fix(emacs/lean-mode.el): invoke lean from project root if existent

src/emacs/lean-company.el

@@ -84,8 +84,6 @@
 (defun company-lean--import-candidates (prefix)
   (let* ((cur-dir (f-dirname (buffer-file-name)))
          (parent-dir (f-parent cur-dir))
-         (project-dir (f--traverse-upwards (f-exists? (f-expand ".project" it))
-                                           (f-dirname (buffer-file-name))))
          (candidates
           (cond
            ;; prefix = ".."

src/emacs/lean-mode.el

@@ -150,6 +150,7 @@ will be flushed everytime it's executed."
           (pcase (lean-choose-minor-mode-based-on-extension)
             (`standard "--lean")
             (`hott     "--hlean")))
+         (default-directory (or (lean-project-find-root) default-directory))
          (process-args (append `(,process-name
                                  ,process-buffer-name
                                  ,(lean-get-executable lean-executable-name)

src/emacs/lean-project.el

@@ -11,7 +11,10 @@
   "Project file name")
 
 (defun lean-project-find-root ()
-  (lean-find-file-upward lean-project-file-name))
+  (let ((p (f--traverse-upwards (f-exists? (f-expand lean-project-file-name it))
+                                (f-dirname (buffer-file-name)))))
+    (if p (file-name-as-directory p)
+          nil)))
 
 (defun lean-project-inside-p ()
   (if (lean-project-find-root) t nil))