From 0bba771a2a5cb8d16ed659a89db4ab13f319b352 Mon Sep 17 00:00:00 2001
From: Alex Hoppen <ahoppen@apple.com>
Date: Mon, 14 Jul 2025 17:05:45 +0200
Subject: [PATCH] Accept `Location` for `workspace/peekDocument`

This allows the peek window to scroll to a position within the peeked document.
---
 src/sourcekit-lsp/LanguageClientConfiguration.ts  |  1 +
 .../extensions/PeekDocumentsRequest.ts            |  6 +++---
 src/sourcekit-lsp/peekDocuments.ts                | 15 ++++++++++-----
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/sourcekit-lsp/LanguageClientConfiguration.ts b/src/sourcekit-lsp/LanguageClientConfiguration.ts
index 6a36cfe09..104ed99bf 100644
--- a/src/sourcekit-lsp/LanguageClientConfiguration.ts
+++ b/src/sourcekit-lsp/LanguageClientConfiguration.ts
@@ -45,6 +45,7 @@ function initializationOptions(swiftVersion: Version): any {
         options = {
             "workspace/peekDocuments": {
                 supported: true, // workaround for client capability to handle `PeekDocumentsRequest`
+                peekLocation: true, // allow SourceKit-LSP to send `Location` instead of `DocumentUri` for the locations to peek.
             },
             "workspace/getReferenceDocument": {
                 supported: true, // the client can handle URIs with scheme `sourcekit-lsp:`
diff --git a/src/sourcekit-lsp/extensions/PeekDocumentsRequest.ts b/src/sourcekit-lsp/extensions/PeekDocumentsRequest.ts
index ea1302b40..ca38a5136 100644
--- a/src/sourcekit-lsp/extensions/PeekDocumentsRequest.ts
+++ b/src/sourcekit-lsp/extensions/PeekDocumentsRequest.ts
@@ -15,7 +15,7 @@
 // We use namespaces to store request information just like vscode-languageclient
 /* eslint-disable @typescript-eslint/no-namespace */
 
-import { DocumentUri, Position, MessageDirection, RequestType } from "vscode-languageclient";
+import { DocumentUri, Position, Location, MessageDirection, RequestType } from "vscode-languageclient";
 
 /** Parameters used to make a {@link PeekDocumentsRequest}. */
 export interface PeekDocumentsParams {
@@ -30,9 +30,9 @@ export interface PeekDocumentsParams {
     position: Position;
 
     /**
-     * An array `DocumentUri` of the documents to appear inside the "peeked" editor
+     * An array `DocumentUri` or `Location` of the documents to appear inside the "peeked" editor
      */
-    locations: DocumentUri[];
+    locations: DocumentUri[] | Location[];
 }
 
 /** Response to indicate the `success` of the {@link PeekDocumentsRequest}. */
diff --git a/src/sourcekit-lsp/peekDocuments.ts b/src/sourcekit-lsp/peekDocuments.ts
index bfbfb44fa..27881d431 100644
--- a/src/sourcekit-lsp/peekDocuments.ts
+++ b/src/sourcekit-lsp/peekDocuments.ts
@@ -89,11 +89,16 @@ export function activatePeekDocuments(client: langclient.LanguageClient): vscode
             );
 
             const peekLocations = params.locations.map(
-                location =>
-                    new vscode.Location(
-                        client.protocol2CodeConverter.asUri(location),
-                        new vscode.Position(0, 0)
-                    )
+                location => {
+                    if (typeof location === "string") { // DocumentUri is a typedef of `string`, so effectively we are checking for DocumentUri here
+                        return new vscode.Location(
+                            client.protocol2CodeConverter.asUri(location),
+                            new vscode.Position(0, 0)
+                        )
+                    } else {
+                        return client.protocol2CodeConverter.asLocation(location)
+                    }
+                }
             );
 
             await openPeekedEditorIn(peekURI, peekPosition, peekLocations);