[libcxx][test] Fix span tests.
span.cons/container.pass.cpp
N4842 22.7.3.2 [span.cons]/13 constrains span's range constructor
for ranges::contiguous_range (among other criteria).
24.4.5 [range.refinements]/2 says that contiguous_range requires data(),
and (via contiguous_range, random_access_range, bidirectional_range,
forward_range, input_range, range) it also requires begin() and end()
(see 24.4.2 [range.range]/1).
Therefore, IsAContainer needs to provide begin() and end().
(Detected by MSVC's concept-constrained implementation.)
span.cons/stdarray.pass.cpp
This test uses std::array, so it must include <array>.
<span> isn't guaranteed to drag in <array>.
(Detected by MSVC's implementation which uses a forward declaration to
avoid dragging in <array>, for increased compiler throughput.)
span.objectrep/as_bytes.pass.cpp
span.objectrep/as_writable_bytes.pass.cpp
Testing `sp.extent == std::dynamic_extent` triggers MSVC warning
C4127 "conditional expression is constant". Using `if constexpr` is a
simple way to avoid this without disrupting anyone else (as span
requires C++20 mode).
span.tuple/get.pass.cpp
22.7.3.2 [span.cons]/4.3: "Preconditions: If extent is not equal to
dynamic_extent, then count is equal to extent."
These lines were triggering undefined behavior (detected by assertions
in MSVC's implementation).
I changed the count arguments in the first two chunks, followed by
changing the span extents, in order to preserve the test's coverage
and follow the existing pattern.
span.cons/span.pass.cpp
22.7.3.2 [span.cons]/18.1 constrains span's converting constructor with
"Extent == dynamic_extent || Extent == OtherExtent is true".
This means that converting from dynamic extent to static extent is
not allowed. (Other constructors tested elsewhere, like
span(It first, size_type count), can be used to write such code.)
As this is the test for the converting constructor, I have:
* Removed the "dynamic -> static" case from checkCV(), which is
comprehensive.
* Changed the initialization of std::span<T, 0> s1{}; in
testConstexprSpan() and testRuntimeSpan(), because s1 is used below.
* Removed ASSERT_NOEXCEPT(std::span<T, 0>{s0}); from those functions,
as they are otherwise comprehensive.
* Deleted testConversionSpan() entirely. Note that this could never
compile (it had a bool return type, but forgot to say `return`). And it
couldn't have provided useful coverage, as the /18.2 constraint
"OtherElementType(*)[] is convertible to ElementType(*)[]"
permits only cv-qualifications, which are already tested by checkCV().
diff --git a/libcxx/test/std/containers/views/span.cons/span.pass.cpp b/libcxx/test/std/containers/views/span.cons/span.pass.cpp
index 62f8b9d..4ec80ef 100644
--- a/libcxx/test/std/containers/views/span.cons/span.pass.cpp
+++ b/libcxx/test/std/containers/views/span.cons/span.pass.cpp
@@ -63,14 +63,7 @@
assert(s1.size() + s2.size() + s3.size() + s4.size() == 0);
}
-// dynamic -> static
- {
- std::span<const int, 0> s1{ sp}; // a span<const int> pointing at int.
- std::span< volatile int, 0> s2{ sp}; // a span< volatile int> pointing at int.
- std::span<const volatile int, 0> s3{ sp}; // a span<const volatile int> pointing at int.
- std::span<const volatile int, 0> s4{ vsp}; // a span<const volatile int> pointing at volatile int.
- assert(s1.size() + s2.size() + s3.size() + s4.size() == 0);
- }
+// dynamic -> static (not allowed)
}
@@ -78,12 +71,11 @@
constexpr bool testConstexprSpan()
{
std::span<T> s0{};
- std::span<T, 0> s1(s0); // dynamic -> static
+ std::span<T, 0> s1{};
std::span<T> s2(s1); // static -> dynamic
ASSERT_NOEXCEPT(std::span<T> {s0});
ASSERT_NOEXCEPT(std::span<T, 0>{s1});
ASSERT_NOEXCEPT(std::span<T> {s1});
- ASSERT_NOEXCEPT(std::span<T, 0>{s0});
return
s1.data() == nullptr && s1.size() == 0
@@ -95,30 +87,17 @@
void testRuntimeSpan()
{
std::span<T> s0{};
- std::span<T, 0> s1(s0); // dynamic -> static
+ std::span<T, 0> s1{};
std::span<T> s2(s1); // static -> dynamic
ASSERT_NOEXCEPT(std::span<T> {s0});
ASSERT_NOEXCEPT(std::span<T, 0>{s1});
ASSERT_NOEXCEPT(std::span<T> {s1});
- ASSERT_NOEXCEPT(std::span<T, 0>{s0});
assert(s1.data() == nullptr && s1.size() == 0);
assert(s2.data() == nullptr && s2.size() == 0);
}
-template <typename Dest, typename Src>
-bool testConversionSpan()
-{
- static_assert(std::is_convertible_v<Src(*)[], Dest(*)[]>, "Bad input types to 'testConversionSpan");
- std::span<Src> s0d{};
- std::span<Src> s0s{};
- std::span<Dest, 0> s1(s0d); // dynamic -> static
- std::span<Dest> s2(s0s); // static -> dynamic
- s1.data() == nullptr && s1.size() == 0
- && s2.data() == nullptr && s2.size() == 0;
-}
-
struct A{};
int main(int, char**)
@@ -134,9 +113,6 @@
testRuntimeSpan<std::string>();
testRuntimeSpan<A>();
-// TODO: Add some conversion tests here that aren't "X --> const X"
-// assert((testConversionSpan<unsigned char, char>()));
-
checkCV();
return 0;