Exception when formatting ("textDocument/formatting")

[adrianchong518]

I have set up racket-langserver with neovim via nvim-lspconfig.

When I try to format code via :lua vim.lsp.buf.format(), the code is not formatted and a "method not found" exception can be seen in the logs.

Here is the complete log (:LspLog):

[ERROR][2023-10-18 14:05:12] .../vim/lsp/rpc.lua:734	"rpc"	"/opt/homebrew/bin/racket"	"stderr"	"Caught exn in request "
[ERROR][2023-10-18 14:05:12] .../vim/lsp/rpc.lua:734	"rpc"	"/opt/homebrew/bin/racket"	"stderr"	'"textDocument/formatting"\nsend: no such method\n  method name: position-paragraph\n  class name: lsp-editor%\n  context...:\n   /Applications/Racket v8.10/collects/racket/private/class-internal.rkt:4728:0: obj-error\n   /Applications/Racket v8.10/share/pkgs/gui-lib/scribble/private/indentation.rkt:408:0: determine-spaces\n   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/doc.rkt:268:2\n   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/doc.rkt:302:0: indent-line!\n   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/doc.rkt:237:6: loop\n   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/text-document.rkt:426:0: formatting!\n   /Applications/Racket v8.10/collects/racket/contract/private/arrow-val-first.rkt:486:18\n   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/methods.rkt:26:0: process-message\n   /Applications/Racket v8.10/collects/racket/contract/private/arrow-val-first.rkt:486:18\n   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/main.rkt:60:2: consume\n\n'

And a formatted version:

"textDocument/formatting"
send: no such method
  method name: position-paragraph
  class name: lsp-editor%
  context...:
   /Applications/Racket v8.10/collects/racket/private/class-internal.rkt:4728:0: obj-error
   /Applications/Racket v8.10/share/pkgs/gui-lib/scribble/private/indentation.rkt:408:0: determine-spaces
   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/doc.rkt:268:2
   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/doc.rkt:302:0: indent-line!
   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/doc.rkt:237:6: loop
   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/text-document.rkt:426:0: formatting!
   /Applications/Racket v8.10/collects/racket/contract/private/arrow-val-first.rkt:486:18
   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/methods.rkt:26:0: process-message
   /Applications/Racket v8.10/collects/racket/contract/private/arrow-val-first.rkt:486:18
   /Users/<user>/Library/Racket/8.10/pkgs/racket-langserver/main.rkt:60:2: consume

After a brief look at the relevant code, I assume that the position-paragraph method should be called on a racket:text% object, but somehow an lsp-editor% is used. I believe that there are some issues with how the indenter passed into indent-line! works.

However, my limited experience with Racket (as I'm still starting out) prevented me to dive deeper into how the whole thing works. Some help is greatly appreciated!

[6cdh]

The error might come from here:

racket-langserver/doc.rkt

Line 276 in 3f23f43

(or (indenter doc-text line-start)

indenter is a function of this type:

(-> (is-a?/c racket:text<%>)
    exact-nonnegative-integer?
    (or/c #f exact-nonnegative-integer?))

but doc-text is a lsp-editor% object. I think add a new method to lsp-editor% called like indent can solve it.

[6cdh]

I made a change: https://github.com/6cdh/racket-langserver/tree/fix-formatting
please try it

[adrianchong518]

I've tried it and it works!
(It looks like a simple fix in hindsight, but I just couldn't get my head around how all the things go together 🙃 )

[6cdh]

In an older version, doc-text is a text% object, and the code is correct.
But then I refactored that wrapped text% object in lsp-editor% class, that is the core variable.
That was a mistake to leave that line of code unchanged.
So this change basically replace doc-text with core. core is a class private variable, so I added a new method.