How does Angular compiler process multiple template reference variables with the same name

I want to start contributing to angular, I have an idea for a feature, I want the template compiler to issue a warning if a template contains two template variables of the same name. I think I managed to get close to the source files responsible: https://github.com/angular/angular/blob/master/packages/compiler/src/view_compiler/view_compiler.ts but couldn't quite find the spot, understandably. Is there anyone here who can guide me ?