(In reply to Callum Farmer from comment #11) > Looks like C++20 incompatibility. Needs a newer Clang hence why it passes on > 15.5. Not sure if I can send a newer LLVM via maintenance request. If this is the only error, maybe you can just move the declaration into the class in a patch? That might of course create problems if certain headers aren't included where the class is defined, but maybe not. (In reply to Andreas Stieger from comment #13) > Breaking change: > https://chromium-review.googlesource.com/c/chromium/src/+/4239546/16/ > components/password_manager/core/browser/affiliation/ > affiliation_fetcher_base.cc#183 > Related C++ spec: > https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2085r0.html Interestingly that paper "[retains] the restriction that [defaulted comparisons] be declared in the relevant class to avoid encouraging clients to add to a class���������s interface (and to avoid questions of access)." But in that change, there is no declaration in the class, only afterwards. (In reply to Andreas Stieger from comment #13) > LLVM: https://reviews.llvm.org/D103929 Seems that https://reviews.llvm.org/D104478 eventually did it.