[dcl.init.aggr]/9:

An array of unknown bound initialized with a brace-enclosed initializer-list containing n initializer-clauses, where n shall be greater than zero, is defined as having n elements ([dcl.array]).

[dcl.array]/3:

An array bound may also be omitted when the declarator is followed by an initializer or when a declarator for a static data member is followed by a brace-or-equal-initializer ([class.mem]). In both cases the bound is calculated from the number of initial elements (say, N) supplied ([dcl.init.aggr]), and the type of the identifier of D is “array of N T”.

[expr.type.conv]/2:

Otherwise, the expression is a prvalue of the specified type whose result object is direct-initialized with the initializer.

Consider

using T = int[];
auto&& r = T{1,2};

Should r have type int(&&)[2] or int(&&)[] (or be ill-formed, since T is an incomplete type)?

[dcl.init.aggr]/9 seems to imply that the array bound is deduced in this case, but [dcl.array]/3 and [expr.type.conv]/2 seem more ambiguous.

All compilers I tested say that r has type int(&&)[2].