Address a constexpr template point of instantiation issue

...that hits at least when building with Clang and --with-latest-c++ against
recent libc++ or MSVC standard library (where C++20 and esp. C++23 made more and
more class template member functions constexpr).  My understanding is that there
is some leeway at what point a compiler should instantiate such function
specializations, and Clang decides to instantiate constexpr ones early (cf.
<https://github.com/llvm/llvm-project/commit/242ad89a15d5466d166d47978bfff983d40ab511>
"C++11 half of r147023: In C++11, additionally eagerly instantiate:" and its "Do
not defer instantiations of constexpr functions" comment, and the discussion at
<https://discourse.llvm.org/t/point-of-instantiation-of-constexpr-function-template/65129>).

> In file included from vcl/source/app/salvtables.cxx:26:
> In file included from workdir/UnoApiHeadersTarget/offapi/normal/com/sun/star/awt/XWindow.hpp:6:
> In file included from workdir/UnoApiHeadersTarget/offapi/normal/com/sun/star/awt/XWindow.hdl:13:
> In file included from workdir/UnoApiHeadersTarget/udkapi/normal/com/sun/star/lang/XComponent.hdl:7:
> In file included from workdir/UnoApiHeadersTarget/udkapi/normal/com/sun/star/uno/XInterface.hdl:6:
> In file included from include/com/sun/star/uno/Any.h:30:
> In file included from include/rtl/ustring.hxx:34:
> In file included from ~/llvm/inst/bin/../include/c++/v1/ostream:168:
> ~/llvm/inst/bin/../include/c++/v1/__memory/unique_ptr.h:47:19: error: invalid application of 'sizeof' to an incomplete type 'SalFlashAttention'
>     static_assert(sizeof(_Tp) >= 0, "cannot delete an incomplete type");
>                   ^~~~~~~~~~~
> ~/llvm/inst/bin/../include/c++/v1/__memory/unique_ptr.h:281:7: note: in instantiation of member function 'std::default_delete<SalFlashAttention>::operator()' requested here
>       __ptr_.second()(__tmp);
>       ^
> ~/llvm/inst/bin/../include/c++/v1/__memory/unique_ptr.h:247:75: note: in instantiation of member function 'std::unique_ptr<SalFlashAttention>::reset' requested here
>   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX23 ~unique_ptr() { reset(); }
>                                                                           ^
> vcl/source/app/salvtables.cxx:292:20: note: in instantiation of member function 'std::unique_ptr<SalFlashAttention>::~unique_ptr' requested here
> SalInstanceWidget::SalInstanceWidget(vcl::Window* pWidget, SalInstanceBuilder* pBuilder,
>                    ^
> vcl/inc/salvtables.hxx:172:7: note: forward declaration of 'SalFlashAttention'
> class SalFlashAttention;
>       ^

Change-Id: I49523c8db5b3fdd4dc5614fdb5c6f8ced73f5eca
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/141821
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 67 insertions, 67 deletions

diff --git a/vcl/source/app/salvtables.cxx b/vcl/source/app/salvtables.cxx
index d4f9b41e329c..7af5cccb4e6b 100644
--- a/vcl/source/app/salvtables.cxx
+++ b/vcl/source/app/salvtables.cxx
@@ -241,6 +241,73 @@ void SalMenu::ApplyPersona() {}
 
 SalMenuItem::~SalMenuItem() {}
 
+class SalFlashAttention
+{
+private:
+    VclPtr<vcl::Window> m_xWidget;
+    Timer m_aFlashTimer;
+    Color m_aOrigControlBackground;
+    Wallpaper m_aOrigBackground;
+    bool m_bOrigControlBackground;
+    int m_nFlashCount;
+
+    void SetFlash()
+    {
+        Color aColor(Application::GetSettings().GetStyleSettings().GetHighlightColor());
+        m_xWidget->SetControlBackground(aColor);
+    }
+
+    void ClearFlash()
+    {
+        if (m_bOrigControlBackground)
+            m_xWidget->SetControlBackground(m_aOrigControlBackground);
+        else
+            m_xWidget->SetControlBackground();
+    }
+
+    void Flash()
+    {
+        constexpr int FlashesWanted = 1;
+
+        if (m_nFlashCount % 2 == 0)
+            ClearFlash();
+        else
+            SetFlash();
+
+        if (m_nFlashCount == FlashesWanted * 2)
+            return;
+
+        ++m_nFlashCount;
+
+        m_aFlashTimer.Start();
+    }
+
+    DECL_LINK(FlashTimeout, Timer*, void);
+
+public:
+    SalFlashAttention(VclPtr<vcl::Window> xWidget)
+        : m_xWidget(std::move(xWidget))
+        , m_aFlashTimer("SalFlashAttention")
+        , m_bOrigControlBackground(false)
+        , m_nFlashCount(1)
+    {
+        m_aFlashTimer.SetTimeout(150);
+        m_aFlashTimer.SetInvokeHandler(LINK(this, SalFlashAttention, FlashTimeout));
+    }
+
+    void Start()
+    {
+        m_bOrigControlBackground = m_xWidget->IsControlBackground();
+        if (m_bOrigControlBackground)
+            m_aOrigControlBackground = m_xWidget->GetControlBackground();
+        m_aFlashTimer.Start();
+    }
+
+    ~SalFlashAttention() { ClearFlash(); }
+};
+
+IMPL_LINK_NOARG(SalFlashAttention, FlashTimeout, Timer*, void) { Flash(); }
+
 void SalInstanceWidget::ensure_event_listener()
 {
     if (!m_bEventListener)
@@ -599,73 +666,6 @@ VclPtr<VirtualDevice> SalInstanceWidget::create_virtual_device() const
                                          DeviceFormat::DEFAULT);
 }
 
-class SalFlashAttention
-{
-private:
-    VclPtr<vcl::Window> m_xWidget;
-    Timer m_aFlashTimer;
-    Color m_aOrigControlBackground;
-    Wallpaper m_aOrigBackground;
-    bool m_bOrigControlBackground;
-    int m_nFlashCount;
-
-    void SetFlash()
-    {
-        Color aColor(Application::GetSettings().GetStyleSettings().GetHighlightColor());
-        m_xWidget->SetControlBackground(aColor);
-    }
-
-    void ClearFlash()
-    {
-        if (m_bOrigControlBackground)
-            m_xWidget->SetControlBackground(m_aOrigControlBackground);
-        else
-            m_xWidget->SetControlBackground();
-    }
-
-    void Flash()
-    {
-        constexpr int FlashesWanted = 1;
-
-        if (m_nFlashCount % 2 == 0)
-            ClearFlash();
-        else
-            SetFlash();
-
-        if (m_nFlashCount == FlashesWanted * 2)
-            return;
-
-        ++m_nFlashCount;
-
-        m_aFlashTimer.Start();
-    }
-
-    DECL_LINK(FlashTimeout, Timer*, void);
-
-public:
-    SalFlashAttention(VclPtr<vcl::Window> xWidget)
-        : m_xWidget(std::move(xWidget))
-        , m_aFlashTimer("SalFlashAttention")
-        , m_bOrigControlBackground(false)
-        , m_nFlashCount(1)
-    {
-        m_aFlashTimer.SetTimeout(150);
-        m_aFlashTimer.SetInvokeHandler(LINK(this, SalFlashAttention, FlashTimeout));
-    }
-
-    void Start()
-    {
-        m_bOrigControlBackground = m_xWidget->IsControlBackground();
-        if (m_bOrigControlBackground)
-            m_aOrigControlBackground = m_xWidget->GetControlBackground();
-        m_aFlashTimer.Start();
-    }
-
-    ~SalFlashAttention() { ClearFlash(); }
-};
-
-IMPL_LINK_NOARG(SalFlashAttention, FlashTimeout, Timer*, void) { Flash(); }
-
 void SalInstanceWidget::call_attention_to()
 {
     m_xFlashAttention.reset(new SalFlashAttention(m_xWidget));