Clang: make workaround for multibyte utf8

Correct columns in clang diagnostics and completion

Task-number: QTCREATORBUG-16775
Change-Id: I7260a0e52007fe261e83492dca5d457c34476497
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/clangcodemodel/clangcompletionassistprocessor.cpp

@@ -552,7 +552,8 @@ bool ClangCompletionAssistProcessor::sendCompletionRequest(int position,
 {
     int line, column;
     TextEditor::Convenience::convertPosition(m_interface->textDocument(), position, &line, &column);
-    ++column;
+    const QTextBlock block = m_interface->textDocument()->findBlock(position);
+    column += ClangCodeModel::Utils::extraUtf8CharsShift(block.text(), column) + 1;
 
     const QString filePath = m_interface->fileName();
 

src/plugins/clangcodemodel/clangdiagnosticmanager.cpp

@@ -26,6 +26,7 @@
 #include "clangdiagnosticfilter.h"
 #include "clangdiagnosticmanager.h"
 #include "clangisdiagnosticrelatedtolocation.h"
+#include "clangutils.h"
 
 #include <coreplugin/actionmanager/actionmanager.h>
 #include <coreplugin/actionmanager/command.h>
@@ -60,9 +61,11 @@ QTextEdit::ExtraSelection createExtraSelections(const QTextCharFormat &mainforma
 int positionInText(QTextDocument *textDocument,
                    const ClangBackEnd::SourceLocationContainer &sourceLocationContainer)
 {
-    auto textBlock = textDocument->findBlockByNumber(int(sourceLocationContainer.line()) - 1);
-
-    return textBlock.position() + int(sourceLocationContainer.column()) - 1;
+    auto textBlock = textDocument->findBlockByNumber(
+                static_cast<int>(sourceLocationContainer.line()) - 1);
+    int column = static_cast<int>(sourceLocationContainer.column()) - 1;
+    column -= ClangCodeModel::Utils::extraUtf8CharsShift(textBlock.text(), column);
+    return textBlock.position() + column;
 }
 
 void addRangeSelections(const ClangBackEnd::DiagnosticContainer &diagnostic,

src/plugins/clangcodemodel/clangutils.cpp

@@ -169,5 +169,29 @@ void setLastSentDocumentRevision(const QString &filePath, uint revision)
         document->sendTracker().setLastSentRevision(int(revision));
 }
 
+int extraUtf8CharsShift(const QString &str, int column)
+{
+    int shift = 0;
+    const QByteArray byteArray = str.toUtf8();
+    for (int i = 0; i < qMin(str.length(), column); ++i) {
+        const uchar firstByte = static_cast<uchar>(byteArray.at(i));
+        // Skip different amount of bytes depending on value
+        if (firstByte < 0xC0) {
+            continue;
+        } else if (firstByte < 0xE0) {
+            ++shift;
+            ++i;
+        } else if (firstByte < 0xF0) {
+            shift += 2;
+            i += 2;
+        } else {
+            shift += 3;
+            i += 3;
+        }
+    }
+    return shift;
+}
+
+
 } // namespace Utils
 } // namespace Clang

src/plugins/clangcodemodel/clangutils.h

@@ -47,5 +47,7 @@ CppTools::ProjectPart::Ptr projectPartForFileBasedOnProcessor(const QString &fil
 bool isProjectPartLoaded(const CppTools::ProjectPart::Ptr projectPart);
 QString projectPartIdForFile(const QString &filePath);
 
+int extraUtf8CharsShift(const QString &str, int column);
+
 } // namespace Utils
 } // namespace Clang