offsetof is only guaranteed to work with standard layout types

Change-Id: If9ba41a219d3c3b5bff838104b9a0df53030b8f5
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/119181
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 2699c09ac03f..96bb504f77a8 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -110,6 +110,7 @@ private:
     static constexpr void assertLayout() {
         // These static_asserts verifying the layout compatibility with rtl_uString cannot be class
         // member declarations, as offsetof requires a complete type, so defer them to here:
+        static_assert(std::is_standard_layout_v<OUStringLiteral>);
         static_assert(offsetof(OUStringLiteral, str.refCount) == offsetof(OUStringLiteral, more.refCount));
         static_assert(offsetof(OUStringLiteral, str.length) == offsetof(OUStringLiteral, more.length));
         static_assert(offsetof(OUStringLiteral, str.buffer) == offsetof(OUStringLiteral, more.buffer));