diff --git a/src/attributes.h b/src/attributes.h index 45099bd8b8802..9d5c1d44a04c5 100644 --- a/src/attributes.h +++ b/src/attributes.h @@ -19,4 +19,14 @@ # endif #endif +#if defined(__clang__) +# if __has_attribute(lifetimebound) +# define LIFETIMEBOUND [[clang::lifetimebound]] +# else +# define LIFETIMEBOUND +# endif +#else +# define LIFETIMEBOUND +#endif + #endif // BITCOIN_ATTRIBUTES_H diff --git a/src/span.h b/src/span.h index 744845676ea14..88a078e902ead 100644 --- a/src/span.h +++ b/src/span.h @@ -18,6 +18,16 @@ #define ASSERT_IF_DEBUG(x) #endif +#if defined(__clang__) +#if __has_attribute(lifetimebound) +#define SPAN_ATTR_LIFETIMEBOUND [[clang::lifetimebound]] +#else +#define SPAN_ATTR_LIFETIMEBOUND +#endif +#else +#define SPAN_ATTR_LIFETIMEBOUND +#endif + /** A Span is an object that can refer to a contiguous sequence of objects. * * It implements a subset of C++20's std::span. @@ -28,6 +38,14 @@ class Span C* m_data; std::size_t m_size; + template + struct is_Span_int : public std::false_type {}; + template + struct is_Span_int> : public std::true_type {}; + template + struct is_Span : public is_Span_int::type>{}; + + public: constexpr Span() noexcept : m_data(nullptr), m_size(0) {} @@ -78,8 +96,19 @@ class Span * To prevent surprises, only Spans for constant value types are supported when passing in temporaries. * Note that this restriction does not exist when converting arrays or other Spans (see above). */ - template ::value || std::is_lvalue_reference::value) && std::is_convertible().data())>::type (*)[], C (*)[]>::value && std::is_convertible().size()), std::size_t>::value, int>::type = 0> - constexpr Span(V&& v) noexcept : m_data(v.data()), m_size(v.size()) {} + template + constexpr Span(V& other SPAN_ATTR_LIFETIMEBOUND, + typename std::enable_if::value && + std::is_convertible().data())>::type (*)[], C (*)[]>::value && + std::is_convertible().size()), std::size_t>::value, std::nullptr_t>::type = nullptr) + : m_data(other.data()), m_size(other.size()){} + + template + constexpr Span(const V& other SPAN_ATTR_LIFETIMEBOUND, + typename std::enable_if::value && + std::is_convertible().data())>::type (*)[], C (*)[]>::value && + std::is_convertible().size()), std::size_t>::value, std::nullptr_t>::type = nullptr) + : m_data(other.data()), m_size(other.size()){} constexpr C* data() const noexcept { return m_data; } constexpr C* begin() const noexcept { return m_data; } @@ -135,9 +164,9 @@ class Span /** MakeSpan for arrays: */ template Span constexpr MakeSpan(A (&a)[N]) { return Span(a, N); } /** MakeSpan for temporaries / rvalue references, only supporting const output. */ -template constexpr auto MakeSpan(V&& v) -> typename std::enable_if::value, Span::type>>::type { return std::forward(v); } +template constexpr auto MakeSpan(V&& v SPAN_ATTR_LIFETIMEBOUND) -> typename std::enable_if::value, Span::type>>::type { return std::forward(v); } /** MakeSpan for (lvalue) references, supporting mutable output. */ -template constexpr auto MakeSpan(V& v) -> Span::type> { return v; } +template constexpr auto MakeSpan(V& v SPAN_ATTR_LIFETIMEBOUND) -> Span::type> { return v; } /** Pop the last element off a span, and return a reference to that element. */ template