From c5c4db4f5191fe5e76cbf68dcc71fb28702f7d2b Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Mon, 5 Aug 2019 11:32:04 -0700 Subject: Export of internal Abseil changes -- f8fe0f483378c7520d8f8bdfabe4b20de4d96c7e by Andy Soffer : Ensure that Invoke can support C++17 in the sense that noexcept is part of the type. PiperOrigin-RevId: 261730155 -- bf796ab71653a80498f9374bc8c5111d065c64ba by Abseil Team : Fix typo in static_assert message for copy/move constructible by replacing "by" with "be". PiperOrigin-RevId: 261713992 -- 8c7c17c40d03a322f304a2fd73ed34462dbf265a by Andy Soffer : Add absl::is_function drop-in replacement for std::is_function. Some standard libraries incorrectly implement std::is_function in a few corner cases. In particular, libstdc++ functions marked noexcept. The trick being used here is that function types decay to pointers. After excluding cases like is_class, etc, we can distinguish function types by testing for this decay. Many thanks to ericwf@ for essentially writing this CL. PiperOrigin-RevId: 261705008 -- c5adf42d0a132c2525d17a719329eab2ffe0aa94 by Abseil Team : Add microbenchmark for StrSplit that uses delimiter ByAnyChar. PiperOrigin-RevId: 261424010 -- 66a342f9381ec56be2fe3aa5b3193dd3538a9740 by Andy Soffer : CMake support for Abseil Random This change touches almost build-related files for CMake almost exclusively. The one minor exception is random/internal/salted_seed_seq.h. The default warnings configuration for one of our CI builds requests not having named but unused parameters. The change in this file cleans up that warning. PiperOrigin-RevId: 261192369 GitOrigin-RevId: f8fe0f483378c7520d8f8bdfabe4b20de4d96c7e Change-Id: I05f662baacfe78750651535aa658f61c2327bc44 --- absl/meta/type_traits.h | 17 +++++++++++++++++ absl/meta/type_traits_test.cc | 16 ++++++++++++++++ 2 files changed, 33 insertions(+) (limited to 'absl/meta') diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index c08e3754..927244e0 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -224,6 +224,23 @@ struct disjunction<> : std::false_type {}; template struct negation : std::integral_constant {}; +// is_function() +// +// Determines whether the passed type `T` is a function type. +// +// This metafunction is designed to be a drop-in replacement for the C++11 +// `std::is_function()` metafunction for platforms that have incomplete C++11 +// support (such as libstdc++ 4.x). +// +// This metafunction works because appending `const` to a type does nothing to +// function types and reference types (and forms a const-qualified type +// otherwise). +template +struct is_function + : std::integral_constant< + bool, !(std::is_reference::value || + std::is_const::type>::value)> {}; + // is_trivially_destructible() // // Determines whether the passed type `T` is trivially destructable. diff --git a/absl/meta/type_traits_test.cc b/absl/meta/type_traits_test.cc index 82b1be51..a7a9c5c9 100644 --- a/absl/meta/type_traits_test.cc +++ b/absl/meta/type_traits_test.cc @@ -385,6 +385,22 @@ class Base { #define ABSL_GCC_BUG_TRIVIALLY_CONSTRUCTIBLE_ON_ARRAY_OF_NONTRIVIAL 1 #endif +TEST(TypeTraitsTest, TestIsFunction) { + struct Callable { + void operator()() {} + }; + EXPECT_TRUE(absl::is_function::value); + EXPECT_TRUE(absl::is_function::value); + EXPECT_TRUE(absl::is_function::value); + EXPECT_TRUE(absl::is_function::value); + EXPECT_TRUE(absl::is_function::value); + + EXPECT_FALSE(absl::is_function::value); + EXPECT_FALSE(absl::is_function::value); + EXPECT_FALSE(absl::is_function::value); + EXPECT_FALSE(absl::is_function::value); +} + TEST(TypeTraitsTest, TestTrivialDestructor) { // Verify that arithmetic types and pointers have trivial destructors. EXPECT_TRUE(absl::is_trivially_destructible::value); -- cgit v1.2.3