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Fix indirect comparisons #489

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Fix indirect comparisons #489

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28 changes: 11 additions & 17 deletions DRAFT.md
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,9 @@ should not be considered in isolation.

* Add discussion of constraints and incomplete type support.

* TODO: Fix spec of `<=>`.
* Fix spec of `<=>` to use `synth-three-way-result`.

* Remove constraints on `operator==` and `operator<=>` for `indirect`.

## Changes in R11

Expand Down Expand Up @@ -867,12 +869,12 @@ class indirect {
template <class U, class AA>
friend constexpr auto operator<=>(
const indirect& lhs, const indirect<U, AA>& rhs) noexcept(see below)
-> compare_three_way_result_t<T, U>;
-> synth-three-way-result<T, U>;
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I thought we had previously made this change in the LWG session in Tokyo. This is want we want.


template <class U>
friend constexpr auto operator<=>(
const indirect& lhs, const U& rhs) noexcept(see below)
-> compare_three_way_result_t<T, U>;
-> synth-three-way-result<T, U>;

private:
pointer p; // exposition only
Expand Down Expand Up @@ -1215,21 +1217,17 @@ constexpr bool operator==(const indirect& lhs, const indirect<U, AA>& rhs)
noexcept(noexcept(*lhs == *rhs));
```

1. _Constraints_: `*lhs == *rhs` is well-formed and its result is convertible to bool.

2. _Returns_: If `lhs` is valueless or `rhs` is valueless,\
1. _Returns_: If `lhs` is valueless or `rhs` is valueless,\
`lhs.valueless_after_move() == rhs.valueless_after_move()`; otherwise `*lhs == *rhs`.

```c++
template <class U, class AA>
constexpr synth-three-way-result<T> operator<=>(const indirect& lhs,
constexpr synth-three-way-result<T, U> operator<=>(const indirect& lhs,
const indirect<U, AA>& rhs)
noexcept(noexcept(synth-three-way(*lhs, *rhs)));
```

3. _Constraints_: `*lhs <=> *rhs` is well-formed.

4. _Returns_: If `lhs` is valueless or `rhs` is valueless,\
2. _Returns_: If `lhs` is valueless or `rhs` is valueless,\
`!lhs.valueless_after_move() <=> !rhs.valueless_after_move()`; otherwise\
`synth-three-way(*lhs, *rhs)`.

Expand All @@ -1241,20 +1239,16 @@ constexpr bool operator==(const indirect& lhs, const U& rhs)
noexcept(noexcept(*lhs == rhs));
```

1. _Constraints_: `*lhs == rhs` is well-formed.

2. _Returns_: If `lhs` is valueless, false; otherwise `*lhs == rhs`.
1. _Returns_: If `lhs` is valueless, false; otherwise `*lhs == rhs`.

```c++
template <class U>
constexpr synth-three-way-result<T> operator<=>(const indirect& lhs,
constexpr synth-three-way-result<T, U> operator<=>(const indirect& lhs,
const U& rhs)
noexcept(noexcept(synth-three-way(*lhs, rhs)));
```

3. _Constraints_: `*lhs <=> rhs` is well-formed.

4. _Returns_: If `rhs` is valueless, `false < true`; otherwise `synth-three-way(*lhs, rhs)`.
2. _Returns_: If `rhs` is valueless, `false < true`; otherwise `synth-three-way(*lhs, rhs)`.

### X.Y.10 Hash support [indirect.hash]

Expand Down
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