Debug Adapter Protocol (DAP) basic support

[angelozerr]

In my spare time I have worked since several month to implement a "generic" Debug Adapter Protocol (DAP) support which will be available in 0.10.0.

If you want to test it, please install nightly-builds.

I have pushed my work and you can read doc at https://github.com/redhat-developer/lsp4ij/blob/main/docs/dap/DAP.md I have tested the DAP support with 2 DAP servers:

• vscode JS debug, see https://github.com/redhat-developer/lsp4ij/blob/main/docs/dap/user-defined-dap/vscode-js-debug.md (socket)
• swift lldb dap, see https://github.com/redhat-developer/lsp4ij/blob/main/docs/dap/user-defined-dap/swift-lldb.md (stdio)
• go with delve, see https://github.com/redhat-developer/lsp4ij/blob/main/docs/dap/user-defined-dap/go-delve.md (socket)

Socket and stdio are supported..

Please also read DAP support to know what is supported.

It is not perfect and it will require some improvement, but please give us feedback by testing it with your DAP server in order to improve it:

• @SCWells72 please try it with JavaScript debugging. We need to investigate how to support TypeScript.
• @FalsePattern please try it with zigbrains
• @CppCXY please try it with your lua DAP server
• @InSyncWithFoo please try it with a Python DAP server (I don't know if it is interesting)?
• @ericdallo please try it with Clojure DAP server

Please be don't be disaspointed, it is a first pass and I know this DAP support must be improved. Any feedback are welcome!

Thanks!

[ericdallo]

@angelozerr thanks, but there is no Clojure DAP server ATM, but it's something I have in plans to create

[angelozerr]

@angelozerr thanks, but there is no Clojure DAP server ATM, but it's something I have in plans to create

What about https://github.com/Olical/clojure-dap ?

[ericdallo]

AFAIK it's experimental and not working, to be honest, the Clojure community relies a lot in REPL, that's why a debugger is not that needed.

[CppCXY]

I tried it, but my DAP communicates via stdio, so it can't take effect for now. Additionally, may I ask if the debug inline values protocol in LSP is supported?

[CppCXY]

I tried it, but my DAP communicates via stdio, so it can't take effect for now. Additionally, may I ask if the debug inline values protocol in LSP is supported?

@CppCXY please reinstall nighty when https://github.com/redhat-developer/lsp4ij/actions/runs/12906483568 will be finished.

stdio should works now.

It appears to work initially, but it doesn't function entirely because we need to register certain events using VS Code's mechanisms to locate breakpoint files. To fully support DAP, we must remove some dependencies on VS Code. Considering that we already have a debugger based on xdebugger, I can only look at it when I have time.

[angelozerr]

If I understand correctly, you need to support custom event with LSP4IJ DAP client, right?

[CppCXY]

If I understand correctly, you need to support custom event with LSP4IJ DAP client, right?

yes, but, the Chinese New Year is approaching, and we will be taking a break for about half a month. May not be able to adapt to the changes and do testing immediately.

[angelozerr]

If I understand correctly, you need to support custom event with LSP4IJ DAP client, right?

yes, but, the Chinese New Year is approaching, and we will be taking a break for about half a month. May not be able to adapt to the changes and do testing immediately.

Ok no problem. Do you think you could do a zip with your dap server and attach it here in order to I try it please.

[angelozerr]

@CppCXY after seeing your code, I think the best solution is to update your DAP server to be compatible with the DAP sepcification. Hope you will find time to do that.

[angelozerr]

@jansorg I have add a DAP template for debugging swift files, see https://github.com/redhat-developer/lsp4ij/blob/main/docs/dap/user-defined-dap/swift-lldb.md

I have noticed that you have contributed to LSP4J to add DAP properties required to support locationReference ( to support "inline values" I think) in your PR eclipse-lsp4j/lsp4j#863 I suppose that you are implementing your own DAP support.

[jansorg]

@angelozerr The PR I contributed is to support the navigation to a variable's definition. But I haven't found an LSP server yet, which is actually support this feature :)
With a few changes to a XNamedValue it should also enable inline variables. But in my experience it's better to show the inline value closest to the current debugger position. The definition could be far away, it would be better to find the reference closest to the current debugger position, but AFAIK that's only possible with LSP's textDocument/inlineValue request. And I couldn't find an LSP server for that, either...

You're right that I'm implementing my own DAP client.

[angelozerr]

@angelozerr The PR I contributed is to support the navigation to a variable's definition. But I haven't found an LSP server yet, which is actually support this feature :) With a few changes to a XNamedValue it should also enable inline variables.

Yes I have tried with snapshot of LSP4J by using locationReferences and it should work but for vscode js debug, it doesn't support that today.

But in my experience it's better to show the inline value closest to the current debugger position.

I agree and locationReference is the best mean. I have in my mind to provide an extension point to customize DAP support and the idea is to have the capability to manage like you wish:

• with LSP textDocument/inlineValue
• with locationReferences
• with the PsiFile

The definition could be far away, it would be better to find the reference closest to the current debugger position, but AFAIK that's only possible with LSP's textDocument/inlineValue request. And I couldn't find an LSP server for that, either...

You're right that I'm implementing my own DAP client.

That's shame for LSP4IJ. But for now I cannot say you please swith to LSP4IJ since LSP SourceKit crashes LSP4IJ. I created the issue in SourceKit LSP swiftlang/sourcekit-lsp#1890

[jansorg]

There's no reason to devalue LSP4IJ!
Even though I disagree on technical terms, you're doing great work with the LSP and DAP client implementations.
I've stated my reasons before and will not change my course, but that shouldn't block you or the community to appreciate LSP4IJ.

I wasn't able to reproduce the crashes of sourcekit-lsp with master of LSP4IJ. I wasn't seeing any $/cancel requests for completions in the log, probably because my local machine is too fast and completions complete before I managed to type more.
If I find the time, I'll test on a slower machine.

[angelozerr]

To have a better overview of LSP4IJ DAP support, I have added https://github.com/redhat-developer/lsp4ij/blob/main/docs/dap/DAPSupport.md to know what is supported (ex : evaluate expression, completion, set value, etc) and what is not supported.