This allows it to accurately measure tokens, so that we get:
t.cpp:8:13: error: unknown type name 'X'
static foo::X P;
~~~~~^
instead of the woefully inferior:
t.cpp:8:13: error: unknown type name 'X'
static foo::X P;
~~~~ ^
Most of this is just plumbing to push the reference around.
llvm-svn: 69099