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14ca007916
Also adds missing includes in some files, these were previously only transivitely included through mozilla/TypeTraits.h. Differential Revision: https://phabricator.services.mozilla.com/D68561 --HG-- extra : moz-landing-system : lando
104 lines
4.3 KiB
C++
104 lines
4.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include <type_traits>
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#include "mozilla/CompactPair.h"
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using mozilla::CompactPair;
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using mozilla::MakeCompactPair;
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// Sizes aren't part of the guaranteed CompactPair interface, but we want to
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// verify our attempts at compactness through EBO are moderately functional,
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// *somewhere*.
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#define INSTANTIATE(T1, T2, name, size) \
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CompactPair<T1, T2> name##_1(T1(0), T2(0)); \
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static_assert(sizeof(name##_1.first()) > 0, \
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"first method should work on CompactPair<" #T1 ", " #T2 ">"); \
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\
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static_assert(sizeof(name##_1.second()) > 0, \
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"second method should work on CompactPair<" #T1 ", " #T2 ">"); \
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\
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static_assert(sizeof(name##_1) == (size), \
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"CompactPair<" #T1 ", " #T2 "> has an unexpected size"); \
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\
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CompactPair<T2, T1> name##_2(T2(0), T1(0)); \
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static_assert(sizeof(name##_2.first()) > 0, \
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"first method should work on CompactPair<" #T2 ", " #T1 ">"); \
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\
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static_assert(sizeof(name##_2.second()) > 0, \
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"second method should work on CompactPair<" #T2 ", " #T1 ">"); \
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\
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static_assert(sizeof(name##_2) == (size), \
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"CompactPair<" #T2 ", " #T1 "> has an unexpected size");
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INSTANTIATE(int, int, prim1, 2 * sizeof(int));
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INSTANTIATE(int, long, prim2, 2 * sizeof(long));
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struct EmptyClass {
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explicit EmptyClass(int) {}
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};
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struct NonEmpty {
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char mC;
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explicit NonEmpty(int) : mC('\0') {}
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};
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INSTANTIATE(int, EmptyClass, both1, sizeof(int));
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INSTANTIATE(int, NonEmpty, both2, 2 * sizeof(int));
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INSTANTIATE(EmptyClass, NonEmpty, both3, 1);
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struct A {
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char dummy;
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explicit A(int) : dummy('\0') {}
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};
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struct B : A {
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explicit B(int aI) : A(aI) {}
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};
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INSTANTIATE(A, A, class1, 2);
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INSTANTIATE(A, B, class2, 2);
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INSTANTIATE(A, EmptyClass, class3, 1);
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struct OtherEmpty : EmptyClass {
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explicit OtherEmpty(int aI) : EmptyClass(aI) {}
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};
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// C++11 requires distinct objects of the same type, within the same "most
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// derived object", to have different addresses. CompactPair allocates its
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// elements as two bases, a base and a member, or two members. If the two
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// elements have non-zero size or are unrelated, no big deal. But if they're
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// both empty and related, something -- possibly both -- must be inflated.
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// Exactly which are inflated depends which CompactPairHelper specialization is
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// used. We could potentially assert something about size for this case, but
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// whatever we could assert would be very finicky. Plus it's two empty classes
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// -- hardly likely. So don't bother trying to assert anything about this case.
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// INSTANTIATE(EmptyClass, OtherEmpty, class4, ...something finicky...);
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int main() {
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A a(0);
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B b(0);
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const A constA(0);
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const B constB(0);
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// Check that MakeCompactPair generates CompactPair objects of the correct
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// types.
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static_assert(
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std::is_same_v<decltype(MakeCompactPair(A(0), B(0))), CompactPair<A, B>>,
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"MakeCompactPair should strip rvalue references");
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static_assert(
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std::is_same_v<decltype(MakeCompactPair(a, b)), CompactPair<A, B>>,
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"MakeCompactPair should strip lvalue references");
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static_assert(std::is_same_v<decltype(MakeCompactPair(constA, constB)),
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CompactPair<A, B>>,
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"MakeCompactPair should strip CV-qualifiers");
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// Check that copy assignment and move assignment work.
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a = constA;
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a = A(0);
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return 0;
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}
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