https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107085
--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:895dd027d5dda51a95d242aec8a49a6dfa5db58d commit r13-3173-g895dd027d5dda51a95d242aec8a49a6dfa5db58d Author: Marek Polacek <pola...@redhat.com> Date: Wed Oct 5 15:51:30 2022 -0400 c++: fixes for derived-to-base reference binding [PR107085] This PR reports that struct Base {}; struct Derived : Base {}; static_assert(__reference_constructs_from_temporary(Base const&, Derived)); doesn't pass, which it should: it's just like const Base& b(Derived{}); where we bind 'b' to the Base subobject of a temporary object of type Derived. The ck_base conversion didn't have ->need_temporary_p set because we didn't need to create a temporary object just for the base, but the whole object is a temporary so we're still binding to a temporary. Since the Base subobject is an xvalue, a new function is introduced. PR c++/107085 gcc/cp/ChangeLog: * call.cc (conv_binds_ref_to_temporary): New. (ref_conv_binds_directly): Rename to... (ref_conv_binds_to_temporary): ...this. Use conv_binds_ref_to_temporary. * cp-tree.h (ref_conv_binds_directly): Rename to... (ref_conv_binds_to_temporary): ...this. * method.cc (ref_xes_from_temporary): Use ref_conv_binds_to_temporary. * parser.cc (warn_for_range_copy): Likewise. gcc/testsuite/ChangeLog: * g++.dg/ext/reference_constructs_from_temporary1.C: Adjust expected result. * g++.dg/ext/reference_converts_from_temporary1.C: Likewise. * g++.dg/cpp0x/elision4.C: New test.
