From e88b4ebce80561400436798c43744a4a78295170 Mon Sep 17 00:00:00 2001
From: David Schulz <david.schulz@qt.io>
Date: Wed, 11 Aug 2021 12:37:52 +0200
Subject: [PATCH] clangd: open documents just once

Opening a document in the language client while the server is still
initializing will postpone the opening after the server is fully
initialized. So if a document was scheduled for opening by
ClangModelManagerSupport::onEditorOpened while clangd is still
initializing, skip the superfluous opening in the ClangdClient
initialize callback. Clangd seems to have issues if files are opened
twice, resulting in strange diagnostics after editing the file. This is
reproducible for me when starting Qt Creator with a session that
contains open files.

Change-Id: I200d5c8afb685403f0435e0553f5a475f75e8ea2
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
---
 .../clangcodemodel/clangmodelmanagersupport.cpp  |  3 ++-
 src/plugins/languageclient/client.cpp            | 16 +++++++++++-----
 src/plugins/languageclient/client.h              |  1 +
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
index 9a6b1ef6e15..12d70c80002 100644
--- a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
+++ b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
@@ -331,7 +331,8 @@ void ClangModelManagerSupport::updateLanguageClient(ProjectExplorer::Project *pr
                     continue;
                 if (fallbackClient && fallbackClient->documentOpen(editor->textDocument()))
                     fallbackClient->closeDocument(editor->textDocument());
-                client->openDocument(editor->textDocument());
+                if (!client->documentOpen(editor->textDocument()))
+                    client->openDocument(editor->textDocument());
                 ClangEditorDocumentProcessor::clearTextMarks(editor->textDocument()->filePath());
                 hasDocuments = true;
             }
diff --git a/src/plugins/languageclient/client.cpp b/src/plugins/languageclient/client.cpp
index 4d0abf56708..a2a61f12244 100644
--- a/src/plugins/languageclient/client.cpp
+++ b/src/plugins/languageclient/client.cpp
@@ -354,10 +354,12 @@ void Client::openDocument(TextEditor::TextDocument *document)
     if (!isSupportedDocument(document))
         return;
 
-    m_openedDocument[document] = document->plainText();
-
-    if (m_state != Initialized)
+    if (m_state != Initialized) {
+        m_postponedDocuments << document;
         return;
+    }
+
+    QTC_ASSERT(!m_openedDocument.contains(document), return);
 
     const FilePath &filePath = document->filePath();
     const QString method(DidOpenTextDocumentNotification::methodName);
@@ -377,6 +379,8 @@ void Client::openDocument(TextEditor::TextDocument *document)
                 return;
         }
     }
+
+    m_openedDocument[document] = document->plainText();
     connect(document, &TextDocument::contentsChangedWithPosition, this,
             [this, document](int position, int charsRemoved, int charsAdded) {
         documentContentsChanged(document, position, charsRemoved, charsAdded);
@@ -427,6 +431,7 @@ void Client::closeDocument(TextEditor::TextDocument *document)
     deactivateDocument(document);
     const DocumentUri &uri = DocumentUri::fromFilePath(document->filePath());
     m_highlights[uri].clear();
+    m_postponedDocuments.remove(document);
     if (m_openedDocument.remove(document) != 0) {
         handleDocumentClosed(document);
         if (m_state == Initialized) {
@@ -1452,8 +1457,9 @@ void Client::initializeCallback(const InitializeRequest::Response &initResponse)
         }
     }
 
-    for (auto it = m_openedDocument.cbegin(); it != m_openedDocument.cend(); ++it)
-        openDocument(it.key());
+    for (TextEditor::TextDocument *doc : m_postponedDocuments)
+        openDocument(doc);
+    m_postponedDocuments.clear();
 
     emit initialized(m_serverCapabilities);
 }
diff --git a/src/plugins/languageclient/client.h b/src/plugins/languageclient/client.h
index cd0c01b986d..d046064e30a 100644
--- a/src/plugins/languageclient/client.h
+++ b/src/plugins/languageclient/client.h
@@ -246,6 +246,7 @@ private:
     LanguageFilter m_languagFilter;
     QJsonObject m_initializationOptions;
     QMap<TextEditor::TextDocument *, QString> m_openedDocument;
+    QSet<TextEditor::TextDocument *> m_postponedDocuments;
     QMap<Utils::FilePath, int> m_documentVersions;
     QMap<TextEditor::TextDocument *,
          QList<LanguageServerProtocol::DidChangeTextDocumentParams::TextDocumentContentChangeEvent>>