fix(command): add setup function to reserve buffers

There was a change in Emacs 30 that may lead to
`ship-mate--command-buffer-p` returning nil, meaning that hooking into
`compilation-start-hook` may fail.

Function `ship-mate-command` now sets
`compilation-process-setup-function` to set new local variable
`ship-mate--reserved` that may also be checked instead of
`ship-mate--this-command`.

ship-mate.el

@@ -129,6 +129,9 @@ This is either nil, `ship-mate' or `other'.")
 
 This is set by `ship-mate-command'.")
 
+(defvar-local ship-mate--reserved nil
+  "Marker set to indicate the compilation was started by `ship-mate'.")
+
 (defvar ship-mate--current-command-name nil
   "The symbol name of the currently executed command.")
 
@@ -207,7 +210,8 @@ command hidden and 5 lets you edit the environment first."
          ;; Binding external variables.
          (default-directory (project-root current))
          (compilation-save-buffers-predicate (lambda () (memq (current-buffer) project-buffers)))
-         (compilation-buffer-name-function (funcall ship-mate-command-buffer-name-function-generator lowercase)))
+         (compilation-buffer-name-function (funcall ship-mate-command-buffer-name-function-generator lowercase))
+         (compilation-process-setup-function #'ship-mate-command--reserve))
 
     (when command
 
@@ -229,6 +233,10 @@ command hidden and 5 lets you edit the environment first."
 
         buffer))))
 
+(defun ship-mate-command--reserve ()
+  "Reserve the current buffer for `ship-mate'."
+  (setq ship-mate--reserved t))
+
 (defun ship-mate-command--current-project (&optional arg)
   "Get the current project.
 
@@ -725,7 +733,8 @@ Optionally the PROJECT may be passed directly."
   (let ((buffer (or buffer (current-buffer))))
 
     (and (string-match-p "\\*ship-mate" (buffer-name buffer))
-         (not (null ship-mate--this-command)))))
+         (or (not (null ship-mate--this-command))
+             ship-mate--reserved))))
 
 (defun ship-mate--command-buffer-predicate (buffer)
   "Predicate to check if BUFFER is a `ship-mate' buffer.

test/ship-mate-test.el

@@ -192,6 +192,17 @@
       (bydi-was-called ship-mate-environment--edit-in-minibuffer)
       (bydi-was-set-to compilation-environment '("MOC=KING")))))
 
+(ert-deftest ship-mate-command--reserve ()
+  :tags '(command)
+
+  (bydi ((:watch ship-mate--reserved))
+
+    (ert-with-test-buffer (:name "reserve")
+
+      (ship-mate-command--reserve)
+
+      (bydi-was-set-to ship-mate--reserved t))))
+
 (ert-deftest ship-mate-command--current-project ()
   (bydi ((:always project-current)
          (:always project-prompt-project-dir)
@@ -824,6 +835,17 @@
 
     (should-error (ship-mate--complete-buffer "Some prompt: "))))
 
+(ert-deftest ship-mate--command-buffer-p--check-for-reserved ()
+  :tags '(command)
+
+  (ert-with-test-buffer (:name "*ship-mate-reserved*")
+
+    (should-not (ship-mate--command-buffer-p))
+
+    (ship-mate-command--reserve)
+
+    (should (ship-mate--command-buffer-p))))
+
 (ert-deftest ship-mate--command-buffer-predicate ()
   :tags '(completion)