Eglot choosing wrong server for a derived mode when there also exists a definition for the parent mode.

[Lenbok]

I'm not sure how I am supposed to configure eglot-server-programs to avoid this problem.

I can add support for groovy-mode via:

  (with-eval-after-load 'eglot
    (add-to-list 'eglot-server-programs
                 '((groovy-mode :language-id "groovy") . ("java" "-jar" "/home/len/dev/groovy-language-server/build/libs/groovy-language-server-all.jar"))))

But now I want to try out the language server for nextflow-mode, (which is derived from groovy-mode), using a similar construct:

  (with-eval-after-load 'eglot
    (add-to-list 'eglot-server-programs
                 '((nextflow-mode :language-id "nextflow") . ("nextflow-language-server"))))

However, when I start eglot in a buffer that is in nextflow-mode, it starts the groovy language server instead.

[joaotavora]

I think it has to do with the order of entries in eglot-server-programs. Show the contents of that variable.

In theory, Eglot is doing nothing wrong. nextflow-mode is telling it that "nextflow" is a dialect of "groovy" so starting the "groovy" server for "nextflow" is not wrong under that lens. But if it's not a dialect at all, then maybe nextflow-mode should not be deriving and rather use a different kind of mechanism to reuse some of groovy-mode's code. And then the order of entries in e-s-programs wouldn't matter.

[Lenbok]

OK, I found that by shuffling the order of the entries in eglot-server-programs I can get it to start the nextflow language server rather the groovy one.

I guess I was surprised by the assumption that because a mode X derives implementation from another mode Y, any language server for mode Y should be usable with mode X, when the server program list contains an entry that is a more specific match to the mode.

For now I'll change my groovy declaration to append the entry to the end of eglot-server-programs (and will do so with any servers for "generic" modes as yaml-mode that might have derived modes with their own servers).