renderer_vulkan/wrapper: Add Vulakn wrapper and a span helper

The intention behind a Vulkan wrapper is to drop Vulkan-Hpp.

The issues with Vulkan-Hpp are:
- Regular breaks of the API.
- Copy constructors that do the same as the aggregates (fixed recently)
- External dynamic dispatch that is hard to remove
- Alias KHR handles with non-KHR handles making it impossible to use
smart handles on Vulkan 1.0 instances with extensions that were included
on Vulkan 1.1.
- Dynamic dispatchers silently change size depending on preprocessor
definitions. Different files will have different dispatch definitions,
generating all kinds of hard to debug memory issues.

In other words, Vulkan-Hpp is not "production ready" for our needs and
this wrapper aims to replace it without losing RAII and exception
safety.

src/video_core/CMakeLists.txt

@@ -210,6 +210,7 @@ if (ENABLE_VULKAN)
         renderer_vulkan/vk_texture_cache.h
         renderer_vulkan/vk_update_descriptor.cpp
         renderer_vulkan/vk_update_descriptor.h
+        renderer_vulkan/wrapper.h
     )
 
     target_include_directories(video_core PRIVATE sirit ../../externals/Vulkan-Headers/include)

src/video_core/renderer_vulkan/wrapper.h

@@ -0,0 +1,83 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <exception>
+#include <iterator>
+#include <limits>
+#include <memory>
+#include <optional>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#define VK_NO_PROTOTYPES
+#include <vulkan/vulkan.h>
+
+#include "common/common_types.h"
+
+namespace Vulkan::vk {
+
+/**
+ * Span for Vulkan arrays.
+ * Based on std::span but optimized for array access instead of iterators.
+ * Size returns uint32_t instead of size_t to ease interaction with Vulkan functions.
+ */
+template <typename T>
+class Span {
+public:
+    /// Construct an empty span.
+    constexpr Span() noexcept = default;
+
+    /// Construct a span from a single element.
+    constexpr Span(const T& value) noexcept : ptr{&value}, num{1} {}
+
+    /// Construct a span from a range.
+    template <typename Range>
+    // requires std::data(const Range&)
+    // requires std::size(const Range&)
+    constexpr Span(const Range& range) : ptr{std::data(range)}, num{std::size(range)} {}
+
+    /// Construct a span from a pointer and a size.
+    /// This is inteded for subranges.
+    constexpr Span(const T* ptr, std::size_t num) noexcept : ptr{ptr}, num{num} {}
+
+    /// Returns the data pointer by the span.
+    constexpr const T* data() const noexcept {
+        return ptr;
+    }
+
+    /// Returns the number of elements in the span.
+    constexpr u32 size() const noexcept {
+        return static_cast<u32>(num);
+    }
+
+    /// Returns true when the span is empty.
+    constexpr bool empty() const noexcept {
+        return num == 0;
+    }
+
+    /// Returns a reference to the element in the passed index.
+    /// @pre: index < size()
+    constexpr const T& operator[](std::size_t index) const noexcept {
+        return ptr[index];
+    }
+
+    /// Returns an iterator to the beginning of the span.
+    constexpr const T* begin() const noexcept {
+        return ptr;
+    }
+
+    /// Returns an iterator to the end of the span.
+    constexpr const T* end() const noexcept {
+        return ptr + num;
+    }
+
+private:
+    const T* ptr = nullptr;
+    std::size_t num = 0;
+};
+
+} // namespace Vulkan::vk