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8258853: Support separate function declaration and definition with ENABLE_IF-based SFINAE

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Add ENABLE_IF_SDEFN, unit tests

Reviewed-by: jrose, eosterlund
This commit is contained in:
Kim Barrett 2021-01-22 14:44:35 +00:00
parent 154e1d637e
commit a97f3c18d5
2 changed files with 97 additions and 12 deletions
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56
test/hotspot/gtest/metaprogramming/test_enableIf.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2017, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -23,11 +23,13 @@
*/
#include "precompiled.hpp"
#include "memory/allocation.hpp"
#include "memory/allStatic.hpp"
#include "metaprogramming/enableIf.hpp"
#include "utilities/debug.hpp"
#include <type_traits>
#include "unittest.hpp"
class EnableIfTest {
class EnableIfTest: AllStatic {
class A: AllStatic {
public:
template <bool condition>
@ -42,3 +44,51 @@ class EnableIfTest {
static const bool A_test_false_is_long = sizeof(A::test<false>()) == sizeof(long);
STATIC_ASSERT(A_test_false_is_long);
};
template<typename T, ENABLE_IF(std::is_integral<T>::value)>
static T sub1(T x) { return x - 1; }
TEST(TestEnableIf, one_decl_and_def) {
EXPECT_EQ(15, sub1(16));
}
template<typename T, ENABLE_IF(std::is_integral<T>::value)>
static T sub2(T x);
template<typename T, ENABLE_IF_SDEFN(std::is_integral<T>::value)>
T sub2(T x) { return x - 2; }
TEST(TestEnableIf, separate_decl_and_def) {
EXPECT_EQ(14, sub2(16));
}
template<typename T>
struct TestEnableIfNested {
template<typename U, ENABLE_IF(std::is_integral<U>::value)>
static U sub1(U x);
};
template<typename T>
template<typename U, ENABLE_IF_SDEFN(std::is_integral<U>::value)>
U TestEnableIfNested<T>::sub1(U x) { return x - 1; }
TEST(TestEnableIf, nested_separate_decl_and_def) {
EXPECT_EQ(15, TestEnableIfNested<void>::sub1(16));
}
// Demonstrate workaround for non-dependent condition.
template<typename T>
struct TestEnableIfNonDependent {
// Dependent is used to make the ENABLE_IF condition dependent on
// the type parameters for this function.
template<typename Dependent = T, ENABLE_IF(std::is_same<int, Dependent>::value)>
static T value() { return T{}; }
static int instantiate() { return 5; }
};
TEST(TestEnableIf, non_dependent) {
EXPECT_EQ(int{}, TestEnableIfNonDependent<int>::value());
// This fails to compile if the ENABLE_IF for value() directly uses
// T rather than indirectly via Dependent.
EXPECT_EQ(5, TestEnableIfNonDependent<void>::instantiate());
}