From 5d33982513e0bbb517120d2cb216490a0c110de6 Mon Sep 17 00:00:00 2001
From: David Schulz <david.schulz@qt.io>
Date: Mon, 5 Jul 2021 09:45:44 +0200
Subject: [PATCH] LSP: reload semantic token if we encounter corrupted data

Change-Id: I73185b0b7be57d348fc1a461b1db0383313d7208
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
---
 .../semantichighlightsupport.cpp              | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/plugins/languageclient/semantichighlightsupport.cpp b/src/plugins/languageclient/semantichighlightsupport.cpp
index db6cd9f907d..3aafaf5b42f 100644
--- a/src/plugins/languageclient/semantichighlightsupport.cpp
+++ b/src/plugins/languageclient/semantichighlightsupport.cpp
@@ -39,10 +39,11 @@ using namespace LanguageServerProtocol;
 using namespace TextEditor;
 
 namespace LanguageClient {
-namespace SemanticHighligtingSupport {
 
 static Q_LOGGING_CATEGORY(LOGLSPHIGHLIGHT, "qtc.languageclient.highlight", QtWarningMsg);
 
+namespace SemanticHighligtingSupport {
+
 static const QList<QList<QString>> highlightScopes(const ServerCapabilities &capabilities)
 {
     return capabilities.semanticHighlighting()
@@ -399,15 +400,27 @@ void SemanticTokenSupport::handleSemanticTokensDelta(
         newData.reserve(newDataSize);
 
         auto it = data.begin();
+        const auto end = data.end();
         for (const SemanticTokensEdit &edit : qAsConst(edits)) {
             if (edit.start() > data.size()) // prevent edits after the previously reported data
                 return;
             for (const auto start = data.begin() + edit.start(); it < start; ++it)
                 newData.append(*it);
             newData.append(edit.data().value_or(QList<int>()));
-            it += edit.deleteCount();
+            int deleteCount = edit.deleteCount();
+            if (deleteCount > std::distance(it, end)) {
+                qCDebug(LOGLSPHIGHLIGHT)
+                    << "We shall delete more highlight data entries than we actually have, "
+                       "so we are out of sync with the server. "
+                       "Request full semantic tokens again.";
+                TextDocument *doc = TextDocument::textDocumentForFilePath(filePath);
+                if (doc && LanguageClientManager::clientForDocument(doc) == m_client)
+                    reloadSemanticTokens(doc);
+                return;
+            }
+            it += deleteCount;
         }
-        for (const auto end = data.end(); it != end; ++it)
+        for (; it != end; ++it)
             newData.append(*it);
 
         tokens.setData(newData);