Casting pointers from one type to another does change the value of the pointer in some cases. Therefore, casting a span that contains pointers of one type to a span that contains pointers of another type, is not generally safe. In practice, this issue mainly comes up when dealing with classes that have a vtable. There are some special cases that are still allowed. For example, adding const to the pointer does not change the address. Also, casting to a void pointer is fine. In cases where implicit conversion is disabled, but one is sure that the cast is valid, an explicit call of `span.cast<NewType>()` can be used.
173 lines
5.3 KiB
C++
173 lines
5.3 KiB
C++
/* Apache License, Version 2.0 */
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#include "BLI_float3.hh"
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#include "BLI_memory_utils.hh"
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#include "BLI_strict_flags.h"
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#include "testing/testing.h"
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namespace blender::tests {
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namespace {
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struct MyValue {
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static inline int alive = 0;
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MyValue()
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{
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if (alive == 15) {
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throw std::exception();
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}
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alive++;
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}
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MyValue(const MyValue &UNUSED(other))
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{
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if (alive == 15) {
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throw std::exception();
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}
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alive++;
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}
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~MyValue()
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{
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alive--;
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}
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};
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} // namespace
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TEST(memory_utils, DefaultConstructN_ActuallyCallsConstructor)
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{
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constexpr int amount = 10;
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TypedBuffer<MyValue, amount> buffer;
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EXPECT_EQ(MyValue::alive, 0);
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default_construct_n(buffer.ptr(), amount);
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EXPECT_EQ(MyValue::alive, amount);
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destruct_n(buffer.ptr(), amount);
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EXPECT_EQ(MyValue::alive, 0);
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}
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TEST(memory_utils, DefaultConstructN_StrongExceptionSafety)
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{
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constexpr int amount = 20;
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TypedBuffer<MyValue, amount> buffer;
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EXPECT_EQ(MyValue::alive, 0);
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EXPECT_THROW(default_construct_n(buffer.ptr(), amount), std::exception);
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EXPECT_EQ(MyValue::alive, 0);
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}
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TEST(memory_utils, UninitializedCopyN_ActuallyCopies)
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{
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constexpr int amount = 5;
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TypedBuffer<MyValue, amount> buffer1;
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TypedBuffer<MyValue, amount> buffer2;
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EXPECT_EQ(MyValue::alive, 0);
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default_construct_n(buffer1.ptr(), amount);
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EXPECT_EQ(MyValue::alive, amount);
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uninitialized_copy_n(buffer1.ptr(), amount, buffer2.ptr());
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EXPECT_EQ(MyValue::alive, 2 * amount);
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destruct_n(buffer1.ptr(), amount);
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EXPECT_EQ(MyValue::alive, amount);
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destruct_n(buffer2.ptr(), amount);
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EXPECT_EQ(MyValue::alive, 0);
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}
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TEST(memory_utils, UninitializedCopyN_StrongExceptionSafety)
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{
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constexpr int amount = 10;
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TypedBuffer<MyValue, amount> buffer1;
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TypedBuffer<MyValue, amount> buffer2;
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EXPECT_EQ(MyValue::alive, 0);
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default_construct_n(buffer1.ptr(), amount);
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EXPECT_EQ(MyValue::alive, amount);
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EXPECT_THROW(uninitialized_copy_n(buffer1.ptr(), amount, buffer2.ptr()), std::exception);
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EXPECT_EQ(MyValue::alive, amount);
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destruct_n(buffer1.ptr(), amount);
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EXPECT_EQ(MyValue::alive, 0);
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}
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TEST(memory_utils, UninitializedFillN_ActuallyCopies)
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{
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constexpr int amount = 10;
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TypedBuffer<MyValue, amount> buffer;
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EXPECT_EQ(MyValue::alive, 0);
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{
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MyValue value;
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EXPECT_EQ(MyValue::alive, 1);
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uninitialized_fill_n(buffer.ptr(), amount, value);
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EXPECT_EQ(MyValue::alive, 1 + amount);
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destruct_n(buffer.ptr(), amount);
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EXPECT_EQ(MyValue::alive, 1);
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}
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EXPECT_EQ(MyValue::alive, 0);
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}
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TEST(memory_utils, UninitializedFillN_StrongExceptionSafety)
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{
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constexpr int amount = 20;
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TypedBuffer<MyValue, amount> buffer;
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EXPECT_EQ(MyValue::alive, 0);
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{
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MyValue value;
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EXPECT_EQ(MyValue::alive, 1);
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EXPECT_THROW(uninitialized_fill_n(buffer.ptr(), amount, value), std::exception);
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EXPECT_EQ(MyValue::alive, 1);
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}
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EXPECT_EQ(MyValue::alive, 0);
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}
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class TestBaseClass {
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virtual void mymethod(){};
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};
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class TestChildClass : public TestBaseClass {
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void mymethod() override
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{
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}
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};
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static_assert(is_convertible_pointer_v<int *, int *>);
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static_assert(is_convertible_pointer_v<int *, const int *>);
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static_assert(is_convertible_pointer_v<int *, int *const>);
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static_assert(is_convertible_pointer_v<int *, const int *const>);
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static_assert(!is_convertible_pointer_v<const int *, int *>);
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static_assert(!is_convertible_pointer_v<int, int *>);
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static_assert(!is_convertible_pointer_v<int *, int>);
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static_assert(is_convertible_pointer_v<TestBaseClass *, const TestBaseClass *>);
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static_assert(!is_convertible_pointer_v<const TestBaseClass *, TestBaseClass *>);
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static_assert(is_convertible_pointer_v<TestChildClass *, TestBaseClass *>);
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static_assert(!is_convertible_pointer_v<TestBaseClass *, TestChildClass *>);
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static_assert(is_convertible_pointer_v<const TestChildClass *, const TestBaseClass *>);
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static_assert(!is_convertible_pointer_v<TestBaseClass, const TestChildClass *>);
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static_assert(!is_convertible_pointer_v<float3, float *>);
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static_assert(!is_convertible_pointer_v<float *, float3>);
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static_assert(!is_convertible_pointer_v<int **, int *>);
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static_assert(!is_convertible_pointer_v<int *, int **>);
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static_assert(is_convertible_pointer_v<int **, int **>);
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static_assert(is_convertible_pointer_v<const int **, const int **>);
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static_assert(!is_convertible_pointer_v<const int **, int **>);
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static_assert(!is_convertible_pointer_v<int *const *, int **>);
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static_assert(!is_convertible_pointer_v<int *const *const, int **>);
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static_assert(is_convertible_pointer_v<int **, int **const>);
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static_assert(is_convertible_pointer_v<int **, int *const *>);
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static_assert(is_convertible_pointer_v<int **, int const *const *>);
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static_assert(is_span_convertible_pointer_v<int *, int *>);
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static_assert(is_span_convertible_pointer_v<int *, const int *>);
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static_assert(!is_span_convertible_pointer_v<const int *, int *>);
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static_assert(is_span_convertible_pointer_v<const int *, const int *>);
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static_assert(is_span_convertible_pointer_v<const int *, const void *>);
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static_assert(!is_span_convertible_pointer_v<const int *, void *>);
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static_assert(is_span_convertible_pointer_v<int *, void *>);
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static_assert(is_span_convertible_pointer_v<int *, const void *>);
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static_assert(!is_span_convertible_pointer_v<TestBaseClass *, TestChildClass *>);
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static_assert(!is_span_convertible_pointer_v<TestChildClass *, TestBaseClass *>);
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} // namespace blender::tests
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