Error: invalid new-expression of abstract class type ‘llvm::AVRAsmBackend’

Beginners
1

In the directory llvm/lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp
I’m getting the following error which I don’t have any clue of.
Even though I haven’t edited anytihng of AVRAsmBackend.cpp
while hovering over the AVRAsmBackend

class llvm::AVRAsmBackend

Utilities for manipulating generated AVR machine code.

object of abstract class type "llvm::AVRAsmBackend" is not allowed:C/C++(322)

AVRAsmBackend.cpp(489, 14): pure virtual function "llvm::MCAsmBackend::getFixupKindLog2Size" has no overrider

and while building it I get the following error.

llvm/lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp:489:57: error: invalid new-expression of abstract class type ‘llvm::AVRAsmBackend’
   return new AVRAsmBackend(STI.getTargetTriple().getOS());