fdo#58539: Resizing matrix should also resize the flag storage too.

Or else resizing and then putting empty elements may crash.  The flag
storage is used only for empty elements.

Change-Id: I1ada8f795a01336af185e6180bc03247c44472ba

sc/qa/unit/ucalc.cxx

@@ -1548,6 +1548,16 @@ void Test::testMatrix()
     pMat->PutString(aStr, 8, 2);
     pMat->PutEmptyPath(8, 11);
     checkMatrixElements<PartiallyFilledEmptyMatrix>(*pMat);
+
+    // Test resizing.
+    pMat = new ScMatrix(0, 0);
+    pMat->Resize(2, 2, 1.5);
+    pMat->PutEmpty(1, 1);
+
+    CPPUNIT_ASSERT_EQUAL(1.5, pMat->GetDouble(0, 0));
+    CPPUNIT_ASSERT_EQUAL(1.5, pMat->GetDouble(0, 1));
+    CPPUNIT_ASSERT_EQUAL(1.5, pMat->GetDouble(1, 0));
+    CPPUNIT_ASSERT_MESSAGE("PutEmpty() call failed.", pMat->IsEmpty(1, 1));
 }
 
 void Test::testEnterMixedMatrix()

sc/source/core/tool/scmatrix.cxx

@@ -418,11 +418,13 @@ bool ScMatrixImpl::IsImmutable() const
 void ScMatrixImpl::Resize(SCSIZE nC, SCSIZE nR)
 {
     maMat.resize(nR, nC);
+    maMatFlag.resize(nR, nC);
 }
 
 void ScMatrixImpl::Resize(SCSIZE nC, SCSIZE nR, double fVal)
 {
     maMat.resize(nR, nC, fVal);
+    maMatFlag.resize(nR, nC);
 }
 
 void ScMatrixImpl::SetErrorInterpreter( ScInterpreter* p)