Mark [Scoped]VclPtrInstance as SAL_WARN_UNUSED

Stack-allocated instances of the non-Instance [Scoped]VclPtr variants are
occasionally used merely for the side-effect of holding objects alive (like
css::uno::Reference and rtl::Reference, which are also not SAL_WARN_UNUSED for
that reason).

Change-Id: I37ebfaf028a646cb2777c0baf0d99992057a22bd

2 files changed, 34 insertions, 10 deletions

diff --git a/include/vcl/vclptr.hxx b/include/vcl/vclptr.hxx
index 31f97dc50602..39e4fe918d52 100644
--- a/include/vcl/vclptr.hxx
+++ b/include/vcl/vclptr.hxx
@@ -295,7 +295,7 @@ template<typename T> inline bool operator !=(T * p1, VclPtr<T> const & p2) {
  * @param reference_type must be a subclass of vcl::Window
  */
 template <class reference_type>
-class VclPtrInstance : public VclPtr<reference_type>
+class SAL_WARN_UNUSED VclPtrInstance : public VclPtr<reference_type>
 {
 public:
     template<typename... Arg> VclPtrInstance(Arg &&... arg)
@@ -407,7 +407,7 @@ protected:
 #pragma warning(disable: 4521) // " multiple copy constructors specified"
 #endif
 template <class reference_type>
-class ScopedVclPtrInstance : public ScopedVclPtr<reference_type>
+class SAL_WARN_UNUSED ScopedVclPtrInstance : public ScopedVclPtr<reference_type>
 {
 public:
     template<typename... Arg> ScopedVclPtrInstance(Arg &&... arg)
diff --git a/vcl/qa/cppunit/lifecycle.cxx b/vcl/qa/cppunit/lifecycle.cxx
index 0ec8b4cd17d8..67f2e9bce9db 100644
--- a/vcl/qa/cppunit/lifecycle.cxx
+++ b/vcl/qa/cppunit/lifecycle.cxx
@@ -92,18 +92,42 @@ void LifecycleTest::testMultiDispose()
 
 void LifecycleTest::testWidgets(vcl::Window *pParent)
 {
-    { ScopedVclPtrInstance< PushButton > aPtr( pParent );   }
-    { ScopedVclPtrInstance< OKButton > aPtr( pParent );     }
-    { ScopedVclPtrInstance< CancelButton > aPtr( pParent ); }
-    { ScopedVclPtrInstance< HelpButton > aPtr( pParent );   }
+    {
+        ScopedVclPtrInstance< PushButton > aPtr( pParent );
+        (void)aPtr; // silence unused variable warning
+    }
+    {
+        ScopedVclPtrInstance< OKButton > aPtr( pParent );
+        (void)aPtr; // silence unused variable warning
+    }
+    {
+        ScopedVclPtrInstance< CancelButton > aPtr( pParent );
+        (void)aPtr; // silence unused variable warning
+    }
+    {
+        ScopedVclPtrInstance< HelpButton > aPtr( pParent );
+        (void)aPtr; // silence unused variable warning
+    }
 
     // Some widgets really insist on adoption.
     if (pParent)
     {
-        { ScopedVclPtrInstance< CheckBox > aPtr( pParent );     }
-        { ScopedVclPtrInstance< Edit > aPtr( pParent );         }
-        { ScopedVclPtrInstance< ComboBox > aPtr( pParent );     }
-        { ScopedVclPtrInstance< RadioButton > aPtr( pParent );  }
+        {
+            ScopedVclPtrInstance< CheckBox > aPtr( pParent );
+            (void)aPtr; // silence unused variable warning
+        }
+        {
+            ScopedVclPtrInstance< Edit > aPtr( pParent );
+            (void)aPtr; // silence unused variable warning
+        }
+        {
+            ScopedVclPtrInstance< ComboBox > aPtr( pParent );
+            (void)aPtr; // silence unused variable warning
+        }
+        {
+            ScopedVclPtrInstance< RadioButton > aPtr( pParent );
+            (void)aPtr; // silence unused variable warning
+        }
     }
 }