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Tightened SFINAE for span<U> to span<T> conversions.

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This commit is contained in:
Neil MacIntosh
2016-06-12 18:28:19 -07:00
parent ba8ebef509
commit c94a66f468
2 changed files with 104 additions and 96 deletions
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tests/span_tests.cpp
+47 -62
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@@ -395,14 +395,14 @@ SUITE(span_tests)
{
auto get_an_array = []()->std::array<int, 4> { return{1, 2, 3, 4}; };
auto take_a_span = [](span<int> s) { (void)s; };
auto take_a_span = [](span<int> s) { static_cast<void>(s); };
// try to take a temporary std::array
take_a_span(get_an_array());
}
#endif
{
auto get_an_array = []() -> std::array<int, 4> { return { 1, 2, 3, 4 }; };
auto take_a_span = [](span<const int> s) { (void)s; };
auto take_a_span = [](span<const int> s) { static_cast<void>(s); };
// try to take a temporary std::array
take_a_span(get_an_array());
}
@@ -438,7 +438,7 @@ SUITE(span_tests)
{
auto get_an_array = []() -> const std::array<int, 4> { return {1, 2, 3, 4}; };
auto take_a_span = [](span<const int> s) { (void) s; };
auto take_a_span = [](span<const int> s) { static_cast<void>(s); };
// try to take a temporary std::array
take_a_span(get_an_array());
}
@@ -482,35 +482,35 @@ SUITE(span_tests)
{
#ifdef CONFIRM_COMPILATION_ERRORS
auto get_temp_vector = []() -> std::vector<int> { return {}; };
auto use_span = [](span<int> s) { (void) s; };
auto use_span = [](span<int> s) { static_cast<void>(s); };
use_span(get_temp_vector());
#endif
}
{
auto get_temp_vector = []() -> std::vector<int> { return{}; };
auto use_span = [](span<const int> s) { (void)s; };
auto use_span = [](span<const int> s) { static_cast<void>(s); };
use_span(get_temp_vector());
}
{
#ifdef CONFIRM_COMPILATION_ERRORS
auto get_temp_string = []() -> std::string { return{}; };
auto use_span = [](span<char> s) { (void)s; };
auto use_span = [](span<char> s) { static_cast<void>(s); };
use_span(get_temp_string());
#endif
}
{
auto get_temp_string = []() -> std::string { return {}; };
auto use_span = [](span<const char> s) { (void) s; };
auto use_span = [](span<const char> s) { static_cast<void>(s); };
use_span(get_temp_string());
}
{
#ifdef CONFIRM_COMPILATION_ERRORS
auto get_temp_vector = []() -> const std::vector<int> { return {}; };
auto use_span = [](span<const char> s) { (void) s; };
auto use_span = [](span<const char> s) { static_cast<void>(s); };
use_span(get_temp_vector());
#endif
}
@@ -518,7 +518,7 @@ SUITE(span_tests)
{
#ifdef CONFIRM_COMPILATION_ERRORS
auto get_temp_string = []() -> const std::string { return {}; };
auto use_span = [](span<const char> s) { (void) s; };
auto use_span = [](span<const char> s) { static_cast<void>(s); };
use_span(get_temp_string());
#endif
}
@@ -536,34 +536,34 @@ SUITE(span_tests)
{
span<DerivedClass> avd;
span<const DerivedClass> avcd = avd;
(void)avcd;
static_cast<void>(avcd);
}
{
#ifdef CONFIRM_COMPILATION_ERRORS
span<DerivedClass> avd;
span<BaseClass> avb = avd;
(void) avb;
static_cast<void>(avb);
#endif
}
{
span<int> s;
span<unsigned int> s2 = s;
(void)s2;
static_cast<void>(s2);
}
{
span<int> s;
span<const unsigned int> s2 = s;
(void)s2;
static_cast<void>(s2);
}
{
#ifdef CONFIRM_COMPILATION_ERRORS
span<int> s;
span<short> s2 = s;
(void)s2;
static_cast<void>(s2);
#endif
}
}
@@ -984,72 +984,59 @@ SUITE(span_tests)
}
}
#if 0
TEST(fixed_size_conversions)
{
int arr[] = {1, 2, 3, 4};
// converting to an span from an equal size array is ok
span<int, 4> av4 = arr;
CHECK(av4.length() == 4);
span<int, 4> s4 = arr;
CHECK(s4.length() == 4);
// converting to dynamic_range a_v is always ok
// converting to dynamic_range is always ok
{
span<int, dynamic_range> av = av4;
(void) av;
}
{
span<int, dynamic_range> av = arr;
(void) av;
span<int> s = s4;
CHECK(s.length() == s4.length());
static_cast<void>(s);
}
// initialization or assignment to static span that REDUCES size is NOT ok
#ifdef CONFIRM_COMPILATION_ERRORS
{
span<int, 2> av2 = arr;
span<int, 2> s = arr;
}
{
span<int, 2> av2 = av4;
span<int, 2> s2 = s4;
static_cast<void>(s2);
}
#endif
// even when done dynamically
{
span<int, dynamic_range> av = arr;
span<int, 2> av2 = av;
(void) av2;
}
#ifdef CONFIRM_COMPILATION_ERRORS
{
span<int, dynamic_range> av = arr;
span<int, 2, 1> av2 = av.as_span(dim<2>(), dim<2>());
}
#endif
{
span<int, dynamic_range> av = arr;
span<int, 2, 1> av2 = as_span(av, dim<>(2), dim<>(2));
auto workaround_macro = [&]() { return av2[{1, 0}] == 2; };
CHECK(workaround_macro());
span<int> s = arr;
auto f = [&]() {
span<int, 2> s2 = s;
static_cast<void>(s2);
};
CHECK_THROW(f(), fail_fast);
}
// but doing so explicitly is ok
// you can convert statically
{
span<int, 2> av2 = {arr, 2};
(void) av2;
span<int, 2> s2 = {arr, 2};
static_cast<void>(s2);
}
{
span<int, 1> av2 = av4.first<1>();
(void) av2;
span<int, 1> s1 = s4.first<1>();
static_cast<void>(s1);
}
// ...or dynamically
{
// NB: implicit conversion to span<int,2> from span<int,dynamic_range>
span<int, 1> av2 = av4.first(1);
(void) av2;
// NB: implicit conversion to span<int,1> from span<int>
span<int, 1> s1 = s4.first(1);
static_cast<void>(s1);
}
// initialization or assignment to static span that requires size INCREASE is not ok.
@@ -1057,31 +1044,29 @@ SUITE(span_tests)
#ifdef CONFIRM_COMPILATION_ERRORS
{
span<int, 4> av4 = arr2;
span<int, 4> s3 = arr2;
}
{
span<int, 2> av2 = arr2;
span<int, 4> av4 = av2;
span<int, 2> s2 = arr2;
span<int, 4> s4a = s2;
}
#endif
{
auto f = [&]() {
span<int, 4> av9 = {arr2, 2};
(void) av9;
};
span<int, 4> s4 = {arr2, 2};
static_cast<void>(s4);
};
CHECK_THROW(f(), fail_fast);
}
// this should fail - we are trying to assign a small dynamic a_v to a fixed_size larger one
span<int, dynamic_range> av = arr2;
// this should fail - we are trying to assign a small dynamic span to a fixed_size larger one
span<int> av = arr2;
auto f = [&]() {
span<int, 4> av2 = av;
(void) av2;
span<int, 4> s4 = av;
static_cast<void>(s4);
};
CHECK_THROW(f(), fail_fast);
}
#endif
}
int main(int, const char* []) { return UnitTest::RunAllTests(); }