- 0320844dcd8219965647f86db7c6c7296e40e41e Introduce internal macros for inline variable emulation s... by Matt Calabrese <calabrese@google.com> - 85197d0105805e6aab3a0a648351cb1582a61be0 Internal change. by Alex Strelnikov <strel@google.com> GitOrigin-RevId: 0320844dcd8219965647f86db7c6c7296e40e41e Change-Id: I7dce37f6839ff099462951059a9047c5c9377638pull/83/head
Abseil Team
7 years ago
committed by
John Olson
parent
dcf112f074
commit
cf1db73d2a
10 changed files with 285 additions and 11 deletions
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <type_traits> |
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#include "absl/base/internal/inline_variable.h" |
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#include "absl/base/internal/inline_variable_testing.h" |
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#include "gtest/gtest.h" |
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namespace absl { |
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namespace inline_variable_testing_internal { |
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namespace { |
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TEST(InlineVariableTest, Constexpr) { |
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static_assert(inline_variable_foo.value == 5, ""); |
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static_assert(other_inline_variable_foo.value == 5, ""); |
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static_assert(inline_variable_int == 5, ""); |
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static_assert(other_inline_variable_int == 5, ""); |
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} |
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TEST(InlineVariableTest, DefaultConstructedIdentityEquality) { |
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EXPECT_EQ(get_foo_a().value, 5); |
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EXPECT_EQ(get_foo_b().value, 5); |
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EXPECT_EQ(&get_foo_a(), &get_foo_b()); |
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} |
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TEST(InlineVariableTest, DefaultConstructedIdentityInequality) { |
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EXPECT_NE(&inline_variable_foo, &other_inline_variable_foo); |
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} |
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TEST(InlineVariableTest, InitializedIdentityEquality) { |
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EXPECT_EQ(get_int_a(), 5); |
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EXPECT_EQ(get_int_b(), 5); |
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EXPECT_EQ(&get_int_a(), &get_int_b()); |
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} |
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TEST(InlineVariableTest, InitializedIdentityInequality) { |
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EXPECT_NE(&inline_variable_int, &other_inline_variable_int); |
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} |
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TEST(InlineVariableTest, FunPtrType) { |
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static_assert( |
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std::is_same<void(*)(), |
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std::decay<decltype(inline_variable_fun_ptr)>::type>::value, |
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""); |
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} |
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} // namespace
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} // namespace inline_variable_testing_internal
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} // namespace absl
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/base/internal/inline_variable_testing.h" |
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namespace absl { |
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namespace inline_variable_testing_internal { |
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const Foo& get_foo_b() { return inline_variable_foo; } |
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const int& get_int_b() { return inline_variable_int; } |
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} // namespace inline_variable_testing_internal
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} // namespace absl
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_BASE_INTERNAL_INLINE_VARIABLE_EMULATION_H_ |
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#define ABSL_BASE_INTERNAL_INLINE_VARIABLE_EMULATION_H_ |
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#include <type_traits> |
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#include "absl/base/internal/identity.h" |
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// File:
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// This file define a macro that allows the creation of or emulation of C++17
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// inline variables based on whether or not the feature is supported.
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////////////////////////////////////////////////////////////////////////////////
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// Macro: ABSL_INTERNAL_INLINE_CONSTEXPR(type, name, init)
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//
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// Description:
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// Expands to the equivalent of an inline constexpr instance of the specified
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// `type` and `name`, initialized to the value `init`. If the compiler being
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// used is detected as supporting actual inline variables as a language
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// feature, then the macro expands to an actual inline variable definition.
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//
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// Requires:
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// `type` is a type that is usable in an extern variable declaration.
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//
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// Requires: `name` is a valid identifier
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//
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// Requires:
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// `init` is an expression that can be used in the following definition:
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// constexpr type name = init;
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//
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// Usage:
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//
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// // Equivalent to: `inline constexpr size_t variant_npos = -1;`
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// ABSL_INTERNAL_INLINE_CONSTEXPR(size_t, variant_npos, -1);
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//
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// Differences in implementation:
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// For a direct, language-level inline variable, decltype(name) will be the
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// type that was specified along with const qualification, whereas for
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// emulated inline variables, decltype(name) may be different (in practice
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// it will likely be a reference type).
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////////////////////////////////////////////////////////////////////////////////
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#ifdef __cpp_inline_variables |
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// Clang's -Wmissing-variable-declarations option erroneously warned that
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// inline constexpr objects need to be pre-declared. This has now been fixed,
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// but we will need to support this workaround for people building with older
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// versions of clang.
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//
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// Bug: https://bugs.llvm.org/show_bug.cgi?id=35862
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//
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// Note:
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// identity_t is used here so that the const and name are in the
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// appropriate place for pointer types, reference types, function pointer
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// types, etc..
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#if defined(__clang__) |
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#define ABSL_INTERNAL_EXTERN_DECL(type, name) \ |
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extern const ::absl::internal::identity_t<type> name; |
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#else // Otherwise, just define the macro to do nothing.
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#define ABSL_INTERNAL_EXTERN_DECL(type, name) |
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#endif // defined(__clang__)
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// See above comment at top of file for details.
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#define ABSL_INTERNAL_INLINE_CONSTEXPR(type, name, init) \ |
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ABSL_INTERNAL_EXTERN_DECL(type, name) \
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inline constexpr ::absl::internal::identity_t<type> name = init |
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#else |
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// See above comment at top of file for details.
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//
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// Note:
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// identity_t is used here so that the const and name are in the
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// appropriate place for pointer types, reference types, function pointer
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// types, etc..
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#define ABSL_INTERNAL_INLINE_CONSTEXPR(var_type, name, init) \ |
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template <class /*AbslInternalDummy*/ = void> \
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struct AbslInternalInlineVariableHolder##name { \
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static constexpr ::absl::internal::identity_t<var_type> kInstance = init; \
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}; \
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\
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template <class AbslInternalDummy> \
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constexpr ::absl::internal::identity_t<var_type> \
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AbslInternalInlineVariableHolder##name<AbslInternalDummy>::kInstance; \
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\
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static constexpr const ::absl::internal::identity_t<var_type>& \
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name = /* NOLINT */ \
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AbslInternalInlineVariableHolder##name<>::kInstance; \
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static_assert(sizeof(void (*)(decltype(name))) != 0, \
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"Silence unused variable warnings.") |
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#endif // __cpp_inline_variables
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#endif // ABSL_BASE_INTERNAL_INLINE_VARIABLE_EMULATION_H_
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_BASE_INLINE_VARIABLE_TESTING_H_ |
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#define ABSL_BASE_INLINE_VARIABLE_TESTING_H_ |
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#include "absl/base/internal/inline_variable.h" |
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namespace absl { |
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namespace inline_variable_testing_internal { |
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struct Foo { |
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int value = 5; |
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}; |
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ABSL_INTERNAL_INLINE_CONSTEXPR(Foo, inline_variable_foo, {}); |
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ABSL_INTERNAL_INLINE_CONSTEXPR(Foo, other_inline_variable_foo, {}); |
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ABSL_INTERNAL_INLINE_CONSTEXPR(int, inline_variable_int, 5); |
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ABSL_INTERNAL_INLINE_CONSTEXPR(int, other_inline_variable_int, 5); |
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ABSL_INTERNAL_INLINE_CONSTEXPR(void(*)(), inline_variable_fun_ptr, nullptr); |
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const Foo& get_foo_a(); |
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const Foo& get_foo_b(); |
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const int& get_int_a(); |
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const int& get_int_b(); |
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} // namespace inline_variable_testing_internal
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} // namespace absl
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#endif // ABSL_BASE_INLINE_VARIABLE_TESTING_H_
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