UE 5.8 Mac build fails with -Werror,-Wunreachable-code in VRM4ULoader

[MarksonChen]

Describe the bug

Building VRM4U on Mac with UE 5.8 fails in VRM4ULoader because Clang treats unreachable-code warnings as errors.

The build command was:

"$UE_ROOT/Engine/Build/BatchFiles/Mac/Build.sh" \
  "${PROJECT_NAME}Editor" \
  Mac \
  Development \
  -Project="$PROJECT" \
  -WaitMutex \
  -NoHotReloadFromIDE \
  -Verbose

Errors are:

VrmConvertModel.cpp:2292:8: error: code will never be executed [-Werror,-Wunreachable-code]
VrmConvertModel.cpp:2159:7: error: code will never be executed [-Werror,-Wunreachable-code]

VrmConvertPose.cpp:1092:31: error: loop will run at most once (loop increment never executed) [-Werror,-Wunreachable-code-loop-increment]

VrmConvertModel_Description.cpp:2269:8: error: code will never be executed [-Werror,-Wunreachable-code]
VrmConvertModel_Description.cpp:2136:7: error: code will never be executed [-Werror,-Wunreachable-code]

The workaround is simple. Adding Clang diagnostic suppression for these warnings in those files allows the plugin to build:

#if defined(__clang__)
#pragma clang diagnostic ignored "-Wunreachable-code"
#pragma clang diagnostic ignored "-Wunreachable-code-loop-increment"
#endif

UnrealEngine Version:

• Unreal Engine: 5.8
• Platform: macOS
• Architecture: arm64
• Compiler: Apple Clang 21.x / Xcode
• Project type: C++/project build
• Plugin: VRM4U latest UE5.8-compatible release (20260622)