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Add enum types to what is captured by value by default
As it turns out, enums can be used to declare bitfields, and we cannot form a reference to a bitfield in the cpature. Thus, we add `std::is_enum` as a criteria to the default for `capture_by_value`, so that enum-based bitfields are also captured by value and thus decomposable. Closes #3001
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@@ -78,10 +78,11 @@
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*
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* 3) If a type has no linkage, we also cannot capture it by reference.
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* The solution is once again to capture them by value. We handle
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* the common cases by using `std::is_arithmetic` as the default
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* for `Catch::capture_by_value`, but that is only a some-effort
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* heuristic. But as with 2), users can specialize `capture_by_value`
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* for their own types as needed.
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* the common cases by using `std::is_arithmetic` and `std::is_enum`
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* as the default for `Catch::capture_by_value`, but that is only a
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* some-effort heuristic. These combine to capture all possible bitfield
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* bases, and also some trait-like types. As with 2), users can
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* specialize `capture_by_value` for their own types as needed.
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*
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* 4) To support C++20 and make the SFINAE on our decomposing operators
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* work, the SFINAE has to happen in return type, rather than in
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@@ -133,13 +134,22 @@ namespace Catch {
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using RemoveCVRef_t = std::remove_cv_t<std::remove_reference_t<T>>;
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}
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// Note: There is nothing that stops us from extending this,
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// e.g. to `std::is_scalar`, but the more encompassing
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// traits are usually also more expensive. For now we
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// keep this as it used to be and it can be changed later.
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// Note: This is about as much as we can currently reasonably support.
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// In an ideal world, we could capture by value small trivially
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// copyable types, but the actual `std::is_trivially_copyable`
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// trait is a huge mess with standard-violating results on
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// GCC and Clang, which are unlikely to be fixed soon due to ABI
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// concerns.
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// `std::is_scalar` also causes issues due to the `is_pointer`
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// component, which causes ambiguity issues with (references-to)
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// function pointer. If those are resolved, we still need to
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// disambiguate the overload set for arrays, through explicit
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// overload for references to sized arrays.
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template <typename T>
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struct capture_by_value
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: std::integral_constant<bool, std::is_arithmetic<T>{}> {};
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: std::integral_constant<bool,
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std::is_arithmetic<T>::value ||
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std::is_enum<T>::value> {};
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#if defined( CATCH_CONFIG_CPP20_COMPARE_OVERLOADS )
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template <>
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