a1857e2ce3
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().
120 lines
3.9 KiB
C++
120 lines
3.9 KiB
C++
// -*- C++ -*-
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//===------------------------------ span ---------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===---------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
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// <span>
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// template<class OtherElementType, size_t OtherExtent>
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// constexpr span(const span<OtherElementType, OtherExtent>& s) noexcept;
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//
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// Remarks: This constructor shall not participate in overload resolution unless:
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// Extent == dynamic_extent || Extent == OtherExtent is true, and
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// OtherElementType(*)[] is convertible to ElementType(*)[].
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#include <span>
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#include <cassert>
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#include <string>
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#include "test_macros.h"
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void checkCV()
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{
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std::span< int> sp;
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// std::span<const int> csp;
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std::span< volatile int> vsp;
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// std::span<const volatile int> cvsp;
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std::span< int, 0> sp0;
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// std::span<const int, 0> csp0;
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std::span< volatile int, 0> vsp0;
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// std::span<const volatile int, 0> cvsp0;
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// dynamic -> dynamic
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{
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std::span<const int> s1{ sp}; // a span<const int> pointing at int.
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std::span< volatile int> s2{ sp}; // a span< volatile int> pointing at int.
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std::span<const volatile int> s3{ sp}; // a span<const volatile int> pointing at int.
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std::span<const volatile int> s4{ vsp}; // a span<const volatile int> pointing at volatile int.
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assert(s1.size() + s2.size() + s3.size() + s4.size() == 0);
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}
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// static -> static
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{
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std::span<const int, 0> s1{ sp0}; // a span<const int> pointing at int.
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std::span< volatile int, 0> s2{ sp0}; // a span< volatile int> pointing at int.
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std::span<const volatile int, 0> s3{ sp0}; // a span<const volatile int> pointing at int.
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std::span<const volatile int, 0> s4{ vsp0}; // a span<const volatile int> pointing at volatile int.
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assert(s1.size() + s2.size() + s3.size() + s4.size() == 0);
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}
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// static -> dynamic
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{
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std::span<const int> s1{ sp0}; // a span<const int> pointing at int.
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std::span< volatile int> s2{ sp0}; // a span< volatile int> pointing at int.
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std::span<const volatile int> s3{ sp0}; // a span<const volatile int> pointing at int.
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std::span<const volatile int> s4{ vsp0}; // a span<const volatile int> pointing at volatile int.
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assert(s1.size() + s2.size() + s3.size() + s4.size() == 0);
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}
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// dynamic -> static (not allowed)
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}
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template <typename T>
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constexpr bool testConstexprSpan()
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{
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std::span<T> s0{};
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std::span<T, 0> s1{};
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std::span<T> s2(s1); // static -> dynamic
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ASSERT_NOEXCEPT(std::span<T> {s0});
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ASSERT_NOEXCEPT(std::span<T, 0>{s1});
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ASSERT_NOEXCEPT(std::span<T> {s1});
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return
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s1.data() == nullptr && s1.size() == 0
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&& s2.data() == nullptr && s2.size() == 0;
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}
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template <typename T>
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void testRuntimeSpan()
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{
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std::span<T> s0{};
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std::span<T, 0> s1{};
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std::span<T> s2(s1); // static -> dynamic
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ASSERT_NOEXCEPT(std::span<T> {s0});
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ASSERT_NOEXCEPT(std::span<T, 0>{s1});
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ASSERT_NOEXCEPT(std::span<T> {s1});
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assert(s1.data() == nullptr && s1.size() == 0);
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assert(s2.data() == nullptr && s2.size() == 0);
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}
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struct A{};
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int main(int, char**)
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{
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static_assert(testConstexprSpan<int>(), "");
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static_assert(testConstexprSpan<long>(), "");
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static_assert(testConstexprSpan<double>(), "");
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static_assert(testConstexprSpan<A>(), "");
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testRuntimeSpan<int>();
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testRuntimeSpan<long>();
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testRuntimeSpan<double>();
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testRuntimeSpan<std::string>();
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testRuntimeSpan<A>();
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checkCV();
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return 0;
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}
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