Clang: Show info bar for parse errors in header files

...because those errors can lead to a substantial performance/functional
regression.

The actual diagnostics (possibly with children) are shown as details in
the info bar.

The info bar can be hidden with the "Do Not Show Again" button.
Re-enabling the info bar is possible with the new editor tool bar
button.

Change-Id: I03394ff8e3c84127946b0b791930b28a385f5a46
Reviewed-by: David Schulz <david.schulz@qt.io>

13 files changed, 199 insertions, 29 deletions

diff --git a/src/plugins/clangcodemodel/clangbackendipcintegration.cpp b/src/plugins/clangcodemodel/clangbackendipcintegration.cpp
index 1edce8fbd4..831a3bdea6 100644
--- a/src/plugins/clangcodemodel/clangbackendipcintegration.cpp
+++ b/src/plugins/clangcodemodel/clangbackendipcintegration.cpp
@@ -182,7 +182,9 @@ void IpcReceiver::documentAnnotationsChanged(const DocumentAnnotationsChangedMes
         const QString documentProjectPartId = CppTools::CppToolsBridge::projectPartIdForFile(filePath);
         if (projectPartId == documentProjectPartId) {
             const quint32 documentRevision = message.fileContainer().documentRevision();
-            processor->updateCodeWarnings(message.diagnostics(), documentRevision);
+            processor->updateCodeWarnings(message.diagnostics(),
+                                          message.firstHeaderErrorDiagnostic(),
+                                          documentRevision);
             processor->updateHighlighting(message.highlightingMarks(),
                                           message.skippedPreprocessorRanges(),
                                           documentRevision);
diff --git a/src/plugins/clangcodemodel/clangdiagnosticmanager.cpp b/src/plugins/clangcodemodel/clangdiagnosticmanager.cpp
index 2bfa7baac7..52c441443d 100644
--- a/src/plugins/clangcodemodel/clangdiagnosticmanager.cpp
+++ b/src/plugins/clangcodemodel/clangdiagnosticmanager.cpp
@@ -41,6 +41,7 @@
 #include <utils/proxyaction.h>
 #include <utils/qtcassert.h>
 
+#include <QFileInfo>
 #include <QTextBlock>
 
 namespace  {
diff --git a/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp b/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp
index 52c097f305..5b6c48c953 100644
--- a/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp
+++ b/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.cpp
@@ -129,9 +129,10 @@ enum IndentType { IndentDiagnostic, DoNotIndentDiagnostic };
 
 QWidget *createDiagnosticLabel(const ClangBackEnd::DiagnosticContainer &diagnostic,
                                const QString &mainFilePath,
-                               IndentType indentType = DoNotIndentDiagnostic)
+                               IndentType indentType = DoNotIndentDiagnostic,
+                               bool enableClickableFixits = true)
 {
-    const bool hasFixit = !diagnostic.fixIts().isEmpty();
+    const bool hasFixit = enableClickableFixits ? !diagnostic.fixIts().isEmpty() : false;
     const QString diagnosticText = diagnostic.text().toString().toHtmlEscaped();
     const QString text = clickableLocation(mainFilePath, diagnostic.location())
                        + QStringLiteral(": ")
@@ -159,25 +160,35 @@ class MainDiagnosticWidget : public QWidget
 {
     Q_OBJECT
 public:
-    MainDiagnosticWidget(const ClangBackEnd::DiagnosticContainer &diagnostic)
+    MainDiagnosticWidget(const ClangBackEnd::DiagnosticContainer &diagnostic,
+                         const ClangCodeModel::Internal::DisplayHints &displayHints)
     {
         setContentsMargins(0, 0, 0, 0);
         auto *mainLayout = createLayout<QVBoxLayout>();
 
-        // Set up header row: category + responsible option
-        const QString category = diagnostic.category();
-        const QString responsibleOption = diagnostic.enableOption();
         const ClangBackEnd::SourceLocationContainer location = diagnostic.location();
 
-        auto *headerLayout = createLayout<QHBoxLayout>();
-        headerLayout->addWidget(new QLabel(wrapInBoldTags(category)), 1);
+        // Set up header row: category + responsible option
+        if (displayHints.showMainDiagnosticHeader) {
+            const QString category = diagnostic.category();
+            const QString responsibleOption = diagnostic.enableOption();
+
+            auto *headerLayout = createLayout<QHBoxLayout>();
+            headerLayout->addWidget(new QLabel(wrapInBoldTags(category)), 1);
 
-        auto *responsibleOptionLabel = new QLabel(wrapInColor(responsibleOption, "gray"));
-        headerLayout->addWidget(responsibleOptionLabel, 0);
-        mainLayout->addLayout(headerLayout);
+            auto *responsibleOptionLabel = new QLabel(wrapInColor(responsibleOption, "gray"));
+            headerLayout->addWidget(responsibleOptionLabel, 0);
+            mainLayout->addLayout(headerLayout);
+        }
 
         // Set up main row: diagnostic text
-        mainLayout->addWidget(createDiagnosticLabel(diagnostic, location.filePath()));
+        const Utf8String mainFilePath = displayHints.showFileNameInMainDiagnostic
+                ? Utf8String()
+                : location.filePath();
+        mainLayout->addWidget(createDiagnosticLabel(diagnostic,
+                                                    mainFilePath,
+                                                    DoNotIndentDiagnostic,
+                                                    displayHints.enableClickableFixits));
 
         setLayout(mainLayout);
     }
@@ -186,26 +197,35 @@ public:
 void addChildrenToLayout(const QString &mainFilePath,
                          const QVector<ClangBackEnd::DiagnosticContainer>::const_iterator first,
                          const QVector<ClangBackEnd::DiagnosticContainer>::const_iterator last,
+                         bool enableClickableFixits,
                          QLayout &boxLayout)
 {
-    for (auto it = first; it != last; ++it)
-        boxLayout.addWidget(createDiagnosticLabel(*it, mainFilePath, IndentDiagnostic));
+    for (auto it = first; it != last; ++it) {
+        boxLayout.addWidget(createDiagnosticLabel(*it,
+                                                  mainFilePath,
+                                                  IndentDiagnostic,
+                                                  enableClickableFixits));
+    }
 }
 
 void setupChildDiagnostics(const QString &mainFilePath,
                            const QVector<ClangBackEnd::DiagnosticContainer> &diagnostics,
+                           bool enableClickableFixits,
                            QLayout &boxLayout)
 {
     if (diagnostics.size() <= 10) {
-        addChildrenToLayout(mainFilePath, diagnostics.begin(), diagnostics.end(), boxLayout);
+        addChildrenToLayout(mainFilePath, diagnostics.begin(), diagnostics.end(),
+                            enableClickableFixits, boxLayout);
     } else {
-        addChildrenToLayout(mainFilePath, diagnostics.begin(), diagnostics.begin() + 7, boxLayout);
+        addChildrenToLayout(mainFilePath, diagnostics.begin(), diagnostics.begin() + 7,
+                            enableClickableFixits, boxLayout);
 
         auto ellipsisLabel = new QLabel(QStringLiteral("..."));
         ellipsisLabel->setContentsMargins(childIndentationOnTheLeftInPixel, 0, 0, 0);
         boxLayout.addWidget(ellipsisLabel);
 
-        addChildrenToLayout(mainFilePath, diagnostics.end() - 3, diagnostics.end(), boxLayout);
+        addChildrenToLayout(mainFilePath, diagnostics.end() - 3, diagnostics.end(),
+                            enableClickableFixits, boxLayout);
     }
 }
 
@@ -214,13 +234,18 @@ void setupChildDiagnostics(const QString &mainFilePath,
 namespace ClangCodeModel {
 namespace Internal {
 
-void addToolTipToLayout(const ClangBackEnd::DiagnosticContainer &diagnostic, QLayout *target)
+void addToolTipToLayout(const ClangBackEnd::DiagnosticContainer &diagnostic,
+                        QLayout *target,
+                        const DisplayHints &displayHints)
 {
     // Set up header and text row for main diagnostic
-    target->addWidget(new MainDiagnosticWidget(diagnostic));
+    target->addWidget(new MainDiagnosticWidget(diagnostic, displayHints));
 
     // Set up child rows for notes
-    setupChildDiagnostics(diagnostic.location().filePath(), diagnostic.children(), *target);
+    setupChildDiagnostics(diagnostic.location().filePath(),
+                          diagnostic.children(),
+                          displayHints.enableClickableFixits,
+                          *target);
 }
 
 } // namespace Internal
diff --git a/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.h b/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.h
index 600ccf22d8..839952fc77 100644
--- a/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.h
+++ b/src/plugins/clangcodemodel/clangdiagnostictooltipwidget.h
@@ -34,7 +34,15 @@ QT_END_NAMESPACE
 namespace ClangCodeModel {
 namespace Internal {
 
-void addToolTipToLayout(const ClangBackEnd::DiagnosticContainer &diagnostic, QLayout *target);
+struct DisplayHints {
+    bool showMainDiagnosticHeader = true;
+    bool showFileNameInMainDiagnostic = false;
+    bool enableClickableFixits = true;
+};
+
+void addToolTipToLayout(const ClangBackEnd::DiagnosticContainer &diagnostic,
+                        QLayout *target,
+                        const DisplayHints &displayHints = DisplayHints());
 
 } // namespace Internal
 } // namespace ClangCodeModel
diff --git a/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp b/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp
index 99c6a67033..09a7b76b6f 100644
--- a/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp
+++ b/src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp
@@ -57,6 +57,8 @@
 #include <utils/runextensions.h>
 
 #include <QTextBlock>
+#include <QVBoxLayout>
+#include <QWidget>
 
 namespace ClangCodeModel {
 namespace Internal {
@@ -167,14 +169,21 @@ void ClangEditorDocumentProcessor::clearProjectPart()
     m_projectPart.clear();
 }
 
-void ClangEditorDocumentProcessor::updateCodeWarnings(const QVector<ClangBackEnd::DiagnosticContainer> &diagnostics,
-                                                      uint documentRevision)
+void ClangEditorDocumentProcessor::updateCodeWarnings(
+        const QVector<ClangBackEnd::DiagnosticContainer> &diagnostics,
+        const ClangBackEnd::DiagnosticContainer &firstHeaderErrorDiagnostic,
+        uint documentRevision)
 {
     if (documentRevision == revision()) {
         m_diagnosticManager.processNewDiagnostics(diagnostics);
         const auto codeWarnings = m_diagnosticManager.takeExtraSelections();
         const auto fixitAvailableMarkers = m_diagnosticManager.takeFixItAvailableMarkers();
-        emit codeWarningsUpdated(revision(), codeWarnings, fixitAvailableMarkers);
+        const auto creator = creatorForHeaderErrorDiagnosticWidget(firstHeaderErrorDiagnostic);
+
+        emit codeWarningsUpdated(revision(),
+                                 codeWarnings,
+                                 creator,
+                                 fixitAvailableMarkers);
     }
 }
 namespace {
@@ -333,6 +342,38 @@ void ClangEditorDocumentProcessor::requestDocumentAnnotations(const QString &pro
     m_ipcCommunicator.requestDocumentAnnotations(fileContainer);
 }
 
+static Internal::DisplayHints displayHintsForInfoBar()
+{
+    Internal::DisplayHints displayHints;
+    displayHints.showMainDiagnosticHeader = false;
+    displayHints.showFileNameInMainDiagnostic = true;
+    displayHints.enableClickableFixits = false; // Tool chain headers might be changed, so disable.
+
+    return displayHints;
+}
+
+CppTools::BaseEditorDocumentProcessor::HeaderErrorDiagnosticWidgetCreator
+ClangEditorDocumentProcessor::creatorForHeaderErrorDiagnosticWidget(
+        const ClangBackEnd::DiagnosticContainer &firstHeaderErrorDiagnostic)
+{
+    if (firstHeaderErrorDiagnostic.text().isEmpty())
+        return CppTools::BaseEditorDocumentProcessor::HeaderErrorDiagnosticWidgetCreator();
+
+    return [firstHeaderErrorDiagnostic]() {
+        auto vbox = new QVBoxLayout;
+        vbox->setMargin(0);
+        vbox->setContentsMargins(10, 0, 0, 2);
+        vbox->setSpacing(2);
+
+        addToolTipToLayout(firstHeaderErrorDiagnostic, vbox, displayHintsForInfoBar());
+
+        auto widget = new QWidget;
+        widget->setLayout(vbox);
+
+        return widget;
+    };
+}
+
 static CppTools::ProjectPart projectPartForLanguageOption(CppTools::ProjectPart *projectPart)
 {
     if (projectPart)
diff --git a/src/plugins/clangcodemodel/clangeditordocumentprocessor.h b/src/plugins/clangcodemodel/clangeditordocumentprocessor.h
index a23d93d72f..10355e349d 100644
--- a/src/plugins/clangcodemodel/clangeditordocumentprocessor.h
+++ b/src/plugins/clangcodemodel/clangeditordocumentprocessor.h
@@ -68,6 +68,7 @@ public:
     void clearProjectPart();
 
     void updateCodeWarnings(const QVector<ClangBackEnd::DiagnosticContainer> &diagnostics,
+                            const ClangBackEnd::DiagnosticContainer &firstHeaderErrorDiagnostic,
                             uint documentRevision);
     void updateHighlighting(const QVector<ClangBackEnd::HighlightingMarkContainer> &highlightingMarks,
                             const QVector<ClangBackEnd::SourceRangeContainer> &skippedPreprocessorRanges,
@@ -96,6 +97,8 @@ private:
     void registerTranslationUnitForEditor(CppTools::ProjectPart *projectPart);
     void updateTranslationUnitIfProjectPartExists();
     void requestDocumentAnnotations(const QString &projectpartId);
+    HeaderErrorDiagnosticWidgetCreator creatorForHeaderErrorDiagnosticWidget(
+            const ClangBackEnd::DiagnosticContainer &firstHeaderErrorDiagnostic);
     ClangBackEnd::FileContainer fileContainerWithArguments(CppTools::ProjectPart *projectPart) const;
     ClangBackEnd::FileContainer fileContainerWithDocumentContent(const QString &projectpartId) const;
 
diff --git a/src/plugins/clangcodemodel/clangtextmark.cpp b/src/plugins/clangcodemodel/clangtextmark.cpp
index 137787daa6..8057d66cb6 100644
--- a/src/plugins/clangcodemodel/clangtextmark.cpp
+++ b/src/plugins/clangcodemodel/clangtextmark.cpp
@@ -84,7 +84,7 @@ void ClangTextMark::setIcon(ClangBackEnd::DiagnosticSeverity severity)
 
 bool ClangTextMark::addToolTipContent(QLayout *target)
 {
-    Internal::addToolTipToLayout(m_diagnostic, target);
+    Internal::addToolTipToLayout(m_diagnostic, target, Internal::DisplayHints());
     return true;
 }
 
diff --git a/src/plugins/cppeditor/cppeditor.cpp b/src/plugins/cppeditor/cppeditor.cpp
index c26a8b25f1..0492635d1a 100644
--- a/src/plugins/cppeditor/cppeditor.cpp
+++ b/src/plugins/cppeditor/cppeditor.cpp
@@ -44,6 +44,7 @@
 #include <coreplugin/actionmanager/actionmanager.h>
 #include <coreplugin/editormanager/editormanager.h>
 #include <coreplugin/editormanager/documentmodel.h>
+#include <coreplugin/infobar.h>
 
 #include <cpptools/cppchecksymbols.h>
 #include <cpptools/cppcodeformatter.h>
@@ -77,6 +78,7 @@
 #include <cplusplus/FastPreprocessor.h>
 #include <cplusplus/MatchingText.h>
 #include <utils/qtcassert.h>
+#include <utils/utilsicons.h>
 
 #include <QApplication>
 #include <QAction>
@@ -126,9 +128,13 @@ public:
     QSharedPointer<FunctionDeclDefLink> m_declDefLink;
 
     QScopedPointer<FollowSymbolUnderCursor> m_followSymbolUnderCursor;
-    QToolButton *m_preprocessorButton;
+
+    QToolButton *m_preprocessorButton = nullptr;
+    QToolButton *m_headerErrorsIndicatorButton = nullptr;
 
     CppSelectionChanger m_cppSelectionChanger;
+
+    CppEditorWidget::HeaderErrorDiagnosticWidgetCreator m_headerErrorDiagnosticWidgetCreator;
 };
 
 CppEditorWidgetPrivate::CppEditorWidgetPrivate(CppEditorWidget *q)
@@ -139,7 +145,6 @@ CppEditorWidgetPrivate::CppEditorWidgetPrivate(CppEditorWidget *q)
     , m_useSelectionsUpdater(q)
     , m_declDefLinkFinder(new FunctionDeclDefLinkFinder(q))
     , m_followSymbolUnderCursor(new FollowSymbolUnderCursor(q))
-    , m_preprocessorButton(0)
     , m_cppSelectionChanger()
 {
 }
@@ -224,7 +229,15 @@ void CppEditorWidget::finalizeInitialization()
     connect(cmd, &Command::keySequenceChanged, this, &CppEditorWidget::updatePreprocessorButtonTooltip);
     updatePreprocessorButtonTooltip();
     connect(d->m_preprocessorButton, &QAbstractButton::clicked, this, &CppEditorWidget::showPreProcessorWidget);
+
+    d->m_headerErrorsIndicatorButton = new QToolButton(this);
+    d->m_headerErrorsIndicatorButton->setIcon(Utils::Icons::WARNING_TOOLBAR.pixmap());
+    connect(d->m_headerErrorsIndicatorButton, &QAbstractButton::clicked,
+            this, &CppEditorWidget::showHeaderErrorInfoBar);
+    d->m_headerErrorsIndicatorButton->setEnabled(false);
+
     insertExtraToolBarWidget(TextEditorWidget::Left, d->m_preprocessorButton);
+    insertExtraToolBarWidget(TextEditorWidget::Left, d->m_headerErrorsIndicatorButton);
     insertExtraToolBarWidget(TextEditorWidget::Left, d->m_cppEditorOutline->widget());
 }
 
@@ -287,6 +300,7 @@ void CppEditorWidget::onCppDocumentUpdated()
 
 void CppEditorWidget::onCodeWarningsUpdated(unsigned revision,
                                             const QList<QTextEdit::ExtraSelection> selections,
+                                            const HeaderErrorDiagnosticWidgetCreator &creator,
                                             const TextEditor::RefactorMarkers &refactorMarkers)
 {
     if (revision != documentRevision())
@@ -294,6 +308,9 @@ void CppEditorWidget::onCodeWarningsUpdated(unsigned revision,
 
     setExtraSelections(TextEditorWidget::CodeWarningsSelection, selections);
     setRefactorMarkers(refactorMarkersWithoutClangMarkers() + refactorMarkers);
+
+    d->m_headerErrorDiagnosticWidgetCreator = creator;
+    updateHeaderErrorWidgets();
 }
 
 void CppEditorWidget::onIfdefedOutBlocksUpdated(unsigned revision,
@@ -304,6 +321,24 @@ void CppEditorWidget::onIfdefedOutBlocksUpdated(unsigned revision,
     setIfdefedOutBlocks(ifdefedOutBlocks);
 }
 
+void CppEditorWidget::updateHeaderErrorWidgets()
+{
+    const Id id(Constants::ERRORS_IN_HEADER_FILES);
+    InfoBar *infoBar = textDocument()->infoBar();
+
+    infoBar->removeInfo(id);
+
+    if (d->m_headerErrorDiagnosticWidgetCreator) {
+        if (infoBar->canInfoBeAdded(id)) {
+            addHeaderErrorInfoBarEntryAndHideIndicator();
+        } else {
+            d->m_headerErrorsIndicatorButton->setEnabled(true);
+        }
+    } else {
+        d->m_headerErrorsIndicatorButton->setEnabled(false);
+    }
+}
+
 void CppEditorWidget::findUsages()
 {
     if (!d->m_modelManager)
@@ -399,6 +434,25 @@ void CppEditorWidget::renameSymbolUnderCursorBuiltin()
         renameUsages(); // Rename non-local symbol or macro
 }
 
+void CppEditorWidget::addHeaderErrorInfoBarEntryAndHideIndicator() const
+{
+    InfoBarEntry info(Constants::ERRORS_IN_HEADER_FILES,
+                      tr("<b>Warning</b>: The code model could not parse an included file, "
+                         "which might lead to slow or incorrect code completion and "
+                         "highlighting, for example."),
+                      InfoBarEntry::GlobalSuppressionEnabled);
+    info.setDetailsWidgetCreator(d->m_headerErrorDiagnosticWidgetCreator);
+    info.setShowDefaultCancelButton(false);
+    info.setSuppressionButtonInfo([this](){
+        d->m_headerErrorsIndicatorButton->setEnabled(true);
+    });
+
+    InfoBar *infoBar = textDocument()->infoBar();
+    infoBar->addInfo(info);
+
+    d->m_headerErrorsIndicatorButton->setEnabled(false);
+}
+
 namespace {
 
 QList<ProjectPart::Ptr> fetchProjectParts(CppTools::CppModelManager *modelManager,
@@ -970,5 +1024,14 @@ void CppEditorWidget::showPreProcessorWidget()
     }
 }
 
+void CppEditorWidget::showHeaderErrorInfoBar()
+{
+    const Id id(Constants::ERRORS_IN_HEADER_FILES);
+    QTC_CHECK(!textDocument()->infoBar()->canInfoBeAdded(id));
+
+    InfoBar::globallyUnsuppressInfo(id);
+    addHeaderErrorInfoBarEntryAndHideIndicator();
+}
+
 } // namespace Internal
 } // namespace CppEditor
diff --git a/src/plugins/cppeditor/cppeditor.h b/src/plugins/cppeditor/cppeditor.h
index 7fb26e93c3..cce22cebcd 100644
--- a/src/plugins/cppeditor/cppeditor.h
+++ b/src/plugins/cppeditor/cppeditor.h
@@ -31,6 +31,10 @@
 
 #include <QScopedPointer>
 
+namespace Core {
+class InfoBarEntry;
+}
+
 namespace CppTools {
 class CppEditorOutline;
 class RefactoringEngineInterface;
@@ -87,6 +91,7 @@ public:
 
     void switchDeclarationDefinition(bool inNextSplit);
     void showPreProcessorWidget();
+    void showHeaderErrorInfoBar();
 
     void findUsages();
     void renameSymbolUnderCursor();
@@ -108,6 +113,9 @@ protected:
 
     void slotCodeStyleSettingsChanged(const QVariant &) override;
 
+public:
+    using HeaderErrorDiagnosticWidgetCreator = std::function<QWidget*()>;
+
 private:
     void updateFunctionDeclDefLink();
     void updateFunctionDeclDefLinkNow();
@@ -118,10 +126,12 @@ private:
 
     void onCodeWarningsUpdated(unsigned revision,
                                const QList<QTextEdit::ExtraSelection> selections,
+                               const HeaderErrorDiagnosticWidgetCreator &creator,
                                const TextEditor::RefactorMarkers &refactorMarkers);
     void onIfdefedOutBlocksUpdated(unsigned revision,
                                    const QList<TextEditor::BlockRange> ifdefedOutBlocks);
 
+    void updateHeaderErrorWidgets();
     void updateSemanticInfo(const CppTools::SemanticInfo &semanticInfo,
                             bool updateUseSelectionSynchronously = false);
     void updatePreprocessorButtonTooltip();
@@ -140,6 +150,8 @@ private:
     void renameSymbolUnderCursorClang();
     void renameSymbolUnderCursorBuiltin();
 
+    void addHeaderErrorInfoBarEntryAndHideIndicator() const;
+
     CppTools::ProjectPart *projectPart() const;
 
 private:
diff --git a/src/plugins/cppeditor/cppeditorconstants.h b/src/plugins/cppeditor/cppeditorconstants.h
index 1d72be7a7a..761822d101 100644
--- a/src/plugins/cppeditor/cppeditorconstants.h
+++ b/src/plugins/cppeditor/cppeditorconstants.h
@@ -36,6 +36,7 @@ const char OPEN_DECLARATION_DEFINITION_IN_NEXT_SPLIT[] = "CppEditor.OpenDeclarat
 const char RENAME_SYMBOL_UNDER_CURSOR[] = "CppEditor.RenameSymbolUnderCursor";
 const char FIND_USAGES[] = "CppEditor.FindUsages";
 const char OPEN_PREPROCESSOR_DIALOG[] = "CppEditor.OpenPreprocessorDialog";
+const char ERRORS_IN_HEADER_FILES[] = "CppEditor.ErrorsInHeaderFiles";
 const char M_REFACTORING_MENU_INSERTION_POINT[] = "CppEditor.RefactorGroup";
 const char UPDATE_CODEMODEL[] = "CppEditor.UpdateCodeModel";
 const char INSPECT_CPP_CODEMODEL[] = "CppEditor.InspectCppCodeModel";
diff --git a/src/plugins/cppeditor/cppeditordocument.h b/src/plugins/cppeditor/cppeditordocument.h
index 953e24de3e..985e9a41b6 100644
--- a/src/plugins/cppeditor/cppeditordocument.h
+++ b/src/plugins/cppeditor/cppeditordocument.h
@@ -59,9 +59,13 @@ public:
                                  const QByteArray &defines);
     void scheduleProcessDocument();
 
+public:
+    using HeaderErrorDiagnosticWidgetCreator = std::function<QWidget*()>;
+
 signals:
     void codeWarningsUpdated(unsigned contentsRevision,
                              const QList<QTextEdit::ExtraSelection> selections,
+                             const HeaderErrorDiagnosticWidgetCreator &creator,
                              const TextEditor::RefactorMarkers &refactorMarkers);
 
     void ifdefedOutBlocksUpdated(unsigned contentsRevision,
diff --git a/src/plugins/cpptools/baseeditordocumentprocessor.h b/src/plugins/cpptools/baseeditordocumentprocessor.h
index da6a20ca94..3ac8a3524d 100644
--- a/src/plugins/cpptools/baseeditordocumentprocessor.h
+++ b/src/plugins/cpptools/baseeditordocumentprocessor.h
@@ -37,6 +37,8 @@
 
 #include <QTextEdit>
 
+#include <functional>
+
 namespace TextEditor {
 class TextDocument;
 class QuickFixOperations;
@@ -69,10 +71,15 @@ public:
 
     virtual void editorDocumentTimerRestarted();
 
+public:
+    using HeaderErrorDiagnosticWidgetCreator = std::function<QWidget*()>;
+
 signals:
+
     // Signal interface to implement
     void codeWarningsUpdated(unsigned revision,
                              const QList<QTextEdit::ExtraSelection> selections,
+                             const HeaderErrorDiagnosticWidgetCreator &creator,
                              const TextEditor::RefactorMarkers &refactorMarkers);
 
     void ifdefedOutBlocksUpdated(unsigned revision,
diff --git a/src/plugins/cpptools/builtineditordocumentprocessor.cpp b/src/plugins/cpptools/builtineditordocumentprocessor.cpp
index a7a7ac1a33..284e1af8ae 100644
--- a/src/plugins/cpptools/builtineditordocumentprocessor.cpp
+++ b/src/plugins/cpptools/builtineditordocumentprocessor.cpp
@@ -310,7 +310,10 @@ void BuiltinEditorDocumentProcessor::onCodeWarningsUpdated(
 
     m_codeWarnings += toTextEditorSelections(codeWarnings, textDocument());
     m_codeWarningsUpdated = true;
-    emit codeWarningsUpdated(revision(), m_codeWarnings, TextEditor::RefactorMarkers());
+    emit codeWarningsUpdated(revision(),
+                             m_codeWarnings,
+                             HeaderErrorDiagnosticWidgetCreator(),
+                             TextEditor::RefactorMarkers());
 }
 
 SemanticInfo::Source BuiltinEditorDocumentProcessor::createSemanticInfoSource(bool force) const