https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78209
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:e6fd02cc6d874c523466250a1cb724e0c7af9d75 commit r11-4758-ge6fd02cc6d874c523466250a1cb724e0c7af9d75 Author: Marek Polacek <pola...@redhat.com> Date: Tue Nov 3 15:10:31 2020 -0500 c++: Fix decltype(auto) deduction with rvalue ref [PR78209] Here's a small deficiency in decltype(auto). [dcl.type.auto.deduct]/5: If the placeholder-type-specifier is of the form decltype(auto), [...] the type deduced for T is determined [...] as though E had been the operand of the decltype. So: int &&i = 0; decltype(auto) j = i; // should behave like int &&j = i; error We deduce j's type in do_auto_deduction via finish_decltype_type which takes an 'id' argument. Currently we compute 'id' as false, because stripped_init is *i (a REFERENCE_REF_P). But it seems to me we should rather set 'id' to true here, by looking through the REFERENCE_REF_P, so that finish_decltype_type DTRT. gcc/cp/ChangeLog: PR c++/78209 * pt.c (do_auto_deduction): If init is REFERENCE_REF_P, use its first operand. gcc/testsuite/ChangeLog: PR c++/78209 * g++.dg/cpp1y/decltype-auto1.C: New test.
