[gtkmm/gtkmm-3-24] tests/builder: Default-init members at declaration

[Daniel Boles <dboles src gnome org>]

commit 5fc879cc6e608a0d31a70f672033450a99723df5
Author: Daniel Boles <dboles src gmail com>
Date:   Sun Nov 24 14:02:30 2019 +0000

    tests/builder: Default-init members at declaration
    
    as that is safer than having to remember to default-construct pointers
    in every constructor overload—& getting undefined behaviour if we don’t.

 tests/builder/main.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/tests/builder/main.cc b/tests/builder/main.cc
index 302562d4..3c35c952 100644
--- a/tests/builder/main.cc
+++ b/tests/builder/main.cc
@@ -114,7 +114,7 @@ class MainWindow : public Gtk::Window
 {
 public:
   MainWindow(BaseObjectType* cobject, const Glib::RefPtr<Gtk::Builder>& refBuilder)
-  : Gtk::Window(cobject), m_pDerivedButton(nullptr), m_pStandardButton(nullptr)
+  : Gtk::Window(cobject)
   {
     std::cout << "MainWindow::ctor" << std::endl;
 
@@ -136,8 +136,8 @@ public:
   const Gtk::Button* get_standard_button() const { return m_pStandardButton; }
 
 private:
-  DerivedButton* m_pDerivedButton;
-  Gtk::Button* m_pStandardButton;
+  DerivedButton* m_pDerivedButton = nullptr;
+  Gtk::Button* m_pStandardButton = nullptr;
 };
 
 } // end of anonymous namespace