O[U]String move ctors should be constexpr, too

...similar to 5f2206e3ccf1cf64d2b11b0e5d419973269920a8 "O{U]String copy ctor
should be constexpr", which will again be useful for some upcoming replacements
of OUStringConstExpr with OUString, and making data actually constexpr.  (For
example, the

static o3tl::enumarray<INetProtocol, SchemeInfo> const map

in INetURLObject::getSchemeInfo (tools/source/fsys/urlobj.cxx) can actually be
constexpr, but the o3tl::enumarray ctor forwards its SchemeInfo arguments by
forwarding references, so uses an implicitly generated constexpr SchemeInfo move
ctor, which in turn requires constexpr member move ctors.  So when the m_sScheme
member will be changed from rtl::OUStringConstExpr to OUString, the OUString
move ctor better be constexpr.)

Change-Id: Icfc5edbb8422919186517667f876ea90bec1be90
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/158099
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 28 insertions, 0 deletions

diff --git a/include/rtl/string.hxx b/include/rtl/string.hxx
index de468f127757..a2be12ab320d 100644
--- a/include/rtl/string.hxx
+++ b/include/rtl/string.hxx
@@ -240,9 +240,23 @@ public:
       @param    str         an OString.
       @since LibreOffice 5.2
     */
+#if !(defined _MSC_VER && _MSC_VER <= 1929 && defined _MANAGED)
+    constexpr
+#endif
     OString( OString && str ) noexcept
     {
         pData = str.pData;
+#if !(defined _MSC_VER && _MSC_VER <= 1929 && defined _MANAGED)
+        if (std::is_constant_evaluated()) {
+            //TODO: We would want to
+            //
+            //   assert(SAL_STRING_IS_STATIC(pData));
+            //
+            // here, but that wouldn't work because read of member `str` of OUStringLiteral's
+            // anonymous union with active member `more` is not allowed in a constant expression.
+            return;
+        }
+#endif
         str.pData = nullptr;
         rtl_string_new( &str.pData );
     }
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 8e8bd8e9580e..a88c2a303194 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -250,9 +250,23 @@ public:
       @param    str         an OUString.
       @since LibreOffice 5.2
     */
+#if !(defined _MSC_VER && _MSC_VER <= 1929 && defined _MANAGED)
+    constexpr
+#endif
     OUString( OUString && str ) noexcept
     {
         pData = str.pData;
+#if !(defined _MSC_VER && _MSC_VER <= 1929 && defined _MANAGED)
+        if (std::is_constant_evaluated()) {
+            //TODO: We would want to
+            //
+            //   assert(SAL_STRING_IS_STATIC(pData));
+            //
+            // here, but that wouldn't work because read of member `str` of OUStringLiteral's
+            // anonymous union with active member `more` is not allowed in a constant expression.
+            return;
+        }
+#endif
         str.pData = nullptr;
         rtl_uString_new( &str.pData );
     }