text: //===- unittests/ErrorOrTest.cpp - ErrorOr.h tests ------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/Support/ErrorOr.h"
  #include "llvm/Support/Errc.h"
  #include "gtest/gtest.h"
  #include <memory>
  
  using namespace llvm;
  
  namespace {
  
  ErrorOr<int> t1() {return 1;}
  ErrorOr<int> t2() { return errc::invalid_argument; }
  
  TEST(ErrorOr, SimpleValue) {
    ErrorOr<int> a = t1();
    // FIXME: This is probably a bug in gtest. EXPECT_TRUE should expand to
    // include the !! to make it friendly to explicit bool operators.
    EXPECT_TRUE(!!a);
    EXPECT_EQ(1, *a);
  
    ErrorOr<int> b = a;
    EXPECT_EQ(1, *b);
  
    a = t2();
    EXPECT_FALSE(a);
    EXPECT_EQ(a.getError(), errc::invalid_argument);
  #ifdef EXPECT_DEBUG_DEATH
    EXPECT_DEBUG_DEATH(*a, "Cannot get value when an error exists");
  #endif
  }
  
  ErrorOr<std::unique_ptr<int> > t3() {
    return std::unique_ptr<int>(new int(3));
  }
  
  TEST(ErrorOr, Types) {
    int x;
    ErrorOr<int&> a(x);
    *a = 42;
    EXPECT_EQ(42, x);
  
    // Move only types.
    EXPECT_EQ(3, **t3());
  }
  
  struct B {};
  struct D : B {};
  
  TEST(ErrorOr, Covariant) {
    ErrorOr<B*> b(ErrorOr<D*>(nullptr));
    b = ErrorOr<D*>(nullptr);
  
    ErrorOr<std::unique_ptr<B> > b1(ErrorOr<std::unique_ptr<D> >(nullptr));
    b1 = ErrorOr<std::unique_ptr<D> >(nullptr);
  
    ErrorOr<std::unique_ptr<int>> b2(ErrorOr<int *>(nullptr));
    ErrorOr<int *> b3(nullptr);
    ErrorOr<std::unique_ptr<int>> b4(b3);
  }
  
  // ErrorOr<int*> x(nullptr);
  // ErrorOr<std::unique_ptr<int>> y = x; // invalid conversion
  static_assert(
      !std::is_convertible<const ErrorOr<int *> &,
                           ErrorOr<std::unique_ptr<int>>>::value,
      "do not invoke explicit ctors in implicit conversion from lvalue");
  
  // ErrorOr<std::unique_ptr<int>> y = ErrorOr<int*>(nullptr); // invalid
  //                                                           // conversion
  static_assert(
      !std::is_convertible<ErrorOr<int *> &&,
                           ErrorOr<std::unique_ptr<int>>>::value,
      "do not invoke explicit ctors in implicit conversion from rvalue");
  
  // ErrorOr<int*> x(nullptr);
  // ErrorOr<std::unique_ptr<int>> y;
  // y = x; // invalid conversion
  static_assert(!std::is_assignable<ErrorOr<std::unique_ptr<int>>,
                                    const ErrorOr<int *> &>::value,
                "do not invoke explicit ctors in assignment");
  
  // ErrorOr<std::unique_ptr<int>> x;
  // x = ErrorOr<int*>(nullptr); // invalid conversion
  static_assert(!std::is_assignable<ErrorOr<std::unique_ptr<int>>,
                                    ErrorOr<int *> &&>::value,
                "do not invoke explicit ctors in assignment");
  } // end anon namespace
  