From d19f440986e9651cc5694c2adc04ac0484580c40 Mon Sep 17 00:00:00 2001
From: Troy Brown <brownts@troybrown.dev>
Date: Mon, 16 Dec 2024 15:25:08 -0500
Subject: [PATCH] Add SignatureInformation activeParameter support.

---
 lsp-mode.el     | 5 ++++-
 lsp-protocol.el | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/lsp-mode.el b/lsp-mode.el
index 58b71ea13e3..156b59fb58c 100644
--- a/lsp-mode.el
+++ b/lsp-mode.el
@@ -3804,7 +3804,8 @@ disappearing, unset all the variables related to it."
                                                         (insertTextModeSupport . ((valueSet . [1 2])))))
                                      (contextSupport . t)
                                      (dynamicRegistration . t)))
-                      (signatureHelp . ((signatureInformation . ((parameterInformation . ((labelOffsetSupport . t)))))
+                      (signatureHelp . ((signatureInformation . ((parameterInformation . ((labelOffsetSupport . t)))
+                                                                 (activeParameterSupport . t)))
                                         (dynamicRegistration . t)))
                       (documentLink . ((dynamicRegistration . t)
                                        (tooltipSupport . t)))
@@ -5912,6 +5913,8 @@ It will show up only if current point has signature help."
             (active-signature? (or lsp--signature-last-index active-signature? 0))
             (_ (setq lsp--signature-last-index active-signature?))
             ((signature &as &SignatureInformation? :label :parameters?) (seq-elt signatures active-signature?))
+            (active-parameter? (or (lsp:signature-information-active-parameter? signature)
+                                   active-parameter?))
             (prefix (if (= (length signatures) 1)
                         ""
                       (concat (propertize (format " %s/%s"
diff --git a/lsp-protocol.el b/lsp-protocol.el
index a56e2b8e51c..ea70041d007 100644
--- a/lsp-protocol.el
+++ b/lsp-protocol.el
@@ -695,7 +695,7 @@ See `-let' for a description of the destructuring mechanism."
  (SignatureHelpCapabilities nil (:contextSupport :dynamicRegistration :signatureInformation))
  (SignatureHelpContext (:triggerKind :isRetrigger) (:activeSignatureHelp :triggerCharacter))
  (SignatureHelpOptions nil (:retriggerCharacters :triggerCharacters))
- (SignatureInformation (:label) (:documentation :parameters))
+ (SignatureInformation (:label) (:documentation :parameters :activeParameter))
  (SignatureInformationCapabilities nil (:documentationFormat :parameterInformation))
  (StaticRegistrationOptions nil (:documentSelector :id))
  (SymbolCapabilities nil (:dynamicRegistration :symbolKind))