This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 117b. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2025-08-11
2796. Function pointer conversions for relational operatorsSection: 7.6.9 [expr.rel] Status: DRWP Submitter: Alisdair Meredith Date: 2023-09-14[Accepted as a DR at the November, 2023 meeting.]
Consider:
void f() {}
void g() noexcept {}
void q() {
bool b1 = f == g; // OK
bool b2 = f > g; // error: different types
}
For the equality operators, 7.6.10 [expr.eq] paragraph 3 specifies:
If at least one of the operands is a pointer, pointer conversions (7.3.12 [conv.ptr]), function pointer conversions (7.3.14 [conv.fctptr]), and qualification conversions (7.3.6 [conv.qual]) are performed on both operands to bring them to their composite pointer type (7.2.2 [expr.type]). Comparing pointers is defined as follows: ...
In contrast, the corresponding rule for relational operators in 7.6.9 [expr.rel] paragraph 3 specifies:
The usual arithmetic conversions (7.4 [expr.arith.conv]) are performed on operands of arithmetic or enumeration type. If both operands are pointers, pointer conversions (7.3.12 [conv.ptr]) and qualification conversions (7.3.6 [conv.qual]) are performed to bring them to their composite pointer type (7.2.2 [expr.type]). After conversions, the operands shall have the same type.
However, all major implementations accept the example.
Proposed resolution (approved by CWG 2023-10-06):
Change in 7.6.9 [expr.rel] paragraph 3 as follows:
The usual arithmetic conversions (7.4 [expr.arith.conv]) are performed on operands of arithmetic or enumeration type. If both operands are pointers, pointer conversions (7.3.12 [conv.ptr]) , function pointer conversions (7.3.14 [conv.fctptr]), and qualification conversions (7.3.6 [conv.qual]) are performed to bring them to their composite pointer type (7.2.2 [expr.type]). After conversions, the operands shall have the same type.
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