blob: 9d1a6fb7e38867f41538bc04126b6f1427cd5698 [file] [log] [blame]
diff --git a/src/google/protobuf/port_def.inc b/src/google/protobuf/port_def.inc
index afd7f0ed..cbd130e6 100644
--- a/src/google/protobuf/port_def.inc
+++ b/src/google/protobuf/port_def.inc
@@ -347,6 +347,165 @@
#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
diff --git a/src/google/protobuf/port_undef.inc b/src/google/protobuf/port_undef.inc
index 7df776b5..b7e67fe4 100644
--- a/src/google/protobuf/port_undef.inc
+++ b/src/google/protobuf/port_undef.inc
@@ -64,6 +64,24 @@
#undef PROTOBUF_NAMESPACE_OPEN
#undef PROTOBUF_NAMESPACE_CLOSE
#undef PROTOBUF_UNUSED
+#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
diff --git a/src/google/protobuf/repeated_field.h b/src/google/protobuf/repeated_field.h
index fb8301bf..7c96ce71 100644
--- a/src/google/protobuf/repeated_field.cc
+++ b/src/google/protobuf/repeated_field.cc
@@ -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
diff --git a/src/google/protobuf/repeated_field.h b/src/google/protobuf/repeated_field.h
index fb8301bf..205c529b 100644
--- a/src/google/protobuf/repeated_field.h
+++ b/src/google/protobuf/repeated_field.h
@@ -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