ui: improve help message for cxx "source file extensions" in project settings (#1039)

src/lib_gui/qt/project_wizard/content/QtProjectWizardContentExtensions.cpp

@@ -1,10 +1,18 @@
 #include "QtProjectWizardContentExtensions.h"
 
+#include "language_packages.h"
+
 #include <QFormLayout>
 
 #include "QtStringListBox.h"
 #include "SourceGroupSettingsWithSourceExtensions.h"
 
+#if BUILD_CXX_LANGUAGE_PACKAGE
+#	include "SourceGroupSettingsWithSourceExtensionsC.h"
+#	include "SourceGroupSettingsWithSourceExtensionsCpp.h"
+#	include "SourceGroupSettingsWithSourceExtensionsCxx.h"
+#endif
+
 QtProjectWizardContentExtensions::QtProjectWizardContentExtensions(
 	std::shared_ptr<SourceGroupSettingsWithSourceExtensions> settings, QtProjectWizardWindow* window)
 	: QtProjectWizardContent(window), m_settings(settings)
@@ -16,9 +24,23 @@ void QtProjectWizardContentExtensions::populate(QGridLayout* layout, int& row)
 	QLabel* sourceLabel = createFormLabel(QStringLiteral("Source File Extensions"));
 	layout->addWidget(sourceLabel, row, QtProjectWizardWindow::FRONT_COL, Qt::AlignTop);
 
+	QString cxxAddition("");
+#if BUILD_CXX_LANGUAGE_PACKAGE
+	if (std::dynamic_pointer_cast<SourceGroupSettingsWithSourceExtensionsC>(m_settings) ||
+		std::dynamic_pointer_cast<SourceGroupSettingsWithSourceExtensionsCpp>(m_settings) ||
+		std::dynamic_pointer_cast<SourceGroupSettingsWithSourceExtensionsCxx>(m_settings))
+	{
+		cxxAddition = QStringLiteral(
+			" Files with these extensions will serve as entry points for the indexer. Headers that "
+			"are included by these files will be traversed on the fly.");
+	}
+#endif
+
 	addHelpButton(
 		QStringLiteral("Source File Extensions"),
-		QStringLiteral("Define extensions for source files including the dot (e.g. .cpp or .java)"),
+		QStringLiteral(
+			"Define extensions for source files including the dot (e.g. \".cpp\" or \".java\").") +
+			cxxAddition,
 		layout,
 		row);