Title
Function pointer conversions for relational operators
Status
drwp
Section
7.6.9 [expr.rel]
Submitter
Alisdair Meredith

Created on 2023-09-14.00:00:00 last changed 4 months ago

Messages

Date: 2023-10-06.22:55:13

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.
Date: 2023-11-15.00:00:00

[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.

History
Date User Action Args
2024-04-05 21:43:46adminsetstatus: dr -> drwp
2023-12-19 10:15:28adminsetstatus: ready -> dr
2023-10-06 22:55:13adminsetstatus: open -> ready
2023-09-16 08:00:19adminsetmessages: + msg7438
2023-09-14 00:00:00admincreate