5 Expressions [expr]

5.3 Unary expressions [expr.unary]

5.3.7 noexcept operator [expr.unary.noexcept]

1

The noexcept operator determines whether the evaluation of its operand, which is an unevaluated operand (Clause [expr]), can throw an exception ([except.throw]).

noexcept-expression:
  noexcept ( expression )
2

The result of the noexcept operator is a constant of type bool and is a prvalue.

3

The result of the noexcept operator is true unless the expression is potentially-throwing ([except.spec]).