This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
(From submission #561.)
Consider:
bool f() { constexpr int z = 42; return requires { sizeof(int [*&z]); } && requires (int x) { sizeof(int [*&z]); }; }
The second requires-expression introduces a function parameter scope according to 6.4.4 [basic.scope.param]. This affects odr-usability as specified in 6.3 [basic.def.odr] paragraph 10, but the two requires-expression in the example ought to actually behave the same.
Proposed resolution (approved by CWG 2024-10-11):
Change in 6.3 [basic.def.odr] bullet 10.2.2 as follows:
A local entity (6.1 [basic.pre]) is odr-usable in a scope (6.4.1 [basic.scope.scope]) if:
- ...
- for each intervening scope (6.4.1 [basic.scope.scope]) between the point at which the entity is introduced and the scope (where *this is considered to be introduced within the innermost enclosing class or non-lambda function definition scope), either:
- the intervening scope is a block scope,
or- the intervening scope is the function parameter scope of a requires-expression, or
- the intervening scope is the function parameter scope of a lambda-expression that has a simple-capture naming the entity or has a capture-default, and the block scope of the lambda-expression is also an intervening scope.