Re: master 2c79a8f 2/2: Use posix_spawn if possible.

[Saulius Menkevicius <sauliusmenkevicius@fastmail.com>]

I certainly cannot answer that, it probably does some kind of sniffing 
on FDs and changes behaviour.

To actually figure that out I would need to build a minimal test fixture 
for this bug/issue and submit to dotnet/runtime repo on github for them 
to check and/or fix it.

-Saulius

Am 25.01.22 um 14:22 schrieb Eli Zaretskii:
>> Date: Tue, 25 Jan 2022 10:58:51 +0200
>> Cc: p.stephani2@gmail.com, alan@idiocy.org, mituharu@math.s.chiba-u.ac.jp
>> From: Saulius Menkevicius <sauliusmenkevicius@fastmail.com>
>>
>> Sorry I did not mention the platform, this happens on Linux/x64 and has
>> been reported by multiple persons:
>>
>> - https://github.com/razzmatazz/csharp-language-server/issues/12
>>
>>
>> The issue has been noticed when dotnet-based LSP servers are used with
>> emacs/lsp-mode, -- in particular lsp-mode starts the server using
>> `make-process` and then communicates over stdio. Link to the code that
>> launches the server:
>>
>> - https://github.com/emacs-lsp/lsp-mode/blob/master/lsp-mode.el#L6925
>>
>>
>> We have csharp-ls and fsac servers launched with the same mechanism as
>> are for other languages -- which are working ok with posix_spawn
>> enabled. It only breaks for those before-mentioned LSP servers that are
>> implemented on top of dotnet and use dotnet runtime (same thing as JVM,
>> but for C#/F#/CLR languages).
>>
>> Now it appears, that switch to posix_spawn broke communication over
>> stdio to those dotnet-based LSP servers for some technical reason, -- I
>> didn't investigate yet why, because it is a bit over my head. I *think*
>> there is an interplay between posix_spawn-based process launch
>> implementation in emacs and dotnet runtime stdio abstractions/platform
>> layer -- because otherwise other language servers work with that commit
>> that enables posix_spawn, like those based on JVM too.
> What is special about dotnet's runtime stdio usage?