3d01c7c2f2
* include/std/variant (__do_visit): Add a template parameter for enforcing same return types for visit. (__gen_vtable_impl): Likewise. (_S_apply_single_alt): Adjust. (__visit_invoke_impl): New. Handle casting to void. (__do_visit_invoke): New. Enforces same return types. (__do_visit_invoke_r): New. Converts return types. (__visit_invoke): Adjust. (__gen_vtable): Add a template parameter for enforcing same return types for visit. * testsuite/20_util/variant/visit_r.cc: Add a test for a visitor with different return types. * testsuite/20_util/variant/visit_neg.cc: New. Ensures that visitors with different return types don't accidentally compile with regular visitation. From-SVN: r270216
file: libstdc++-v3/README New users may wish to point their web browsers to the file index.html in the 'doc/html' subdirectory. It contains brief building instructions and notes on how to configure the library in interesting ways.