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, 9 insertions, 9 deletions

diff --git a/sc/inc/dptabsrc.hxx b/sc/inc/dptabsrc.hxx
index a5eb7f74ecc1..a6ddf33e5c12 100644
--- a/sc/inc/dptabsrc.hxx
+++ b/sc/inc/dptabsrc.hxx
@@ -48,7 +48,7 @@
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
-#include <boost/optional.hpp>
+#include <o3tl/optional.hxx>
 
 namespace com { namespace sun { namespace star {
     namespace sheet {
@@ -109,7 +109,7 @@ private:
     bool                    bResultOverflow;
     bool                    bPageFiltered;      // set if page field filters have been applied to cache table
 
-    boost::optional<OUString> mpGrandTotalName;
+    o3tl::optional<OUString> mpGrandTotalName;
 
     void                    CreateRes_Impl();
     void                    FillMemberResults();
@@ -144,7 +144,7 @@ public:
     ScDPTableData*          GetData()       { return pData; }
     const ScDPTableData*    GetData() const { return pData; }
 
-    const boost::optional<OUString> &
+    const o3tl::optional<OUString> &
                             GetGrandTotalName() const;
 
     css::sheet::DataPilotFieldOrientation
@@ -268,8 +268,8 @@ class ScDPDimension : public cppu::WeakImplHelper<
     rtl::Reference<ScDPHierarchies> mxHierarchies;
     ScGeneralFunction   nFunction;
     OUString            aName;              // if empty, take from source
-    boost::optional<OUString> mpLayoutName;
-    boost::optional<OUString> mpSubtotalName;
+    o3tl::optional<OUString> mpLayoutName;
+    o3tl::optional<OUString> mpSubtotalName;
     long                nSourceDim;         // >=0 if dup'ed
     css::sheet::DataPilotFieldReference
                         aReferenceValue;    // settings for "show data as" / "displayed value"
@@ -291,8 +291,8 @@ public:
     ScDPDimension*          CreateCloneObject();
     ScDPHierarchies*        GetHierarchiesObject();
 
-    const boost::optional<OUString> & GetLayoutName() const;
-    const boost::optional<OUString> & GetSubtotalName() const;
+    const o3tl::optional<OUString> & GetLayoutName() const;
+    const o3tl::optional<OUString> & GetSubtotalName() const;
 
                             // XNamed
     virtual OUString SAL_CALL getName() override;
@@ -604,7 +604,7 @@ private:
     long const      nLev;
 
     SCROW const     mnDataId;
-    boost::optional<OUString> mpLayoutName;
+    o3tl::optional<OUString> mpLayoutName;
 
     sal_Int32       nPosition;          // manual sorting
     bool            bVisible;
@@ -622,7 +622,7 @@ public:
     SCROW GetItemDataId() const { return mnDataId; }
     bool IsNamedItem(SCROW nIndex) const;
 
-    const boost::optional<OUString> & GetLayoutName() const;
+    const o3tl::optional<OUString> & GetLayoutName() const;
     long GetDim() const { return nDim;}
 
     sal_Int32               Compare( const ScDPMember& rOther ) const;      // visible order