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>

1 files changed, 10 insertions, 10 deletions

diff --git a/sw/source/filter/ww8/docxattributeoutput.cxx b/sw/source/filter/ww8/docxattributeoutput.cxx
index 113d26170423..91d77e81ddbb 100644
--- a/sw/source/filter/ww8/docxattributeoutput.cxx
+++ b/sw/source/filter/ww8/docxattributeoutput.cxx
@@ -2486,7 +2486,7 @@ const NameToId constNameToIdMapping[] =
     { OUString("styleSet"),     FSNS( XML_w14, XML_styleSet ) },
 };
 
-boost::optional<sal_Int32> lclGetElementIdForName(const OUString& rName)
+o3tl::optional<sal_Int32> lclGetElementIdForName(const OUString& rName)
 {
     for (auto const & i : constNameToIdMapping)
     {
@@ -2495,7 +2495,7 @@ boost::optional<sal_Int32> lclGetElementIdForName(const OUString& rName)
             return i.maId;
         }
     }
-    return boost::optional<sal_Int32>();
+    return o3tl::optional<sal_Int32>();
 }
 
 void lclProcessRecursiveGrabBag(sal_Int32 aElementId, const css::uno::Sequence<css::beans::PropertyValue>& rElements, sax_fastparser::FSHelperPtr const & pSerializer)
@@ -2525,7 +2525,7 @@ void lclProcessRecursiveGrabBag(sal_Int32 aElementId, const css::uno::Sequence<c
             aValue =  OUStringToOString(aAny.get<OUString>(), RTL_TEXTENCODING_ASCII_US);
         }
 
-        boost::optional<sal_Int32> aSubElementId = lclGetElementIdForName(rAttribute.Name);
+        o3tl::optional<sal_Int32> aSubElementId = lclGetElementIdForName(rAttribute.Name);
         if(aSubElementId)
             pAttributes->add(*aSubElementId, aValue.getStr());
     }
@@ -2538,7 +2538,7 @@ void lclProcessRecursiveGrabBag(sal_Int32 aElementId, const css::uno::Sequence<c
     {
         css::uno::Sequence<css::beans::PropertyValue> aSumElements;
 
-        boost::optional<sal_Int32> aSubElementId = lclGetElementIdForName(rElement.Name);
+        o3tl::optional<sal_Int32> aSubElementId = lclGetElementIdForName(rElement.Name);
         if(aSubElementId)
         {
             rElement.Value >>= aSumElements;
@@ -2585,7 +2585,7 @@ void DocxAttributeOutput::WriteCollectedRunProperties()
 
     for (const beans::PropertyValue & i : m_aTextEffectsGrabBag)
     {
-        boost::optional<sal_Int32> aElementId = lclGetElementIdForName(i.Name);
+        o3tl::optional<sal_Int32> aElementId = lclGetElementIdForName(i.Name);
         if(aElementId)
         {
             uno::Sequence<beans::PropertyValue> aGrabBagSeq;
@@ -6320,13 +6320,13 @@ static OString impl_LevelNFC( sal_uInt16 nNumberingType , const SfxItemSet *pOut
 }
 
 
-void DocxAttributeOutput::SectionPageNumbering( sal_uInt16 nNumType, const ::boost::optional<sal_uInt16>& oPageRestartNumber )
+void DocxAttributeOutput::SectionPageNumbering( sal_uInt16 nNumType, const ::o3tl::optional<sal_uInt16>& oPageRestartNumber )
 {
     // FIXME Not called properly with page styles like "First Page"
 
     FastAttributeList* pAttr = FastSerializerHelper::createAttrList();
 
-    // boost::none means no restart: then don't output that attribute if it is negative
+    // o3tl::nullopt means no restart: then don't output that attribute if it is negative
     if ( oPageRestartNumber )
        pAttr->add( FSNS( XML_w, XML_start ), OString::number( *oPageRestartNumber ) );
 
@@ -8285,9 +8285,9 @@ void DocxAttributeOutput::FormatAnchor( const SwFormatAnchor& )
     // Fly frames: anchors here aren't matching the anchors in docx
 }
 
-static boost::optional<sal_Int32> lcl_getDmlAlpha(const SvxBrushItem& rBrush)
+static o3tl::optional<sal_Int32> lcl_getDmlAlpha(const SvxBrushItem& rBrush)
 {
-    boost::optional<sal_Int32> oRet;
+    o3tl::optional<sal_Int32> oRet;
     sal_Int32 nTransparency = rBrush.GetColor().GetTransparency();
     if (nTransparency)
     {
@@ -8306,7 +8306,7 @@ void DocxAttributeOutput::FormatBackground( const SvxBrushItem& rBrush )
 {
     const Color aColor = rBrush.GetColor();
     OString sColor = msfilter::util::ConvertColor( aColor.GetRGBColor() );
-    boost::optional<sal_Int32> oAlpha = lcl_getDmlAlpha(rBrush);
+    o3tl::optional<sal_Int32> oAlpha = lcl_getDmlAlpha(rBrush);
     if (m_rExport.SdrExporter().getTextFrameSyntax())
     {
         // Handle 'Opacity'