Suppose you try to call, say, `AddEntryPoint` with a `std::vector<Id>`
as the `interfaces` argument - something that yuzu does. This can match
the non-variadic overload, since `std::vector<Id>` is implicitly
convertible to the argument type `std::span<const Id>`. But it can also
match the variadic overload, and the compiler sees that as a 'better'
match because it doesn't require implicit conversion. So it picks that
overload and promptly errors out trying to convert `std::vector<Id>` to
`Id`.
To make the compiler pick the right overload, you would have to
explicitly convert to `std::span<const Id>`, which is annoyingly
verbose.
To avoid this, add `requires` clauses to all variadic convenience
overloads, requiring each of the variadic arguments to be convertible to
the corresponding element type. If you pass a vector/array/etc., this
rules out the variadic overload as a candidate, and the call goes
through with the non-variadic overload.
Also, use slightly different code to forward to the non-variadic
overloads, that works even if the arguments need to be converted.
Note: I used this in a WIP branch updating yuzu to the latest version of
sirit.
Note 2: I tried to run clang-format on this, but it mangled the requires
clauses pretty horribly, so I didn't accept its changes. I googled it,
and apparently clang-format doesn't properly support concepts yet...
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