From cebee890793733b164f83f908764244b864511d7 Mon Sep 17 00:00:00 2001
From: Zhanlue Yang <jim19930609@gmail.com>
Date: Sat, 7 May 2022 10:32:29 +0800
Subject: [PATCH] [build] Warning Suppression PR #1: Turned on
 -Wno-ignored-attributes & Removed unused functions (#4916)

---
 cmake/TaichiCXXFlags.cmake                    | 18 ++++++++++
 .../backends/interop/vulkan_cpu_interop.cpp   |  1 -
 taichi/backends/vulkan/vulkan_program.cpp     |  4 +--
 taichi/backends/vulkan/vulkan_utils.cpp       | 36 -------------------
 4 files changed, 20 insertions(+), 39 deletions(-)
 delete mode 100644 taichi/backends/vulkan/vulkan_utils.cpp

diff --git a/cmake/TaichiCXXFlags.cmake b/cmake/TaichiCXXFlags.cmake
index 79fe36770b646..da3ff8432982a 100644
--- a/cmake/TaichiCXXFlags.cmake
+++ b/cmake/TaichiCXXFlags.cmake
@@ -46,7 +46,25 @@ else()
         message("Invalid compiler ${CMAKE_CXX_COMPILER_ID} detected.")
         message(FATAL_ERROR "clang and MSVC are the only supported compilers for Taichi compiler development. Consider using 'cmake -DCMAKE_CXX_COMPILER=clang' if you are on Linux.")
     endif()
+
+    # [Global] CXX compilation option to enable all warnings.
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall ")
+
+    # [Global] By default, CXX compiler will throw a warning if it decides to ignore an attribute, for example "[[ maybe unused ]]".
+    # However, this behaviour diverges across different compilers (GCC/CLANG), as well as different compiler versions.
+    # Therefore we disable such warnings for now.
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-ignored-attributes ")
+
+    # [Global] Clang warns if a C++ pointer's nullability wasn't marked explicitly (__nonnull, nullable, ...).
+    # Nullability seems to be a clang-specific feature, thus we disable this warning.
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nullability-completeness ")
+
+    # [Global] Disable warning for unused-private-field for convenience in development.
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unused-private-field ")
+
+    # [Global] By evaluating "constexpr", compiler throws a warning for functions known to be dead at compile time.
+    # However, some of these "constexpr" are debug flags and will be manually enabled upon debuging.
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unneeded-internal-declaration ")
 endif ()
 
 message("Building for processor ${CMAKE_SYSTEM_PROCESSOR}")
diff --git a/taichi/backends/interop/vulkan_cpu_interop.cpp b/taichi/backends/interop/vulkan_cpu_interop.cpp
index 11359dcc2b8bb..126d9eca7e256 100644
--- a/taichi/backends/interop/vulkan_cpu_interop.cpp
+++ b/taichi/backends/interop/vulkan_cpu_interop.cpp
@@ -22,7 +22,6 @@ void memcpy_cpu_to_vulkan_via_staging(DevicePtr dst,
   VulkanDevice *vk_dev = dynamic_cast<VulkanDevice *>(dst.device);
   CpuDevice *cpu_dev = dynamic_cast<CpuDevice *>(src.device);
 
-  DeviceAllocation dst_alloc(dst);
   DeviceAllocation src_alloc(src);
 
   CpuDevice::AllocInfo src_alloc_info = cpu_dev->get_alloc_info(src_alloc);
diff --git a/taichi/backends/vulkan/vulkan_program.cpp b/taichi/backends/vulkan/vulkan_program.cpp
index 81184bdd56722..63511189d99fb 100644
--- a/taichi/backends/vulkan/vulkan_program.cpp
+++ b/taichi/backends/vulkan/vulkan_program.cpp
@@ -71,8 +71,8 @@ FunctionType compile_to_executable(Kernel *kernel,
                                    VkRuntime *runtime,
                                    SNodeTreeManager *snode_tree_mgr) {
   auto handle = runtime->register_taichi_kernel(
-      std::move(run_codegen(kernel, runtime->get_ti_device(),
-                            snode_tree_mgr->get_compiled_structs())));
+      run_codegen(kernel, runtime->get_ti_device(),
+                  snode_tree_mgr->get_compiled_structs()));
   return [runtime, handle](RuntimeContext &ctx) {
     runtime->launch_kernel(handle, &ctx);
   };
diff --git a/taichi/backends/vulkan/vulkan_utils.cpp b/taichi/backends/vulkan/vulkan_utils.cpp
deleted file mode 100644
index e54133ce0757a..0000000000000
--- a/taichi/backends/vulkan/vulkan_utils.cpp
+++ /dev/null
@@ -1,36 +0,0 @@
-#include "taichi/backends/vulkan/vulkan_utils.h"
-
-#include <spirv-tools/libspirv.hpp>
-
-namespace taichi {
-namespace lang {
-namespace vulkan {
-namespace {
-
-std::vector<VkExtensionProperties> GetInstanceExtensionProperties() {
-  constexpr char *kNoLayerName = nullptr;
-  uint32_t count = 0;
-  vkEnumerateInstanceExtensionProperties(kNoLayerName, &count, nullptr);
-  std::vector<VkExtensionProperties> extensions(count);
-  vkEnumerateInstanceExtensionProperties(kNoLayerName, &count,
-                                         extensions.data());
-  return extensions;
-}
-
-std::vector<VkExtensionProperties> GetDeviceExtensionProperties(
-    VkPhysicalDevice physicalDevice) {
-  constexpr char *kNoLayerName = nullptr;
-  uint32_t count = 0;
-  vkEnumerateDeviceExtensionProperties(physicalDevice, kNoLayerName, &count,
-                                       nullptr);
-  std::vector<VkExtensionProperties> extensions(count);
-  vkEnumerateDeviceExtensionProperties(physicalDevice, kNoLayerName, &count,
-                                       extensions.data());
-  return extensions;
-}
-
-}  // namespace
-
-}  // namespace vulkan
-}  // namespace lang
-}  // namespace taichi