ClangFormat: Use pre-existing code style settings

Instead using of default code style settings, this commit
modifies the ClangFormat plugin to use the code style
settings that were set before applying ClangFormat.
By doing so, we preserve the previously defined code style.

Fixes: QTCREATORBUG-29185
Change-Id: I347d44d5ed49a2c50e130a983b62c844c8964391
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangformat/clangformatbaseindenter.cpp

@@ -7,15 +7,16 @@
 
 #include <coreplugin/icore.h>
 
+#include <cppeditor/cppcodestylepreferences.h>
+
 #include <projectexplorer/editorconfiguration.h>
 #include <projectexplorer/project.h>
 #include <projectexplorer/projectmanager.h>
 
 #include <texteditor/icodestylepreferences.h>
+#include <texteditor/tabsettings.h>
 #include <texteditor/texteditorsettings.h>
 
-#include <clang/Tooling/Core/Replacement.h>
-
 #include <utils/algorithm.h>
 #include <utils/fileutils.h>
 #include <utils/qtcassert.h>
@@ -24,6 +25,8 @@
 #include <QDebug>
 #include <QTextDocument>
 
+#include <clang/Tooling/Core/Replacement.h>
+
 namespace ClangFormat {
 
 Internal::LlvmFileSystemAdapter llvmFileSystemAdapter = {};
@@ -760,7 +763,7 @@ clang::format::FormatStyle overrideStyle(const Utils::FilePath &fileName)
     Utils::FilePath filePath = filePathToCurrentSettings(preferences);
 
     if (!filePath.exists())
-        return qtcStyle();
+        return currentQtStyle(preferences);
 
     clang::format::FormatStyle currentSettingsStyle;
     currentSettingsStyle.Language = clang::format::FormatStyle::LK_Cpp;
@@ -769,7 +772,7 @@ clang::format::FormatStyle overrideStyle(const Utils::FilePath &fileName)
                                                                         .toStdString(),
                                                                     &currentSettingsStyle);
     QTC_ASSERT(error.value() == static_cast<int>(clang::format::ParseError::Success),
-               return qtcStyle());
+               return currentQtStyle(preferences));
 
     return currentSettingsStyle;
 }