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Fix classic COM errors on non-supported compilers #1194

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Merged
kennykerr merged 2 commits into from
Oct 7, 2022
Merged

Fix classic COM errors on non-supported compilers #1194

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14ca018
Fix classic COM errors on non-supported compilers
sylveon Oct 1, 2022
16ab08b
Bring back the ability to use guid_v when unknwn.h is included after …
sylveon Oct 6, 2022
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27 changes: 19 additions & 8 deletions strings/base_meta.h
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Original file line number Diff line number Diff line change
Expand Up @@ -117,22 +117,33 @@ namespace winrt::impl
static constexpr auto data{ category_signature<category_t<T>, T>::data };
};

#if defined(__clang__)
template <typename T>
struct classic_com_guid
struct classic_com_guid_error
{
#if __has_declspec_attribute(uuid) && defined(WINRT_IMPL_IUNKNOWN_DEFINED)
static constexpr guid value{ __uuidof(T) };
#else
static_assert(std::is_void_v<T> /* dependent_false */, "To use classic COM interfaces, you must compile with -fms-extensions and include <unknwn.h> before including C++/WinRT headers.");
#ifdef __clang__
#if !__has_declspec_attribute(uuid)
static_assert(std::is_void_v<T> /* dependent_false */, "To use classic COM interfaces, you must compile with -fms-extensions.");
#endif

#ifndef WINRT_IMPL_IUNKNOWN_DEFINED
static_assert(std::is_void_v<T> /* dependent_false */, "To use classic COM interfaces, you must include <unknwn.h> before including C++/WinRT headers.");
#endif
#else // MSVC won't hit this struct, so we can safely assume everything that isn't Clang isn't supported
static_assert(std::is_void_v<T> /* dependent_false */, "Classic COM interfaces are not supported with this compiler.");
#endif
};

template <typename T>
inline constexpr guid guid_v = classic_com_guid<T>::value;
#ifdef __clang__
#if __has_declspec_attribute(uuid) && defined(WINRT_IMPL_IUNKNOWN_DEFINED)
inline constexpr guid guid_v{ __uuidof(T) };
#else
template <typename T>
inline constexpr guid guid_v = classic_com_guid_error<T>::value;
#endif
#elif defined(_MSC_VER)
inline constexpr guid guid_v{ __uuidof(T) };
#else
inline constexpr guid guid_v = classic_com_guid_error<T>::value;
#endif

template <typename T>
Expand Down