Eglot: fix thinko in recent diagnostics logic change

If the pushed diagnostics are outdated and we have pulled diagnostics,
we want to report them.  And if the pushed diagnostics are up to date,
we want to report them along with any pulled ones.  The do-nothing
update happens only if the pulled response indicated so explicitly or if
there are no pulled diagnostics and the pushed ones are out-of-date.

* lisp/progmodes/eglot.el (eglot--flymake-report): Tweak.

1 files changed, 20 insertions, 18 deletions

diff --git a/lisp/progmodes/eglot.el b/lisp/progmodes/eglot.el
index b2dd76f0ea8..979de22c1df 100644
--- a/lisp/progmodes/eglot.el
+++ b/lisp/progmodes/eglot.el
@@ -3291,33 +3291,35 @@ When response arrives call registered `eglot--flymake-report-fn'."
                         (remove origin (eglot--managed-buffers server))))))))
 
 (cl-defun eglot--flymake-report
-    (&optional void
+    (&optional keep
      &aux
-     (diags (append (car eglot--pulled-diagnostics)
-                    (car eglot--pushed-diagnostics)))
-     (version (cadr eglot--pushed-diagnostics)))
+     (pushed-docver (cadr eglot--pushed-diagnostics))
+     (pushed-outdated-p (and pushed-docver (< pushed-docver eglot--docver))))
   "Push previously collected diagnostics to `eglot--flymake-report-fn'.
-If VOID, knowingly push a dummy do-nothing update."
+If KEEP, knowingly push a dummy do-nothing update."
   (unless eglot--flymake-report-fn
     ;; Occasionally called from contexts where report-fn not setup, such
     ;; as a `didOpen''ed but yet undisplayed buffer.
     (cl-return-from eglot--flymake-report))
   (eglot--widening
-   (if (or void (and version (< version eglot--docver)))
-       ;; Here, we don't have anything interesting to give to Flymake: we
-       ;; just want to keep whatever diagnostics it has annotated in the
-       ;; buffer. However, as a nice-to-have, we still want to signal
-       ;; we're alive and clear a possible "Wait" state.  We hackingly
-       ;; achieve this by reporting an empty list and making sure it
-       ;; pertains to a 0-length region.
+   (if (or keep (and (null eglot--pulled-diagnostics) pushed-outdated-p))
+       ;; Here, we don't have anything interesting to give to
+       ;; Flymake.  Either a textDocument/diagnostics response
+       ;; specifically told use that nothing changed, or
+       ;; `flymake-start' kicked in before server had a chance to
+       ;; push something.  We just want to keep whatever diagnostics
+       ;; it has annotated in the buffer but as a nice-to-have, we
+       ;; want to signal we're alive and clear a possible "Wait"
+       ;; state.  We hackingly achieve this by reporting an empty
+       ;; list and making sure it pertains to a 0-length region.
        (funcall eglot--flymake-report-fn nil
                 :region (cons (point-min) (point-min)))
-     (funcall eglot--flymake-report-fn diags
-              ;; If the buffer hasn't changed since last
-              ;; call to the report function, flymake won't
-              ;; delete old diagnostics.  Using :region
-              ;; keyword forces flymake to delete
-              ;; them (github#159).
+     ;; Using :region keyword always forces Flymake to delete them
+     ;; (github#159).
+     (funcall eglot--flymake-report-fn
+              (append (car eglot--pulled-diagnostics)
+                      (unless pushed-outdated-p
+                        (car eglot--pushed-diagnostics)))
               :region (cons (point-min) (point-max))))))
 
 (defun eglot-xref-backend () "Eglot xref backend." 'eglot)