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Enable PROTOBUF_EXPORT/PROTOBUF_USE_DLL on clang/gcc

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m0hamed authored and acozzette committed Aug 19, 2019
1 parent 5102df2 commit f74b56007249e6c542b00e616eab1f058cf70aed
@@ -331,22 +331,195 @@
reinterpret_cast<const char*>(16))
#endif

#if defined(_MSC_VER) && defined(PROTOBUF_USE_DLLS)
#ifdef LIBPROTOBUF_EXPORTS
#define PROTOBUF_EXPORT __declspec(dllexport)
#else
#define PROTOBUF_EXPORT __declspec(dllimport)
#endif
#ifdef LIBPROTOC_EXPORTS
#define PROTOC_EXPORT __declspec(dllexport)
#else
#define PROTOC_EXPORT __declspec(dllimport)
#endif
#else
#define PROTOBUF_EXPORT
#define PROTOC_EXPORT
#if defined(PROTOBUF_USE_DLLS)
#if defined(_MSC_VER)
#ifdef LIBPROTOBUF_EXPORTS
#define PROTOBUF_EXPORT __declspec(dllexport)
#else
#define PROTOBUF_EXPORT __declspec(dllimport)
#endif
#ifdef LIBPROTOC_EXPORTS
#define PROTOC_EXPORT __declspec(dllexport)
#else
#define PROTOC_EXPORT __declspec(dllimport)
#endif
#else // defined(_MSC_VER)
#ifdef LIBPROTOBUF_EXPORTS
#define PROTOBUF_EXPORT __attribute__((visibility("default")))
#else
#define PROTOBUF_EXPORT
#endif
#ifdef LIBPROTOC_EXPORTS
#define PROTOC_EXPORT __attribute__((visibility("default")))
#else
#define PROTOC_EXPORT
#endif
#endif
#else // defined(PROTOBUF_USE_DLLS)
#define PROTOBUF_EXPORT
#define PROTOC_EXPORT
#endif


// This portion provides macros for using FOO_EXPORT macros with explicit
// template instantiation declarations and definitions.
// Generally, the FOO_EXPORT macros are used at declarations,
// and GCC requires them to be used at explicit instantiation declarations,
// but MSVC requires __declspec(dllexport) to be used at the explicit
// instantiation definitions instead.

// Usage
//
// In a header file, write:
//
// extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(FOO_EXPORT) foo<bar>;
//
// In a source file, write:
//
// template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(FOO_EXPORT) foo<bar>;
//
// Where FOO_EXPORT is either PROTOBUF_EXPORT or PROTOC_EXPORT

// Implementation notes
//
// The implementation of these macros uses some subtle macro semantics to
// detect what the provided FOO_EXPORT value was defined as and then
// to dispatch to appropriate macro definitions. Unfortunately,
// MSVC's C preprocessor is rather non-compliant and requires special
// care to make it work.
//
// Issue 1.
//
// #define F(x)
// F()
//
// MSVC emits warning C4003 ("not enough actual parameters for macro
// 'F'), even though it's a valid macro invocation. This affects the
// macros below that take just an "export" parameter, because export
// may be empty.
//
// As a workaround, we can add a dummy parameter and arguments:
//
// #define F(x,_)
// F(,)
//
// Issue 2.
//
// #define F(x) G##x
// #define Gj() ok
// F(j())
//
// The correct replacement for "F(j())" is "ok", but MSVC replaces it
// with "Gj()". As a workaround, we can pass the result to an
// identity macro to force MSVC to look for replacements again. (This
// is why PROTOBUF_EXPORT_TEMPLATE_STYLE_3 exists.)

#define PROTOBUF_EXPORT_TEMPLATE_DECLARE(export) \
PROTOBUF_EXPORT_TEMPLATE_INVOKE( \
DECLARE, PROTOBUF_EXPORT_TEMPLATE_STYLE(export, ), export)
#define PROTOBUF_EXPORT_TEMPLATE_DEFINE(export) \
PROTOBUF_EXPORT_TEMPLATE_INVOKE( \
DEFINE, PROTOBUF_EXPORT_TEMPLATE_STYLE(export, ), export)

// INVOKE is an internal helper macro to perform parameter replacements
// and token pasting to chain invoke another macro. E.g.,
// PROTOBUF_EXPORT_TEMPLATE_INVOKE(DECLARE, DEFAULT, FOO_EXPORT)
// will export to call
// PROTOBUF_EXPORT_TEMPLATE_DECLARE_DEFAULT(FOO_EXPORT, )
// (but with FOO_EXPORT expanded too).
#define PROTOBUF_EXPORT_TEMPLATE_INVOKE(which, style, export) \
PROTOBUF_EXPORT_TEMPLATE_INVOKE_2(which, style, export)
#define PROTOBUF_EXPORT_TEMPLATE_INVOKE_2(which, style, export) \
PROTOBUF_EXPORT_TEMPLATE_##which##_##style(export, )

// Default style is to apply the FOO_EXPORT macro at declaration sites.
#define PROTOBUF_EXPORT_TEMPLATE_DECLARE_DEFAULT(export, _) export
#define PROTOBUF_EXPORT_TEMPLATE_DEFINE_DEFAULT(export, _)

// The "MSVC hack" style is used when FOO_EXPORT is defined
// as __declspec(dllexport), which MSVC requires to be used at
// definition sites instead.
#define PROTOBUF_EXPORT_TEMPLATE_DECLARE_MSVC_HACK(export, _)
#define PROTOBUF_EXPORT_TEMPLATE_DEFINE_MSVC_HACK(export, _) export

// PROTOBUF_EXPORT_TEMPLATE_STYLE is an internal helper macro that identifies
// which export style needs to be used for the provided FOO_EXPORT macro
// definition. "", "__attribute__(...)", and "__declspec(dllimport)" are
// mapped to "DEFAULT"; while "__declspec(dllexport)" is mapped to "MSVC_HACK".
//
// It's implemented with token pasting to transform the __attribute__ and
// __declspec annotations into macro invocations. E.g., if FOO_EXPORT is
// defined as "__declspec(dllimport)", it undergoes the following sequence of
// macro substitutions:
// PROTOBUF_EXPORT_TEMPLATE_STYLE(FOO_EXPORT, )
// PROTOBUF_EXPORT_TEMPLATE_STYLE_2(__declspec(dllimport), )
// PROTOBUF_EXPORT_TEMPLATE_STYLE_3(
// PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH__declspec(dllimport))
// PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH__declspec(dllimport)
// PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_DECLSPEC_dllimport
// DEFAULT
#define PROTOBUF_EXPORT_TEMPLATE_STYLE(export, _) \
PROTOBUF_EXPORT_TEMPLATE_STYLE_2(export, )
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_2(export, _) \
PROTOBUF_EXPORT_TEMPLATE_STYLE_3( \
PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA##export)
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_3(style) style

// Internal helper macros for PROTOBUF_EXPORT_TEMPLATE_STYLE.
//
// XXX: C++ reserves all identifiers containing "__" for the implementation,
// but "__attribute__" and "__declspec" already contain "__" and the token-paste
// operator can only add characters; not remove them. To minimize the risk of
// conflict with implementations, we include "foj3FJo5StF0OvIzl7oMxA" (a random
// 128-bit string, encoded in Base64) in the macro name.
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA DEFAULT
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA__attribute__(...) \
DEFAULT
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA__declspec(arg) \
PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_DECLSPEC_##arg

// Internal helper macros for PROTOBUF_EXPORT_TEMPLATE_STYLE.
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_DECLSPEC_dllexport MSVC_HACK
#define PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_DECLSPEC_dllimport DEFAULT

// Sanity checks.
//
// PROTOBUF_EXPORT_TEMPLATE_TEST uses the same macro invocation pattern as
// PROTOBUF_EXPORT_TEMPLATE_DECLARE and PROTOBUF_EXPORT_TEMPLATE_DEFINE do to
// check that they're working correctly. When they're working correctly, the
// sequence of macro replacements should go something like:
//
// PROTOBUF_EXPORT_TEMPLATE_TEST(DEFAULT, __declspec(dllimport));
//
// static_assert(PROTOBUF_EXPORT_TEMPLATE_INVOKE(TEST_DEFAULT,
// PROTOBUF_EXPORT_TEMPLATE_STYLE(__declspec(dllimport), ),
// __declspec(dllimport)), "__declspec(dllimport)");
//
// static_assert(PROTOBUF_EXPORT_TEMPLATE_INVOKE(TEST_DEFAULT,
// DEFAULT, __declspec(dllimport)), "__declspec(dllimport)");
//
// static_assert(PROTOBUF_EXPORT_TEMPLATE_TEST_DEFAULT_DEFAULT(
// __declspec(dllimport)), "__declspec(dllimport)");
//
// static_assert(true, "__declspec(dllimport)");
//
// When they're not working correctly, a syntax error should occur instead.
#define PROTOBUF_EXPORT_TEMPLATE_TEST(want, export) \
static_assert(PROTOBUF_EXPORT_TEMPLATE_INVOKE( \
TEST_##want, PROTOBUF_EXPORT_TEMPLATE_STYLE(export, ), \
export), #export)
#define PROTOBUF_EXPORT_TEMPLATE_TEST_DEFAULT_DEFAULT(...) true
#define PROTOBUF_EXPORT_TEMPLATE_TEST_MSVC_HACK_MSVC_HACK(...) true

PROTOBUF_EXPORT_TEMPLATE_TEST(DEFAULT, );
PROTOBUF_EXPORT_TEMPLATE_TEST(DEFAULT, __attribute__((visibility("default"))));
PROTOBUF_EXPORT_TEMPLATE_TEST(MSVC_HACK, __declspec(dllexport));
PROTOBUF_EXPORT_TEMPLATE_TEST(DEFAULT, __declspec(dllimport));

#undef PROTOBUF_EXPORT_TEMPLATE_TEST
#undef PROTOBUF_EXPORT_TEMPLATE_TEST_DEFAULT_DEFAULT
#undef PROTOBUF_EXPORT_TEMPLATE_TEST_MSVC_HACK_MSVC_HACK

// Windows declares several inconvenient macro names. We #undef them and then
// restore them in port_undef.inc.
#ifdef _MSC_VER
@@ -65,6 +65,22 @@
#undef PROTOBUF_NAMESPACE_CLOSE
#undef PROTOBUF_UNUSED
#undef PROTOBUF_ASSUME
#undef PROTOBUF_EXPORT_TEMPLATE_DECLARE
#undef PROTOBUF_EXPORT_TEMPLATE_DEFINE
#undef PROTOBUF_EXPORT_TEMPLATE_INVOKE
#undef PROTOBUF_EXPORT_TEMPLATE_INVOKE_2
#undef PROTOBUF_EXPORT_TEMPLATE_DECLARE_DEFAULT
#undef PROTOBUF_EXPORT_TEMPLATE_DEFINE_DEFAULT
#undef PROTOBUF_EXPORT_TEMPLATE_DECLARE_MSVC_HACK
#undef PROTOBUF_EXPORT_TEMPLATE_DEFINE_MSVC_HACK
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_2
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_3
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA__attribute__
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_foj3FJo5StF0OvIzl7oMxA__declspec
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_DECLSPEC_dllexport
#undef PROTOBUF_EXPORT_TEMPLATE_STYLE_MATCH_DECLSPEC_dllimport

// Restore macro that may have been #undef'd in port_def.inc.
#ifdef _MSC_VER
@@ -122,15 +122,22 @@ MessageLite* RepeatedPtrFieldBase::AddWeak(const MessageLite* prototype) {

} // namespace internal


template class PROTOBUF_EXPORT RepeatedField<bool>;
template class PROTOBUF_EXPORT RepeatedField<int32>;
template class PROTOBUF_EXPORT RepeatedField<uint32>;
template class PROTOBUF_EXPORT RepeatedField<int64>;
template class PROTOBUF_EXPORT RepeatedField<uint64>;
template class PROTOBUF_EXPORT RepeatedField<float>;
template class PROTOBUF_EXPORT RepeatedField<double>;
template class PROTOBUF_EXPORT RepeatedPtrField<std::string>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<bool>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<int32>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<uint32>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<int64>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<uint64>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<float>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedField<double>;
template class PROTOBUF_EXPORT_TEMPLATE_DEFINE(PROTOBUF_EXPORT)
RepeatedPtrField<std::string>;

} // namespace protobuf
} // namespace google
@@ -2655,14 +2655,22 @@ UnsafeArenaAllocatedRepeatedPtrFieldBackInserter(
}

// Extern declarations of common instantiations to reduce libray bloat.
extern template class PROTOBUF_EXPORT RepeatedField<bool>;
extern template class PROTOBUF_EXPORT RepeatedField<int32>;
extern template class PROTOBUF_EXPORT RepeatedField<uint32>;
extern template class PROTOBUF_EXPORT RepeatedField<int64>;
extern template class PROTOBUF_EXPORT RepeatedField<uint64>;
extern template class PROTOBUF_EXPORT RepeatedField<float>;
extern template class PROTOBUF_EXPORT RepeatedField<double>;
extern template class PROTOBUF_EXPORT RepeatedPtrField<std::string>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<bool>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<int32>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<uint32>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<int64>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<uint64>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<float>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedField<double>;
extern template class PROTOBUF_EXPORT_TEMPLATE_DECLARE(PROTOBUF_EXPORT)
RepeatedPtrField<std::string>;

} // namespace protobuf
} // namespace google

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