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Fix set_value template deduction for smart string types #633

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Fix set_value template deduction for smart string types #633

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2391e6f
Fix set_value template deduction for smart string types
Apr 21, 2026
d783f27
Refactor set_value_type to use struct template with remove_cv_t
Apr 22, 2026
851030a
Merge branch 'master' into fix-set-value-type-const-deduction
dunhor May 1, 2026
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88 changes: 47 additions & 41 deletions include/wil/registry_helpers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -925,10 +925,16 @@ namespace reg
static_assert(!wistd::is_same_v<T, T>, "Unsupported type for get_value_type");
}

template <typename T = void>
DWORD set_value_type() WI_NOEXCEPT
template <typename T>
struct set_value_type_t
{
static_assert(!wistd::is_same_v<T, T>, "Unsupported type for set_value_type");
};

template <typename T>
constexpr DWORD set_value_type() WI_NOEXCEPT
{
return set_value_type_t<wistd::remove_cv_t<T>>::value;
}

template <>
Expand All @@ -937,76 +943,76 @@ namespace reg
return get_value_flags_from_value_type(REG_DWORD);
}
template <>
constexpr DWORD set_value_type<int32_t>() WI_NOEXCEPT
struct set_value_type_t<int32_t>
{
return REG_DWORD;
}
static constexpr DWORD value = REG_DWORD;
};

template <>
constexpr DWORD get_value_type<uint32_t>() WI_NOEXCEPT
{
return get_value_flags_from_value_type(REG_DWORD);
}
template <>
constexpr DWORD set_value_type<uint32_t>() WI_NOEXCEPT
struct set_value_type_t<uint32_t>
{
return REG_DWORD;
}
static constexpr DWORD value = REG_DWORD;
};

template <>
constexpr DWORD get_value_type<long>() WI_NOEXCEPT
{
return get_value_flags_from_value_type(REG_DWORD);
}
template <>
constexpr DWORD set_value_type<long>() WI_NOEXCEPT
struct set_value_type_t<long>
{
return REG_DWORD;
}
static constexpr DWORD value = REG_DWORD;
};

template <>
constexpr DWORD get_value_type<unsigned long>() WI_NOEXCEPT
{
return get_value_flags_from_value_type(REG_DWORD);
}
template <>
constexpr DWORD set_value_type<unsigned long>() WI_NOEXCEPT
struct set_value_type_t<unsigned long>
{
return REG_DWORD;
}
static constexpr DWORD value = REG_DWORD;
};

template <>
constexpr DWORD get_value_type<int64_t>() WI_NOEXCEPT
{
return get_value_flags_from_value_type(REG_QWORD);
}
template <>
constexpr DWORD set_value_type<int64_t>() WI_NOEXCEPT
struct set_value_type_t<int64_t>
{
return REG_QWORD;
}
static constexpr DWORD value = REG_QWORD;
};

template <>
constexpr DWORD get_value_type<uint64_t>() WI_NOEXCEPT
{
return get_value_flags_from_value_type(REG_QWORD);
}
template <>
constexpr DWORD set_value_type<uint64_t>() WI_NOEXCEPT
struct set_value_type_t<uint64_t>
{
return REG_QWORD;
}
static constexpr DWORD value = REG_QWORD;
};

template <>
constexpr DWORD get_value_type<PCWSTR>() WI_NOEXCEPT
{
return get_value_flags_from_value_type(REG_SZ);
}
template <>
constexpr DWORD set_value_type<PCWSTR>() WI_NOEXCEPT
struct set_value_type_t<PCWSTR>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};

#if (WIL_USE_STL && defined(WIL_ENABLE_EXCEPTIONS)) || defined(WIL_DOXYGEN)
template <>
Expand All @@ -1016,10 +1022,10 @@ namespace reg
}

template <>
constexpr DWORD set_value_type<const ::std::wstring>() WI_NOEXCEPT
struct set_value_type_t<::std::wstring>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};
#endif

#if defined(__WIL_OLEAUTO_H_)
Expand All @@ -1035,16 +1041,16 @@ namespace reg
}

template <>
constexpr DWORD set_value_type<const BSTR>() WI_NOEXCEPT
struct set_value_type_t<BSTR>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};

template <>
constexpr DWORD set_value_type<const ::wil::unique_bstr>() WI_NOEXCEPT
struct set_value_type_t<::wil::unique_bstr>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};
#endif // #if defined(__WIL_OLEAUTO_H_)

#if defined(__WIL_OLEAUTO_H_STL)
Expand All @@ -1056,10 +1062,10 @@ namespace reg
}

template <>
constexpr DWORD set_value_type<const ::wil::shared_bstr>() WI_NOEXCEPT
struct set_value_type_t<::wil::shared_bstr>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};
#endif // #if defined(__WIL_OLEAUTO_H_STL)

#if defined(__WIL_OBJBASE_H_)
Expand All @@ -1070,10 +1076,10 @@ namespace reg
}

template <>
constexpr DWORD set_value_type<const ::wil::unique_cotaskmem_string>() WI_NOEXCEPT
struct set_value_type_t<::wil::unique_cotaskmem_string>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};
#endif // defined(__WIL_OBJBASE_H_)

#if defined(__WIL_OBJBASE_H_STL)
Expand All @@ -1084,10 +1090,10 @@ namespace reg
}

template <>
constexpr DWORD set_value_type<const ::wil::shared_cotaskmem_string>() WI_NOEXCEPT
struct set_value_type_t<::wil::shared_cotaskmem_string>
{
return REG_SZ;
}
static constexpr DWORD value = REG_SZ;
};
#endif // #if defined(__WIL_OBJBASE_H_STL)
} // namespace reg_value_type_info

Expand Down
37 changes: 37 additions & 0 deletions tests/RegistryTests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2272,6 +2272,43 @@ TEST_CASE("BasicRegistryTests::string types", "[registry]")
#endif
}

SECTION("strings set_value with std::wstring lvalue: with opened key")
{
wil::unique_hkey hkey;
REQUIRE_SUCCEEDED(wil::reg::create_unique_key_nothrow(HKEY_CURRENT_USER, testSubkey, hkey, wil::reg::key_access::readwrite));

// verify non-const std::wstring lvalue works with set_value (issue #624)
std::wstring stringValue{L"wstring lvalue test"};
wil::reg::set_value(hkey.get(), stringValueName, stringValue);
auto result = wil::reg::get_value<std::wstring>(hkey.get(), stringValueName);
REQUIRE(result == stringValue);

// verify const std::wstring lvalue also works
const std::wstring constStringValue{L"const wstring test"};
wil::reg::set_value(hkey.get(), stringValueName, constStringValue);
result = wil::reg::get_value<std::wstring>(hkey.get(), stringValueName);
REQUIRE(result == constStringValue);

// verify empty std::wstring
std::wstring emptyValue;
wil::reg::set_value(hkey.get(), stringValueName, emptyValue);
result = wil::reg::get_value<std::wstring>(hkey.get(), stringValueName);
REQUIRE(result.empty());
}

SECTION("strings set_value with std::wstring lvalue: with string key")
{
std::wstring stringValue{L"wstring lvalue subkey test"};
wil::reg::set_value(HKEY_CURRENT_USER, testSubkey, stringValueName, stringValue);
auto result = wil::reg::get_value<std::wstring>(HKEY_CURRENT_USER, testSubkey, stringValueName);
REQUIRE(result == stringValue);

const std::wstring constStringValue{L"const wstring subkey test"};
wil::reg::set_value(HKEY_CURRENT_USER, testSubkey, stringValueName, constStringValue);
result = wil::reg::get_value<std::wstring>(HKEY_CURRENT_USER, testSubkey, stringValueName);
REQUIRE(result == constStringValue);
}

#if defined(__cpp_lib_optional)
SECTION("strings set_value_string/try_get_value_string: with open key")
{
Expand Down
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