Fix Flymake's diagnostic count with custom error types

Fixes: bug#33187

* lisp/progmodes/flymake.el (flymake--mode-line-format): Replace
cl-union with iterative cl-pushnew.

1 files changed, 7 insertions, 10 deletions

diff --git a/lisp/progmodes/flymake.el b/lisp/progmodes/flymake.el
index 5831301a57c..f0f93f10878 100644
--- a/lisp/progmodes/flymake.el
+++ b/lisp/progmodes/flymake.el
@@ -1183,20 +1183,17 @@ default) no filter is applied."
       ,@(unless (or all-disabled
                     (null known))
           (cl-loop
-           for (type . severity)
-           in (cl-sort (mapcar (lambda (type)
-                                 (cons type (flymake--severity type)))
-                               (cl-union (hash-table-keys diags-by-type)
-                                         '(:error :warning)
-                                         :key #'flymake--severity))
-                       #'>
-                       :key #'cdr)
+           with types = (hash-table-keys diags-by-type)
+           with _augmented = (cl-loop for extra in '(:error :warning)
+                                      do (cl-pushnew extra types
+                                                     :key #'flymake--severity))
+           for type in (cl-sort types #'> :key #'flymake--severity)
            for diags = (gethash type diags-by-type)
            for face = (flymake--lookup-type-property type
                                                      'mode-line-face
                                                      'compilation-error)
-           when (or diags
-                    (>= severity (warning-numeric-level :warning)))
+           when (or diags (>= (flymake--severity type)
+                              (warning-numeric-level :warning)))
            collect `(:propertize
                      ,(format "%d" (length diags))
                      face ,face