old class Stack pop'ed 0 from empty stack, which std::stack doesn't

Some places in the code assumed that if the stack is empty a null pointer is
returned by top() (or old Pop()), this doesn't work anymore with ::std::stack
that instead has undefined behavior in that case, so check !stack.empty()
first before accessing top.
(cherry picked from commit ac40f7d6503533954127e818f2bf009200c1e3f2)

1 files changed, 6 insertions, 3 deletions

diff --git a/filter/source/svg/svgwriter.hxx b/filter/source/svg/svgwriter.hxx
index 0b6048e7fb18..b4fe4ae06b5f 100644
--- a/filter/source/svg/svgwriter.hxx
+++ b/filter/source/svg/svgwriter.hxx
@@ -186,9 +186,12 @@ private:
     }
     void                    ImplReleaseContext()
     {
-        delete maContextStack.top();
-        maContextStack.pop();
-        mpContext = maContextStack.top();
+        if (!maContextStack.empty())
+        {
+            delete maContextStack.top();
+            maContextStack.pop();
+        }
+        mpContext = (maContextStack.empty() ? NULL : maContextStack.top());
     }
 
     long                    ImplMap( sal_Int32 nVal ) const;