This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 114a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-04-28

2712. Simplify restrictions on built-in assignment operator candidates

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

Subclause 12.2.2.3 [over.match.oper] paragraph 5 specifies:

For the built-in assignment operators, conversions of the left operand are restricted as follows:

• no temporaries are introduced to hold the left operand, and
• no user-defined conversions are applied to the left operand to achieve a type match with the left-most parameter of a built-in candidate.

The first bullet is redundant, because standard conversion sequences cannot bind "vq T&" (the type of the first parameter of a built-in assignment operator) to a temporary.

Proposed resolution (approved by CWG 2023-03-30):

Change in 12.2.2.3 [over.match.oper] paragraph 5 as follows:

For the first parameter of the built-in assignment operators, only standard conversion sequences (12.2.4.2.2 [over.ics.scs]) are considered. conversions of the left operand are restricted as follows:

• no temporaries are introduced to hold the left operand, and
• no user-defined conversions are applied to the left operand to achieve a type match with the left-most parameter of a built-in candidate.