Proposed resolution:

This wording is relative to N4727.

1. Modify [variant.visit] as indicated:

   template<class Visitor, class... Variants>
     constexpr see below visit(Visitor&& vis, Variants&&... vars);
   

   […]

   -4- Throws: bad_variant_access if any variant in vars is valueless_by_exception()(vars.valueless_by_exception() || ...) is true.

   -5- Complexity: […]

   -?- Remarks: This function shall not participate in overload resolution unless remove_cvref_t<Variants_i> is a specialization of variant for all 0 <= i < n.

[ 2021-04-19 P2162R2 was adopted at February 2021 plenary. Status changed: Tentatively Resolved → Resolved. ]

[ 2020-11-18; this will be resolved by P2162. ]

[ 2018-06-18 after reflector discussion ]

Priority set to 2; status to LEWG

[ 2018-01-24, Daniel comments ]

This issue should be reviewed in common with LWG 2970.

std::visit accepts a parameter pack of forwarding references named vars whose types are the parameter pack Variants. Despite that:

1. the names of both packs are variants of "variant",
2. para 1 passes the types in Variants (modified) to variant_size_v,
3. para 3 uses the expression vars_i.index(),
4. para 4 says "...if any variant in vars is valueless_by_exception, and
5. para 5 mentions "..the number of alternative types of Variants₀"