[over.best.ics] Remove redundant sub-bullet CWG2829

[sdkrystian]

The wording in [over.best.ics] p4 sub 3 is not only incorrect, but also redundant:

However, if the target is [...] the first parameter of a constructor or [...] and the constructor or user-defined conversion function is a candidate by:
[over.match.ctor], when the argument is the temporary in the second step of a class copy-initialization, [...]
user-defined conversion sequences are not considered.

The "temporary" wording referred to here was removed by P0135 in [dcl.init]/17.6.3. Additionally, this wording is not even necessary. Consider the following:

struct S
{
  S(std::string);
};

S a = "abc"; // ill-formed

[dcl.init]/17.6.3 dictates that the candidate functions here are chosen by [over.match.copy], meaning that [over.best.ics] p4 sub 4 applies from the get-go, thus not allowing the implicit conversion sequence from const char[4] to std::string to be formed as a user defined conversion sequence would be required but is not permitted.

The direct-initialization that is performed as the second step in [dcl.init]/17.6.3 will always follow the rules of [dcl.init]/17.6.1 since it is a prvalue of the same type, meaning the constructor selected by [over.match.copy] is the only function that will be called.

[zygoloid]

This is too subtle to proceed with without CWG oversight.

[tkoeppe]

CWG meeting consensus, Nov 11: This should become a CWG issue.

[jensmaurer]

CWG2829