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merged 2 commits into from
Sep 30, 2025
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Define and use BSONCXX_PRIVATE_INLINE_CXX17 for inline variables #1468

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ea693e4
Define and use BSONCXX_PRIVATE_INLINE_CXX17 for inline variables
eramongodb Jun 6, 2025
f880a25
Reorder macros in declaration-dependent order for clarity
eramongodb Sep 29, 2025
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29 changes: 14 additions & 15 deletions src/bsoncxx/include/bsoncxx/v1/detail/compare.hpp
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Expand Up @@ -93,23 +93,22 @@ class strong_ordering {
#pragma pop_macro("DEFOP")

// nonstd: Swap greater/less values
constexpr strong_ordering inverted() const noexcept {
return *this < nullptr ? greater : *this > nullptr ? less : *this;
}
constexpr strong_ordering inverted() const noexcept;
};

#pragma push_macro("INLINE_VAR")
#undef INLINE_VAR
#define INLINE_VAR \
BSONCXX_PRIVATE_IF_GNU_LIKE([[gnu::weak]]) \
BSONCXX_PRIVATE_IF_MSVC(__declspec(selectany))

INLINE_VAR const strong_ordering strong_ordering::less = strong_ordering(strong_ordering::_construct{}, -1);
INLINE_VAR const strong_ordering strong_ordering::greater = strong_ordering(strong_ordering::_construct{}, 1);
INLINE_VAR const strong_ordering strong_ordering::equivalent = strong_ordering(strong_ordering::_construct{}, 0);
INLINE_VAR const strong_ordering strong_ordering::equal = strong_ordering(strong_ordering::_construct{}, 0);

#pragma pop_macro("INLINE_VAR")
BSONCXX_PRIVATE_INLINE_CXX17 strong_ordering const strong_ordering::less =
strong_ordering(strong_ordering::_construct{}, -1);
BSONCXX_PRIVATE_INLINE_CXX17 strong_ordering const strong_ordering::greater =
strong_ordering(strong_ordering::_construct{}, 1);
BSONCXX_PRIVATE_INLINE_CXX17 strong_ordering const strong_ordering::equivalent =
strong_ordering(strong_ordering::_construct{}, 0);
BSONCXX_PRIVATE_INLINE_CXX17 strong_ordering const strong_ordering::equal =
strong_ordering(strong_ordering::_construct{}, 0);

// Define out-of-line to avoid GCC error: ‘bsoncxx::detail::strong_ordering::*’ declared weak after being used
inline constexpr strong_ordering strong_ordering::inverted() const noexcept {
return *this < nullptr ? greater : *this > nullptr ? less : *this;
}

// Implements a three-way comparison between two objects. That is, in
// a single operation, determine whether the left operand is less-than, greater-than,
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25 changes: 25 additions & 0 deletions src/bsoncxx/include/bsoncxx/v1/detail/macros.hpp
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Expand Up @@ -107,6 +107,31 @@
#endif
// clang-format on

// Use this on variables that can only be inline in C++17 or newer, such as static constexpr data members.
//
// GCC does not allow __inline__ (even with __extension__) given -std=c++11 and -pedantic-errors (unconditional
// compilation error until GCC 12 which added -Wc++17-extensions suppression), but supports [[gnu::weak]] even with
// constant-evaluation and constant-folding on all currently-supported GCC versions (GCC 4.8.x and newer).
//
// Clang: does not allow using [[gnu::weak]] with constexpr, but supports __inline__ as a language extension even with
// -std=c++11 and -pedantic-errors via diagnostic suppression on all currently-supported Clang versions
// (-Wc++1z-extensions suppression since Clang 3.9 and -Wc++17-extensions suppression since Clang 5.0).
//
// MSVC: supports inline variables since 19.12 (with /std:c++latest), but behavior is broken for static data members
// (multiple definitions) until 19.20 even when __cpp_inline_variables is defined.
#if ( \
!defined(_MSC_VER) && \
(__cplusplus >= 201703L || (defined(__cpp_inline_variables) && __cpp_inline_variables >= 201606L))) || \
(defined(_MSC_VER) && _MSC_VER >= 1920 && defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
#define BSONCXX_PRIVATE_INLINE_CXX17 inline
#else
#define BSONCXX_PRIVATE_INLINE_CXX17 \
BSONCXX_PRIVATE_IF_GCC([[gnu::weak]]) \
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@kevinAlbs kevinAlbs Sep 29, 2025

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I expect this needs to be moved below where BSONCXX_PRIVATE_IF_GCC (and others) are defined below.

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@eramongodb eramongodb Sep 29, 2025

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This is not necessary due to BSONCXX_PRIVATE_IF_GCC(...) only being evaluated/substituted when BSONCXX_PRIVATE_INLINE_CXX17 is evaluated/substituted. So long as both macro definitions are visible at the point of substitution, the order does not matter. Nevertheless, moved them below as suggested to better match a typical declaration-dependent order.

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@kevinAlbs kevinAlbs Sep 30, 2025

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Doh right. Thank you for the example.

BSONCXX_PRIVATE_IF_CLANG(_Pragma("clang diagnostic push") _Pragma( \
"clang diagnostic ignored \"-Wc++17-extensions\"") __inline__ _Pragma("clang diagnostic pop")) \
BSONCXX_PRIVATE_IF_MSVC(__declspec(selectany))
#endif

// Disable a warning for a particular compiler.
//
// The argument should be of the form:
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1 change: 1 addition & 0 deletions src/bsoncxx/include/bsoncxx/v1/detail/postlude.hpp
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Expand Up @@ -51,6 +51,7 @@
#pragma pop_macro("BSONCXX_PRIVATE_IF_GCC")
#pragma pop_macro("BSONCXX_PRIVATE_IF_GNU_LIKE")
#pragma pop_macro("BSONCXX_PRIVATE_IF_MSVC")
#pragma pop_macro("BSONCXX_PRIVATE_INLINE_CXX17")
#pragma pop_macro("BSONCXX_PRIVATE_PRAGMA_IMPL")
#pragma pop_macro("BSONCXX_PRIVATE_PRAGMA")
#pragma pop_macro("BSONCXX_PRIVATE_RETURNS")
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2 changes: 2 additions & 0 deletions src/bsoncxx/include/bsoncxx/v1/detail/prelude.hpp
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Expand Up @@ -76,6 +76,8 @@
#undef BSONCXX_PRIVATE_IF_GNU_LIKE
#pragma push_macro("BSONCXX_PRIVATE_IF_MSVC")
#undef BSONCXX_PRIVATE_IF_MSVC
#pragma push_macro("BSONCXX_PRIVATE_INLINE_CXX17")
#undef BSONCXX_PRIVATE_INLINE_CXX17
#pragma push_macro("BSONCXX_PRIVATE_PRAGMA")
#undef BSONCXX_PRIVATE_PRAGMA
#pragma push_macro("BSONCXX_PRIVATE_PRAGMA_IMPL")
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4 changes: 3 additions & 1 deletion src/bsoncxx/include/bsoncxx/v1/oid.hpp
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Expand Up @@ -43,7 +43,7 @@ class oid {
///
/// The number of bytes required to represent an ObjectID.
///
static constexpr BSONCXX_ABI_EXPORT std::size_t k_oid_length = 12;
static constexpr std::size_t k_oid_length = 12;

private:
std::array<std::uint8_t, k_oid_length> _bytes;
Expand Down Expand Up @@ -198,6 +198,8 @@ class oid {
/* explicit(false) */ oid(for_overwrite_tag) : _bytes{} {}
};

BSONCXX_PRIVATE_INLINE_CXX17 constexpr std::size_t oid::k_oid_length;

} // namespace v1
} // namespace bsoncxx

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48 changes: 27 additions & 21 deletions src/bsoncxx/include/bsoncxx/v1/types/view.hpp
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Expand Up @@ -49,7 +49,7 @@ struct b_double {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_double;
static constexpr id type_id = id::k_double;

///
/// The represented value.
Expand Down Expand Up @@ -100,7 +100,7 @@ struct b_string {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_string;
static constexpr id type_id = id::k_string;

///
/// The represented value.
Expand Down Expand Up @@ -148,7 +148,7 @@ struct b_document {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_document;
static constexpr id type_id = id::k_document;

///
/// The represented value.
Expand Down Expand Up @@ -200,7 +200,7 @@ struct b_array {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_array;
static constexpr id type_id = id::k_array;

///
/// The represented value.
Expand Down Expand Up @@ -248,7 +248,7 @@ struct b_binary {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_binary;
static constexpr id type_id = id::k_binary;

///
/// The represented value's binary subtype component.
Expand Down Expand Up @@ -317,7 +317,7 @@ struct b_undefined {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_undefined;
static constexpr id type_id = id::k_undefined;

///
/// Return true.
Expand All @@ -343,7 +343,7 @@ struct b_oid {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_oid;
static constexpr id type_id = id::k_oid;

///
/// The represented value.
Expand Down Expand Up @@ -391,7 +391,7 @@ struct b_bool {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_bool;
static constexpr id type_id = id::k_bool;

///
/// The represented value.
Expand Down Expand Up @@ -439,7 +439,7 @@ struct b_date {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_date;
static constexpr id type_id = id::k_date;

///
/// The represented value (milliseconds relative to the Unix epoch).
Expand Down Expand Up @@ -498,7 +498,7 @@ struct b_null {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_null;
static constexpr id type_id = id::k_null;

///
/// Return true.
Expand All @@ -524,7 +524,7 @@ struct b_regex {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_regex;
static constexpr id type_id = id::k_regex;

///
/// The represented value's "pattern" component.
Expand Down Expand Up @@ -577,7 +577,7 @@ struct b_dbpointer {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_dbpointer;
static constexpr id type_id = id::k_dbpointer;

///
/// The represented value's "$ref" (namespace) component.
Expand Down Expand Up @@ -623,7 +623,7 @@ struct b_code {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_code;
static constexpr id type_id = id::k_code;

///
/// The represented value.
Expand Down Expand Up @@ -673,7 +673,7 @@ struct b_symbol {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_symbol;
static constexpr id type_id = id::k_symbol;

///
/// The represented value.
Expand Down Expand Up @@ -723,7 +723,7 @@ struct b_codewscope {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_codewscope;
static constexpr id type_id = id::k_codewscope;

///
/// The represented value's "$code" component.
Expand Down Expand Up @@ -769,7 +769,7 @@ struct b_int32 {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_int32;
static constexpr id type_id = id::k_int32;

///
/// The represented value.
Expand Down Expand Up @@ -817,7 +817,7 @@ struct b_timestamp {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_timestamp;
static constexpr id type_id = id::k_timestamp;

///
/// The represented value's "i" component.
Expand Down Expand Up @@ -863,7 +863,7 @@ struct b_int64 {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_int64;
static constexpr id type_id = id::k_int64;

///
/// The represented value.
Expand Down Expand Up @@ -911,7 +911,7 @@ struct b_decimal128 {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_decimal128;
static constexpr id type_id = id::k_decimal128;

///
/// The represented value.
Expand Down Expand Up @@ -959,7 +959,7 @@ struct b_maxkey {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_maxkey;
static constexpr id type_id = id::k_maxkey;

///
/// Return true.
Expand All @@ -985,7 +985,7 @@ struct b_minkey {
///
/// The type represented by this BSON type value.
///
static constexpr BSONCXX_ABI_EXPORT id type_id = id::k_minkey;
static constexpr id type_id = id::k_minkey;

///
/// Return true.
Expand All @@ -1004,6 +1004,12 @@ struct b_minkey {

// BSONCXX_V1_TYPES_XMACRO: update above.

#pragma push_macro("X")
#undef X
#define X(_name, _val) BSONCXX_PRIVATE_INLINE_CXX17 constexpr id b_##_name::type_id;
BSONCXX_V1_TYPES_XMACRO(X)
#pragma pop_macro("X")

///
/// A non-owning, read-only union of BSON type values.
///
Expand Down
4 changes: 3 additions & 1 deletion src/bsoncxx/include/bsoncxx/v_noabi/bsoncxx/oid.hpp
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Expand Up @@ -43,7 +43,7 @@ class oid {
v1::oid _oid;

public:
static constexpr BSONCXX_ABI_EXPORT std::size_t k_oid_length = v1::oid::k_oid_length;
static constexpr std::size_t k_oid_length = v1::oid::k_oid_length;

///
/// Constructs an oid and initializes it to a newly generated ObjectId.
Expand Down Expand Up @@ -165,6 +165,8 @@ class oid {
friend BSONCXX_ABI_EXPORT_CDECL(int) oid_compare(oid const& lhs, oid const& rhs);
};

BSONCXX_PRIVATE_INLINE_CXX17 constexpr std::size_t oid::k_oid_length;

///
/// Convert to the @ref bsoncxx::v_noabi equivalent of `v`.
///
Expand Down
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