Expose lsp-bash-allowed-shell and improve warning (#4620)

* lsp-bash: Remove major mode duplication

These are already filtered by `:major-modes` so there's no need to
filter them again in the `:activation-fn`.

`:major-modes` was originally removed in:

- b77aecf

But then reintroduced in:

- 771342f

* lsp-bash: Expose lsp-bash-allowed-shells

Make the `sh-shell` values that are filtered by `:activation-fn`
configurable without needing to override `lsp-bash-check-sh-shell`

This allows people to allow values like `bats` and also makes it
slightly clearer why those values aren't supported by default when the
major mode is, which took me a long time to debug.

* lsp-mode: Improve warning about :activation-fn

To make it easier to debug situations where the `:major-mode` is
supported but `:activation-fn` prevents the buffer from being supported
for other reasons, such as `lsp-bash` rejecting an `sh-shell` value of
`bats`.

* lsp-bash: Fix for unbound sh-shell

Fix the following test:

    Test lsp-mock-doc-changes-wrong-version condition:

        (void-variable sh-shell)

By only checking `lsp-bash-allowed-shells` when `sh-shell` is bound to a
value. For reasons that I'm not entirely clear about, this was fine
previously when checking against a static list.

---------

Co-authored-by: Jen-Chieh Shen <jcs090218@gmail.com>

Author: dcarley

CHANGELOG.org

@@ -26,6 +26,8 @@
   * Add TypeSpec support
   * Add Tree-sitter query support
   * Add [[https://github.com/mrjosh/helm-ls][helm-ls]] (YAML Kubernetes Helm) support.
+  * Add ~lsp-bash-allowed-shells~ to configure supported ~sh-shell~ values.
+  * Add hint about ~activation-fn~ for unsupported buffers.
 
 ** 9.0.0
   * Add language server config for QML (Qt Modeling Language) using qmlls.

clients/lsp-bash.el

@@ -33,6 +33,12 @@
   :link '(url-link "https://github.com/bash-lsp/bash-language-server")
   :package-version '(lsp-mode . "6.2"))
 
+(defcustom lsp-bash-allowed-shells '(sh bash)
+  "List of allowed `sh-shell` values that LSP will be enabled for."
+  :type '(list symbol)
+  :group 'lsp-bash
+  :package-version '(lsp-mode . "9.0.1"))
+
 (defcustom lsp-bash-explainshell-endpoint nil
   "The endpoint to use explainshell.com to answer `onHover' queries.
 See instructions at https://marketplace.visualstudio.com/items?itemName=mads-hartmann.bash-ide-vscode"
@@ -65,11 +71,11 @@ See instructions at https://marketplace.visualstudio.com/items?itemName=mads-har
 (defvar sh-shell)
 
 (defun lsp-bash-check-sh-shell (&rest _)
-  "Check whether `sh-shell' is sh or bash.
+  "Check whether `sh-shell' is supported.
 
-This prevents the Bash server from being turned on in zsh files."
-  (and (memq major-mode '(sh-mode bash-ts-mode ebuild-mode envrc-file-mode))
-       (memq sh-shell '(sh bash))))
+This prevents the Bash server from being turned on for unsupported dialects, e.g. `zsh`."
+  (and (boundp 'sh-shell)
+       (memq sh-shell lsp-bash-allowed-shells)))
 
 (lsp-register-client
  (make-lsp-client

lsp-mode.el

@@ -9495,9 +9495,10 @@ You may find the installation instructions at https://emacs-lsp.github.io/lsp-mo
 This issue might be caused by:
 1. The language you are trying to use does not have built-in support in `lsp-mode'. You must install the required support manually. Examples of this are `lsp-java' or `lsp-metals'.
 2. The language server that you expect to run is not configured to run for major mode `%s'. You may check that by checking the `:major-modes' that are passed to `lsp-register-client'.
-3. `lsp-mode' doesn't have any integration for the language behind `%s'. Refer to https://emacs-lsp.github.io/lsp-mode/page/languages and https://langserver.org/ .
-4. You are over `tramp'. In this case follow https://emacs-lsp.github.io/lsp-mode/page/remote/.
-5. You have disabled the `lsp-mode' clients for that file. (Check `lsp-enabled-clients' and `lsp-disabled-clients').
+3. The language server that you expect to run has an `:activation-fn` passed to `lsp-register-client` that prevents it supporting this buffer.
+4. `lsp-mode' doesn't have any integration for the language behind `%s'. Refer to https://emacs-lsp.github.io/lsp-mode/page/languages and https://langserver.org/ .
+5. You are over `tramp'. In this case follow https://emacs-lsp.github.io/lsp-mode/page/remote/.
+6. You have disabled the `lsp-mode' clients for that file. (Check `lsp-enabled-clients' and `lsp-disabled-clients').
 You can customize `lsp-warn-no-matched-clients' to disable this message."
                     major-mode major-mode major-mode))))))