diff --git a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
index db95be93d45..0f3ffd3efe8 100644
--- a/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
+++ b/src/plugins/clangcodemodel/clangmodelmanagersupport.cpp
@@ -616,18 +616,13 @@ void addFixItsActionsToMenu(QMenu *menu, const TextEditor::QuickFixOperations &f
     }
 }
 
-static int lineToPosition(const QTextDocument *textDocument, int lineNumber)
-{
-    QTC_ASSERT(textDocument, return 0);
-    const QTextBlock textBlock = textDocument->findBlockByLineNumber(lineNumber);
-    return textBlock.isValid() ? textBlock.position() - 1 : 0;
-}
-
 static TextEditor::AssistInterface createAssistInterface(TextEditor::TextEditorWidget *widget,
                                                          int lineNumber)
 {
-    return TextEditor::AssistInterface(widget->document(),
-                                       lineToPosition(widget->document(), lineNumber),
+    QTextCursor cursor(widget->document()->findBlockByLineNumber(lineNumber));
+    if (!cursor.atStart())
+        cursor.movePosition(QTextCursor::PreviousCharacter);
+    return TextEditor::AssistInterface(cursor,
                                        widget->textDocument()->filePath(),
                                        TextEditor::IdleEditor);
 }
diff --git a/src/plugins/cppeditor/cppcompletion_test.cpp b/src/plugins/cppeditor/cppcompletion_test.cpp
index 683056f6b3e..d03c4b8390f 100644
--- a/src/plugins/cppeditor/cppcompletion_test.cpp
+++ b/src/plugins/cppeditor/cppcompletion_test.cpp
@@ -105,9 +105,12 @@ public:
         QStringList completions;
         LanguageFeatures languageFeatures = LanguageFeatures::defaultFeatures();
         languageFeatures.objCEnabled = false;
+        QTextCursor textCursor = m_editorWidget->textCursor();
+        textCursor.setPosition(m_position);
+        m_editorWidget->setTextCursor(textCursor);
         CppCompletionAssistInterface *ai
             = new CppCompletionAssistInterface(m_editorWidget->textDocument()->filePath(),
-                                               m_textDocument, m_position,
+                                               m_editorWidget,
                                                ExplicitlyInvoked, m_snapshot,
                                                ProjectExplorer::HeaderPaths(),
                                                languageFeatures);
diff --git a/src/plugins/cppeditor/cppcompletionassist.cpp b/src/plugins/cppeditor/cppcompletionassist.cpp
index 19fbab8972f..5ce93504483 100644
--- a/src/plugins/cppeditor/cppcompletionassist.cpp
+++ b/src/plugins/cppeditor/cppcompletionassist.cpp
@@ -426,7 +426,6 @@ AssistInterface *InternalCompletionAssistProvider::createAssistInterface(
     const Utils::FilePath &filePath,
     const TextEditorWidget *textEditorWidget,
     const LanguageFeatures &languageFeatures,
-    int position,
     AssistReason reason) const
 {
     QTC_ASSERT(textEditorWidget, return nullptr);
@@ -435,7 +434,6 @@ AssistInterface *InternalCompletionAssistProvider::createAssistInterface(
                                             textEditorWidget,
                                             BuiltinEditorDocumentParser::get(filePath.toString()),
                                             languageFeatures,
-                                            position,
                                             reason,
                                             CppModelManager::instance()->workingCopy());
 }
diff --git a/src/plugins/cppeditor/cppcompletionassist.h b/src/plugins/cppeditor/cppcompletionassist.h
index 1d477cff792..adcdcaa798a 100644
--- a/src/plugins/cppeditor/cppcompletionassist.h
+++ b/src/plugins/cppeditor/cppcompletionassist.h
@@ -87,7 +87,6 @@ public:
         const Utils::FilePath &filePath,
         const TextEditor::TextEditorWidget *textEditorWidget,
         const CPlusPlus::LanguageFeatures &languageFeatures,
-        int position,
         TextEditor::AssistReason reason) const override;
 };
 
@@ -168,10 +167,9 @@ public:
                                  const TextEditor::TextEditorWidget *textEditorWidget,
                                  BuiltinEditorDocumentParser::Ptr parser,
                                  const CPlusPlus::LanguageFeatures &languageFeatures,
-                                 int position,
                                  TextEditor::AssistReason reason,
                                  const WorkingCopy &workingCopy)
-        : TextEditor::AssistInterface(textEditorWidget->document(), position, filePath, reason)
+        : TextEditor::AssistInterface(textEditorWidget->textCursor(), filePath, reason)
         , m_parser(parser)
         , m_gotCppSpecifics(false)
         , m_workingCopy(workingCopy)
@@ -179,13 +177,12 @@ public:
     {}
 
     CppCompletionAssistInterface(const Utils::FilePath &filePath,
-                                 QTextDocument *textDocument,
-                                 int position,
+                                 const TextEditor::TextEditorWidget *textEditorWidget,
                                  TextEditor::AssistReason reason,
                                  const CPlusPlus::Snapshot &snapshot,
                                  const ProjectExplorer::HeaderPaths &headerPaths,
                                  const CPlusPlus::LanguageFeatures &features)
-        : TextEditor::AssistInterface(textDocument, position, filePath, reason)
+        : TextEditor::AssistInterface(textEditorWidget->textCursor(), filePath, reason)
         , m_gotCppSpecifics(true)
         , m_snapshot(snapshot)
         , m_headerPaths(headerPaths)
diff --git a/src/plugins/cppeditor/cppcompletionassistprovider.h b/src/plugins/cppeditor/cppcompletionassistprovider.h
index eb9410973a2..bd851b0d02c 100644
--- a/src/plugins/cppeditor/cppcompletionassistprovider.h
+++ b/src/plugins/cppeditor/cppcompletionassistprovider.h
@@ -59,7 +59,6 @@ public:
         const Utils::FilePath &filePath,
         const TextEditor::TextEditorWidget *textEditorWidget,
         const CPlusPlus::LanguageFeatures &languageFeatures,
-        int position,
         TextEditor::AssistReason reason) const = 0;
 
     static int activationSequenceChar(const QChar &ch, const QChar &ch2,
diff --git a/src/plugins/cppeditor/cppeditorwidget.cpp b/src/plugins/cppeditor/cppeditorwidget.cpp
index 62da35451aa..7c00340fd5c 100644
--- a/src/plugins/cppeditor/cppeditorwidget.cpp
+++ b/src/plugins/cppeditor/cppeditorwidget.cpp
@@ -1312,7 +1312,6 @@ AssistInterface *CppEditorWidget::createAssistInterface(AssistKind kind, AssistR
             return cap->createAssistInterface(textDocument()->filePath(),
                                               this,
                                               features,
-                                              position(),
                                               reason);
         } else {
             return TextEditorWidget::createAssistInterface(kind, reason);
diff --git a/src/plugins/cppeditor/cppquickfixassistant.cpp b/src/plugins/cppeditor/cppquickfixassistant.cpp
index 9d5d2271a6c..5310ef7f7a7 100644
--- a/src/plugins/cppeditor/cppquickfixassistant.cpp
+++ b/src/plugins/cppeditor/cppquickfixassistant.cpp
@@ -74,10 +74,8 @@ IAssistProcessor *CppQuickFixAssistProvider::createProcessor(const AssistInterfa
 // --------------------------
 // CppQuickFixAssistInterface
 // --------------------------
-CppQuickFixInterface::CppQuickFixInterface(CppEditorWidget *editor,
-                                                       AssistReason reason)
-    : AssistInterface(editor->document(), editor->position(),
-                      editor->textDocument()->filePath(), reason)
+CppQuickFixInterface::CppQuickFixInterface(CppEditorWidget *editor, AssistReason reason)
+    : AssistInterface(editor->textCursor(), editor->textDocument()->filePath(), reason)
     , m_editor(editor)
     , m_semanticInfo(editor->semanticInfo())
     , m_snapshot(CppModelManager::instance()->snapshot())
diff --git a/src/plugins/glsleditor/glslcompletionassist.cpp b/src/plugins/glsleditor/glslcompletionassist.cpp
index 60ee6c8214a..853209f392d 100644
--- a/src/plugins/glsleditor/glslcompletionassist.cpp
+++ b/src/plugins/glsleditor/glslcompletionassist.cpp
@@ -545,13 +545,12 @@ bool GlslCompletionAssistProcessor::acceptsIdleEditor() const
 // -----------------------------
 // GlslCompletionAssistInterface
 // -----------------------------
-GlslCompletionAssistInterface::GlslCompletionAssistInterface(QTextDocument *textDocument,
-                                                             int position,
+GlslCompletionAssistInterface::GlslCompletionAssistInterface(const QTextCursor &cursor,
                                                              const Utils::FilePath &fileName,
                                                              AssistReason reason,
                                                              const QString &mimeType,
                                                              const Document::Ptr &glslDoc)
-    : AssistInterface(textDocument, position, fileName, reason)
+    : AssistInterface(cursor, fileName, reason)
     , m_mimeType(mimeType)
     , m_glslDoc(glslDoc)
 {
diff --git a/src/plugins/glsleditor/glslcompletionassist.h b/src/plugins/glsleditor/glslcompletionassist.h
index 596ddac25ff..c54ffe6e368 100644
--- a/src/plugins/glsleditor/glslcompletionassist.h
+++ b/src/plugins/glsleditor/glslcompletionassist.h
@@ -107,8 +107,7 @@ private:
 class GlslCompletionAssistInterface : public TextEditor::AssistInterface
 {
 public:
-    GlslCompletionAssistInterface(QTextDocument *textDocument,
-                                  int position, const Utils::FilePath &fileName,
+    GlslCompletionAssistInterface(const QTextCursor &cursor, const Utils::FilePath &fileName,
                                   TextEditor::AssistReason reason,
                                   const QString &mimeType,
                                   const Document::Ptr &glslDoc);
diff --git a/src/plugins/glsleditor/glsleditor.cpp b/src/plugins/glsleditor/glsleditor.cpp
index 1f76e997eb2..85d4c15ae7d 100644
--- a/src/plugins/glsleditor/glsleditor.cpp
+++ b/src/plugins/glsleditor/glsleditor.cpp
@@ -369,8 +369,7 @@ AssistInterface *GlslEditorWidget::createAssistInterface(
     AssistKind kind, AssistReason reason) const
 {
     if (kind == Completion)
-        return new GlslCompletionAssistInterface(document(),
-                                                 position(),
+        return new GlslCompletionAssistInterface(textCursor(),
                                                  textDocument()->filePath(),
                                                  reason,
                                                  textDocument()->mimeType(),
diff --git a/src/plugins/qmldesigner/components/bindingeditor/bindingeditorwidget.cpp b/src/plugins/qmldesigner/components/bindingeditor/bindingeditorwidget.cpp
index 5b9c54b4d41..6cf747e9d5d 100644
--- a/src/plugins/qmldesigner/components/bindingeditor/bindingeditorwidget.cpp
+++ b/src/plugins/qmldesigner/components/bindingeditor/bindingeditorwidget.cpp
@@ -103,7 +103,7 @@ TextEditor::AssistInterface *BindingEditorWidget::createAssistInterface(
 {
     Q_UNUSED(assistKind)
     return new QmlJSEditor::QmlJSCompletionAssistInterface(
-                document(), position(), Utils::FilePath(),
+                textCursor(), Utils::FilePath(),
                 assistReason, qmljsdocument->semanticInfo());
 }
 
diff --git a/src/plugins/qmljseditor/qmljscompletionassist.cpp b/src/plugins/qmljseditor/qmljscompletionassist.cpp
index 5fc1e3d7041..21c23274e2e 100644
--- a/src/plugins/qmljseditor/qmljscompletionassist.cpp
+++ b/src/plugins/qmljseditor/qmljscompletionassist.cpp
@@ -334,10 +334,11 @@ QStringList qmlJSAutoComplete(QTextDocument *textDocument,
 {
     QStringList list;
     QmlJSCompletionAssistProcessor processor;
+    QTextCursor cursor(textDocument);
+    cursor.setPosition(position);
     QScopedPointer<IAssistProposal> proposal(processor.perform( /* The processor takes ownership. */
                                                  new QmlJSCompletionAssistInterface(
-                                                     textDocument,
-                                                     position,
+                                                     cursor,
                                                      fileName,
                                                      reason,
                                                      info)));
@@ -978,12 +979,11 @@ bool QmlJSCompletionAssistProcessor::completeUrl(const QString &relativeBasePath
 // ------------------------------
 // QmlJSCompletionAssistInterface
 // ------------------------------
-QmlJSCompletionAssistInterface::QmlJSCompletionAssistInterface(QTextDocument *textDocument,
-                                                               int position,
+QmlJSCompletionAssistInterface::QmlJSCompletionAssistInterface(const QTextCursor &cursor,
                                                                const Utils::FilePath &fileName,
                                                                AssistReason reason,
                                                                const SemanticInfo &info)
-    : AssistInterface(textDocument, position, fileName, reason)
+    : AssistInterface(cursor, fileName, reason)
     , m_semanticInfo(info)
 {}
 
diff --git a/src/plugins/qmljseditor/qmljscompletionassist.h b/src/plugins/qmljseditor/qmljscompletionassist.h
index 4c8a5eb53db..e9f0218c28a 100644
--- a/src/plugins/qmljseditor/qmljscompletionassist.h
+++ b/src/plugins/qmljseditor/qmljscompletionassist.h
@@ -105,8 +105,7 @@ private:
 class QMLJSEDITOR_EXPORT QmlJSCompletionAssistInterface : public TextEditor::AssistInterface
 {
 public:
-    QmlJSCompletionAssistInterface(QTextDocument *textDocument,
-                                   int position,
+    QmlJSCompletionAssistInterface(const QTextCursor &cursor,
                                    const Utils::FilePath &fileName,
                                    TextEditor::AssistReason reason,
                                    const QmlJSTools::SemanticInfo &info);
diff --git a/src/plugins/qmljseditor/qmljseditor.cpp b/src/plugins/qmljseditor/qmljseditor.cpp
index 265b59ca1a7..32ff7895600 100644
--- a/src/plugins/qmljseditor/qmljseditor.cpp
+++ b/src/plugins/qmljseditor/qmljseditor.cpp
@@ -1021,11 +1021,8 @@ AssistInterface *QmlJSEditorWidget::createAssistInterface(
     AssistReason reason) const
 {
     if (assistKind == Completion) {
-        return new QmlJSCompletionAssistInterface(document(),
-                                                  position(),
-                                                  textDocument()->filePath(),
-                                                  reason,
-                                                  m_qmlJsEditorDocument->semanticInfo());
+        return new QmlJSCompletionAssistInterface(textCursor(), textDocument()->filePath(),
+                                                  reason, m_qmlJsEditorDocument->semanticInfo());
     } else if (assistKind == QuickFix) {
         return new Internal::QmlJSQuickFixAssistInterface(const_cast<QmlJSEditorWidget *>(this), reason);
     }
diff --git a/src/plugins/qmljseditor/qmljsquickfixassist.cpp b/src/plugins/qmljseditor/qmljsquickfixassist.cpp
index 15feed0cfd5..482bcc34aa8 100644
--- a/src/plugins/qmljseditor/qmljsquickfixassist.cpp
+++ b/src/plugins/qmljseditor/qmljsquickfixassist.cpp
@@ -48,8 +48,7 @@ using namespace Internal;
 // -----------------------
 QmlJSQuickFixAssistInterface::QmlJSQuickFixAssistInterface(QmlJSEditorWidget *editor,
                                                            AssistReason reason)
-    : AssistInterface(editor->document(), editor->position(),
-                      editor->textDocument()->filePath(), reason)
+    : AssistInterface(editor->textCursor(), editor->textDocument()->filePath(), reason)
     , m_semanticInfo(editor->qmlJsEditorDocument()->semanticInfo())
     , m_currentFile(QmlJSRefactoringChanges::file(editor, m_semanticInfo.document))
 {}
diff --git a/src/plugins/texteditor/codeassist/assistinterface.cpp b/src/plugins/texteditor/codeassist/assistinterface.cpp
index 0a25e1ff34f..43edc19196a 100644
--- a/src/plugins/texteditor/codeassist/assistinterface.cpp
+++ b/src/plugins/texteditor/codeassist/assistinterface.cpp
@@ -101,13 +101,14 @@ using namespace TextEditor;
 
 namespace TextEditor {
 
-AssistInterface::AssistInterface(QTextDocument *textDocument,
-                                               int position,
-                                               const Utils::FilePath &filePath,
-                                               AssistReason reason)
-    : m_textDocument(textDocument)
+AssistInterface::AssistInterface(const QTextCursor &cursor,
+                                 const Utils::FilePath &filePath,
+                                 AssistReason reason)
+    : m_textDocument(cursor.document())
+    , m_cursor(cursor)
     , m_isAsync(false)
-    , m_position(position)
+    , m_position(cursor.position())
+    , m_anchor(cursor.anchor())
     , m_filePath(filePath)
     , m_reason(reason)
 {}
@@ -141,6 +142,9 @@ void AssistInterface::prepareForAsyncUse()
 void AssistInterface::recreateTextDocument()
 {
     m_textDocument = new QTextDocument(m_text);
+    m_cursor = QTextCursor(m_textDocument);
+    m_cursor.setPosition(m_anchor);
+    m_cursor.setPosition(m_position, QTextCursor::KeepAnchor);
     m_text.clear();
 
     QTC_CHECK(m_textDocument->blockCount() == m_userStates.count());
diff --git a/src/plugins/texteditor/codeassist/assistinterface.h b/src/plugins/texteditor/codeassist/assistinterface.h
index 85a738309ad..abe1b396382 100644
--- a/src/plugins/texteditor/codeassist/assistinterface.h
+++ b/src/plugins/texteditor/codeassist/assistinterface.h
@@ -30,21 +30,17 @@
 #include <texteditor/texteditor_global.h>
 
 #include <QString>
+#include <QTextCursor>
 #include <QVector>
 
 #include <utils/fileutils.h>
 
-QT_BEGIN_NAMESPACE
-class QTextDocument;
-QT_END_NAMESPACE
-
 namespace TextEditor {
 
 class TEXTEDITOR_EXPORT AssistInterface
 {
 public:
-    AssistInterface(QTextDocument *textDocument,
-                    int position,
+    AssistInterface(const QTextCursor &cursor,
                     const Utils::FilePath &filePath,
                     AssistReason reason);
     virtual ~AssistInterface();
@@ -52,6 +48,7 @@ public:
     virtual int position() const { return m_position; }
     virtual QChar characterAt(int position) const;
     virtual QString textAt(int position, int length) const;
+    QTextCursor cursor() const { return m_cursor; }
     virtual Utils::FilePath filePath() const { return m_filePath; }
     virtual QTextDocument *textDocument() const { return m_textDocument; }
     virtual void prepareForAsyncUse();
@@ -60,8 +57,10 @@ public:
 
 private:
     QTextDocument *m_textDocument;
+    QTextCursor m_cursor;
     bool m_isAsync;
     int m_position;
+    int m_anchor;
     Utils::FilePath m_filePath;
     AssistReason m_reason;
     QString m_text;
diff --git a/src/plugins/texteditor/texteditor.cpp b/src/plugins/texteditor/texteditor.cpp
index 333f5f37aa5..d2eb9e43e3b 100644
--- a/src/plugins/texteditor/texteditor.cpp
+++ b/src/plugins/texteditor/texteditor.cpp
@@ -8169,10 +8169,10 @@ void TextEditorWidget::invokeAssist(AssistKind kind, IAssistProvider *provider)
 }
 
 AssistInterface *TextEditorWidget::createAssistInterface(AssistKind kind,
-                                                             AssistReason reason) const
+                                                         AssistReason reason) const
 {
     Q_UNUSED(kind)
-    return new AssistInterface(document(), position(), d->m_document->filePath(), reason);
+    return new AssistInterface(textCursor(), d->m_document->filePath(), reason);
 }
 
 QString TextEditorWidget::foldReplacementText(const QTextBlock &) const