llvm/unittests/ADT/TypeTraitsTest.cpp

   1 //===- TypeTraitsTest.cpp - type_traits unit tests ------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/ADT/STLExtras.h"
  10 #include "gtest/gtest.h"
  11
  12 using namespace llvm;
  13
  14 //===----------------------------------------------------------------------===//
  15 // function_traits
  16 //===----------------------------------------------------------------------===//
  17
  18 namespace {
  19 /// Check a callable type of the form `bool(const int &)`.
  20 template <typename CallableT> struct CheckFunctionTraits {
  21   static_assert(
  22       std::is_same_v<typename function_traits<CallableT>::result_t, bool>,
  23       "expected result_t to be `bool`");
  24   static_assert(
  25       std::is_same_v<typename function_traits<CallableT>::template arg_t<0>,
  26                      const int &>,
  27       "expected arg_t<0> to be `const int &`");
  28   static_assert(function_traits<CallableT>::num_args == 1,
  29                 "expected num_args to be 1");
  30 };
  31
  32 /// Test function pointers.
  33 using FuncType = bool (*)(const int &);
  34 struct CheckFunctionPointer : CheckFunctionTraits<FuncType> {};
  35
  36 /// Test method pointers.
  37 struct Foo {
  38   bool func(const int &v);
  39 };
  40 struct CheckMethodPointer : CheckFunctionTraits<decltype(&Foo::func)> {};
  41
  42 /// Test lambda references.
  43 LLVM_ATTRIBUTE_UNUSED auto lambdaFunc = [](const int &v) -> bool {
  44   return true;
  45 };
  46 struct CheckLambda : CheckFunctionTraits<decltype(lambdaFunc)> {};
  47
  48 } // end anonymous namespace
  49
  50 //===----------------------------------------------------------------------===//
  51 // is_detected
  52 //===----------------------------------------------------------------------===//
  53
  54 namespace {
  55 struct HasFooMethod {
  56   void foo() {}
  57 };
  58 struct NoFooMethod {};
  59
  60 template <class T> using has_foo_method_t = decltype(std::declval<T &>().foo());
  61
  62 static_assert(is_detected<has_foo_method_t, HasFooMethod>::value,
  63               "expected foo method to be detected");
  64 static_assert(!is_detected<has_foo_method_t, NoFooMethod>::value,
  65               "expected no foo method to be detected");
  66 } // end anonymous namespace