Improve move semantics in Expected #4326
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This patch unconditionally moves an `Unexpected<U>` value parameter as long as `U` is not a reference. If `U` is a reference the code should not compile. An error type that holds a reference is a strange use-case, and an overload is not provided. If it is required in the future it can be added. The `Expected(U r)` overload should take a forwarding ref.
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I'm a little tempted to replace the |
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I did add a patch to replace Edit: Ugh, I just noticed how our automatic formatting screws that up. We might have to update our clang-format before we start using concepts. |
| typename = std::enable_if_t<std::is_convertible_v<U, T>>> | ||
| constexpr Expected(U r) : Base(T{std::forward<U>(r)}) | ||
| template <typename U> | ||
| requires std::convertible_to<U, T> constexpr Expected(U && r) |
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Huh. We really need to tune up clang-format for requires clauses. I think this would read way better as...
template <typename U>
requires std::convertible_to<U, T>
constexpr Expected(U&& r)
: Base(T{std::forward<U>(r)})
{
}
But we need to get a few test cases into the code base before we clean that up. Carry on...
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This is because we use clang 10 for formatting. When I use clang 15 is formats in a reasonable way. I hope we can update our clang format shortly. I also don't mind delaying this patch until after we update formatting.
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* Improve move semantics in Expected: This patch unconditionally moves an `Unexpected<U>` value parameter as long as `U` is not a reference. If `U` is a reference the code should not compile. An error type that holds a reference is a strange use-case, and an overload is not provided. If it is required in the future it can be added. The `Expected(U r)` overload should take a forwarding ref. * Replace enable_if with concepts in Expected
* Improve move semantics in Expected: This patch unconditionally moves an `Unexpected<U>` value parameter as long as `U` is not a reference. If `U` is a reference the code should not compile. An error type that holds a reference is a strange use-case, and an overload is not provided. If it is required in the future it can be added. The `Expected(U r)` overload should take a forwarding ref. * Replace enable_if with concepts in Expected
This patch unconditionally moves an
Unexpected<U>value parameter as long asUis not a reference. IfUis a reference the code should not compile. An error type that holds a reference is a strange use-case, and an overload is not provided. If it is required in the future it can be added.The
Expected(U r)overload should take a forwarding ref.