Docker: validate clangd version

Do not automatically setup a clangd that is too old and mark them as
invalid if they are manually selected.

Change-Id: Ie9662a8821df8fc678eabc4b8a08375723b4d1c3
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/clangutils.cpp

@@ -0,0 +1,66 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include "clangutils.h"
+
+#include "filepath.h"
+#include "qtcprocess.h"
+#include "utilstr.h"
+
+#include <QVersionNumber>
+
+namespace Utils {
+
+static QVersionNumber getClangdVersion(const FilePath &clangdFilePath)
+{
+    QtcProcess clangdProc;
+    clangdProc.setCommand({clangdFilePath, {"--version"}});
+    clangdProc.runBlocking();
+    if (clangdProc.result() != ProcessResult::FinishedWithSuccess)
+        return {};
+    const QString output = clangdProc.allOutput();
+    static const QString versionPrefix = "clangd version ";
+    const int prefixOffset = output.indexOf(versionPrefix);
+    if (prefixOffset == -1)
+        return {};
+    return QVersionNumber::fromString(output.mid(prefixOffset + versionPrefix.length()));
+}
+
+QVersionNumber clangdVersion(const FilePath &clangd)
+{
+    static QHash<FilePath, QPair<QDateTime, QVersionNumber>> versionCache;
+    const QDateTime timeStamp = clangd.lastModified();
+    const auto it = versionCache.find(clangd);
+    if (it == versionCache.end()) {
+        const QVersionNumber version = getClangdVersion(clangd);
+        versionCache.insert(clangd, {timeStamp, version});
+        return version;
+    }
+    if (it->first != timeStamp) {
+        it->first = timeStamp;
+        it->second = getClangdVersion(clangd);
+    }
+    return it->second;
+}
+
+bool checkClangdVersion(const FilePath &clangd, QString *error)
+{
+    const QVersionNumber version = clangdVersion(clangd);
+    if (version >= minimumClangdVersion())
+        return true;
+    if (error) {
+        *error = version.isNull()
+                     ? Tr::tr("Failed to retrieve clangd version: Unexpected clangd output.")
+                     : Tr::tr("The clangd version is %1, but %2 or greater is required.")
+                           .arg(version.toString())
+                           .arg(minimumClangdVersion().majorVersion());
+    }
+    return false;
+}
+
+QVersionNumber minimumClangdVersion()
+{
+    return QVersionNumber(14);
+}
+
+} // namespace Utils