https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110853
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-13 branch has been updated by Jonathan Wakely <[email protected]>: https://gcc.gnu.org/g:ac28c9730c14e7e6868c18420a803aed0d3935f1 commit r13-9867-gac28c9730c14e7e6868c18420a803aed0d3935f1 Author: Jonathan Wakely <[email protected]> Date: Tue Sep 2 22:30:46 2025 +0100 libstdc++: Make CTAD ignore pair(const T1&, const T2&) constructor [PR110853] For the pair(T1, T2) explicit deduction type to decay its arguments as intended, we need the pair(const T1&, const T2&) constructor to not be used for CTAD. Otherwise we try to instantiate pair<T1, T2> without decaying, which is ill-formed for function lvalues. Use std::type_identity_t<T1> to make the constructor unusable for an implicit deduction guide. libstdc++-v3/ChangeLog: PR libstdc++/110853 * include/bits/stl_pair.h [C++20] (pair(const T1&, const T2&)): Use std::type_identity_t<T1> for first parameter. * testsuite/20_util/pair/cons/110853.cc: New test. Reviewed-by: Patrick Palka <[email protected]> Reviewed-by: Tomasz KamiÅski <[email protected]> (cherry picked from commit 0bb0d1d2880d562298eeec8eee4ab4e8ba943260)
