Feature request: documentHighlightProvider support

[nujabse]

Currently fortls does not implement the documentHighlightProvider language server feature, which makes emacs lsp-mode do not have symbol highlighting feature. Can you implement this feature ?

[gnikit]

Could you please elaborate a bit about what you mean by "symbol highlighting feature"? From what I understand documentHighlightProvider should be nearly identical to textDocument/references which is already implemented.
If by any chance you mean syntax highlighting, that is usually provided by the extension and not the language server since it is a big task of its own.

Document Highlights Request (:leftwards_arrow_with_hook:)
The document highlight request is sent from the client to the server to resolve a document highlights for a given text document position. For programming languages this usually highlights all references to the symbol scoped to this file. However we kept ‘textDocument/documentHighlight’ and ‘textDocument/references’ separate requests since the first one is allowed to be more fuzzy. Symbol matches usually have a DocumentHighlightKind of Read or Write whereas fuzzy or textual matches use Textas the kind.

see: https://microsoft.github.io/language-server-protocol/specifications/specification-3-17/#textDocument_documentHighlight

[gnikit]

Further elaborating on my previous comments, this is the current status of the reference highlighting, which I suspect is what you are asking

Could you please post the settings you use for fortls?

[nujabse]

Yes, what I mean by "symbol highlighting" is reference highlighting, see the example code in Emacs using fortls with lsp-mode:

The dist variables under the curser should have been highlighted, but I can not get it working in Emacs with lsp-mode. However, reference highlighting usingfortls works just fine in Vscode.
The settings for fortls I'm using are "--variable_hover" "--hover_signature" "--lowercase_intrinsics"

[gnikit]

So I would guess then that lsp-mode does not support textDocument/references, which is weird. Has that always been the case? Your client should be able to handle both textDocument/references and documentHighlightProvider.

[nujabse]

Well, it seems that lsp-mode needs documentHighlightProvider to do the reference highlighting, as discussed in the issue. Maybe I just need to wait for lsp-mode to support it. Thanks anyway for your help! fortls is very useful.

[gnikit]

I don't think there is any harm registering both references and documentHighlight.

[rcoacci]

Hi, after some time struggling with this problem, I discovered that you missed adding "documentHighlightProvider": True to the server_capabilities dictionary in langserver.py::serve_initialize. Without it, LSP clients don't request the documentHighlight and the symbol highlight doesn't work. After adding it in a local copy of fortls, Emacs' lsp-mode does symbol highlight correctly. Should I open a new issue?