[temp.deduct.call] Unclear relationship among the notional template parameters introduced for an array parameter

[t3nsor]

Full name of submitter: Brian Bi

Issue description: [temp.deduct.call]/1 specifies:

[...] If removing references and cv-qualifiers from P gives std::initializer_list<P'> or P'[N] for some P' and N and the argument is a non-empty initializer list ([dcl.init.list]), then deduction is performed instead for each element of the initializer list independently, taking P' as separate function template parameter types P'_i and the i^th initializer element as the corresponding argument. [...]

The presumed intent is all P'_i for a given P' must either be successfully deduced and agree with each other, or be non-deduced contexts, and at least one must succeed. However, the wording does not clearly state this.

Suggested resolution: Edit [temp.deduct.call]/1 as follows:

[...] If removing references and cv-qualifiers from P gives std::initializer_list<P'> or P'[N] for some P' and N and the argument is a non-empty initializer list ([dcl.init.list]), then deduction is instead performed instead for each element of the initializer list independently, taking P' as separate function template parameter types P'_i and the i^th initializer element as the corresponding argumentas if each element of the initializer list were the argument for a separate parameter having type P'. [...]