https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113208
--- Comment #24 from Jakub Jelinek <jakub at gcc dot gnu.org> --- As documented in https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling-special-ctor-dtor C2 is base object constructor (C1 is complete object constructor, C3 is allocating complete constructor). C5 is an extension we use in the PR3187 r0-97383-g24b3ff2c53806d3d (related discussion starts at https://gcc.gnu.org/legacy-ml/gcc-patches/2009-11/threads.html#00700 and continues to https://gcc.gnu.org/legacy-ml/gcc-patches/2009-12/threads.html#00023 ) optimization for the comdat name containing both the C1 and C2 versions of the constructors as aliases.
