Why are incorrect attributes attached to redeclarations

This note diagnostic is what raised concern for me. I don't know if it should be on the last 'correct' declaration instead of an incorrect one. Anyway like I said - we don't need to worry about it in this patch.

_Originally posted by @elizabethandrews in https://github.com/intel/llvm/pull/5535#r827156451_

Looks like incorrect attributes are attached to redeclaration instead of skipping. Investigate why. Should we be dropping attribute instead of returning nullptr in merge logic?

AST dump of invalid declarations show attribute attached.