How is `FieldName`, which is a std::string, being passed as the third
argument to SetValue on line 1848 of TGParser.cpp, which is declared
as being an Init*? The nearly identical (FIXME) codepath in
ParseDeclaration immediately puts the string into a StringInit, which
makes sense, but how on earth is the std::string being passed in? This
is really freaking me out.
-- Sean Silva