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>

4 files changed, 27 insertions, 27 deletions

diff --git a/jvmfwk/inc/elements.hxx b/jvmfwk/inc/elements.hxx
index 4ec2e5c2fb28..89802e9ec200 100644
--- a/jvmfwk/inc/elements.hxx
+++ b/jvmfwk/inc/elements.hxx
@@ -27,7 +27,7 @@
 #include <rtl/ustring.hxx>
 #include <rtl/byteseq.hxx>
 #include <libxml/parser.h>
-#include <boost/optional.hpp>
+#include <o3tl/optional.hxx>
 
 struct JavaInfo;
 
@@ -159,28 +159,28 @@ private:
         If /java/enabled@xsi:nil == true then the value will be uninitialized
         after a call to load().
     */
-    boost::optional<sal_Bool> m_enabled;
+    o3tl::optional<sal_Bool> m_enabled;
 
     /** User configurable option. /java/userClassPath
         If /java/userClassPath@xsi:nil == true then the value is uninitialized
         after a call to load().
     */
-    boost::optional< OUString> m_userClassPath;
+    o3tl::optional< OUString> m_userClassPath;
     /** User configurable option.  /java/javaInfo
         If /java/javaInfo@xsi:nil == true then the value is uninitialized
         after a call to load.
      */
-    boost::optional<CNodeJavaInfo> m_javaInfo;
+    o3tl::optional<CNodeJavaInfo> m_javaInfo;
     /** User configurable option. /java/vmParameters
         If /java/vmParameters@xsi:nil == true then the value is uninitialized
         after a call to load.
     */
-    boost::optional< ::std::vector< OUString> > m_vmParameters;
+    o3tl::optional< ::std::vector< OUString> > m_vmParameters;
     /** User configurable option. /java/jreLocations
         If /java/jreLocaltions@xsi:nil == true then the value is uninitialized
         after a call to load.
     */
-    boost::optional< ::std::vector< OUString> > m_JRELocations;
+    o3tl::optional< ::std::vector< OUString> > m_JRELocations;
 
 public:
 
@@ -225,22 +225,22 @@ public:
 
     /** returns the value of the element /java/enabled
      */
-    const boost::optional<sal_Bool> & getEnabled() const { return m_enabled;}
+    const o3tl::optional<sal_Bool> & getEnabled() const { return m_enabled;}
     /** returns the value of the element /java/userClassPath.
      */
-    const boost::optional< OUString> & getUserClassPath() const { return m_userClassPath;}
+    const o3tl::optional< OUString> & getUserClassPath() const { return m_userClassPath;}
 
     /** returns the value of the element /java/javaInfo.
      */
-    const boost::optional<CNodeJavaInfo> & getJavaInfo() const { return m_javaInfo;}
+    const o3tl::optional<CNodeJavaInfo> & getJavaInfo() const { return m_javaInfo;}
 
     /** returns the parameters from the element /java/vmParameters/param.
      */
-    const boost::optional< ::std::vector< OUString> > & getVmParameters() const { return m_vmParameters;}
+    const o3tl::optional< ::std::vector< OUString> > & getVmParameters() const { return m_vmParameters;}
 
     /** returns the parameters from the element /java/jreLocations/location.
      */
-    const boost::optional< ::std::vector< OUString> > & getJRELocations() const { return m_JRELocations;}
+    const o3tl::optional< ::std::vector< OUString> > & getJRELocations() const { return m_JRELocations;}
 };
 
 /** merges the settings for shared, user and installation during construction.
diff --git a/jvmfwk/inc/fwkbase.hxx b/jvmfwk/inc/fwkbase.hxx
index 790b9a40d8f7..07ea10a67ad1 100644
--- a/jvmfwk/inc/fwkbase.hxx
+++ b/jvmfwk/inc/fwkbase.hxx
@@ -21,7 +21,7 @@
 
 #include <sal/config.h>
 
-#include <boost/optional.hpp>
+#include <o3tl/optional.hxx>
 
 #include <rtl/ustring.hxx>
 #include "libxmlutil.hxx"
@@ -40,7 +40,7 @@ class VendorSettings
 public:
     VendorSettings();
 
-    boost::optional<VersionInfo> getVersionInformation(const OUString & sVendor) const;
+    o3tl::optional<VersionInfo> getVersionInformation(const OUString & sVendor) const;
 };
 
 /* The class offers functions to retrieve verified bootstrap parameters.
diff --git a/jvmfwk/source/elements.cxx b/jvmfwk/source/elements.cxx
index bc4a4b7554b7..69688df85295 100644
--- a/jvmfwk/source/elements.cxx
+++ b/jvmfwk/source/elements.cxx
@@ -34,7 +34,7 @@
 #include <libxml/parser.h>
 #include <libxml/xpath.h>
 #include <libxml/xpathInternals.h>
-#include <boost/optional.hpp>
+#include <o3tl/optional.hxx>
 #include <string.h>
 
 // For backwards compatibility, the nFeatures and nRequirements flag words are
@@ -236,9 +236,9 @@ void NodeJava::load()
                 CXmlCharPtr sEnabled( xmlNodeListGetString(
                     docUser, cur->children, 1));
                 if (xmlStrcmp(sEnabled, reinterpret_cast<xmlChar const *>("true")) == 0)
-                    m_enabled = boost::optional<sal_Bool>(true);
+                    m_enabled = o3tl::optional<sal_Bool>(true);
                 else if (xmlStrcmp(sEnabled, reinterpret_cast<xmlChar const *>("false")) == 0)
-                    m_enabled = boost::optional<sal_Bool>(false);
+                    m_enabled = o3tl::optional<sal_Bool>(false);
             }
         }
         else if (xmlStrcmp(cur->name, reinterpret_cast<xmlChar const *>("userClassPath")) == 0)
@@ -251,7 +251,7 @@ void NodeJava::load()
             {
                 CXmlCharPtr sUser(xmlNodeListGetString(
                     docUser, cur->children, 1));
-                m_userClassPath = boost::optional<OUString>(OUString(sUser));
+                m_userClassPath = o3tl::optional<OUString>(OUString(sUser));
             }
         }
         else if (xmlStrcmp(cur->name, reinterpret_cast<xmlChar const *>("javaInfo")) == 0)
@@ -264,7 +264,7 @@ void NodeJava::load()
             if (xmlStrcmp(sNil, reinterpret_cast<xmlChar const *>("false")) == 0)
             {
                 if (! m_javaInfo)
-                    m_javaInfo = boost::optional<CNodeJavaInfo>(CNodeJavaInfo());
+                    m_javaInfo = o3tl::optional<CNodeJavaInfo>(CNodeJavaInfo());
                 m_javaInfo->loadFromNode(docUser, cur);
             }
         }
@@ -277,7 +277,7 @@ void NodeJava::load()
             if (xmlStrcmp(sNil, reinterpret_cast<xmlChar const *>("false")) == 0)
             {
                 if ( ! m_vmParameters)
-                    m_vmParameters = boost::optional<std::vector<OUString> >(
+                    m_vmParameters = o3tl::optional<std::vector<OUString> >(
                         std::vector<OUString> ());
 
                 xmlNode * pOpt = cur->children;
@@ -302,7 +302,7 @@ void NodeJava::load()
             if (xmlStrcmp(sNil, reinterpret_cast<xmlChar const *>("false")) == 0)
             {
                 if (! m_JRELocations)
-                    m_JRELocations = boost::optional<std::vector<OUString> >(
+                    m_JRELocations = o3tl::optional<std::vector<OUString> >(
                         std::vector<OUString>());
 
                 xmlNode * pLoc = cur->children;
@@ -418,7 +418,7 @@ void NodeJava::write() const
                      reinterpret_cast<xmlChar const *>("nil"),
                      reinterpret_cast<xmlChar const *>("false"));
 
-        if (m_enabled == boost::optional<sal_Bool>(true))
+        if (m_enabled == o3tl::optional<sal_Bool>(true))
             xmlNodeSetContent(nodeEnabled,reinterpret_cast<xmlChar const *>("true"));
         else
             xmlNodeSetContent(nodeEnabled,reinterpret_cast<xmlChar const *>("false"));
@@ -531,19 +531,19 @@ void NodeJava::write() const
 
 void NodeJava::setEnabled(bool bEnabled)
 {
-    m_enabled =  boost::optional<sal_Bool>(bEnabled);
+    m_enabled =  o3tl::optional<sal_Bool>(bEnabled);
 }
 
 
 void NodeJava::setUserClassPath(const OUString & sClassPath)
 {
-    m_userClassPath = boost::optional<OUString>(sClassPath);
+    m_userClassPath = o3tl::optional<OUString>(sClassPath);
 }
 
 void NodeJava::setJavaInfo(const JavaInfo * pInfo, bool bAutoSelect)
 {
     if (!m_javaInfo)
-        m_javaInfo = boost::optional<CNodeJavaInfo>(CNodeJavaInfo());
+        m_javaInfo = o3tl::optional<CNodeJavaInfo>(CNodeJavaInfo());
     m_javaInfo->bAutoSelect = bAutoSelect;
     m_javaInfo->bNil = false;
 
@@ -571,13 +571,13 @@ void NodeJava::setJavaInfo(const JavaInfo * pInfo, bool bAutoSelect)
 
 void NodeJava::setVmParameters(std::vector<OUString> const & arOptions)
 {
-    m_vmParameters = boost::optional<std::vector<OUString> >(arOptions);
+    m_vmParameters = o3tl::optional<std::vector<OUString> >(arOptions);
 }
 
 void NodeJava::addJRELocation(OUString const & sLocation)
 {
     if (!m_JRELocations)
-        m_JRELocations = boost::optional<std::vector<OUString> >(
+        m_JRELocations = o3tl::optional<std::vector<OUString> >(
             std::vector<OUString> ());
      //only add the path if not already present
     std::vector<OUString>::const_iterator it =
diff --git a/jvmfwk/source/fwkbase.cxx b/jvmfwk/source/fwkbase.cxx
index ece4dd2bd717..df00365fd4c7 100644
--- a/jvmfwk/source/fwkbase.cxx
+++ b/jvmfwk/source/fwkbase.cxx
@@ -113,7 +113,7 @@ VendorSettings::VendorSettings():
     }
 }
 
-boost::optional<VersionInfo> VendorSettings::getVersionInformation(const OUString & sVendor) const
+o3tl::optional<VersionInfo> VendorSettings::getVersionInformation(const OUString & sVendor) const
 {
     OSL_ASSERT(!sVendor.isEmpty());
     OString osVendor = OUStringToOString(sVendor, RTL_TEXTENCODING_UTF8);