General: Make use of std::nullopt where applicable

Allows some implementations to avoid completely zeroing out the internal
buffer of the optional, and instead only set the validity byte within
the structure.

This also makes it consistent how we return empty optionals.

7 files changed, 29 insertions, 32 deletions

diff --git a/src/video_core/engines/maxwell_3d.cpp b/src/video_core/engines/maxwell_3d.cpp
index 33854445f..57ebc785f 100644
--- a/src/video_core/engines/maxwell_3d.cpp
+++ b/src/video_core/engines/maxwell_3d.cpp
@@ -597,7 +597,7 @@ std::optional<u64> Maxwell3D::GetQueryResult() {
         // Deferred.
         rasterizer->Query(regs.query.QueryAddress(), VideoCore::QueryType::SamplesPassed,
                           system.GPU().GetTicks());
-        return {};
+        return std::nullopt;
     default:
         LOG_DEBUG(HW_GPU, "Unimplemented query select type {}",
                   static_cast<u32>(regs.query.query_get.select.Value()));
diff --git a/src/video_core/macro/macro.cpp b/src/video_core/macro/macro.cpp
index a50e7b4e0..cd21a2112 100644
--- a/src/video_core/macro/macro.cpp
+++ b/src/video_core/macro/macro.cpp
@@ -36,7 +36,7 @@ void MacroEngine::Execute(Engines::Maxwell3D& maxwell3d, u32 method,
         }
     } else {
         // Macro not compiled, check if it's uploaded and if so, compile it
-        std::optional<u32> mid_method = std::nullopt;
+        std::optional<u32> mid_method;
         const auto macro_code = uploaded_macro_code.find(method);
         if (macro_code == uploaded_macro_code.end()) {
             for (const auto& [method_base, code] : uploaded_macro_code) {
diff --git a/src/video_core/memory_manager.cpp b/src/video_core/memory_manager.cpp
index 16b2aaa27..02cf53d15 100644
--- a/src/video_core/memory_manager.cpp
+++ b/src/video_core/memory_manager.cpp
@@ -58,7 +58,7 @@ void MemoryManager::Unmap(GPUVAddr gpu_addr, std::size_t size) {
 std::optional<GPUVAddr> MemoryManager::AllocateFixed(GPUVAddr gpu_addr, std::size_t size) {
     for (u64 offset{}; offset < size; offset += page_size) {
         if (!GetPageEntry(gpu_addr + offset).IsUnmapped()) {
-            return {};
+            return std::nullopt;
         }
     }
 
@@ -135,13 +135,13 @@ std::optional<GPUVAddr> MemoryManager::FindFreeRange(std::size_t size, std::size
         }
     }
 
-    return {};
+    return std::nullopt;
 }
 
 std::optional<VAddr> MemoryManager::GpuToCpuAddress(GPUVAddr gpu_addr) const {
     const auto page_entry{GetPageEntry(gpu_addr)};
     if (!page_entry.IsValid()) {
-        return {};
+        return std::nullopt;
     }
 
     return page_entry.ToAddress() + (gpu_addr & page_mask);
diff --git a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
index ce3a65122..bbb8fb095 100644
--- a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
@@ -813,7 +813,7 @@ private:
         const u8 location = static_cast<u8>(static_cast<u32>(index) * 4 + element);
         const auto it = transform_feedback.find(location);
         if (it == transform_feedback.end()) {
-            return {};
+            return std::nullopt;
         }
         return it->second.components;
     }
@@ -1295,21 +1295,21 @@ private:
             switch (element) {
             case 0:
                 UNIMPLEMENTED();
-                return {};
+                return std::nullopt;
             case 1:
                 if (stage == ShaderType::Vertex && !device.HasVertexViewportLayer()) {
-                    return {};
+                    return std::nullopt;
                 }
                 return {{"gl_Layer", Type::Int}};
             case 2:
                 if (stage == ShaderType::Vertex && !device.HasVertexViewportLayer()) {
-                    return {};
+                    return std::nullopt;
                 }
                 return {{"gl_ViewportIndex", Type::Int}};
             case 3:
                 return {{"gl_PointSize", Type::Float}};
             }
-            return {};
+            return std::nullopt;
         case Attribute::Index::FrontColor:
             return {{"gl_FrontColor"s + GetSwizzle(element), Type::Float}};
         case Attribute::Index::FrontSecondaryColor:
@@ -1332,7 +1332,7 @@ private:
                          Type::Float}};
             }
             UNIMPLEMENTED_MSG("Unhandled output attribute: {}", static_cast<u32>(attribute));
-            return {};
+            return std::nullopt;
         }
     }
 
diff --git a/src/video_core/shader/ast.h b/src/video_core/shader/ast.h
index cca13bcde..8e5a22ab3 100644
--- a/src/video_core/shader/ast.h
+++ b/src/video_core/shader/ast.h
@@ -199,55 +199,48 @@ public:
     }
 
     std::optional<u32> GetGotoLabel() const {
-        auto inner = std::get_if<ASTGoto>(&data);
-        if (inner) {
+        if (const auto* inner = std::get_if<ASTGoto>(&data)) {
             return {inner->label};
         }
-        return {};
+        return std::nullopt;
     }
 
     Expr GetGotoCondition() const {
-        auto inner = std::get_if<ASTGoto>(&data);
-        if (inner) {
+        if (const auto* inner = std::get_if<ASTGoto>(&data)) {
             return inner->condition;
         }
         return nullptr;
     }
 
     void MarkLabelUnused() {
-        auto inner = std::get_if<ASTLabel>(&data);
-        if (inner) {
+        if (auto* inner = std::get_if<ASTLabel>(&data)) {
             inner->unused = true;
         }
     }
 
     bool IsLabelUnused() const {
-        auto inner = std::get_if<ASTLabel>(&data);
-        if (inner) {
+        if (const auto* inner = std::get_if<ASTLabel>(&data)) {
             return inner->unused;
         }
         return true;
     }
 
     std::optional<u32> GetLabelIndex() const {
-        auto inner = std::get_if<ASTLabel>(&data);
-        if (inner) {
+        if (const auto* inner = std::get_if<ASTLabel>(&data)) {
             return {inner->index};
         }
-        return {};
+        return std::nullopt;
     }
 
     Expr GetIfCondition() const {
-        auto inner = std::get_if<ASTIfThen>(&data);
-        if (inner) {
+        if (const auto* inner = std::get_if<ASTIfThen>(&data)) {
             return inner->condition;
         }
         return nullptr;
     }
 
     void SetGotoCondition(Expr new_condition) {
-        auto inner = std::get_if<ASTGoto>(&data);
-        if (inner) {
+        if (auto* inner = std::get_if<ASTGoto>(&data)) {
             inner->condition = std::move(new_condition);
         }
     }
diff --git a/src/video_core/shader/track.cpp b/src/video_core/shader/track.cpp
index d5ed81442..6be3ea92b 100644
--- a/src/video_core/shader/track.cpp
+++ b/src/video_core/shader/track.cpp
@@ -205,12 +205,12 @@ std::optional<u32> ShaderIR::TrackImmediate(Node tracked, const NodeBlock& code,
     const auto result = TrackRegister(&std::get<GprNode>(*tracked), code, cursor - 1);
     const auto& found = result.first;
     if (!found) {
-        return {};
+        return std::nullopt;
     }
     if (const auto immediate = std::get_if<ImmediateNode>(&*found)) {
         return immediate->GetValue();
     }
-    return {};
+    return std::nullopt;
 }
 
 std::pair<Node, s64> ShaderIR::TrackRegister(const GprNode* tracked, const NodeBlock& code,
diff --git a/src/video_core/texture_cache/surface_base.cpp b/src/video_core/texture_cache/surface_base.cpp
index dfcf36e0b..b44c09d71 100644
--- a/src/video_core/texture_cache/surface_base.cpp
+++ b/src/video_core/texture_cache/surface_base.cpp
@@ -115,20 +115,24 @@ std::optional<std::pair<u32, u32>> SurfaceBaseImpl::GetLayerMipmap(
     if (gpu_addr == candidate_gpu_addr) {
         return {{0, 0}};
     }
+
     if (candidate_gpu_addr < gpu_addr) {
-        return {};
+        return std::nullopt;
     }
+
     const auto relative_address{static_cast<GPUVAddr>(candidate_gpu_addr - gpu_addr)};
     const auto layer{static_cast<u32>(relative_address / layer_size)};
     if (layer >= params.depth) {
-        return {};
+        return std::nullopt;
     }
+
     const GPUVAddr mipmap_address = relative_address - layer_size * layer;
     const auto mipmap_it =
         Common::BinaryFind(mipmap_offsets.begin(), mipmap_offsets.end(), mipmap_address);
     if (mipmap_it == mipmap_offsets.end()) {
-        return {};
+        return std::nullopt;
     }
+
     const auto level{static_cast<u32>(std::distance(mipmap_offsets.begin(), mipmap_it))};
     return std::make_pair(layer, level);
 }