This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

2792. Clean up specification of noexcept operator

[Accepted as a DR at the November, 2023 meeting.]

The introductory sentence "can throw an exception" is misleading, because it might be interpreted to cover exceptions thrown as the result of encountering undefined behavior.

Proposed resolution (approved by CWG 2023-10-06):

Change all of 7.6.2.7 [expr.unary.noexcept] as follows:

The noexcept operator determines whether the evaluation of its operand, which is an unevaluated operand (7.2.3 [expr.context]), can throw an exception (14.2 [except.throw]).

noexcept-expression:
        noexcept ( expression )

The operand of the noexcept operator is an unevaluated operand (7.2.3 [expr.context]). If the operand is a prvalue, the temporary materialization conversion (7.3.5 [conv.rval]) is applied.

The result of the noexcept operator is a prvalue of type bool. The result is false if the full-expression of the operand is potentially-throwing (14.5 [except.spec]), and true otherwise.

[Note 1: A noexcept-expression is an integral constant expression (7.7 [expr.const]). —end note]

If the operand is a prvalue, the temporary materialization conversion (7.3.5 [conv.rval]) is applied. The result of the noexcept operator is true unless the full-expression of the operand is potentially-throwing (14.5 [except.spec]).