https://cgit.freebsd.org/ports/tree/graphics/libfpx/files/patch-null-casts
https://bugs.gentoo.org/842123

(May well fix libcxx too given the source.)
--- a/oless/expdf.cxx
+++ b/oless/expdf.cxx
@@ -610,5 +610,5 @@
         olErr(EH_Err, STG_E_INVALIDFUNCTION);
     olChk(Validate());
-    if (snbExclude != NULL)
+    if (snbExclude != 0)
         olErr(EH_Err, STG_E_INVALIDPARAMETER);
     olChk(OpenEntry(pwcsName, STGTY_STORAGE, grfMode, (void **)&pdfExp));
@@ -909,5 +909,5 @@
     sc = OpenStorage(pwcsName, (IStorage*)NULL,
                      STGM_DIRECT| STGM_READ| STGM_SHARE_EXCLUSIVE,
-                     (SNBW)NULL, (DWORD)NULL, &pstgsrc);
+                     0, 0, &pstgsrc);
 
     if (SUCCEEDED(sc))
@@ -951,5 +951,5 @@
         olChk(OpenStream(pwcsName, (void *)NULL,
                          STGM_DIRECT | STGM_READ | STGM_SHARE_EXCLUSIVE,
-                         (DWORD)NULL, &pstmsrc));
+                         0, &pstmsrc));
 
         //  It's a stream
@@ -1575,5 +1575,5 @@
     olMemTo(EH_pst, pstExp = new CExposedStream());
     olChkTo(EH_pstExp, pstExp->Init(pstDirect, this,
-                                    df, pdfnName, (ULONG)NULL));
+                                    df, pdfnName, 0));
     *ppStream = pstExp;
     return S_OK;
@@ -1624,5 +1624,5 @@
     olMemTo(EH_pst, pstExp = new CExposedStream());
     olChkTo(EH_pstExp, pstExp->Init(pstDirect, this,
-                                    df, pdfnName, (ULONG)NULL));
+                                    df, pdfnName, 0));
     *ppStream = pstExp;
     return S_OK;
--- a/oless/storage.cxx
+++ b/oless/storage.cxx
@@ -144,5 +144,5 @@
 
     olChk(ValidateNameW(pwcsName, CBMAXPATHCOMPLEN));
-    olMem(pilb = new CFileILB(pwcsName, (DWORD)NULL, FALSE));
+    olMem(pilb = new CFileILB(pwcsName, 0, FALSE));
     olChk(pilb->Open(STGM_READ));
     sc = GetScode( StgIsStorageILockBytes(pilb) );