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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This is a "No Compile Test" suite.
// http://dev.chromium.org/developers/testing/no-compile-tests
#include "base/containers/span.h"
#include <array>
#include <set>
#include <string>
#include <string_view>
#include <type_traits>
#include <vector>
namespace base {
class Base {
};
class Derived : Base {
};
// A default constructed span must have an extent of 0 or dynamic_extent.
void DefaultSpanWithNonZeroStaticExtentDisallowed() {
span<int, 1u> span; // expected-error {{no matching constructor for initialization of 'span<int, 1U>'}}
}
// A span with static extent constructed from an array must match the size of
// the array.
void SpanFromArrayWithNonMatchingStaticExtentDisallowed() {
int array[] = {1, 2, 3};
span<int, 1u> span(array); // expected-error {{no matching constructor for initialization of 'span<int, 1U>'}}
}
// A span with static extent constructed from another span must match the
// extent.
void SpanFromOtherSpanWithMismatchingExtentDisallowed() {
std::array<int, 3> array = {1, 2, 3};
span<int, 3u> span3(array);
span<int, 4u> span4(span3); // expected-error {{no matching constructor for initialization of 'span<int, 4U>'}}
}
// Converting a dynamic span to a static span should not be allowed.
void DynamicSpanToStaticSpanDisallowed() {
span<int> dynamic_span;
span<int, 3u> static_span = dynamic_span; // expected-error-re {{no viable conversion from 'span<[...], (default) dynamic_extent aka {{.*}}>' to 'span<[...], 3>'}}
}
// Internally, this is represented as a pointer to pointers to Derived. An
// implicit conversion to a pointer to pointers to Base must not be allowed.
// If it were allowed, then something like this would be possible:
// Cat** cats = GetCats();
// Animals** animals = cats;
// animals[0] = new Dog(); // Uh oh!
void DerivedToBaseConversionDisallowed() {
span<Derived*> derived_span;
span<Base*> base_span(derived_span); // expected-error {{no matching constructor for initialization of 'span<Base *>'}}
}
// Similarly, converting a span<int*> to span<const int*> requires internally
// converting T** to const T**. This is also disallowed, as it would allow code
// to violate the contract of const.
void PtrToConstPtrConversionDisallowed() {
span<int*> non_const_span;
span<const int*> const_span(non_const_span); // expected-error {{no matching constructor for initialization of 'span<const int *>'}}
}
// A const container should not be convertible to a mutable span.
void ConstContainerToMutableConversionDisallowed() {
const std::vector<int> v = {1, 2, 3};
span<int> span1(v); // expected-error {{no matching constructor for initialization of 'span<int>'}}
span<int, 2u> span2({1, 2}); // expected-error {{no matching constructor for initialization of 'span<int, 2U>'}}
}
// A dynamic const container should not be implicitly convertible to a static span.
void ImplicitConversionFromDynamicConstContainerToStaticSpanDisallowed() {
const std::vector<int> v = {1, 2, 3};
span<const int, 3u> span = v; // expected-error {{no viable conversion from 'const std::vector<int>' to 'span<const int, 3U>'}}
}
// A dynamic mutable container should not be implicitly convertible to a static span.
void ImplicitConversionFromDynamicMutableContainerToStaticSpanDisallowed() {
std::vector<int> v = {1, 2, 3};
span<int, 3u> span = v; // expected-error {{no viable conversion from 'std::vector<int>' to 'span<int, 3U>'}}
}
// Fixed-extent span construction from an initializer list is explicit.
void InitializerListConstructionIsExplicit() {
span<const int, 3u> s = {{1, 2, 3}}; // expected-error {{chosen constructor is explicit in copy-initialization}}
}
// A std::set() should not satisfy the requirements for conversion to a span.
void StdSetConversionDisallowed() {
std::set<int> set;
span<int> span1(set.begin(), 0u); // expected-error {{no matching constructor for initialization of 'span<int>'}}
span<int> span2(set.begin(), set.end()); // expected-error {{no matching constructor for initialization of 'span<int>'}}
span<int> span3(set); // expected-error {{no matching constructor for initialization of 'span<int>'}}
}
// Static views of spans with static extent must not exceed the size.
void OutOfRangeSubviewsOnStaticSpan() {
std::array<int, 3> array = {1, 2, 3};
span<int, 3u> span(array);
auto first = span.first<4>(); // expected-error@*:* {{no matching member function for call to 'first'}}
auto last = span.last<4>(); // expected-error@*:* {{no matching member function for call to 'last'}}
auto subspan1 = span.subspan<4>(); // expected-error@*:* {{no matching member function for call to 'subspan'}}
auto subspan2 = span.subspan<0, 4>(); // expected-error@*:* {{no matching member function for call to 'subspan'}}
}
// Discarding the return value of empty() is not allowed.
void DiscardReturnOfEmptyDisallowed() {
span<int> s;
s.empty(); // expected-error {{ignoring return value of function}}
}
// Getting elements of an empty span with static extent is not allowed.
void RefsOnEmptyStaticSpanDisallowed() {
span<int, 0u> s;
s.front(); // expected-error@*:* {{invalid reference to function 'front': constraints not satisfied}}
s.back(); // expected-error@*:* {{invalid reference to function 'back': constraints not satisfied}}
}
// Calling swap on spans with different extents is not allowed.
void SwapWithDifferentExtentsDisallowed() {
std::array<int, 3> array = {1, 2, 3};
span<int, 3u> static_span(array);
span<int> dynamic_span(array);
std::swap(static_span, dynamic_span); // expected-error {{no matching function for call to 'swap'}}
}
// as_writable_bytes should not be possible for a const container.
void AsWritableBytesWithConstContainerDisallowed() {
const std::vector<int> v = {1, 2, 3};
span<uint8_t> bytes = as_writable_bytes(span(v)); // expected-error {{no matching function for call to 'as_writable_bytes'}}
}
void ConstVectorDeducesAsConstSpan() {
const std::vector<int> v;
span<int> s = span(v); // expected-error-re@*:* {{no viable conversion from 'span<{{.*}}, [...]>' to 'span<int, [...]>'}}
}
// A span can only be constructed from a range rvalue when the element type is
// read-only or the range is a borrowed range.
void SpanFromNonConstRvalueRange() {
std::array<bool, 3> arr = {true, false, true};
[[maybe_unused]] auto a = span(std::move(arr)); // expected-error {{no matching conversion}}
std::string str = "ok";
[[maybe_unused]] auto b = span(std::move(str)); // expected-error {{no matching conversion}}
std::u16string str16 = u"ok";
[[maybe_unused]] auto c = span(std::move(str16)); // expected-error {{no matching conversion}}
std::vector<int> vec = {1, 2, 3, 4, 5};
[[maybe_unused]] auto d = span(std::move(vec)); // expected-error {{no matching conversion}}
}
void Dangling() {
// `std::array` destroyed at the end of the full expression.
[[maybe_unused]] auto a = span<const int>(std::to_array({1, 2, 3})); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto b = span<const int, 3>(std::to_array({1, 2, 3})); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
// Range destroyed at the end of the full expression.
[[maybe_unused]] auto c = span<const int>(std::vector<int>({1, 2, 3})); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto d = span<const int, 3>(std::vector<int>({1, 2, 3})); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
// Here the `std::string` is an lvalue, but the `std::vector`s that copy its
// data aren't.
std::string str = "123";
[[maybe_unused]] auto e =
span<const char>(std::vector<char>(str.begin(), str.end())); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto f =
span<const char, 3>(std::vector<char>(str.begin(), str.end())); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
// `std::string_view`'s safety depends on the life of the referred-to buffer.
// Here the underlying data is destroyed before the end of the full
// expression.
[[maybe_unused]] auto g =
span<const char>(std::string_view(std::string("123"))); // expected-error {{object backing the pointer will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto h =
span<const char, 3>(std::string_view(std::string("123"))); // expected-error {{object backing the pointer will be destroyed at the end of the full-expression}}
// TODO(https://github.com/llvm/llvm-project/issues/111768) Detect dangling
// usage sufficient to enable this testcase.
#if 0
[[maybe_unused]] auto i = as_byte_span(std::string_view(std::string("123"))); // expected-error {{object backing the pointer will be destroyed at the end of the full-expression}}
#endif
// Spans must not outlast a referred-to C-style array. It's tricky to create
// an object of C-style array type (not an initializer list) that is destroyed
// before the end of the full expression, so instead test the case where the
// referred-to array goes out of scope before the referring span.
[] {
int arr[3] = {1, 2, 3};
return span<int>(arr); // expected-error-re {{address of stack memory associated with local variable {{.*}}returned}}
}();
[] {
int arr[3] = {1, 2, 3};
return span<int, 3>(arr); // expected-error-re {{address of stack memory associated with local variable {{.*}}returned}}
}();
// TODO(https://github.com/llvm/llvm-project/issues/99685) Detect dangling
// usage sufficient to enable this testcase.
#if 0
[]() -> std::optional<span<int>> {
int arr[3] = {1, 2, 3};
return span<int>(arr); // expected-error-re {{address of stack memory associated with local variable {{.*}}returned}}
}();
#endif
// span's `std::array` constructor takes lvalue refs, so to test the non-const
// `element_type` case, use the same technique as above.
[] {
std::array arr{1, 2, 3};
return span<int>(arr); // expected-error-re + {{address of stack memory associated with local variable {{.*}}returned}}
}();
[] {
std::array arr{1, 2, 3};
return span<int, 3>(arr); // expected-error-re + {{address of stack memory associated with local variable {{.*}}returned}}
}();
}
void NotSizeTSize() {
std::vector<int> vector = {1, 2, 3};
// Using distinct enum types causes distinct span template instantiations, so
// we get assertion failures below where we expect.
enum Length1 { kSize1 = -1 };
enum Length2 { kSize2 = -1 };
span s(vector.data(), kSize2); // expected-error@*:* {{no matching function for call to 'strict_cast'}}
}
void BadConstConversionsWithStdSpan() {
int kData[] = {10, 11, 12};
{
span<const int, 3u> fixed_base_span(kData);
std::span<int, 3u> s(fixed_base_span); // expected-error {{no matching constructor}}
}
{
std::span<const int, 3u> fixed_std_span(kData);
span<int, 3u> s(fixed_std_span); // expected-error {{no matching constructor}}
}
}
void FromVolatileArrayDisallowed() {
static volatile int array[] = {1, 2, 3};
span<int> s(array); // expected-error {{no matching constructor for initialization of 'span<int>'}}
}
void FixedSizeCopyTooSmall() {
const int src[] = {1, 2, 3};
int dst[2];
span(dst).copy_from(span(src)); // expected-error@*:* {{no matching member function}}
span(dst).copy_from(src); // expected-error@*:* {{no matching member function}}
span(dst).copy_prefix_from(src); // expected-error@*:* {{no matching member function}}
}
void FixedSizeCopyFromNonSpan() {
int dst[2];
// The copy_from() template overload is not selected.
span(dst).copy_from(5); // expected-error@*:* {{no matching member function for call to 'copy_from'}}
}
void FixedSizeSplitAtOutOfBounds() {
const int arr[] = {1, 2, 3};
span(arr).split_at<4u>(); // expected-error@*:* {{no matching member function for call to 'split_at'}}
}
void DerefEmpty() {
constexpr span<int, 0> kEmptySpan;
[[maybe_unused]] int i = kEmptySpan[0]; // expected-error {{no viable overloaded operator[] for type 'const span<int, 0>'}}
}
void FromRefLifetimeBoundErrorForIntLiteral() {
// Testing that `LIFETIME_BOUND` works as intended.
[[maybe_unused]] auto wont_work = span_from_ref<const int>(123); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto wont_work2 = byte_span_from_ref<const int>(123); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
}
void FromRefLifetimeBoundErrorForTemporaryStringObject() {
// Testing that `LIFETIME_BOUND` works as intended.
[[maybe_unused]] auto wont_work =
span_from_ref<const std::string>("temporary string"); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto wont_work2 =
as_byte_span(std::string("temporary string")); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
}
void InitializerListLifetime() {
// `std::initializer_list` destroyed at the end of the full expression.
[[maybe_unused]] auto wont_work = span<const int>({1, 2}); // expected-error-re {{array backing local initializer list {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto wont_work2 = span<const int, 3>({1, 2}); // expected-error-re {{array backing local initializer list {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto wont_work3 = as_byte_span({1, 2}); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
}
void FromCStringThatIsntStaticLifetime() {
[[maybe_unused]] auto wont_work = span_from_cstring({'a', 'b', '\0'}); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
[[maybe_unused]] auto wont_work2 = byte_span_from_cstring({'a', 'b', '\0'}); // expected-error-re {{temporary whose address is used as value of local variable {{.*}}will be destroyed at the end of the full-expression}}
}
void CompareFixedSizeMismatch() {
const int arr[] = {1, 2, 3};
const int arr2[] = {1, 2, 3, 4};
(void)(span(arr) == arr2); // expected-error@*:* {{invalid operands to binary expression}}
(void)(span(arr) == span(arr2)); // expected-error@*:* {{invalid operands to binary expression}}
}
void CompareNotComparable() {
struct NoEq { int i; };
static_assert(!std::equality_comparable<NoEq>);
const NoEq arr[] = {{1}, {2}, {3}};
(void)(span(arr) == arr); // expected-error@*:* {{invalid operands to binary expression}}
(void)(span(arr) == span(arr)); // expected-error@*:* {{invalid operands to binary expression}}
struct SelfEq {
constexpr bool operator==(SelfEq s) const { return i == s.i; }
int i;
};
static_assert(std::equality_comparable<SelfEq>);
static_assert(!std::equality_comparable_with<SelfEq, int>);
const SelfEq self_arr[] = {{1}, {2}, {3}};
const int int_arr[] = {1, 2, 3};
(void)(span(self_arr) == int_arr); // expected-error@*:* {{invalid operands to binary expression}}
(void)(span(self_arr) == span(int_arr)); // expected-error@*:* {{invalid operands to binary expression}}
// Span's operator== works on `const T` and thus won't be able to use the
// non-const operator here. We get this from equality_comparable which also
// requires it.
struct NonConstEq {
constexpr bool operator==(NonConstEq s) { return i == s.i; }
int i;
};
const NonConstEq non_arr[] = {{1}, {2}, {3}};
(void)(span(non_arr) == non_arr); // expected-error@*:* {{invalid operands to binary expression}}
(void)(span(non_arr) == span(non_arr)); // expected-error@*:* {{invalid operands to binary expression}}
}
void ByteConversionsFromNonUnique() {
// Test that byte span constructions from a type the does not meet
// `std::has_unique_object_representations_v<>` fail by default.
struct S {
float f = 0;
};
static_assert(!std::has_unique_object_representations_v<S>);
// `as_[writable_](bytes,chars)()`
S arr[] = {{1}, {2}, {3}};
span sp(arr);
as_bytes(sp); // expected-error {{no matching function for call}}
as_writable_bytes(sp); // expected-error {{no matching function for call}}
as_chars(sp); // expected-error {{no matching function for call}}
as_writable_chars(sp); // expected-error {{no matching function for call}}
// `byte_span_from_ref()`
const S const_obj;
S obj;
// Read-only
byte_span_from_ref(const_obj); // expected-error {{no matching function for call}}
// Writable
byte_span_from_ref(obj); // expected-error {{no matching function for call}}
// `as_[writable_]byte_span()`
std::vector<S> vec;
// Non-borrowed range
as_byte_span(std::vector<S>()); // expected-error {{no matching function for call}}
// Borrowed range
as_byte_span(vec); // expected-error {{no matching function for call}}
as_writable_byte_span(vec); // expected-error {{no matching function for call}}
// Array
as_byte_span(arr); // expected-error {{no matching function for call}}
as_writable_byte_span(arr); // expected-error {{no matching function for call}}
}
void SpanFromCstrings() {
static const char with_null[] = { 'a', 'b', '\0' };
span_from_cstring(with_null);
// Can't call span_from_cstring and friends with a non-null-terminated char
// array.
static const char no_null[] = { 'a', 'b' };
span_from_cstring(no_null); // expected-error@*:* {{no matching function for call to 'span_from_cstring'}}
span_with_nul_from_cstring(no_null); // expected-error@*:* {{no matching function for call to 'span_with_nul_from_cstring'}}
byte_span_from_cstring(no_null); // expected-error@*:* {{no matching function for call to 'byte_span_from_cstring'}}
byte_span_with_nul_from_cstring(no_null); // expected-error@*:* {{no matching function for call to 'byte_span_with_nul_from_cstring'}}
}
} // namespace base
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