing I seem to be missing is whether/how to use clangd via the
LPS client to go from a function call under the cursor to its actual
implementation (not just its definition).
I’m not trying to nitpick, but just to understand precisely: I think you’re using “implementation” to mean what the c++ standard calls a definition, and “definition” to mean a declaration.
// foo.h
void foo(); // this is a declaration, and not a definition
// foo.cc
void foo() { printf(“hello\n”); } // this is the definition (and also a declaration)
// bar.cc
#include “foo.h”
int main() {
foo(); // this is a call site
}
If you use “go to definition” in bar.cc (textDocument/definition), clangd will try to show you the definition (in foo.cc).
However, there’s no systematic way to find it - the declaration must be in a file #included by bar.cc, but the definition could be anywhere.
Clangd should be able to find it if:
A) the definition is in bar.cc itself, or a file it includes
B) the definition is in a file you have opened recently (it’s in the dynamic index)
C) the definition is within the project, and you’ve built a static index (using clangd-indexer and clangd -index-file)
D) the definition is within the project, and the background indexer found it (using clangd -background-index)
If none of these are true, clangd will show you the declaration instead.
We plan to enable background indexing by default for LLVM 9, which should make the situation much better.
I assume that that would be
via textDocument/implementation
(https://microsoft.github.io/language-server-protocol/specification#textDocument_implementation),
but IIUC, that method is not implemented in clangd.
The three related methods here are pretty poorly documented in the spec. Clangd’s interpretation is:
textDocument/declaration: shows the primary declaration (the best one we know about).
textDocument/definition: shows the single definition. If it’s unknown (or you’re already there), shows you the primary declaration instead.
textDocument/implementation: not yet implemented: shows all known overrides of a virtual member function, or derived classes of a class.
Is there some other method that I should be using? If not, are there
plans to implement this?
Apologies too if this list is not the correct place for this. I didn’t
want to file this yet as a bugzilla bug if in fact it is a known issue
already. I tried searching bugzilla for “textDocument” and only saw one
result (https://bugs.llvm.org/show_bug.cgi?id=34497), so figured that
might not even be where features like this are requested.
That’s the official LLVM bugtracker, and we’ll deal with bugs posted there.
We also use a github tracker a bit for convenience; I filed https://github.com/clangd/clangd/issues/29 for textDocument/implementation support.
