I have submitted patch for “–trace-symbol=symbol” (alias -y symbol) option.
This option provides names of all the link time modules which define and reference symbols requested by user. This helps to speed up application development by detecting references causing undefined symbols. It also helps in detecting symbols being resolved to wrong (unintended) definitions in case of applications containing multiple definitions for same symbols with different types, bindings.
Bugzilla - Bug - PR#28226
Patch for review: http://reviews.llvm.org/D21550