Introduce o3tl::optional as an alias for std::optional

...with a boost::optional fallback for Xcode < 10 (as std::optional is only
available starting with Xcode 10 according to
<https://en.cppreference.com/w/cpp/compiler_support>, and our baseline for iOS
and macOS is still Xcode 9.3 according to README.md).  And mechanically rewrite
all code to use o3tl::optional instead of boost::optional.

One immediate benefit is that disabling -Wmaybe-uninitialized for GCC as per
fed7c3deb3f4ec81f78967c2d7f3c4554398cb9d "Slience bogus
-Werror=maybe-uninitialized" should no longer be necessary (and whose check
happened to no longer trigger for GCC 10 trunk, even though that compiler would
still emit bogus -Wmaybe-uninitialized for uses of boost::optional under
--enable-optimized, which made me ponder whether this switch from
boost::optional to std::optional would be a useful thing to do; I keep that
configure.ac check for now, though, and will only remove it in a follow up
commit).

Another longer-term benefit is that the code is now already in good shape for an
eventual switch to std::optional (a switch we would have done anyway once we no
longer need to support Xcode < 10).

Only desktop/qa/desktop_lib/test_desktop_lib.cxx heavily uses
boost::property_tree::ptree::get_child_optional returning boost::optional, so
let it keep using boost::optional for now.

After a number of preceding commits have paved the way for this change, this
commit is completely mechanical, done with

> git ls-files -z | grep -vz -e '^bin/find-unneeded-includes$' -e '^configure.ac$' -e '^desktop/qa/desktop_lib/test_desktop_lib.cxx$' -e '^dictionaries$' -e '^external/' -e '^helpcontent2$' -e '^include/IwyuFilter_include.yaml$' -e '^sc/IwyuFilter_sc.yaml$' -e '^solenv/gdb/boost/optional.py$' -e '^solenv/vs/LibreOffice.natvis$' -e '^translations$' -e '\.svg$' | xargs -0 sed -i -E -e 's|\<boost(/optional)?/optional\.hpp\>|o3tl/optional.hxx|g' -e 's/\<boost(\s*)::(\s*)(make_)?optional\>/o3tl\1::\2\3optional/g' -e 's/\<boost(\s*)::(\s*)none\>/o3tl\1::\2nullopt/g'

(before committing include/o3tl/optional.hxx, and relying on some GNU features).
It excludes some files where mention of boost::optional et al should apparently
not be changed (and the sub-repo directory stubs).  It turned out that all uses
of boost::none across the code base were in combination with boost::optional, so
had all to be rewritten as o3tl::nullopt.

Change-Id: Ibfd9f4b3d5a8aee6e6eed310b988c4e5ffd8b11b
Reviewed-on: https://gerrit.libreoffice.org/84128
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 8 insertions, 8 deletions

diff --git a/filter/source/msfilter/svdfppt.cxx b/filter/source/msfilter/svdfppt.cxx
index a122e6aac203..0c399260d6bf 100644
--- a/filter/source/msfilter/svdfppt.cxx
+++ b/filter/source/msfilter/svdfppt.cxx
@@ -139,7 +139,7 @@
 #include <svtools/embedhlp.hxx>
 #include <o3tl/enumrange.hxx>
 #include <o3tl/safeint.hxx>
-#include <boost/optional.hpp>
+#include <o3tl/optional.hxx>
 #include <sal/log.hxx>
 
 #include <algorithm>
@@ -2339,7 +2339,7 @@ SdrObject* SdrPowerPointImport::ApplyTextObj( PPTTextObj* pTextObj, SdrTextObj*
                     rOutliner.QuickSetAttribs( aPortionAttribs, aSelection );
                     aSelection.nStartPos = aSelection.nEndPos;
                 }
-                boost::optional< sal_Int16 > oStartNumbering;
+                o3tl::optional< sal_Int16 > oStartNumbering;
                 SfxItemSet aParagraphAttribs( rOutliner.GetEmptyItemSet() );
                 pPara->ApplyTo( aParagraphAttribs, oStartNumbering, *this, nDestinationInstance );
 
@@ -3400,7 +3400,7 @@ PPTNumberFormatCreator::~PPTNumberFormatCreator()
 
 bool PPTNumberFormatCreator::ImplGetExtNumberFormat( SdrPowerPointImport const & rManager,
     SvxNumberFormat& rNumberFormat, sal_uInt32 nLevel, TSS_Type nInstance, TSS_Type nDestinationInstance,
-        boost::optional< sal_Int16 >& rStartNumbering, sal_uInt32 nFontHeight,  PPTParagraphObj const * pPara )
+        o3tl::optional< sal_Int16 >& rStartNumbering, sal_uInt32 nFontHeight,  PPTParagraphObj const * pPara )
 {
     bool bHardAttribute = ( nDestinationInstance == TSS_Type::Unknown );
 
@@ -3641,7 +3641,7 @@ bool PPTNumberFormatCreator::ImplGetExtNumberFormat( SdrPowerPointImport const &
             }
             break;
         }
-        rStartNumbering = boost::optional< sal_Int16 >( nAnmScheme >> 16 );
+        rStartNumbering = o3tl::optional< sal_Int16 >( nAnmScheme >> 16 );
         sal_Int16 nBuStart = *rStartNumbering;
         //The Seventh bit of nBuFlags that specifies whether fBulletHasAutoNumber exists,
         //and fBulletHasAutoNumber that specifies whether this paragraph has an automatic numbering scheme.
@@ -3669,7 +3669,7 @@ void PPTNumberFormatCreator::GetNumberFormat( SdrPowerPointImport const & rManag
     nTextOfs = rParaLevel.mnTextOfs;
     nBulletOfs = rParaLevel.mnBulletOfs;
 
-    boost::optional< sal_Int16 > oStartNumbering;
+    o3tl::optional< sal_Int16 > oStartNumbering;
     ImplGetExtNumberFormat( rManager, rNumberFormat, nLevel, nInstance, TSS_Type::Unknown, oStartNumbering, rCharLevel.mnFontHeight, nullptr );
     if ( ( rNumberFormat.GetNumberingType() != SVX_NUM_BITMAP ) && ( nBulletHeight > 0x7fff ) )
         nBulletHeight = rCharLevel.mnFontHeight ? ((- static_cast<sal_Int16>(nBulletHeight)) * 100 ) / rCharLevel.mnFontHeight : 100;
@@ -3702,7 +3702,7 @@ void PPTNumberFormatCreator::GetNumberFormat( SdrPowerPointImport const & rManag
 }
 
 bool PPTNumberFormatCreator::GetNumberFormat( SdrPowerPointImport const & rManager, SvxNumberFormat& rNumberFormat, PPTParagraphObj* pParaObj,
-                                                TSS_Type nDestinationInstance, boost::optional< sal_Int16 >& rStartNumbering )
+                                                TSS_Type nDestinationInstance, o3tl::optional< sal_Int16 >& rStartNumbering )
 {
     sal_uInt32 nHardCount = 0;
     nHardCount += pParaObj->GetAttrib( PPT_ParaAttr_BulletOn, nIsBullet, nDestinationInstance ) ? 1 : 0;
@@ -6168,7 +6168,7 @@ bool PPTParagraphObj::GetAttrib( sal_uInt32 nAttr, sal_uInt32& rRetValue, TSS_Ty
     return bIsHardAttribute;
 }
 
-void PPTParagraphObj::ApplyTo( SfxItemSet& rSet,  boost::optional< sal_Int16 >& rStartNumbering, SdrPowerPointImport const & rManager, TSS_Type nDestinationInstance )
+void PPTParagraphObj::ApplyTo( SfxItemSet& rSet,  o3tl::optional< sal_Int16 >& rStartNumbering, SdrPowerPointImport const & rManager, TSS_Type nDestinationInstance )
 {
     sal_Int16   nVal2;
     sal_uInt32  nVal, nUpperDist, nLowerDist;
diff --git a/filter/source/pdf/impdialog.cxx b/filter/source/pdf/impdialog.cxx
index 4a6fbc0d12a2..1d49f17f3087 100644
--- a/filter/source/pdf/impdialog.cxx
+++ b/filter/source/pdf/impdialog.cxx
@@ -1512,7 +1512,7 @@ IMPL_LINK_NOARG(ImpPDFTabSigningPage, ClickmaPbSignCertSelect, weld::Button&, vo
 
         try
         {
-            boost::optional<css::uno::Sequence<OUString>> aTSAURLs(officecfg::Office::Common::Security::Scripting::TSAURLs::get());
+            o3tl::optional<css::uno::Sequence<OUString>> aTSAURLs(officecfg::Office::Common::Security::Scripting::TSAURLs::get());
             if (aTSAURLs)
             {
                 const css::uno::Sequence<OUString>& rTSAURLs = *aTSAURLs;