Command to show all project errors from LSP in a convenient xref buffer

show-lsp-diagnostics-xref.el

(defun vk/show-lsp-diagnostics-xref ()
  "Display LSP diagnostics in a persistent `xref`-style buffer."
  (interactive)
  (let ((diagnostics (lsp-diagnostics))
        (xref-items '())) ;; Initialize xref items list
    ;; Collect diagnostics as `xref-item` structures
    (maphash
     (lambda (file errors)
       (dolist (error errors)
         (let* ((range (gethash "range" error))
                (start (gethash "start" range))
                (line (1+ (gethash "line" start)))
                (character (gethash "character" start))
                (message (gethash "message" error))
                (location (xref-make-file-location file line character)))
           (push (xref-make message location) xref-items))))
     diagnostics)
    ;; Create a custom xref group for diagnostics
    (let ((xref-buffer-name "*LSP Diagnostics Xref*"))
      (with-current-buffer (get-buffer-create xref-buffer-name)
        ;; Use `xref` display machinery with custom buffer
        (let ((xref-backend-functions
               (list (lambda () (lambda () xref-items)))))
          (xref--show-xrefs (lambda () xref-items) nil)))
      ;; Display the custom xref buffer
      (pop-to-buffer xref-buffer-name))))

I had to adapt the snippet to use map-elt because in my version of lsp the error instance is not a hashmap, that's why the original snippet was failing for me.

The xref buffer appears to me in the minibuffer, which is very nice. I also liked to export the results with embark-export.

(defun vk/show-lsp-diagnostics-xref ()
  "Display LSP diagnostics in a persistent `xref`-style buffer."
  (interactive)
  (let ((diagnostics (lsp-diagnostics))
        (xref-items '())) ;; Initialize xref items list
    ;; Collect diagnostics as `xref-item` structures
    (maphash
     (lambda (file errors)
       (dolist (error errors)
         (let* ((range (map-elt error :range))
                (start (map-elt range :start))
                (line (1+ (map-elt start :line)))
                (character (map-elt start :character))
                (message (map-elt error :message))
                (location (xref-make-file-location file line character)))
           (push (xref-make message location) xref-items))))
     diagnostics)
    ;; Create a custom xref group for diagnostics
    (let ((xref-buffer-name "*LSP Diagnostics Xref*"))
      (with-current-buffer (get-buffer-create xref-buffer-name)
        ;; Use `xref` display machinery with custom buffer
        (let ((xref-backend-functions
               (list (lambda () (lambda () xref-items)))))
          (xref--show-xrefs (lambda () xref-items) nil)))
      ;; Display the custom xref buffer
      (pop-to-buffer xref-buffer-name))))

@ilmotta, thanks for pointing to embark-export, looks very convenient!