llvm/unittests/ADT/FunctionRefTest.cpp

   1 //===- llvm/unittest/ADT/FunctionRefTest.cpp - function_ref 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 namespace {
  15
  16 // Ensure that there is a default constructor and we can test for a null
  17 // function_ref.
  18 TEST(FunctionRefTest, Null) {
  19   function_ref<int()> F;
  20   EXPECT_FALSE(F);
  21
  22   auto L = [] { return 1; };
  23   F = L;
  24   EXPECT_TRUE(F);
  25
  26   F = {};
  27   EXPECT_FALSE(F);
  28 }
  29
  30 // Ensure that copies of a function_ref copy the underlying state rather than
  31 // causing one function_ref to chain to the next.
  32 TEST(FunctionRefTest, Copy) {
  33   auto A = [] { return 1; };
  34   auto B = [] { return 2; };
  35   function_ref<int()> X = A;
  36   function_ref<int()> Y = X;
  37   X = B;
  38   EXPECT_EQ(1, Y());
  39 }
  40
  41 TEST(FunctionRefTest, BadCopy) {
  42   auto A = [] { return 1; };
  43   function_ref<int()> X;
  44   function_ref<int()> Y = A;
  45   function_ref<int()> Z = static_cast<const function_ref<int()> &&>(Y);
  46   X = Z;
  47   Y = nullptr;
  48   ASSERT_EQ(1, X());
  49 }
  50
  51 // Test that overloads on function_refs are resolved as expected.
  52 std::string returns(StringRef) { return "not a function"; }
  53 std::string returns(function_ref<double()> F) { return "number"; }
  54 std::string returns(function_ref<StringRef()> F) { return "string"; }
  55
  56 TEST(FunctionRefTest, SFINAE) {
  57   EXPECT_EQ("not a function", returns("boo!"));
  58   EXPECT_EQ("number", returns([] { return 42; }));
  59   EXPECT_EQ("string", returns([] { return "hello"; }));
  60 }
  61
  62 } // namespace