With the CLANG38 toolset (clang version 13.0.0) MdePkg fails to build in RELEASE mode because Status is only used by an assert.

edk2/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c:141:15: 
error: variable 'Status' set but not used 
[-Werror,-Wunused-but-set-variable]
  EFI_STATUS  Status;
              ^
edk2/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c:347:15: 
error: variable 'Status' set but not used 
[-Werror,-Wunused-but-set-variable]
  EFI_STATUS  Status;
              ^
edk2/MdePkg/Library/UefiMemoryAllocationLib/MemoryAllocationLib.c:818:15: 
error: variable 'Status' set but not used 
[-Werror,-Wunused-but-set-variable]
  EFI_STATUS  Status;

-- 
Rebecca Cran