Would it lessen the pain to know that this doesn't just afflict TCL? Say, if your vendor (who is charging you $30k in licensing) forgot to close an 'extern "C"

Would it lessen the pain to know that this doesn't just afflict TCL? Say, if your vendor (who is charging you $30k in licensing) forgot to close an 'extern "C" {' in one of their system headers? Something that could have been caught by a simple "include all the headers (twice) and compile" unit test. And this in a supposed "real-time" OS.