[#408] add clangd command line options validator

[ghentschke]

if clangd version >= 11, then the clangd binary will be called with configured command line options plus --check and --log=error. If the stderr stream remains empty everything is fine and we can go on. Otherwise we through an IOException in the start() method. This leads to an error dialog with the strings returned from stderr stream.

fixes #408

[ghentschke]

I want to add some unit tests.

[ghentschke]

If clangd version <= 11 then you'll see this log entry:

!ENTRY org.eclipse.cdt.lsp.clangd 2 0 2025-02-01 18:48:32.865
!MESSAGE The clangd version does not support command line option check!

and this is the error message for clangd versions >= 12:

[jonahgraham]

@ghentschke I have left some line comments. However I have concerns that the overall design of this is too harsh. By that I mean it can stop LSP4E from trying to start clangd because clangd --check reports an error.

There are a few cases that concern me:

1. This use of temp files means .clangd and .clang-format will be picked up from /tmp on Linux or even home directory on Windows. This will cause false negatives if that clangd/clangformat file has validation errors.
2. It seems reasonable that there are some arrangement of command line options that may cause error logging, but not stop functioning of clangd

For 1. here is some terminal commands I tried:

$ echo "nonesense" > .clangd
$ clangd --check=a.c --log=error
E[15:27:07.145] config error at /tmp/.clangd:1:0: Config should be a dictionary
$ rm .clangd
$ echo "nonesense" > .clang-format
$ clangd --check=a.c --log=error
/tmp/.clang-format:1:1: error: not a mapping
nonesense
^~~~~~~~~
/tmp/.clang-format:1:1: error: not a mapping
nonesense
^~~~~~~~~

And with the .clangd left in /tmp this is what I see in the UI:

The mitigating factor is that the error message shows that there is an errant dot file in /tmp (or presumably home directory on Windows)

[ghentschke]

There are a few cases that concern me:

• This use of temp files means .clangd and .clang-format will be picked up from /tmp on Linux or even home directory on Windows. This will cause false negatives if that clangd/clangformat file has validation errors.
• It seems reasonable that there are some arrangement of command line options that may cause error logging, but not stop functioning of clangd

I agree. I'll add a regex to filter only for the clangd(.exe)?: <error> messages. These errors seems to prevent clangd from being executed and are the cause for the behavior described in #408.

[ghentschke]

Maybe we should add an option flag to enable this pre-launch check. But I would enable it as default. When the check causes trouble on some OS or clangd versions it can be deactivated.

[ruspl-afed]

Do you think we can remove this method to simplify API and return IStatus.CANCEL from validateCommandLineOptions if binary doesn't support validation?

[ghentschke]

Sure

[jonahgraham]

Maybe we should add an option flag to enable this pre-launch check. But I would enable it as default. When the check causes trouble on some OS or clangd versions it can be deactivated.

Sounds like a good idea - definitely default to on, but this does allow us to field disable an over aggressive command line validation failure.

BTW it would be great if LSP4E could detect the excessive restart problem and prompt user to disable language server. Not sure what that would take.

[ghentschke]

Any objections @jonahgraham or @ruspl-afed ? Otherwise I would merge it

[ghentschke]

@jonahgraham and @ruspl-afed Thank you both for your fast and excellent reviews!