[Bug c++/58201] [4.9 Regression] Undefined reference to `B::B(void const**)'

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58201

--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Perhaps use error_at and DECL_SOURCE_LOCATION of the expr being mangled?
Perhaps temporary set input_location to DECL_SOURCE_LOCATION for the duration
of mangle_decl, and use error_at (EXPR_LOC_OR_HERE (expr), instead of error?